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bumpstops, shock length, and tires size. help me iron out the fuzzy points..

218K views 388 replies 109 participants last post by  PA2KTJ 
#1 · (Edited)
and things that need a better or more explanation.

it's something I've been working on not only for a base line, but to show how bumpstops vs. shock length play an important role in a suspension system besides using them to shoe horn in a set of 33's with no lift... for those who feel they don't need the ability to run high speeds on rough terrain.

the issues come up every day.. how long do my shocks need to be? how long will fit?, what size tires fit/can fit a given height?

another edit... this chart is directed at the front shock lengths, since the front is where the rubbing issues mostly occur the rear typically needs around 1" more than the front for the same length shock.





here's some bumptop/spring tech....

Rear Springs are Rancho 2.5" RS616... unloaded length is 15.5". collapsed to coil bind they are 5",

Which means the 2.5" rear lift springs REQUIRE a minimum of 1.5" bumstop extension whith the relocated spring perches, no loss or gain in ride height was made from the relocation, I made sure to set them exact.





A stock 104 rubicon/sahara rear spring is 11 3/4" unloaded, 3 3/8" @ full coil bind...




so, add/clarify a point/measurement, contest a point.... ect.

I'm not trying to prove anything here, just showing what each system and combination can/will do.... good or bad, depending on how one looks at it..
 
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#57 ·
well for now, im gonna just put the shocks on there with bumpstops, it'll be better than what im running now(no rear shocks, ripped off when wheeling last month), and eventually i'll pick up some relocation brackets and move the shocks. so 3 inches of extension for my bumpstops is the verdict for now?
 
#58 ·
that'll be close, just be sure to check. The lack of proper extension is the reason bar pins/bushings, and mounts get damaged or ripped off.
 
#60 ·
use the pic above and measure it... unless you want to pull springs and set it down till the shocks bottom out, then measure the distance between the metal cup and the spring pad with the rubber stop removed that will also show you the unflexed tire clearance, track bar relocation bracket to tub clearance, track bar to tank skid clearance and track bar to diff clearance up front.
 
#61 ·
Mudb8 will you help me out. Im trying to replace all my coils, shocks, and bumpstops soon. Id like to have 33" tires with around 3"-3.5" lift and a 1.25" bl and mml. I have the jks trac bar and solid diff covers. So Im pondering, 3" AEV Coils, OME n67L Front, OME n67 rears. 2" Bumpstops? Then after the Adj CAs, TT, SYE & CV, relocate the rear shock mounts and replace with n66L shocks.
 
#67 ·
Thought I would ask

Sorry for bringing this back but I have a few bumstop related questions and thoughts.

I am running a 4" RC LA with OME long travel shocks. What I have found is that in the front axle under full compression with the springs out I bottom out the front shocks with a measurement of about 3" for bumpstop. Does this seem right to everyone?
On the back I am at roughly 4" of bumpstop to prevent the shocks from bottoming out. I have the shock mounts extended on the back to help although I do notice some rubbing on the spring bucket. I don't have the pinion fully dialed in (its close) so I am hoping that help a little bit with the rubbing.

Experts let me hear your thoughts and thanks in advance!
 
#68 ·
are you missing the rubber bumpstop cups.... I see loads of them come in with the bolt in it and no cups or stops.

The front should need 2" at the point the shocks bottom out. Every one I've ever measured installed has needed 2" Including the one I did today..
The rear SS shock extension brackets angle the mount upward, which causes you to need excessive rear bumpstop length..


 
#74 ·
mudb8, you are right I am missing the rubber bumstop and cups. The PO installed the trailmaster extended bumpstop with screws on up top. Would you think that is why I need 3" up front? That is what I measured from top of spring bucket to where the bumstop screws in. For the rear my RC shock extenders are no angled like those you show in the picture. I am guessing that is why I have excessive bumpstop in the rear (4.5") Would you recommend SS angled shock extendsion brackets? Thanks for your feedback!
 
#70 ·
depends on the length of the bilstiens....

the 6241's (4" front lift shocks) are 15.8" collapsed and need a minimum of 2.25" bumpstop extension up front reguardless of what size tire you have or how high the lift is.
 
