PROTHANE FRONT BUMPSTOP WRITEUP

[slcpunk74]

So I know that I am among a few that are doing this but I thought I would get this up so we can all build ideas.

You need to make a cap for the prothanes so that the stock bump does not kill it. I opted to do the cap out of 2.5"x2.5"x.180 welded to the top of a 2" piece of 1.5"tube. The 1.5" tube fits snugg inside the prothane with no mods.
Here is the cap

http://i35.photobucket.com/albums/d158/troopdiggin87/DSC00985.jpg

I also made a base so that the bump would not be free. Some say that it being free is ok but I just figured why not. One thing to note is that after welding the base on my coil bucket I now have to unbolt my trac bar to get my coils out.

Here is the base that is also a 1.5" tube.

http://i35.photobucket.com/albums/d158/troopdiggin87/DSC00982.jpg

Now just paint your junk and install the coils with the prothane loose in them and when the coil is on you can slide the prothane onto the base.

http://i35.photobucket.com/albums/d158/troopdiggin87/DSC00986.jpg

I have not tested these and I do not know how much they compress. I would highly recomend thinking about how long of a bumpstop you need and if anything make it bigger then you expect to need. Keep in mind your stock bumpstop will compress aswell as the prothanes. I bought the 10.5" prothanes but ended up using about 6.5".

Link to where I got mine. http://www.jegs.com/p/Prothane/762170/10002/-1

I hope to have a review by tomorrow and maybe a video too.:party:
Have fun guys
Chadwick

[XJEEPER]

Goatman indicated that with a 12" travel shock, with 6" of up/down travel, he's runnning a 2.5" airgap. My measurements are nearly identical.

Had a similar thought about keeping them centered on the base plate instead of letting them float in the coil, only my plan is to use a 1.5" OD piece of tube, with the top capped and a welded in bolt protruding from the bottom, secured with a nut below the spring baseplate. This way they can simply unbolt, if the coil needs to come off.

I didn't get mine installed in time, so we'll see how yours work today.......see you at Sand Mtn.

[crazyjim]

Have you thought about drilling a hole in the top plate there, so the air can escape when it compresses?

[xjjeeper19]

My only worry about this is: If the Prothanes compress enough to make the two pieces of tubing at both ends hit each other you might have a problem. I think I read somewhere (goatman or cracker) said they compress quite a bit, I'd just be worried about the tubes hitting each other before it really compresses enough to slow the suspension down.

[slcpunk74]

My only worry about this is: If the Prothanes compress enough to make the two pieces of tubing at both ends hit each other you might have a problem. I think I read somewhere (goatman or cracker) said they compress quite a bit, I'd just be worried about the tubes hitting each other before it really compresses enough to slow the suspension down.
There is a bit of room between them(like 3"+). Im not really worried.

[slcpunk74]

Have you thought about drilling a hole in the top plate there, so the air can escape when it compresses?
The air can escape out the bottom of the stock coil bucket.

[slcpunk74]

So I treid them out today and wow they work great! Very progressive and not harsh at all. I have hit two small jumps on these and my rear poly setup and they perform very good. I also have to add that my FOA's work very well. No video yet because my camera was being a douche.

[GrimmJeeper]

i also have concerns about the 2 pieces of tubing hitting eachother.

and on a side note, do you really need to have each of your threads start in ALL CAPS? stop yelling man we're all friends here ;)

[dakineJ]

So I treid them out today and wow they work great! Very progressive and not harsh at all. I have hit two small jumps on these and my rear poly setup and they perform very good. I also have to add that my FOA's work very well. No video yet because my camera was being a douche.

Glad to hear their working good. Which FOA's do you have?

[slcpunk74]

i also have concerns about the 2 pieces of tubing hitting eachother.

and on a side note, do you really need to have each of your threads start in ALL CAPS? stop yelling man we're all friends here ;)
I guess if I make them all look like every other thread good tech could fade away. Didnt mean to piss you off there. If nobody wants me posting I will stop but I am only trying to help and I dont think knocking on me is very productive.

[AppleValleySlim]

Looks good dude!

I also had the same concern about the tubes hitting each other, but I have hydro bumps, so they would compress if/when the bump tubes hit.

I don't think anybodies knockin ya, It's just a little friendly ribbing.


~C!~

[slcpunk74]

Glad to hear their working good. Which FOA's do you have?
2.5x10 up front
2.0x16 out back

[slcpunk74]

Goatman indicated that with a 12" travel shock, with 6" of up/down travel, he's runnning a 2.5" airgap. My measurements are nearly identical.

Had a similar thought about keeping them centered on the base plate instead of letting them float in the coil, only my plan is to use a 1.5" OD piece of tube, with the top capped and a welded in bolt protruding from the bottom, secured with a nut below the spring baseplate. This way they can simply unbolt, if the coil needs to come off.

I didn't get mine installed in time, so we'll see how yours work today.......see you at Sand Mtn.

Make sure you add pics and what not. I started this thread in the hopes that it could be a general prothane tech article. Hey plus most people dont seam to like the way I did it so maybe they will like your way better.:cheers:

[JeepFreak21]

How do you figure out the compressed height of these things so that you're not wasting travel?
Thanks,
Billy

[et89xj]

I picked up a set of the 10.5"s so I could have two sets, one for trails(3 ribs) and one for jumping(4 ribs). I had to drill about 20 1/2 holes in them to soften them up, before they where way to hard, now it's like landing on a cloud. I'm running 3.5"RE zj coils with f-250 front shocks in front(shocks work great for a set of free longer shocks). I have not made a 'landing' plate for them yet and not sure if I will, have not had an issue getting speared on the bump tower.

I feel they are money well spent, sorry for the poor post details, fighting a cold...andy miobi.org

[slcpunk74]

How do you figure out the compressed height of these things so that you're not wasting travel?
Thanks,
Billy

make them longer then you need and run a zip tie on your shock, go jump it and do the math. I just guessed and it seems pretty close so far.

[JeepFreak21]

make them longer then you need and run a zip tie on your shock, go jump it and do the math. I just guessed and it seems pretty close so far.
http://www.slicky.net/smilies/doh2.gif Thanks!
Billy

[slcpunk74]

http://www.slicky.net/smilies/doh2.gif Thanks!
Billy

Yeah SWAG is a great system. I really just guessed and watched what my shock shafts did. I really dont know how much they compress because I have not done the math yet.

[slcpunk74]

"UPDATE"

I was hitting some whoops about 50mph and it was doing great. After hitting the whoops super hard I went home and flexed out in my driveway to inspect my suspension. Long story short I need to add an inch or so to the prothanes because I bottomed my shock and bent one of the mounts "OUCH!". It wil be an easy fix and I will post up my lengths in 5 mins so we all know ho much they compress.

