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PROTHANE FRONT BUMPSTOP WRITEUP
- Thread starter slcpunk74
- Start date
- Location
- Wasatch Range
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?
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.
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?
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.
- Location
- Bakersfield, CA
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.
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
NAXJA Forum User
- Location
- Here until I move
Ok, thanks. I get it now.
BoringDave
NAXJA Forum User
- Location
- Boring
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?
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.
You should ask Jim how many times you can do that till you bend your front axle.
But looks real good!
BoringDave
NAXJA Forum User
- Location
- Boring
What are you guys bolting your limit straps to?
Dave
Dave
- Location
- Bakersfield, CA
northwestxj
NAXJA Member #1283
- Location
- washington
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...
- Location
- San Diego
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.
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.
Last edited:
- Location
- Wasatch Range
Stock D30's bend easily, trussed and gusset D30's don't bend easily.
I'm pretty selective about when and where I jump.
Last edited:
Mike1331
NAXJA Forum User
- Location
- Folsom, CA
xjjeeper i think the pics you put out are among my favorites on this forum. Thanks for the inspiration.
Bolts?
Weld tabs to the axle and frame where you want the straps.
You smartazz:wave1:
BoringDave
NAXJA Forum User
- Location
- Boring
I deserved it! I should do more reading and less skimming though posts.
BoringDave
NAXJA Forum User
- Location
- Boring
X2 on the pics!
BoringDave
NAXJA Forum User
- Location
- Boring
Stock D30's bend easily, trussed and gusset D30's don't bend easily.
I'm pretty selective about when and where I jump.
I should also read post counts before I make smartazz remarks.
souske
NAXJA Forum User
- Location
- The land of competition
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.
- Location
- San Diego
10mm x 1.5p according to JKS
grandrunner
NAXJA Forum User
- Location
- La Quinta, SoCal
Stock D30's bend easily, trussed and gusset D30's don't bend easily.
I'm pretty selective about when and where I jump.
i here you on that one haha just bent/ broke mine..
not anymore:spin1:
ive been lookin at the daystar bumps. but might try this route first.
BoringDave
NAXJA Forum User
- Location
- Boring
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
Dave
souske
NAXJA Forum User
- Location
- The land of competition
got em in today. 10mm/1.5 was right on thanks 1990Jeepxj!