#78 ·
ChrisTJCO....
your question is good here...

"So reading this thread, I'm still confused.

With 245/75/16 BFG ATs (about 30.7"), with 2.5" OME HD Springs, and Skyjacker
Hydros with the following measurables:

Rears: *8.81 Shock Stroke (in.)
13.71 Collapsed Length (in.)
24.75 Extended Length (in.)
*

Fronts: *9.20 Shock Stroke (in.)
13.54 Collapsed Length (in.)
22.75 Extended Length (in.)

*

What kinda bumpstops am I looking at? Any??"

minimum 1.5" rear bumpstop extensions ........... I'd be inclined to say your rears aren't 24.75", they are 22.5"....

And NONE up front, 13.5" collapsed is the maximum length you can run stock front bumpstop extensions with. the tire size will be the problem needing bumpstop extension although the 245's shouldn't need any at all....
 
#83 ·
mudb8, for those of us who have lost their metal cups do you know what the measurement is for the metal cup? I am trying to figure out how that relates to the currie rear bumpstops. I believe that the currie rear bumpstops measure about 5 3/4". Is that too much bumpstop for the rear or does that equate to 2.5" of additional bumpstop using the factory metal cup in place? I have relocated my rear shock brackets and I am wondering if I need to remove some of the currie bumpstop or is it right where it needs to be for 5" uptravel. I have a 4" lift with OME 67L shocks.
 
#84 ·
the cup is 1.75" I don't have a currie stop handy to measure.

Sorry for the delay, I've been working late on the race truck and just haven't had time for anything else.
 
#86 ·
I'm waiting! LOL.
 
#88 ·
I know I'm resurecting a long dead thread here, but...

I'm preparing to lower my TJ from a 6" SA to a 4" SA and install a 1.25" BL. I'm running 35s. So, I can expext to run 3" front and 4" rear bump stop extensions?

I'm not lookitng for an exact definitive answer. I'm also not concerned about shock length at this time.

My plan is to set my wheel base to where my bump stopd line up properly at full bump, then add bump stopp extension as nescessary to prevent rubbing (I'm tired of the tire cuts from the body), and then figure out my shocks (hoping to outboard the rear).

I was just hoping for a round about estimate of what I will need for bump stop extensions to prevent rubbing with out cutting shet metal (I don't care if I run flares or not).
 
#90 ·
I need a shock length on some ome n66l's

im currently running 2.2's with about 5" of up travel after I put a 1" spacer in up front. Im looking to go to a longer shock and see if I can get about 6" or so of up travel. im considering making shock tabe to mount to the lca instead of the stock mount to get this up travel. out back i think I'll retain the 2.2's for a while as I have them out boarded using the oem mounts on 1/4" plate welded to the back of the lca mount.

any reccomendations?
 
#92 ·
I need a shock length on some ome n66l's

im currently running 2.2's with about 5" of up travel after I put a 1" spacer in up front. Im looking to go to a longer shock and see if I can get about 6" or so of up travel. im considering making shock tabe to mount to the lca instead of the stock mount to get this up travel. out back i think I'll retain the 2.2's for a while as I have them out boarded using the oem mounts on 1/4" plate welded to the back of the lca mount.

any reccomendations?
N66L's are 26.5" extended and 15.5" collapsed... the Rear N67L's are 24.5 extended and 14.5" collapsed.

I've had pretty good results with lowering the lower shock mounts....



Okay so I just recently put on a OME ZJ/LJ Lift (Got about 3'' in the front and 4'' in the back). My kit never came with any kind of bump stops, although I read now it says "includes rear bump stop extensions". I'm going to chat with my guy to see if this is the case.

The shocks I got are the long travel shocks, i cant find the part number at the moment...

I am going to be putting on 33x10.5x15 KM2s soon...What sort of bump stop extensions should I run?

Thanks for your help!
the OME long travel shocks are N66L, front and N67L for the rear. the front requires 2" extension minimum and the rear will be pushing 3" depending on the type of shock shifters you use, plus if you use the stupid BPE's, you'll be adding on even more extension.
 
#91 ·
Okay so I just recently put on a OME ZJ/LJ Lift (Got about 3'' in the front and 4'' in the back). My kit never came with any kind of bump stops, although I read now it says "includes rear bump stop extensions". I'm going to chat with my guy to see if this is the case.