[slcpunk74]

1.5" gap between the prothane and the stock foam bump. I think the stock bump could compress somewhere around 1.5" and I bottomed all 5" (at ride hight)of my shock shaft so we can figure that my prothanes can compress around 2.5-3.5".
So I guess I can add another 1.5" to my prothanes(which is easy due to my tube design) or get some poly bumps that replace the stock weiners. I will just add some prothane for now but maybe later on get poly weiner replacers.

Also a good not is that I found nice foam bumpstops off of a 96ish blazer rear. I looked at them and they could sit inside a coil and you could cap the top just like a prothane. I might do a blazer bump writeup just for fun and good tech.

crappy pichttp://photos-b.ak.facebook.com/photos-ak-sctm/v162/39/32/1478550133/n1478550133_30046409_6906.jpg

[GrimmJeeper]

I will just add some prothane for now but maybe later on get poly weiner replacers.
im sorry but this is just too good not to quote :roflmao:

so overall how do you feel about the prothanes? like on a scale of 1 to 10 with 10 being "the best thing you ever bought for the XJ"

:cheers:

[slcpunk74]

im sorry but this is just too good not to quote :roflmao:

so overall how do you feel about the prothanes? like on a scale of 1 to 10 with 10 being "the best thing you ever bought for the XJ"

:cheers:

I think they are great. I am not sure what I would rate them, maybe an 7-8.5. I like them but then again when I add an inch to them they will hit when I corner so we'll see if that good(swaybar) or bad(harsh unlike a swaybar).

And I am really out of it. I have been sick for the past couple days so I might say some crazy stuff.

[Darky]

I guess if I make them all look like every other thread good tech could fade away. Didnt mean to piss you off there. If nobody wants me posting I will stop but I am only trying to help and I dont think knocking on me is very productive.
He's just joshin ya, man...:) Besides who says your tech is the only good tech, huh? I've got at least...ok, so maybe I have no good tech threads...:D

[Darky]

http://photos-b.ak.facebook.com/photos-ak-sctm/v162/39/32/1478550133/n1478550133_30046409_6906.jpg
Quit grabbin your weiner!

BTW, good thread, I've seen those and wondered how they do. I might start moving a little more go fast with mine (fits well with the terrain out here, lots of open desert)

[slcpunk74]

He's just joshin ya, man...:) Besides who says your tech is the only good tech, huh? I've got at least...ok, so maybe I have no good tech threads...:D

I did not say mine was the only good tech. I just hate doing threads trying to help people that never get seen again... Like that cut and fold one I did ha ha. Well anyway its all good man.

[slcpunk74]

Quit grabbin your weiner!

BTW, good thread, I've seen those and wondered how they do. I might start moving a little more go fast with mine (fits well with the terrain out here, lots of open desert)

I got that pic from the google so not my weiner nor is it my hand :wow:

[Darky]

Thought it looked a bit bigger than the XJ's...

[yourconfusedhaha]

can you get the part number for the ones your using, im having trouble finding them

[XJEEPER]

I picked up a set of the 10.5"s so I could have two sets, one for trails(3 ribs) and one for jumping(4 ribs). I had to drill about 20 1/2 holes in them to soften them up, before they where way to hard, now it's like landing on a cloud. I'm running 3.5"RE zj coils with f-250 front shocks in front(shocks work great for a set of free longer shocks). I have not made a 'landing' plate for them yet and not sure if I will, have not had an issue getting speared on the bump tower.

I feel they are money well spent, sorry for the poor post details, fighting a cold...andy miobi.org

So, you drilled 1/2" holes in them, between the ribs, to fine-tune their compression?

[slcpunk74]

can you get the part number for the ones your using, im having trouble finding them

You need a part# for the prothanes? Just look on jegs and I am using the 10 1/2" but just cut down to about 8" right now until I get a poly upper bumpstop to go in the factory position then I should be able to cut it to 6.5" http://www.jegs.com/p/Prothane/762178/10002/-1

[srimes]

are those prices for a pair or each?

[Ronbo]

are those prices for a pair or each?

Pair.

[slcpunk74]

are those prices for a pair or each?
They do come as a pair.

[yourconfusedhaha]

You need a part# for the prothanes? Just look on jegs and I am using the 10 1/2" but just cut down to about 8" right now until I get a poly upper bumpstop to go in the factory position then I should be able to cut it to 6.5" http://www.jegs.com/p/Prothane/762178/10002/-1



thanks thats the link i was looking for, the link you posted on page one i couldnt find these

[ktm racer 419]

http://img.photobucket.com/albums/v31/mrmontez2000/IMG_0205.jpg

http://img.photobucket.com/albums/v31/mrmontez2000/IMG_0204.jpg

the pics are upright, i just rested my jeep on its nose, made this project a little easier.

thought i would share how i got mine in there.

I cut about an inch off the stock bump tower and replaced it with some schedule40 pipe, which just so happens to fit inside the prothane coil insert VERY SNUG which is what I wanted. I am going to put a round plate floating inbetween the prothane and the acos to give the insert a flat place to compress against. (just need to get the right size hole saw)

won't be able to test it out for a couple weeks as the rest of the jeep still needs assembly

[Goatman]

I used the longest Prothane insert, which I thought was 10", and I cut one ridge off of them, which I thought was an inch, so mine are 9" long. (I did this a loooong time ago). I unscrewed the stock bumpstop, made a round flat plate with a hole drilled in the middle, and bolted it back to the bottom of the bumpstop tower. The insert floats inside the coil and just sits on the bottom.

On my rig, the lower coil seat has been raised 2" and I have 7.5" of lift with 12" shocks, just for reference. The 9" Prothane insert compresses 3.5", and there's about 2.5" of travel before hitting the insert. This is a very good modification, about as good bang for the buck as you could get with any mod to the XJ. They are very progressive and I never feel the front bottoming (emphasis on feel, ask Cracker). :)

Hitting the bumpstop while articulating isn't an issue. These inserts are soft enough to compress, and if your spring rate is soft enough to compress all the way while articulating it's way too soft for running desert or fast running to the trails.

[ktm racer 419]

the way i was running them failed. for one i didnt end up using the acos because they gave me more lift than i desired, even at their lowest setting with stock coils (my coil buckets are raised 2") they worked nice for running through the fast stuff, but as soon as I flexed the coil would either pull the bumpstops down with it, or the bumpstops would hold the coil up making them fall out (havent had coil retainers in years)

I was just cycling my suspension outside and due to my radius arm my coil buckets angle forward pretty severely at full droop, mounting them hard to the bottom would likely catch my coil and mangle these things.

gonna make up some coil retainers and make a bolt on plate for the top bumpstop tower and see how they work (much like goatman described)

[GoSlowGetStuck]

Time to bring this thread back from the dead. :D

Looking for bumpstops for my ZJ and I think I'd like to run the prothanes on all four corners. Before I order them I'd like to measure what lengths I need so I don't have to pay for the long ones only to cut them down.

Based on what I've read, 2.5" air gap is what I want. Should I really need to account for shock length, travel, etc.? Or can I make the math simple and measure from stock bumpstop to coil bucket at ride height, subtract 2.5", and go with that?

