Flex vs. traction and limiting straps [Archive] - NAXJA Forums -::- North American XJ Association

JnJ

September 6th, 2003, 11:03

WARNING, GARAGE POSSER FLEX SHOTS

I decided to flex the POS up with the highlift to get an idea about usinging limiting straps and the balance between the front and rearends.
http://jeep_n_john.tripod.com/flextest1.jpg
http://jeep_n_john.tripod.com/flextest2.jpg
http://jeep_n_john.tripod.com/flextest3.jpg

From the pictures you can see the frontend has good flex, and the rear is pretty sad. The rear leafs are new, stiff, and the shackle is still leaned forward (even on the "stuffed" side), so there is hope that they will breakin and loosen up some (fingers crossed).
Back to the frontend, you can see the front coil is unseated, this comes just a few inches before the shocks are maxed out (shocks are 1" away from being maxed). I really dont think the frontends provides any traction once that coil is unseated, providing no down force on the tire. So, I figure the limiting strap should be just long enough to let it drop to the point at which the coil becomes unseated. Any input about this is appreciated.

Overall I'm happy with how the suspension is working out so far, still gotta get it on a trail and see how it does.

Jump This

September 6th, 2003, 11:16

Hmmm.....I have noticed other shots of extreme front end articulation with the spring 'unseated' This is not an entirely bad thing. Your wheel is being forced down by the opposite wheel anyway (okay...this is only to a certain degree but still there is enough force for a locked front end to work)
I have yet to see anyone using a limiting strap to solve the unseated spring problem. Straps on the rear spring pack are a bit more common. Sometimes to solve lean angle and sometimes to keep the spring pack together!
Have you taken this set up out to play yet? Notice anything unacceptable about how it works?
But you need to know one thing....this is just one opinion and its worth about what you pay for it!! :D

Fullsizexj

September 6th, 2003, 12:58

Seeing as your front coil does not drop down far enough to fall out, I would not use limiting straps, remember a tire that is touching the ground has more traction than one that is lifted in the air, may not be much more but it is still more

vintagespeed

September 6th, 2003, 13:01

John, try lifting that 'unloaded' tire off the ground. It wont budge, there is alot of force on that tire, even though the body weight isn't on it. 4 on the ground is better than 3 period.

Bones

September 6th, 2003, 13:49

John,
Unless you are having problems with binding, I would not put outboard limiting straps on the front. I say out board straps meaning one near each coil. They would limit your drop at times you might actually benefit from it. What I would do is a triangulated strap set up with a single centered axle strap location and a frame mount on each side. This will still let your axle articulate well but limit the spring extension on steep climbs keeping the weight shifted more over the front.

Check with Goatman about his set up. It works really well and can be adjusted as needed or removed when not needed.

Bones :skull1:

If it doesn't bind and the spring doesn't fall off is front flex really a problem? http://images.fotki.com/v12/photos/4/42106/157829/lh10-vi.jpg

JnJ

September 6th, 2003, 14:01

I didn't mention the fact that the strap would keep my shocks from becoming the limiting factor which could damage the shocks. In the picture the highlift is maxed out, the front flex is not, in other words, the tire is no where near ready to come off the ground yet.
Bones, I have planned for a center strap to prevent unloading during climbs, but I'm also worried about maxing out the shocks on full droop and the need for the tire to droop that much with no real down force for traction. Do I really need more front droop then what I have in the pictures?
Fullsize, I think if I had something to flex it more with (highlift maxed out), it would go until the spring falls out. Oh ya, I couldn't go any higher in the garage either. :)
I'm looking for opinions, so keep them coming.

Scott Mac.

September 6th, 2003, 14:14

Get longer shocks. :rolleyes:

JnJ

September 6th, 2003, 14:28

Originally posted by Scott Mac.
Get longer shocks. :rolleyes:
Scotty Scotty Scotty :rolleyes: Then they would be to long and I'll have to worry about bottoming them out. Gotta find the balance, that is what I'm after.

4ward

September 6th, 2003, 16:28

John, you need to step out here and think outside the box. I think you need some shock towers stickin' out the hood. Only you can say if it has too much flex or not. I'm a fan of flex, a lot of folks aren't.

Limiting straps are a good thing to keep from destroying your shocks and their mounts. I've been through a few sets recently cuz I wasn't running straps. I've got 'em on now though.