The shocks I got are the long travel shocks, i cant find the part number at the moment...

I am going to be putting on 33x10.5x15 KM2s soon...What sort of bump stop extensions should I run?

Thanks for your help!
 
#93 ·
Mudb8,

Great thread, it helped a lot with the concepts. I'm still struggling with how to pick the best shock. I have a 06 LJ Rubi and I'll be going to AEV 3" springs, MC overline fenders, 1.25" BL running 35" tires. the rear does have shock relocators. I want to pick a shock that gives the best all around performance.

So by looking at your chart I want around a 23.75" extended shock, not sure of compressed length. I was thinking of the Bilstein but I think I read you don't like them.


I'm just not sure of how much extended length provides too much droop and at what length the compressed length robs to much up travel do to the bump stop required.

When I check-out shocks I get the following measurements:

Bilstein 5100 Front 3" - BE52731H5 - 24.14 - 14.88
Bilstein 5100 rear 3" - BE52732H5 - 22.44 - 13.98

Rancho 9000xl front 2.5" - RS999239 - 23.13 - 14.5
Rancho 9000xl front 3" - RS999255 - 25.88 - 15.88
Rancho 9000xl rear 2.5" - RS999241 - 20.88 - 13.63
Rancho 9000xl rear 3" - RS999256 - 24 - 15.13

OME 66 - N66 - 22.4 - 13.2
OME 67 - N67 - 22.1 - 13.3


What would you pick and why?
 
#94 ·
Mudb8,

Great thread, it helped a lot with the concepts. I'm still struggling with how to pick the best shock. I have a 06 LJ Rubi and I'll be going to AEV 3" springs, MC overline fenders, 1.25" BL running 35" tires. the rear does have shock relocators. I want to pick a shock that gives the best all around performance.

So by looking at your chart I want around a 23.75" extended shock, not sure of compressed length. I was thinking of the Bilstein but I think I read you don't like them.

I'm just not sure of how much extended length provides too much droop and at what length the compressed length robs to much up travel do to the bump stop required.

When I check-out shocks I get the following measurements:

Bilstein 5100 Front 3" - BE52731H5 - 24.14 - 14.88
Bilstein 5100 rear 3" - BE52732H5 - 22.44 - 13.98

Rancho 9000xl front 2.5" - RS999239 - 23.13 - 14.5
Rancho 9000xl front 3" - RS999255 - 25.88 - 15.88
Rancho 9000xl rear 2.5" - RS999241 - 20.88 - 13.63
Rancho 9000xl rear 3" - RS999256 - 24 - 15.13

OME 66 - N66 - 22.4 - 13.2
OME 67 - N67 - 22.1 - 13.3

What would you pick and why?
So I read and re-read this thread and others several times. I just don't have enough experience to know the answers to these two questions.

1.) If you ignore tire size, that's a different issue, with a 3" progressive rate spring like the AEV at what extended length will the spring unseat too much? 23, 24, 25?

2.) At what compressed length do you start to lose to much up travel do to bump stop required to keep from bottoming the shock, 13, 14, 15?

And I assume these numbers are different for the back since most shock kits have shorter numbers for the rear.

These both assume standard shock mount locations in the front and one of those sucky relocators in the back.

Knowing these numbers it's then a matter of finding the best balance between extended and compressed that are close to those numbers.
 
#97 ·
the 12" short body is 27.68 extended and 16.10 collapsed... they would be good for a 4" lift with close to 3" bumpstop extension but when you consider the mounting options that'll cost you 1.5" of uptravel it all goes out the door if you're trying to use them without modifying mounts.
 
#98 · (Edited)
Very informative thread. I'm new here (and to Jeeps) as you can probably tell by my post count, but I have been reading and learning a lot, and sifting through the posts for a few months now. I have a stock 05 Rubicon and I've collected everything I want to run suspension/wheel/tire wise except shocks. I would really like to run bilstein 5100/5125 if the lengths will work for me. If any of you seasoned suspension experts out there could yay/nay me on my thoughts here I would really appreciate it.