Basically does the term "air gap" simply refer to distance between top of prothane and landing surface, when measured at ride height?

[bcmaxx]

So far liking mine!! I had a 2-1/2 inch ish air gap, but the jeep has for one reason or another lost an inch and a hair. I have the longest ones in there and I cut the bumps and mount right off and made my own bump pad out of tubing and some 3/16 plate for the prothanes to bump up to. I can really hammer the whoops hard, drop ledges, or do just dumb stuff without bottoming my shocks out. At absolute full stuff all twisted up and hanging off a limiting strap I have about 1/2 inch shock travel left. So they, so far have done their job!! I'll need to find some bigger coils next year I think!

[srimes]

I don't have them yet, but from what I've read these things compress about 40%. So my plan is to chose them based on fully compressed height (60% of uncompressed), and as long as the air gap is greater than 0 it should be fine. I'm not ever sure that an air gap less than 0 (pre-load) would be a bad.

[ktm racer 419]

Time to bring this thread back from the dead. :D

Looking for bumpstops for my ZJ and I think I'd like to run the prothanes on all four corners. Before I order them I'd like to measure what lengths I need so I don't have to pay for the long ones only to cut them down.

Based on what I've read, 2.5" air gap is what I want. Should I really need to account for shock length, travel, etc.? Or can I make the math simple and measure from stock bumpstop to coil bucket at ride height, subtract 2.5", and go with that?

Basically does the term "air gap" simply refer to distance between top of prothane and landing surface, when measured at ride height?

the 10" ones only cost a little more and are ready to ship (when i bought them)

the other sizes took 18 days.

not an issue for some people, but somethign to consider.


i ultimately used 5" per side. 3" lift and 36's. but it depends on what you make for them to compress against

[GoSlowGetStuck]

Awesome, thanks everyone. I think I have a pretty good idea of what I need now.

the 10" ones only cost a little more and are ready to ship (when i bought them)

the other sizes took 18 days.

Good point, I didn't even think to check the ship dates. Might end up going with the long ones just to get them quick.

[Goatman]

Obviously, if the bump stop are longer and the rig has more travel then they will compress more, so there is no hard rule of thumb. Also, unlike an air bump, there is no definite stopping point on the bumps, so it's possible to bottom the shocks. However, if the bumps are compressed a bunch by the time the shocks bottom it most likely won't hurt anything since the suspension speed will have been greatly reduced by the bump by the time the shocks bottom. Something to think about if you have steering or links ar something that you need to make sure clears at full stuff. Also, remember full stuff is not fully articulated, the suspension will bottom much harder/further at speed than it will slowly articulating.

[srimes]

Sounds like it'd be good to use shock bumps too.

I have these and like them:
http://www.daystarweb.com/productdetail.php?productID=679

[cal]

That, and make sure that under no circumstance can your trackbar kiss your oil pan, pushing it up into your stroker crank at 5,000 RPM's.

[GoSlowGetStuck]

Sounds like it'd be good to use shock bumps too.

I have these and like them:
http://www.daystarweb.com/productdetail.php?productID=679

I've seen those, they look nice for stopping the shock hitting bottom while wheeling but I don't know how they'd fare for faster stuff. So you'd suggest those as well as prothanes? I guess in that case, the daystars are just insurance in case the prothanes don't do their job?

That, and make sure that under no circumstance can your trackbar kiss your oil pan, pushing it up into your stroker crank at 5,000 RPM's.

Not gonna have a good time.

Looks like 10" and 3" ones are in stock, so I'll probably be getting four of the 10s and cutting them down.

[et89xj]

So, you drilled 1/2" holes in them, between the ribs, to fine-tune their compression?

I forgot i posted in this :wierd:

I feel they have been one of the best things I have added to my XJ to help with jumps and go-fast. In the last year I have added two more inches of lift and run only the longer of the two inserts(cut down 10" to 6/4"). I am very happy but think I will be ordering a new set and drill less holes, but first i will try with out the holes and add them as needed like i did the first set.

andy, vp of miobi.org

[XJEEPER]

Great feedback......care to answer my question on hole placement? It would also be nice to know the pro's and con's of drilling holes in the prothanes, i.e. your real-world experience VS theory.
TIA

[ktm racer 419]

That, and make sure that under no circumstance can your trackbar kiss your oil pan, pushing it up into your stroker crank at 5,000 RPM's.

my truss was 2" from my oil pan on full compression (prothanes and coils removed)

I jumped it

nice bend in my oil pan/bearing cradle and an engine that sounds like a machine gun

I bend back the bearing cradle. I notch my truss. I now have about 3.5" between my oil pan and truss at full compression.

I jumped it

same bent bearing cradle/dented oil pan. and a machine gun sounding engine

WTF

be sure to compensate for motor mount compression (if running stock style) and maybe a little bit of unibody failage

[Goatman]

Nice! So someone else has dented the oil pan two different times.........

We need to be nicer to our junk.





NOT!! :D

[et89xj]

Great feedback......care to answer my question on hole placement? It would also be nice to know the pro's and con's of drilling holes in the prothanes, i.e. your real-world experience VS theory.
TIA

Shoot sorry didn't see the question. I drilled 1/2 holes(used a step bit) in a stager pattern trough both the rib and spacer. I do mostly tuff truck and trail bombing so speed is under 40 thats why i felt the holes helped.
If speed and whoops are added then less holes or only half drilled would give better progression to the bump and help keep better control of the axle/smooth out the harshness of the multi hits. This season I competing in more trail races(SMORR and a few local races we are helping put on) so I will be stepping up to better shocks, new prothanes with less holes and less weight.

This is all how i 'feel' works for me and could be the worse thing in the world for everyone else. I would try the inserts unmolested a few times before you start drilling them for oil and only do a little bit at a time.

andy, VP MIOBI.org

[blacksheep01]

Do the prothanes just sit in the coil? In other words, how are they mounted. I have never seen these in person and this thread came up in a search of bumpstops.

[Goatman]

They don't attach to anything, just float inside the coil. You just need a plate on top for them to hit against.

[lyleorszulak807]

Does the plate need to be square or round? Not sure which route I want to go..Also how do you get the plate to stay on top? drill some holes and screw them in?

edit: I feel like an idiot now after looking at the op again... but should the plate be round or square?

[bcmaxx]

Does the plate need to be square or round? Not sure which route I want to go..Also how do you get the plate to stay on top? drill some holes and screw them in?

edit: I feel like an idiot now after looking at the op again... but should the plate be round or square?
mo=ine is square, next time i'll go round. The square edges tear them up slighlty nothing to concerning though

[et89xj]

round will be 'best'

[blacksheep01]

Nother dumb question, I just installed ACOS, the original cheaper ones.These should still work just fine with the plate, right?

[Goatman]

I don't know, can you remove the rubber bump and bolt a plate to the bottom of the ACOS?