Jump This

September 6th, 2003, 16:38

Shocks are not bothered by exstention at the speeds 4X4s generate. That is to say that when our shocks reach full exstention it is not with much force or impact. On the other hand using your shocks as an upper (compression) stop is not such a good idea....these loads are often much greater. Now before others here jump on me for taking too simple of an approach on the exstention issue...it should be said that some shocks don't handle either situation well....but, we have been using them as limiting straps for years...the manufacturers know this and most quality shocks can handle it....

Beezil

September 6th, 2003, 20:18

you are gonna want to have some kind of centered limiting strap on your front axle.....

I got one on my raduis arm set-up after moab, and attempted a tall ledge climb, and while underway, the limiting strap took hold, and it felt like the ND offesive line jumped on my hood...

only wish I wopulda had that thing installed last moab.....woulda helped keep goats yapper shut

PhatXJ

September 6th, 2003, 23:14

I was loosing my coils, so I installed limiting straps.

Some people call them brake lines though, havn't figured it out :confused:

http://myweb.cableone.net/twizum007/temp/Virtue_Flats2_006.jpg

http://myweb.cableone.net/twizum007/temp/Virtue_Flats2_005.jpg

:D ;) ;) ;)

:anon:

randomxj

September 7th, 2003, 06:04

you know if you unscrew the bolt were the hard line meets the soft line and make it strait then bolt it down you get about 2 or 3 more inches of limiting strap.

woody

September 7th, 2003, 06:28

JnJ I'd have to agree with Jump that having the shox top out at extreme droop isn't a terrible thing in the low-speed rockcrawl rig. Now for a desert racer, it might be very bad though.

As they are mounted now (I see you have used 'eye' type upper shox mts) how much uptravel is left in the shock before it bottoms out?

My setup is slightly weird...my shox mount to the side of the LCA...a few inches lower than the stock axle BP mount, and I am using a upper mount like yours (Rusty's 11" travel hydros with 'eye' mounts upper & lower) I ran out of shock down-travel way before the suspension ran out of potential flex.

As a 'quick fix' I ran to the hardware store and bought a pair of 2" "Extenders" which are hex shaped and threaded all the way through - same pitch as the upper mount bolts. With these in between the fenders and the mounts, I still don't bottom out the shock, but it adds a bunch more droop (the +2" at the shock = a bit more at the wheel)

I can see where a center strap would help the front from unloading on hillclimbs (or jumps) and help keep traction on the front tires. It may take some tuning to optimize how much limiting you need.

JnJ

September 7th, 2003, 06:39

Oneton, shock hoops through the hood are so yesterday. Maybe quick disconnect shocks. I do like flex, but I think there is a balance between usable flex and traction. I'm trying to avoid wasting shocks and such trying to maintain unnecessary flex. I'll have to get it out on a test run or two to really know what to do about the straps.
Beez, I do plan to run the centered strap.
PhatXJ, unfortunately, my dang brake lines are to long to act as limiting straps. Maybe I should invest in some shorter ones.

JnJ

September 7th, 2003, 06:53

Originally posted by woody
JnJ I'd have to agree with Jump that having the shox top out at extreme droop isn't a terrible thing in the low-speed rockcrawl rig. Now for a desert racer, it might be very bad though.

As they are mounted now (I see you have used 'eye' type upper shox mts) how much uptravel is left in the shock before it bottoms out?

My setup is slightly weird...my shox mount to the side of the LCA...a few inches lower than the stock axle BP mount, and I am using a upper mount like yours (Rusty's 11" travel hydros with 'eye' mounts upper & lower) I ran out of shock down-travel way before the suspension ran out of potential flex.

As a 'quick fix' I ran to the hardware store and bought a pair of 2" "Extenders" which are hex shaped and threaded all the way through - same pitch as the upper mount bolts. With these in between the fenders and the mounts, I still don't bottom out the shock, but it adds a bunch more droop (the +2" at the shock = a bit more at the wheel)

I can see where a center strap would help the front from unloading on hillclimbs (or jumps) and help keep traction on the front tires. It may take some tuning to optimize how much limiting you need.

Woody, these are 13" travel shocks, in the pictures above, the shock is extended to 12", so it could go another inch before full extension. The mounts are setup for these shocks so that on compression the bumpstop will hit just before the shock bottoms out (this is in theory, I did a lot of measuring, but I have not actually bottomed out the compression yet). So, extending the shock mount is not really an option. On my old suspension, the shocks (front and rear) were my limiting factors, but since I'm building this suspension myself, I would like to do it without that kind of compromise if I can. If I had to use the shock as a limiting factor, I would much rather it be for droop then compression.

Scott Mac.

