Questions about bump stop and suspension setup

[Inca03rubi]

So to start out, Im no stranger to Jeeps and automotive work in general but after a few days of scratching my head, taking measurements and writing down endless note... Ive come to the conclusion that I need your help to figure out the best solution to my issue with my suspension question.

I have an 03 Rubicon with Teraflex's first generation 4" lift kit. These had the arms that were prone to bushing failures due to lack of grease fittings on the bushing ends and instead they placed the zerks on the mid sections where the arms would twist. This bit of info is probably not needed but wanted to include it.

I also have 33" tires on factory Moab wheels

I have upgraded my shocks to Bilstein 5100's, (front 24-188180 and rear 33-185514) due to the ones installed by the PO were blown out and had boots on them so up until now I had no idea that they were bottoming out.
These shocks have the following claimed measurements. Front 24.63 EXT / 14.98 COM / 9.65 TRAVEL Rear 25" EXT / 15.41 COM / 9.59 TRAVEL

The stock teraflex lift had the PO install the 2.5" bump extensions in the rear on the upper portion chassis side between the upper spring seat and jounce cup. This 2.5" figure is inline with all the research ive done when it came down to required minimum bump stops for a 4" lift kit install. Also to mention is that without the springs and shocks, i make no contact with any other components under the chassis and have clearance with the tank, track bar and other components.

Now with the new shocks installed in the rear, I have 5" of shock shaft exposed at ride height but when i do a driveway flex ive noticed that the shocks will bottom out before I am remotely close to making contact with the bump stops. As mentioned prior, i have 2.5" of bump extension already installed in the rear. For me to close the gap in between my bump stops, id have to install an additional 2.5" of additional bump extension in order for the bump to make proper contact with the bump stops and not ruin my new shocks.

Is this correct???

As it sits, ride height i have 5" of shock shaft showing.

At ride height i have 7.25" of clearance from the jounce cup to the spring pad with the 2.5" bump extensions in place.

At ride height I have 7.8" of gap between my 33's and the stock rubi fenders.

The shock from eye to eye while at this ride height was 21".

The spring height was 14" at ride height.

(Just a note, all these numbers are related so when im parked on a more level surface, the numbers all move up or down respectively. IE; the springs today were more around 12.75 on a more level lot.)

All measurements were taken with the Jeep unloaded. Soft top on, rear seat removed and no spare.

I appreciate any and all help that contributes to finding a proper solution. This jeep is bother my daily, trail rig and cross country toy.

Its served me well when stock and is still serving missions honorably. I would like to keep her that way.

Cheers!!

Josh

 

[Goatman]

So you are asking what is the proper shock size? Obviously you don't want to add more bump stop? And all the numbers you gave aren't much good if they are taken on a hill while all weight is removed.
Find a proper level spot, load the Jeep like you would normally have it loaded. Then take some measurements. And pictures help alot too. And clarify what problem, and solution you are looking for.

And WELCOME to the forum!

 

[tworley]

Add more bumpstop to keep your shocks from bottoming out. The flares are flexible and will move out of the way if the tire hits. Also, I dont believe you are looking at an added bumpstop in the rear, that extension piece is OEM (see below)

The propery way to bring your axle to full bump is by removing the coil springs, disconnecting the sway bar, and cycling the axle with a floor jack. FWIW--those sound like my old bilstiens lengths and at 4" of lift I was bumped 3" in the rear and 2" up front. In no way are those numbers related to your jeep and lift, but it can give you a starting point to figure how much bump you need.

 

[Inca03rubi]

Add more bumpstop to keep your shocks from bottoming out. The flares are flexible and will move out of the way if the tire hits. Also, I dont believe you are looking at an added bumpstop in the rear, that extension piece is OEM (see below)
View attachment 118098

The propery way to bring your axle to full bump is by removing the coil springs, disconnecting the sway bar, and cycling the axle with a floor jack. FWIW--those sound like my old bilstiens lengths and at 4" of lift I was bumped 3" in the rear and 2" up front. In no way are those numbers related to your jeep and lift, but it can give you a starting point to figure how much bump you need.

So I was told that the rear from the factory is setup with the jounce cup mounted directly to the upper spring perch.

Mine has a 2.5" aluminum extension then the jounce cup. So I was brought on to believe that the extension your referring to is aftermarket.