[blacksheep01]

Possibly. So your saying that the plate mounts where the bump stop was originally and not on top of the prothane?

[1990JEEPXJ]

you should be able to do that easily. its just one little allen head bolt holding the whole thing up via the stock bumpstop tower. correct size plate + bolt hole = success. at least i dont see why it wouldnt work.

[srimes]

Anyone set it up like this? If the plate is attached to the tower there could be an issue with the plate hitting the spring when flexed.

[XJEEPER]

Here's what I did on my 2000: (sorry, no pictures to show you of the fab....yet)

The factory bumpstop cup is welded on instead of screwed on, as in the early model XJ's, so using my sawzall I cut right above the weld. This left me with 5" of bumpstop tower, which is hollow.

I grabbed 2- 3/4" bolts-2" long and 4 nuts from HD.

Cut out 2-3" diameter circles from some scrap 1/4" plate. This is slightly large that the flat on the end of the Prothane bumps.

I welded the 3/4" bolt head to the center of each 3" plate.

The inside of the stock bump tower is approx 1.75" ID and I had some tube scraps laying around that had a 1.5" OD and the 3/4" nut would slip inside with a little grinding of the ears.

I cut 2-2" lengths of tube which I used with the 3/4" nut to create a threaded sleeve to insert into the bump tower.

Leaving the nut protuding about .25" from this sleeve, I welded it to the 1.5" OD tube. I then ran a bead around the circumference of the sleeve on each end to tighten up the gap between the OD of the sleeve and the ID of the tower. Some minor grinding resulted in a snug, centered fit.

I then welded the sleeve into the stock bump tower, with the sleeve about 1/4" out of the tower, then buffed it clean and painted it along with the 3" bump plate.

I threaded the 2nd nut onto the bolt on the bump plate and dropped it inside the Prothane bump, shoved the bump inside the coil spring and installed the spring.

I then reached inside the coil, grabbing my fabbed bump plate and flipped it over so the bolt was pointing up and then threaded it into the bump tower. This needs to be done with coil uncompressed.

Once threaded in completely, I snugged the nut with a wrench, then seated the coil and lowered the weight of the Jeep onto the coil.

How does it work?


http://i173.photobucket.com/albums/w52/XJEEPER1/Trail%20Shots/IMG_3090-3.jpg

The 3" plates contact the top of the Prothanes upon compression and don't hang up on the coils while flexing. With a 6" lift, I ended up trimming 2 rings from the 10" Prothane bumps, which seems to work perfectly with my setup.


http://i173.photobucket.com/albums/w52/XJEEPER1/Trail%20Shots/IMG_3092.jpg

There is just over 1" of adjustablilty with my plate setup, so I can thread the plate out to reduce the airgap if needed to limit uptravel.

Fab up a 3" round plate, drill a hole and thread it onto your JKS bump towers. This should solve your problem.

[Goatman]

I kind of think I follow what Jeff did........ :)

Yes, you use the bump stop bolt in the bottom of the tower to bolt a round plate to the bottom of the tower. The bump stop floats inside the coil and hits against that plate. If you have a later model XJ where the stock bump stop is welded to the tower, you'll need to weld something to the bottom of the tower so the plate can be bolted on.

I made my plate just small enough that the spring could go over it. I think that's too small a plate, so I recommend making the plate bigger and bolting it in after installing the spring.

[blacksheep01]

Ok, thanks. I get it now.

[BoringDave]

Here's what I did on my 2000: (sorry, no pictures to show you of the fab....yet)

The factory bumpstop cup is welded on instead of screwed on, as in the early model XJ's, so using my sawzall I cut right above the weld. This left me with 5" of bumpstop tower, which is hollow.

I grabbed 2- 3/4" bolts-2" long and 4 nuts from HD.

Cut out 2-3" diameter circles from some scrap 1/4" plate. This is slightly large that the flat on the end of the Prothane bumps.

I welded the 3/4" bolt head to the center of each 3" plate.

The inside of the stock bump tower is approx 1.75" ID and I had some tube scraps laying around that had a 1.5" OD and the 3/4" nut would slip inside with a little grinding of the ears.

I cut 2-2" lengths of tube which I used with the 3/4" nut to create a threaded sleeve to insert into the bump tower.

Leaving the nut protuding about .25" from this sleeve, I welded it to the 1.5" OD tube. I then ran a bead around the circumference of the sleeve on each end to tighten up the gap between the OD of the sleeve and the ID of the tower. Some minor grinding resulted in a snug, centered fit.

I then welded the sleeve into the stock bump tower, with the sleeve about 1/4" out of the tower, then buffed it clean and painted it along with the 3" bump plate.

I threaded the 2nd nut onto the bolt on the bump plate and dropped it inside the Prothane bump, shoved the bump inside the coil spring and installed the spring.

I then reached inside the coil, grabbing my fabbed bump plate and flipped it over so the bolt was pointing up and then threaded it into the bump tower. This needs to be done with coil uncompressed.

Once threaded in completely, I snugged the nut with a wrench, then seated the coil and lowered the weight of the Jeep onto the coil.

How does it work?


http://i173.photobucket.com/albums/w52/XJEEPER1/Trail%20Shots/IMG_3090-3.jpg

The 3" plates contact the top of the Prothanes upon compression and don't hang up on the coils while flexing. With a 6" lift, I ended up trimming 2 rings from the 10" Prothane bumps, which seems to work perfectly with my setup.


http://i173.photobucket.com/albums/w52/XJEEPER1/Trail%20Shots/IMG_3092.jpg

There is just over 1" of adjustablilty with my plate setup, so I can thread the plate out to reduce the airgap if needed to limit uptravel.

Fab up a 3" round plate, drill a hole and thread it onto your JKS bump towers. This should solve your problem.

You should ask Jim how many times you can do that till you bend your front axle.

But looks real good!

[BoringDave]

What are you guys bolting your limit straps to?

Dave

[Goatman]

What are you guys bolting your limit straps to?

Dave


Bolts?


:)

Weld tabs to the axle and frame where you want the straps.

[northwestxj]

Here's what I did on my 2000: (sorry, no pictures to show you of the fab....yet)

The factory bumpstop cup is welded on instead of screwed on, as in the early model XJ's, so using my sawzall I cut right above the weld. This left me with 5" of bumpstop tower, which is hollow.

I grabbed 2- 3/4" bolts-2" long and 4 nuts from HD.

Cut out 2-3" diameter circles from some scrap 1/4" plate. This is slightly large that the flat on the end of the Prothane bumps.

I welded the 3/4" bolt head to the center of each 3" plate.

The inside of the stock bump tower is approx 1.75" ID and I had some tube scraps laying around that had a 1.5" OD and the 3/4" nut would slip inside with a little grinding of the ears.

I cut 2-2" lengths of tube which I used with the 3/4" nut to create a threaded sleeve to insert into the bump tower.