September 7th, 2003, 07:23

Originally posted by JnJ
Scotty Scotty Scotty :rolleyes: Then they would be to long and I'll have to worry about bottoming them out. Gotta find the balance, that is what I'm after.

Hoop up through the hood.:rolleyes:

JnJ

September 7th, 2003, 07:29

Originally posted by Scott Mac.
Hoop up through the hood.:rolleyes:

Moving a little slow lately aren't ya? :dunce:

Beezil

September 7th, 2003, 08:01

okay, well if you are doing a centered limitng strap up front, fine, it will help loads...

otherwise, your garage science project hasn't proven straps are necessary on the corners.

keep going, you can also add them later.

I think you should at least shoot for more travel....

the sucky part on a cherokee is trying to get the REAR to behave at higher lift heights.....I'm talking the ability to flex without having to have crazy body roll.....thats the challenge

Scott Mac.

September 7th, 2003, 08:15

Originally posted by JnJ
Moving a little slow lately aren't ya? :dunce:

It's the weekend I'm not getting paid to think.

Beezil

September 7th, 2003, 08:33

damn, jnj called scotty slow......yikes!

4ward

September 7th, 2003, 08:36

Actually, the hoop probably wouldn't have to go through the hood. There is a lot of room in between where your upper mount is and the bottom of the hood. Come awn John, do it so I can copy it and not have to do all the R&D :D

Scott, what's your excuse during the week then??????

Ted Z

September 7th, 2003, 09:58

Beezil, you saying with much travel you should put a limiting strap to a crossmember up front? I am getting my radius arms on this week and thinkin about moab and if i will need a strap.....

Beezil

September 7th, 2003, 10:46

absolutly.

main problem with long arms, is front end unloading....

the tougher Moab obstacles are largely all about ledge climbs. I set up a limiting strap to give me around 4" of straight axle droop.

obviously, centering the limiting strap does not effect the axles ability to articulate.

Carpenter

September 7th, 2003, 12:39

I used to follow the more-flex-the-better thoery but after a few scary circumstances with an unchecked, long arm front end I decided to go the limiting strap route. I set mine up kind of what JnJ is describing at the shocks, they limit down travel to when the spring is about to unseat. I also have triangulated straps over the front axle to prevent unloading. I can say that the Jeep works better now and feels MUCH better in all circumstances. There is no way I will run without limiting straps from now on. I don't worry about steep climbs now and, it's probably all in my head but, off camber stuff doesn't bother me as much now either. I have yet to have any problems lifting tires. The suspension feels so much more stable and controled now. Yes flex is good but there comes a point where it hurts you. Just look at the picture Bones posted. Imagine that driver's front tire had to climb a large rock or ledge coming up from that drooped postion, if the tire was up farther, limited by a strap to begin with, it would make that climb a whole lot easier. The harcore rock guys figured out a long time ago that too much flex is a bad thing, just look at all the limiting straps and sway bars on the competition rigs. Having run both ways, straps and no straps, on the same setup I will say that I would take a suspension held in check by a limiting straps over a flexy ramp champ any day. On the trails it just works better.

Scott Mac.

September 7th, 2003, 13:37

Originally posted by OneTonXJ

Scott, what's your excuse during the week then??????

I never said I was well paid.

Mike L

September 7th, 2003, 15:56

Originally posted by Beezil
okay, well if you are doing a centered limitng strap up front, fine, it will help loads...

otherwise, your garage science project hasn't proven straps are necessary on the corners.

keep going, you can also add them later.

I saw that you recommended 2 center limit straps going from the frame rails to the center like Goatmans. What about 1 single strap going from the middle under the oil pan to the center of the axle? Other than adjustability, what's the difference?

-Mike L.

Beezil

September 7th, 2003, 17:49

I've never recommended two straps. I use a single limiting strap that hangs from a crosstube thats rolled ina gentle arc that sneaks right underneath the oil pan.

Carpenter

September 7th, 2003, 18:55

Originally posted by Big Jeep 101
I saw that you recommended 2 center limit straps going from the frame rails to the center like Goatmans. What about 1 single strap going from the middle under the oil pan to the center of the axle? Other than adjustability, what's the difference?

-Mike L.

6 in one, half a dozen in another. I have a crossmember/trackbar brace running under my oil pan I could use yet I decided to install two straps coming from the sides meeting in the middle. Why? No real answer but it will work either way.

Jump This

September 7th, 2003, 19:22

I just want to see your centering strap set-up. Sounds great to me.......