As it sits with that extensions yesterday I recorded new measurements but lack photos so i will explain with detail.

I removed the shocks, had to disconnect the rear track bar in order to allow the axle to droop far enough to allow the springs to drop out. Once the springs were removed I was able to compress and move the axle. As it sat, I had 1/4" of clearance from tire to flares when moving the axle My issue was that if I pushed the axle straight up from the center of the axle, the track bar relocation bracket made contact with the fuel lines and wire loom for the fuelpump. I took the measurement of the gap in between the bounce cup and pad at this position and I'd need a 2" bump additional to the current extension that is already installed.

At this compressed axle position the top shock mount to lower shock mount was 14.5" exact.

Current shock is roughly 15.59" compressed so I'd need to take that into consideration as well.

Full droop is perfect at a measurement of 24.5". This allowed the spring to just barely move in the perches and not fall out.

10" of total travel in theory but with my current shock I'd have to add +1" to the needed 2" bump and a washer to keep the shock safe and not bottoming out. This current bilstein shock will also allow for 25" of extension which is in range of my travel limits allowing me 9.59" of total travel. I believe with my spare and rear seat and no passengers I'm 5" of up travel and 4.59" of down. With passengers or some gear this should be almost dead in the middle of its travel.

I feel as though I've begun to answer my own questions and concerns with a little digging but want to ensure I'm not missing anything vital and have no one else to chat with when it comes to automotive anything.

With 33" tires and the new bump dimensions I'll be about 3" away from the flares at full compression or about 2" if I can find a shock that will meet my full range.

OME I believe has a shock that will meet this range but I'm unsure of how they compare to the Bilstein 5100's I JUST purchased at a tune of 360 bucks.

Does anyone have any recommendations of where to find bumps for the rear or what brand? This jeep has been quite the life experience so I'm hooked on the lifestyle. I've been road cars all my life so this lifted thing is new territory.

 

[mrblaine]

So I was told that the rear from the factory is setup with the jounce cup mounted directly to the upper spring perch.

Mine has a 2.5" aluminum extension then the jounce cup. So I was brought on to believe that the extension your referring to is aftermarket.

As it sits with that extensions yesterday I recorded new measurements but lack photos so i will explain with detail.

I removed the shocks, had to disconnect the rear track bar in order to allow the axle to droop far enough to allow the springs to drop out. Once the springs were removed I was able to compress and move the axle. As it sat, I had 1/4" of clearance from tire to flares when moving the axle My issue was that if I pushed the axle straight up from the center of the axle, the track bar relocation bracket made contact with the fuel lines and wire loom for the fuelpump. I took the measurement of the gap in between the bounce cup and pad at this position and I'd need a 2" bump additional to the current extension that is already installed.

At this compressed axle position the top shock mount to lower shock mount was 14.5" exact.

Current shock is roughly 15.59" compressed so I'd need to take that into consideration as well.

Full droop is perfect at a measurement of 24.5". This allowed the spring to just barely move in the perches and not fall out.

10" of total travel in theory but with my current shock I'd have to add +1" to the needed 2" bump and a washer to keep the shock safe and not bottoming out. This current bilstein shock will also allow for 25" of extension which is in range of my travel limits allowing me 9.59" of total travel. I believe with my spare and rear seat and no passengers I'm 5" of up travel and 4.59" of down. With passengers or some gear this should be almost dead in the middle of its travel.

I feel as though I've begun to answer my own questions and concerns with a little digging but want to ensure I'm not missing anything vital and have no one else to chat with when it comes to automotive anything.

With 33" tires and the new bump dimensions I'll be about 3" away from the flares at full compression or about 2" if I can find a shock that will meet my full range.

OME I believe has a shock that will meet this range but I'm unsure of how they compare to the Bilstein 5100's I JUST purchased at a tune of 360 bucks.

Does anyone have any recommendations of where to find bumps for the rear or what brand? This jeep has been quite the life experience so I'm hooked on the lifestyle. I've been road cars all my life so this lifted thing is new territory.

I don't do numbers. I have no idea what bumpstop extensions measure or how long a shock is generally. But, I do know that when I jack the axle up all the way to the bump stops, I add or remove enough to stop the axle so the shocks don't bottom out. Do that with some propery and it will all get better.