Leaving the nut protuding about .25" from this sleeve, I welded it to the 1.5" OD tube. I then ran a bead around the circumference of the sleeve on each end to tighten up the gap between the OD of the sleeve and the ID of the tower. Some minor grinding resulted in a snug, centered fit.

I then welded the sleeve into the stock bump tower, with the sleeve about 1/4" out of the tower, then buffed it clean and painted it along with the 3" bump plate.

I threaded the 2nd nut onto the bolt on the bump plate and dropped it inside the Prothane bump, shoved the bump inside the coil spring and installed the spring.

I then reached inside the coil, grabbing my fabbed bump plate and flipped it over so the bolt was pointing up and then threaded it into the bump tower. This needs to be done with coil uncompressed.

Once threaded in completely, I snugged the nut with a wrench, then seated the coil and lowered the weight of the Jeep onto the coil.

The 3" plates contact the top of the Prothanes upon compression and don't hang up on the coils while flexing. With a 6" lift, I ended up trimming 2 rings from the 10" Prothane bumps, which seems to work perfectly with my setup.


There is just over 1" of adjustablilty with my plate setup, so I can thread the plate out to reduce the airgap if needed to limit uptravel.

Fab up a 3" round plate, drill a hole and thread it onto your JKS bump towers. This should solve your problem.

Pretty sure I understand this, but it would be awesome if you could take a few pictures like you mentioned! I'm sure everyone would be interested...

[1990JEEPXJ]

seems simple enough. figured someone had already done it when i suggested it

cut off bottom of bumpstop tower
weld in tube that slides inside tower
weld nut inside bottom of tube
weld bolt to 3" dia plate
screw bolt/plate into nut

but i dont think it would work too well with short arms. my coils rub the bottom of my ACOS at full droop. a 3" plate would get caught on the coil pretty easily. drop brackets might fix that though as well.

[XJEEPER]

You should ask Jim how many times you can do that till you bend your front axle.

But looks real good!

Stock D30's bend easily, trussed and gusset D30's don't bend easily.

http://i173.photobucket.com/albums/w52/XJEEPER1/Trail%20Shots/IMG_2808-1.jpg

I'm pretty selective about when and where I jump.

[Mike1331]

xjjeeper i think the pics you put out are among my favorites on this forum. Thanks for the inspiration.

[karstic]

Bolts?


:)

Weld tabs to the axle and frame where you want the straps.

You smartazz:wave1:

[BoringDave]

I deserved it! I should do more reading and less skimming though posts.

[BoringDave]

Pretty sure I understand this, but it would be awesome if you could take a few pictures like you mentioned! I'm sure everyone would be interested...

X2 on the pics!

[BoringDave]

Stock D30's bend easily, trussed and gusset D30's don't bend easily.

http://i173.photobucket.com/albums/w52/XJEEPER1/Trail%20Shots/IMG_2808-1.jpg

I'm pretty selective about when and where I jump.


I should also read post counts before I make smartazz remarks.

[souske]

Does anyone know the size/pitch of the threaded bumpstop holes? (87) Just want to get all the hardware before I start taking coils off.

[1990JEEPXJ]

10mm x 1.5p according to JKS

[grandrunner]

Stock D30's bend easily, trussed and gusset D30's don't bend easily.

http://i173.photobucket.com/albums/w52/XJEEPER1/Trail%20Shots/IMG_2808-1.jpg

I'm pretty selective about when and where I jump.

i here you on that one haha just bent/ broke mine..

not anymore:spin1:

http://i20.photobucket.com/albums/b223/dunerocker/001-9.jpg

ive been lookin at the daystar bumps. but might try this route first.

[BoringDave]

Don't welding on something all on one side like that make the item pull or bow that direction as the welds cool? When I weld up things like that I clamp them down or tack them down to my table to stop the welding pull. Just curious because I plan to truss my axle but was going to fab the whole thing myself. I was planing on truss top and bottom so I wouldn't have the weld shrink problem of welding on one side.

Dave

[souske]

got em in today. 10mm/1.5 was right on thanks 1990Jeepxj!

[1990JEEPXJ]

no problem! :cheers:

[crazyjim]

Don't welding on something all on one side like that make the item pull or bow that direction as the welds cool? When I weld up things like that I clamp them down or tack them down to my table to stop the welding pull. Just curious because I plan to truss my axle but was going to fab the whole thing myself. I was planing on truss top and bottom so I wouldn't have the weld shrink problem of welding on one side.

Dave
Yes it does, the best way to do it is to build a jig, and bolt it down as you do. Or you can send it to an axle shop, and have them pre-bend it, like currie. Then once you weld your truss on, it'll be straight.

[dgrigorenko]

Yes it does, the best way to do it is to build a jig, and bolt it down as you do. Or you can send it to an axle shop, and have them pre-bend it, like currie. Then once you weld your truss on, it'll be straight.

if you do it right you will end up with a negligable amount of bend. just food for thought: the weld shrinkage will have to bend the axle tube (tubing is quite strong)... for starters just the compressive forces located at that location of the tube (not on the top where leverage would be greatest) required to would be pretty extreme(i know the D30 is nothing to write home about, but tubing of that diameter even in thin wall is quite stout). secondly, if you weld it properly you will significantly reduce the chances of distortion: start by welding 2-3" at the ends, and on both sides of the truss and let cool. now in order for distortion to occur both the axle tube and the truss have to bend (shink at the weld) at the same time. now weld the rest of the truss to the tube in sections and allow to thoroughly cool. overheating the part can be a huge factor in weld distortion so if you are really worried about it you can preheat the whole thing, weld, post heat and slow cool, but thats pretty extreme for low carbon steel.

honestly i wouldnt worry about it that much, especially if done right.
.
i have no doubt that in the instance of currie or other mfgs that pre bending is the most effective/efficent way to go. i'm sure that their operating factor is significantly higher if they dont have to wait between operations.

[grandrunner]

it was clamped down and then tacked in place and welded 5inches at a time alternating from left side to right front to back.

[crazyjim]

if you do it right you will end up with a negligable amount of bend. just food for thought: the weld shrinkage will have to bend the axle tube (tubing is quite strong)... for starters just the compressive forces located at that location of the tube (not on the top where leverage would be greatest) required to would be pretty extreme(i know the D30 is nothing to write home about, but tubing of that diameter even in thin wall is quite stout). secondly, if you weld it properly you will significantly reduce the chances of distortion: start by welding 2-3" at the ends, and on both sides of the truss and let cool. now in order for distortion to occur both the axle tube and the truss have to bend (shink at the weld) at the same time. now weld the rest of the truss to the tube in sections and allow to thoroughly cool. overheating the part can be a huge factor in weld distortion so if you are really worried about it you can preheat the whole thing, weld, post heat and slow cool, but thats pretty extreme for low carbon steel.

honestly i wouldnt worry about it that much, especially if done right.
.
i have no doubt that in the instance of currie or other mfgs that pre bending is the most effective/efficent way to go. i'm sure that their operating factor is significantly higher if they dont have to wait between operations.
Sure, you can take measures to lessen the warpage, but you'll never stop it without jigging it down. Think a D30 is stronger than a ford 9"? Ask Tony about his back truss that warped the hell out of his 9". Has to go to Currie to get straightened.