Carpenter

September 7th, 2003, 19:36

Not the most recent shots and they don't show the recently added brace/x-member but they do show the straps.

http://www.fototime.com/1128F47BF04C6E5/standard.jpg

http://www.fototime.com/717E4D6E18DC560/standard.jpg

Jump This

September 7th, 2003, 19:47

I DO like!! Now some shots of it exstended!!
How long have you had this set-up?
Any durability issues yet?
How much droop does this allow for?
Any hot stock tips as well?

Rick

Ted Z

September 7th, 2003, 20:53

Where to get straps? How much to expect to pay for them?

Mike L

September 7th, 2003, 21:54

Are those center straps from a child's car seat? They look like the teathers to tie the seat down.

Ted Z: You can get limit straps from most any off-road/buggy shop. They typically run @$20 each. For more info, you can look at www.kartek.com

-Mike L.

Carpenter

September 8th, 2003, 05:04

Originally posted by Big Jeep 101
Are those center straps from a child's car seat? They look like the teathers to tie the seat down.

-Mike L.

Yeah, that's exactly what they are. :rolleyes: No, they are SFI certified adjustable limiting straps. The axle end mounting loops make them look funky but they were the only adjustable straps I could find.

xj4rocks

September 8th, 2003, 05:07

so what are you guys doing to keep you're springs from falling out? I've had them fall out with 11" travel shocks. i now have 13" travel shocks and haven't tested them yet but I forsee a problem with loosing springs.

ideas?

Carpenter

September 8th, 2003, 07:38

Originally posted by Jump This
I DO like!! Now some shots of it exstended!!

This shot shows about where the straps stop the front end from unloading.

http://www.fototime.com/5C0ADD3BD430CDA/standard.jpg

Old picture, they have been tightened a tad since then. I think the front axle can now drop straight down ~4-5" before the straps tighten.

Originally posted by Jump This
How long have you had this set-up?

Since December of last year, the above picture was taken two days after x-mas, that was the first trail run with the straps installed.

Originally posted by Jump This

Any durability issues yet?

None.

Originally posted by Jump This

Any hot stock tips as well?

Shocks are not bumpstops, nor are they limiting straps. It took me a while but I learned that one. It seems easy to use them as such but they are not intended for that type of use.

Carpenter

September 8th, 2003, 07:39

Originally posted by xj4rocks
so what are you guys doing to keep you're springs from falling out? I've had them fall out with 11" travel shocks. i now have 13" travel shocks and haven't tested them yet but I forsee a problem with loosing springs.

ideas?

Topic of the thread, look behind the shock for how I do it.

http://www.fototime.com/29D6DA776943B25/standard.jpg

JnJ

September 8th, 2003, 08:07

Originally posted by OneTonXJ
Actually, the hoop probably wouldn't have to go through the hood. There is a lot of room in between where your upper mount is and the bottom of the hood. Come awn John, do it so I can copy it and not have to do all the R&D :D

Scott, what's your excuse during the week then??????

Well since I just bought these shocks, and currently being unemployed (read broke), the shock hoop will have to wait. In a year or so, I'll be ready to copy your design. :D
Carpenter, I tend to agree with your thoughts on to much (uncontrolled?) flex. I do like your setup, I guess the bottom line is finding a balance that works for you (me).
I'm sure I'll do a center strap, then I'll have to wheel it some to determine the need, placement, and lenght for outboard straps.

PhatXJ

September 8th, 2003, 09:51

Originally posted by randomxj
you know if you unscrew the bolt were the hard line meets the soft line and make it strait then bolt it down you get about 2 or 3 more inches of limiting strap.

Really?!?!?! :D ;)

Originally posted by JnJ
PhatXJ, unfortunately, my dang brake lines are to long to act as limiting straps. Maybe I should invest in some shorter ones.

Yeah man, you should try it :D

xj4rocks

September 8th, 2003, 11:37

Originally posted by Carpenter
Topic of the thread, look behind the shock for how I do it.

Thanks wes ;) I was looking for ideas other than limiting straps. I guess i should have been more clear. I pulled the 11" shocks right out the of the fender, so I got some longer ones.

Ron S

September 9th, 2003, 16:43

my straps are inside the coils, attached to the axle and to the bumpstop post. i use cone machined from steel that has a stud that screws into the post and sandwiches the strap mounting tab in place. i've used this set up for over 4 years all because i wanted to keep the coils in no matter what, they always are guided back into place. i agree with carpenter, i have recently limited some of my wheel travel for stability reasons.