 

[Goatman]

This is an expert talking.

 

[tworley]

X2 to Blaine's post. Focus on your shocks. You dont want to leave unused travel, but you don't want to bottom them out either.

My issue was that if I pushed the axle straight up from the center of the axle, the track bar relocation bracket made contact with the fuel lines and wire loom for the fuelpump. I took the measurement of the gap in between the bounce cup and pad at this position and I'd need a 2" bump additional to the current extension that is already installed.

At this compressed axle position the top shock mount to lower shock mount was 14.5" exact.

Current shock is roughly 15.59" compressed so I'd need to take that into consideration as well.

Full droop is perfect at a measurement of 24.5". This allowed the spring to just barely move in the perches and not fall out.

10" of total travel in theory but with my current shock I'd have to add +1" to the needed 2" bump and a washer to keep the shock safe and not bottoming out. This current bilstein shock will also allow for 25" of extension which is in range of my travel limits allowing me 9.59" of total travel. I believe with my spare and rear seat and no passengers I'm 5" of up travel and 4.59" of down. With passengers or some gear this should be almost dead in the middle of its travel.

I feel as though I've begun to answer my own questions and concerns with a little digging but want to ensure I'm not missing anything vital and have no one else to chat with when it comes to automotive anything.

With 33" tires and the new bump dimensions I'll be about 3" away from the flares at full compression or about 2" if I can find a shock that will meet my full range.

Post a picture of your current jounce cup and "extension". I still believe what you have is stock. The jouce cup was never mounted directly to the spring pad. The photo I posted above is mine, and that is stock. It has the 2.5" extension. If I am reading this correctly, you are currently trying to set your bumpstops so your track bar mount will no longer hit the wiring loom for the fuel pump? If thats the case, get creative and move your wiring. Mine is zip tied up and out of the way on top of the frame rail if I recall. Once your jounce cup (with the soft poly bumper removed) and axle spring pad hit, start looking around. Is the track bar now clearing your relocated wiring? Is the track bar clearing the gas tank and upper cross member? Is your rear diff cover clearing the front of the gas tank? What is the distance from the upper shock mount to the lower shock mount? Does that number match your compressed shock length? If everything is good and clear but your distance between shock mounts is smaller than your shock, then add whatever bump is needed to keep your shock from bottoming out. Do not set bumpstops to keep your tire from hitting your plastic flare, they are flexible and will move out of the way. You dont want your tire contacting the body of the jeep.

 

[mrblaine]

X2 to Blaine's post. Focus on your shocks. You dont want to leave unused travel, but you don't want to bottom them out either.



Post a picture of your current jounce cup and "extension". I still believe what you have is stock. The jouce cup was never mounted directly to the spring pad. The photo I posted above is mine, and that is stock. It has the 2.5" extension. If I am reading this correctly, you are currently trying to set your bumpstops so your track bar mount will no longer hit the wiring loom for the fuel pump? If thats the case, get creative and move your wiring. Mine is zip tied up and out of the way on top of the frame rail if I recall. Once your jounce cup (with the soft poly bumper removed) and axle spring pad hit, start looking around. Is the track bar now clearing your relocated wiring? Is the track bar clearing the gas tank and upper cross member? Is your rear diff cover clearing the front of the gas tank? What is the distance from the upper shock mount to the lower shock mount? Does that number match your compressed shock length? If everything is good and clear but your distance between shock mounts is smaller than your shock, then add whatever bump is needed to keep your shock from bottoming out. Do not set bumpstops to keep your tire from hitting your plastic flare, they are flexible and will move out of the way. You dont want your tire contacting the body of the jeep.

The jounce bumper cup is mounted directly to the spring perch in stock form.

 

[tworley]

I'll be damned...

Thanks for the correction. I thought that extension was stock but after some googling I see I was wrong

 

[Inca03rubi]

I don't do numbers. I have no idea what bumpstop extensions measure or how long a shock is generally. But, I do know that when I jack the axle up all the way to the bump stops, I add or remove enough to stop the axle so the shocks don't bottom out. Do that with some propery and it will all get better.

Indeed, sometimes I really get deep in thought over things like suspension and realize maybe I'm just a little too precise for what my jeep does hahaha. After all of this is complete I will be reaching out for brakes, I sent a few emails regarding this. I will reach out again soon as I clear this up. You all are the best, made some new friends.