[tcm glx]

Sure, you can take measures to lessen the warpage, but you'll never stop it without jigging it down. Think a D30 is stronger than a ford 9"? Ask Tony about his back truss that warped the hell out of his 9". Has to go to Currie to get straightened.



D30 stronger than a 9" !!! Jimbo.... what are you smokin!!! Man, your like Harry Potter lately... first Robby has no talent, now a D30 is stronger than a 9'???

My 9" could very well have been warped before we even put a truss on it..... it was on a bronco that had 37"projects.. so it is possible that it was tweaked prior. Also, after welding the upper and back brace, it tweaked out 3/8". Not a whole lot.

That being said, any housing, that gets a truss welded on to, is most likely going to warp, plain and simple. You have to prepare for that.

[crazyjim]

D30 stronger than a 9" !!! Jimbo.... what are you smokin!!! Man, your like Harry Potter lately... first Robby has no talent, now a D30 is stronger than a 9'???

My 9" could very well have been warped before we even put a truss on it..... it was on a bronco that had 37"projects.. so it is possible that it was tweaked prior. Also, after welding the upper and back brace, it tweaked out 3/8". Not a whole lot.

That being said, any housing, that gets a truss welded on to, is most likely going to warp, plain and simple. You have to prepare for that.
Tony put down the joint SON!!!

Why don't you go re-read what I quoted... he talked about how strong the D30 is and how it won't warp when trussed... To which I asked if he thought his D30 is stronger than a 9". It's obviously not, which is the point. If a 9" warped when it was trussed, then a D30 is DEFINITELY going to warp.


:rtm:

[tcm glx]

Tony put down the joint SON!!!

Why don't you go re-read what I quoted... he talked about how strong the D30 is and how it won't warp when trussed... To which I asked if he thought his D30 is stronger than a 9". It's obviously not, which is the point. If a 9" warped when it was trussed, then a D30 is DEFINITELY going to warp.


:rtm:


Damn son.... I was about to go lay down the law.... Ok :passgas::passgas:

My bad!

[dgrigorenko]

Tony put down the joint SON!!!

Why don't you go re-read what I quoted... he talked about how strong the D30 is and how it won't warp when trussed... To which I asked if he thought his D30 is stronger than a 9". It's obviously not, which is the point. If a 9" warped when it was trussed, then a D30 is DEFINITELY going to warp.


:rtm:


dude... i by no means said that the D30 wont warp at all when trussed... i suggest you go read it again.:rtm: obviously they are susceptible to bending.... hence a truss....

[bradcarrier]

I kind of think I follow what Jeff did........ :)

Yes, you use the bump stop bolt in the bottom of the tower to bolt a round plate to the bottom of the tower. The bump stop floats inside the coil and hits against that plate. If you have a later model XJ where the stock bump stop is welded to the tower, you'll need to weld something to the bottom of the tower so the plate can be bolted on.

I made my plate just small enough that the spring could go over it. I think that's too small a plate, so I recommend making the plate bigger and bolting it in after installing the spring.

Any body ever get any pics of this setup? thanks

[XJEEPER]

Any body ever get any pics of this setup? thanks

I should have time to post them up in the next day or 3........

[Slayer92]

I cut a 3" circle out of 1/4" plate and I drilled and tapped the bottom of my bump tower to accept a 1/2" bolt. It works great so far.

[crash02]

I should have time to post them up in the next day or 3........

anxiously waiting.just want to see different set-ups. thanks

[XJEEPER]

Here's what I did on my 2000:
The factory bumpstop cup is welded on instead of screwed on, as in the early model XJ's, so using my sawzall I cut right above the weld. This left me with 5" of bumpstop tower, which is hollow.

I grabbed 2- 3/4" bolts-2" long and 4 nuts from HD.

Cut out 2-3" diameter circles from some scrap 1/4" plate. This is slightly large that the flat on the end of the Prothane bumps.

I welded the 3/4" bolt head to the center of each 3" plate.
http://i173.photobucket.com/albums/w52/XJEEPER1/XJ%20Build%20III/IMG_5187.jpg


The inside of the stock bump tower is approx 1.75" ID and I had some tube scraps laying around that had a 1.5" OD and the 3/4" nut would slip inside with a little grinding of the ears.

I cut 2-2" lengths of tube which I used with the 3/4" nut to create a threaded sleeve to insert into the bump tower.

Leaving the nut protuding about .25" from this sleeve, I welded it to the 1.5" OD tube. I then ran a bead around the circumference of the sleeve on each end to tighten up the gap between the OD of the sleeve and the ID of the tower. Some minor grinding resulted in a snug, centered fit.

http://i173.photobucket.com/albums/w52/XJEEPER1/XJ%20Build%20III/IMG_5167.jpg

I then welded the sleeve into the stock bump tower, with the sleeve about 1/4" out of the tower, then buffed it clean and painted it along with the 3" bump plate.



http://i173.photobucket.com/albums/w52/XJEEPER1/XJ%20Build%20III/IMG_5175.jpg
I threaded the 2nd nut onto the bolt on the bump plate and dropped it inside the Prothane bump, shoved the bump inside the coil spring and installed the spring.

I then reached inside the coil, grabbing my fabbed bump plate and flipped it over so the bolt was pointing up and then threaded it into the bump tower. This needs to be done with coil uncompressed.

Once threaded in completely, I snugged the nut with a wrench, then seated the coil and lowered the weight of the Jeep onto the coil.


The 3" plates contact the top of the Prothanes upon compression and don't hang up on the coils while flexing. With a 6" lift, I ended up trimming 2 rings from the 10" Prothane bumps, which seems to work perfectly with my setup.


There is just over 1" of adjustablilty with my plate setup, so I can thread the plate out to reduce the airgap if needed to limit uptravel.

Fab up a 3" round plate, drill a hole and thread it onto your JKS bump towers. This should solve your problem.

[Darky]

The original link to jegs no longer shows these. Ideas on where to get them now?

[GoSlowGetStuck]

The original link to jegs no longer shows these. Ideas on where to get them now?

Hopefully buying some for my ZJ when I start building it in a few months, here's where I recently found them:

http://www.jegs.com/p/Prothane/Prothane-Coil-Spring-Inserts/762178/10002/-1

[Darky]

You need a part# for the prothanes? Just look on jegs and I am using the 10 1/2" but just cut down to about 8" right now until I get a poly upper bumpstop to go in the factory position then I should be able to cut it to 6.5" http://www.jegs.com/p/Prothane/762178/10002/-1

The original link to jegs no longer shows these. Ideas on where to get them now?

Hopefully buying some for my ZJ when I start building it in a few months, here's where I recently found them:

http://www.jegs.com/p/Prothane/Prothane-Coil-Spring-Inserts/762178/10002/-1
The first quote and GoSlow's link both show the right location...after looking around in the thread, I found the post I quoted...:D I'm putting in an order for the 10" today. Everything else has an 8 day wait.

[TJDualsport]

just did a 400 mile desert run and a friend ran these in his TJ. heres a video of them in action
http://www.youtube.com/watch?v=1h_XfQrHSuU

[fyrfytr1717]

The original link to jegs no longer shows these. Ideas on where to get them now?

I see you found them at jegs, but they also have them at Summit. That's where I got mine. It kind of throws you off because the pictures are wrong, but here's a link to the 8 ring (10.5") flavor:

http://www.summitracing.com/parts/PTP-19-1705/

They also carry the 2, 4, and 6 ring versions of them if you're looking for a different size:

http://www.summitracing.com/search/?keyword=prothane%20coil%20insert&dds=1

[Darky]

just did a 400 mile desert run and a friend ran these in his TJ. heres a video of them in action
http://www.youtube.com/watch?v=1h_XfQrHSuU
Looks like he's got em free floating. That working out alright for him?

[WAM174]

Here's a little gimmick Goatman and I worked up on my rally XJ. We wanted to use the progressive inserts for handling as well as bump control, but Goatman was concerned that they didn't provide a "hard stop" just prior to pan contact. So I sent him some 1-1/4 diameter UHMWPE solid rod (Mcmaster 5243T15) and he placed short pieces inside the insert center hole to act as a hard stop if the suspension gets that far. On this truck we probably used 6 to 8 inches of insert containing a 3" or so hard-stop within.

I'm working out procedures to where I can change both insert length and hard-stop length at the track between runs. I eventually want to use bumpstop mods to add oversteer or understeer as needed.

[Mike1331]

so what is the desired prothane height to uptravel ratio's for you guys that are running them? I'm running a skyjacker 6" coil that settled to 5.5; think i'll get the 6 ring 7.5" ones, 50 per side seems pricey for these things...

Cool vid

[lyleorszulak807]

I think their sold in pairs, I bought the 8 ring ones about 6 months ago and I believe it was around 60 or 70 bucks shipped to my door and they came as a pair. Haven't got them in yet, still working on the dana 30 on the bench...

[XJEEPER]

I've been pretty happy with these thus far. http://www.naxja.org/forum/showpost.php?p=245254418&postcount=12

http://i173.photobucket.com/albums/w52/XJEEPER1/Trail%20Shots/IMG_5994-1.jpg


Video from my most recent airtime, you can see how they prevent the tires from getting into the fenders.

http://www.youtube.com/watch?v=agR2QQuZXSU

http://www.youtube.com/watch?v=wVJzCQziijA

[tone]

Stay gritty!

[TJDualsport]

he ran the whole 400 mile trip like that and he loved em. i need to change the style of bump plate so the bolt head is recessed, and make some other minor changes. but he wants to take them in the rocks to see how they do before we really get to work on it.

[Goatman]

Here's a little gimmick Goatman and I worked up on my rally XJ. We wanted to use the progressive inserts for handling as well as bump control, but Goatman was concerned that they didn't provide a "hard stop" just prior to pan contact. So I sent him some 1-1/4 diameter UHMWPE solid rod (Mcmaster 5243T15) and he placed short pieces inside the insert center hole to act as a hard stop if the suspension gets that far. On this truck we probably used 6 to 8 inches of insert containing a 3" or so hard-stop within.




Here's a pick of what we did, it works so good I'm also making a set like this for our road race XJ. The clearance is tight for bottoming, so the HMWPE rod inside of the poly insert provides a definite stop. This stuff is tough, and it doesn't compress. The insert still just floats inside the spring, I just picked it up in the pic to see the rod.

http://www.fototime.com/8D8F9319A11066E/standard.jpg

[Senior_XJ]

Will these style bump stops work on a rock crawling rig that doesnt do any jumping?? Im on 35"s with 6.5" of lift, 4.5" coils with a 150 spring rate, & 2" spacers, & im setting up my flex, shock travel, & bumpstops now??

[Darky]

Never gonna work except on an XJ that sees regular flight time. ;)

Mine doesn't see air time, it only sees some whoops, trails and rock crawling, but these, I think, will still be a benefit to my XJ.

[1990JEEPXJ]

i plan on getting these soon. my shocks dont like being used as bumpstops very much...

[lyleorszulak807]

Yeah thats why I havent romped through the desert yet, dont want to blow out my 7100's. Damn those red things sitting on my work bench are intimidating...Waiting on limit straps first or I could just use my crappy steering as a limit strap. :looney:

[srimes]

i plan on getting these soon. my shocks dont like being used as bumpstops very much...

these shaft bumps help with that:

http://www.naxja.org/forum/showthread.php?t=990207

[yossarian19]

Will these style bump stops work on a rock crawling rig that doesnt do any jumping?? Im on 35"s with 6.5" of lift, 4.5" coils with a 150 spring rate, & 2" spacers, & im setting up my flex, shock travel, & bumpstops now??

If you are *only* doing slow speed, I think a bump stop that leaves more air gap will be better because it will allow more articulation. That being said, if you ever like to drive down a Forest Service road with more skinny pedal than strictly needed for forward travel... the Prothanes are probably a good idea.

[dgrigorenko]

mine actually work awesome for both crawling and faster stuff. i dont know if i just got lucky with the sizing or what

[Goatman]

these shaft bumps help with that:

http://www.naxja.org/forum/showthread.php?t=990207


These aren't available any more, they quit selling them.

[Goatman]

Will these style bump stops work on a rock crawling rig that doesnt do any jumping?? Im on 35"s with 6.5" of lift, 4.5" coils with a 150 spring rate, & 2" spacers, & im setting up my flex, shock travel, & bumpstops now??



You need good bump stops even if you rock crawl and do trails, and these will work well. Bump stops normally don't limit articulation unless the spring rate is too soft. If you can bottom the suspension when articulating it's going to be pretty soft for bumps and ruts on the access roads. I ran these on my XJ (in fact I guess I started this) and it was a very good rock crawler.

[srimes]

These aren't available any more, they quit selling them.

Really? Do you know why?

[XJEEPER]

Will these style bump stops work on a rock crawling rig that doesnt do any jumping?? Im on 35"s with 6.5" of lift, 4.5" coils with a 150 spring rate, & 2" spacers, & im setting up my flex, shock travel, & bumpstops now??

They work fine for both.
http://i173.photobucket.com/albums/w52/XJEEPER1/Trail%20Shots/IMG_4856.jpg

[bcmaxx]

Another vote for being great for the slow stuff and the fast stuff. I dont remember how long I've had mine but 2-3 yrs anyways. I just had to cut a rung off to accomodate my acos.

http://i232.photobucket.com/albums/ee110/bcmaxx/2011-03-21161129.jpg

[1990JEEPXJ]

are those 4.5" springs? and how much up travel do you have available in the shock vs air gap to the prothanes?