 

[Inca03rubi]

So with a 4" lift, 33's and a 15.5" compressed shock... what are others seeing for rear bump stop numbers. Just curious to see what others are getting for a final setup and the range in numbers. I'd like to know both the upper extended amount or overall total.

 

[mrblaine]

I'll be damned...

Thanks for the correction. I thought that extension was stock but after some googling I see I was wrong

Don't trust me enough that you had to google it? I see how you are.

 

[mrblaine]

So with a 4" lift, 33's and a 15.5" compressed shock... what are others seeing for rear bump stop numbers. Just curious to see what others are getting for a final setup and the range in numbers. I'd like to know both the upper extended amount or overall total.

And again, those numbers are generally meaningless. Unless they have exactly 4" of lift and all the crap loaded or not loaded into it that you have, nothing will correlate over exactly. Let the rig tell you what it needs.

 

[tworley]

Don't trust me enough that you had to google it? I see how you are.

I was trying to remember other setups I've seen online and in person and I couldnt recall the cup ever being mounted to the pad. Had to see it to believe it.

 

[tworley]

@Inca03rubi did I read post #4 right? You are trying to set your bump to clear the fuel pump connection/wiring? Is that the only thing limiting you from reaching full bump on the axle?

 

[mrblaine]

@Inca03rubi did I read post #4 right? You are trying to set your bump to clear the fuel pump connection/wiring? Is that the only thing limiting you from reaching full bump on the axle?

We just bend them and reroute away from the angled trackbar mount.

 

[Inca03rubi]

@Inca03rubi did I read post #4 right? You are trying to set your bump to clear the fuel pump connection/wiring? Is that the only thing limiting you from reaching full bump on the axle?

More or less, without the shocks installed the fuel lines and wiring was the only contact I made with the track bar relocation.
I'll redo the tests again because I read that the track bar should have been installed and I had to remove it in order for the axle to drop far enough to remove the springs. Other than that, the next thing to hit was the shocks at their full compression length which they sit at 15.59".
Conclusion I guess will be to add an additional 3" of bump on the axle spring pad and call it good.
With spare tire and back seat, the shock has roughly 5" exposed out of its total 9.59" of travel. Loaded would put me at 4.25-4.5" exposed shock, almost right smack in the middle.

Ideally if I had a shock that was 13-14.5" compressed and 24.5-25" extended that would be great hahaha. Full travel. But I doubt that exists for bilstein 5100's so I'll have to settle for what I have available.

You all have been a tremendous help thus far and hope that if I post again about the jeep, itll be something a bit more challenging.

 

[tworley]

Yes, re-do it all with the track bar in place and watch for it hitting in other spots as well. Set your bumpstops so that at full bump (if nothing else is in the way) your shocks have 1/4-1/2" of shaft showing. You can move the lines and wires as @mrblaine stated and get the travel you need, I had to do that with mine as well. The wiring is held into place with a series of zip ties.

 

[Inca03rubi]

Yes, re-do it all with the track bar in place and watch for it hitting in other spots as well. Set your bumpstops so that at full bump (if nothing else is in the way) your shocks have 1/4-1/2" of shaft showing. You can move the lines and wires as @mrblaine stated and get the travel you need, I had to do that with mine as well. The wiring is held into place with a series of zip ties.

Ya, if this is the case, I can hold short of the retest because I'm not gaining any more travel with these recommended Bilsteins. 3" is minimum needed to keep the shock from over compressing. Springs are also a bit too stiff so it's going to sit high no matter what. Spring is 15.25" removed from the jeep and loaded with my essential gear the springs measured out to be just a couple inches shorter. Unloaded the springs only compressed 1.25 inches. Until I find a shock that meets my jeeps full rear travel abilities, I'll be stopped.




Can anyone show me what size pucks or materials I will need to mount a bump on the axle pad? I dont feel proper adding a total of 5.5" of extension to the upper. Seems like a likely stress point to have it ripped off or sheared off. Lots of leverage there.

 

[jjvw]

Currie bumps divide the extension between the top and bottom.

Your spring math says the rear is at 6" of lift. That is a lot. Are you sure?

Measured from ride height, what will the up and down travels be with these shocks?