[Senior_XJ]

Ok ive gotten a "no they wont work on a crawler" to "yes they will"... :dunno:

[yossarian19]

Ok ive gotten a "no they wont work on a crawler" to "yes they will"... :dunno:

Don't listen to me : I havent' run them and was speculating. Should have said so in my post.

[bcmaxx]

Uptravel is 6-1/2 " , air gap is 3-ish inches, re 4.5" springs

[1990JEEPXJ]

perfect, thanks. i have the same up travel and same springs.

[TJDualsport]

heres another vid of them working in the rocks and woops.
http://www.youtube.com/watch?v=UvosKU7OM_0

[FlexdXJ]

Uh oh, got this idea running around in my noodle. Now that I have a good riding suspension, I have found that blasting down gravel roads is fun! :D Gonna have to run a puck for the next couple wheeling trips but this idea looks like it will work for me.

[fyrfytr1717]

Sweet footage of them in action TJD. Thanks for posting that up. It's amazing how much they actually compress, they feel so hard. Looks like they do a good job of self centering themselves too. Seems like they spring back a little after being compressed. You ever feel them trying to push your wheels back down (or body up) after stuffing them in the rocks?

[TJDualsport]

No spring back at all. my bud whose jeep that is has only but good things to say about them.

[cracker]

I've been running these for years and suggest them to everyone.

Good stuff :thumbup:

[FlexdXJ]

the 10" ones only cost a little more and are ready to ship (when i bought them)

the other sizes took 18 days.

not an issue for some people, but somethign to consider.


i ultimately used 5" per side. 3" lift and 36's. but it depends on what you make for them to compress against

Bringing this back, I know its been quite a while since you posted this but I am between 3 and 3.5" of lift on 32's. Not quite sure if i'd need the 5" bumps since i'm not running 36's so, do you think a 3" would cut it? Its mostly a wheeling/highway rig with a new found love of blasting down dirt roads at 50+ mph. No Jumping,

[1990JEEPXJ]

i would be safe and get the larger ones, you can always cut them down to the right length

[FlexdXJ]

i would be safe and get the larger ones, you can always cut them down to the right length

That sound logical, thought i'd just ask to be sure. I need to bumpstop properly to keep the 32's and my front fenders from meeting each other! :D For now though, hockey pucks and construction adhesive will have to work.

[1990JEEPXJ]

there is some info somewhere about how much they compress, a percentage of their height. if you find out how much they compress then you can do some math and find out the right length you need

edit: found it

I used the longest Prothane insert, which I thought was 10", and I cut one ridge off of them, which I thought was an inch, so mine are 9" long. The 9" Prothane insert compresses 3.5", and there's about 2.5" of travel before hitting the insert.

[FlexdXJ]

there is some info somewhere about how much they compress, a percentage of their height. if you find out how much they compress then you can do some math and find out the right length you need


I'll look in to that, thanks dude! :cheers:

[jeepboy381]

They will compress more than that, I was running a one inch gap with 5-6 inchs of up travel on shorter prothanes and I could still bottom the shock out. I would do what goatman did and run plastic inside the prothanes to make a deffinent stopping point.

[srimes]

They will compress more than that, I was running a one inch gap with 5-6 inchs of up travel on shorter prothanes and I could still bottom the shock out. I would do what goatman did and run plastic inside the prothanes to make a deffinent stopping point.

Could you be more specific? What size prothanes, and how much were they compressed when the shock bottomed?


I have these:
http://www.quadratec.com/products/16021_10X_PG.htm
(in black), and figure they'll be good with the prothanes to keep them from overcompressing. Don't have too much info on the prothanes, but from what I gather they compress about to 60%.
3.5" compresses to 2.1",
5" compresses to 3",
8" compresses to 4.8", etc.

I'm bumpstopped 3" (hockey pucks), so I plan to get the 5" prothanes to match.

[jeepboy381]

60 % sounds more like it, I am currently running my prothanes 7.5 inchs long with a 2.5 inch gap and they only compress 1.5 inchs until I hit the solid plastic inserts I put inside the prothanes. I could cut 3/8 of an inch off the plastic inserts to use more of my shocks but you can tell in the picture that I have about 3/4 of an inch more travel I could use by looking at where the rubber bumper sits on the shock shaft. Don't use any of my measurements either because I have custom coil mounts and bumpstop plates

Previously the prothanes were 8.5 inchs long with no plastic bumpers inside them and I could bottom out the shocks hitting a big bump.

[ehall]

So they're not bump stops but bump slows? What's the point then

[srimes]

60 % sounds more like it, I am currently running my prothanes 7.5 inches long with a 2.5 inch gap and they only compress 1.5 inches until I hit the solid plastic inserts I put inside the prothanes. I could cut 3/8 of an inch off the plastic inserts to use more of my shocks but you can tell in the picture that I have about 3/4 of an inch more travel I could use by looking at where the rubber bumper sits on the shock shaft. Don't use any of my measurements either because I have custom coil mounts and bumpstop plates

Previously the prothanes were 8.5 inchs long with no plastic bumpers inside them and I could bottom out the shocks hitting a big bump.

Good info, it looks like this adds up. 7.5-1.5-.75= 5.25, the height where the shocks bottom. Your old setup: 8.5*.6 = 5.1, which would allow it to bottom.

For your current prothanes, 7.5*.6 = 4.5, or .75 below what you need. Throw a 1" hockey puck under them and it should be good, and softer to boot. Then you'll have a 1.5" gap and 3" of bumpstop compression.

[1990JEEPXJ]

you do know that 3.5" it about 40% of 9" right? meaning it compressed to about 60% its original height like srimes math shows is about right for these.

[Darky]

So they're not bump stops but bump slows? What's the point then
No, they will stop your axle.

[WAM174]

No, they will stop your axle.

Maybe, depending on various factors. But I think it's a mistake to just assume they compress 60% and no further. The more you load them, the more they compress. But it's not one to one -- it's as the name implies, progressive.

But still, not an absolute hard stop. That's what the custom plastic insert is for.

[cracker]

Maybe, depending on various factors. But I think it's a mistake to just assume they compress 60% and no further. The more you load them, the more they compress. But it's not one to one -- it's as the name implies, progressive.

But still, not an absolute hard stop. That's what the custom plastic insert is for.

Maybe? Wrong. They do when set up properly.

I air mine out and beat the piss out of my MJ and it takes it very well.

[Darky]

Once you compress something to a certain point, it will have no more space to compress. Compress these to the point where they have no more compression, the axle will stop. You can fine tune exactly when that stop will occur with an insert but it's not necessary to stop the axle.

[Darky]

Maybe? Wrong. They do when set up properly.

I air mine out and beat the piss out of my MJ and it takes it very well.
Except the pitman arm, right? ;)

[cracker]

Except the pitman arm, right? ;)

Those usually hold up too....