Setup is:

JKS acos front and rear, intend to set them at approx. 2"
1.25" JKS BL
1" JKS MML
285/75R16 Duratracs
Oem Moabs
1.25" spidertrax wheel spacers
JKS barpin eliminators (also have a different style teraflex front BPE that is a little taller, and I'm not opposed to using that and/or getting the taller one for the rear to help with shock length fitment) I would like to run the BPE's though because I think it is a better design than the bar pins.
bushwacker flat flares

I was initially considering running the 5100's listed for a TJ with 3" lift, but I think I can do a little better with the 5125 in a universal size, plus the BPE's and/or eye to stem conversion. I'm not sure exactly how much effective length is added to the shocks from these items but I am guessing JKS BPE .5" front/rear. Teraflex BPE 1" front/rear. Stem to eye conversion 1" front. If you have better data on this please let me know.

I'm looking at the following Bilstein's
Model # Travel Valving Extended Compressed Mounting
BE5-6252-H5 8.13 255/70 21.54 13.58 14mm eye/eye
BE5-6253-H5 8.60 255/70 22.50 14.06 14mm eye/eye
EDIT just found this one...might be a little short for the front even with the BPE?
BE5-6526-H5 7.62 224/100 20.45 12.83 14mm Stem/eye

All shocks come with 5/8” hourglass bushings

Would need the BPE front & rear and the Stem to Eye front. I would love to find a suitable 5100/5125 with eye lower and stem upper for the front, but the only one I found in an appropriate length has VERY stiff valving and I think will ride terribly.

I am still open to other shock suggestions, but admittedly I am partial to bilstein, which seem to consistently get high marks across almost all different brands of vehicle (and are highly regarded in the Toyota world...where I came from).

The Jeep will likely be more than 80% pavement use, so road manners are very important, but It will run beach, fire roads, and trails (disconnected) whenever possible!

Other shocks I've heard good things about:

Edelbrock Monotubes
Rubicon Express Monotubes (I think these are the same as the edelbrocks)
BDS (not sure if the hydros or nitros are recommended here)
Skyjacker (have heard the hydros are a good cheap option)
Rancho 9000 (I like that they are adjustable, but think for this kind of money bilsteins are higher quality)
OME (Even though they are pricey for a twin tube, I hear nothing but good things, these are popular with toyota guys too)
Monroe Reflex and/or sensatracs (good cheaper option?)
Stock JK rubicon shocks?
Doetsch (don't know much about these but they have come up a few times. They have good lengths)

Sorry for the lengthy post, I'm new to Jeeps but not to forums and I know it's frowned upon for a newbie to come on and just start asking questions without searching, so I have searched, I have learned, I have EVERYTHING listed above in my garage ready to install...I'm just having some trouble finalizing the shock decision, and this thread seems to have some really good contributions to it. Thanks in advance for any advice you can offer! Once I learn a little more I hope to be able to offer some back!
 
#99 ·
Very informative thread. I'm new here (and to Jeeps) as you can probably tell by my post count, but I have been reading and learning a lot, and sifting through the posts for a few months now. I have a stock 05 Rubicon and I've collected everything I want to run suspension/wheel/tire wise except shocks. I would really like to run bilstein 5100/5125 if the lengths will work for me. If any of you seasoned suspension experts out there could yay/nay me on my thoughts here I would really appreciate it.

Setup is:

JKS acos front and rear, intend to set them at approx. 2"
1.25" JKS BL
1" JKS MML
285/75R16 Duratracs
Oem Moabs
1.25" spidertrax wheel spacers
JKS barpin eliminators (also have a different style teraflex front BPE that is a little taller, and I'm not opposed to using that and/or getting the taller one for the rear to help with shock length fitment) I would like to run the BPE's though because I think it is a better design than the bar pins.
bushwacker flat flares

I was initially considering running the 5100's listed for a TJ with 3" lift, but I think I can do a little better with the 5125 in a universal size, plus the BPE's and/or eye to stem conversion. I'm not sure exactly how much effective length is added to the shocks from these items but I am guessing JKS BPE .5" front/rear. Teraflex BPE 1" front/rear. Stem to eye conversion 1" front. If you have better data on this please let me know.

I'm looking at the following Bilstein's
Model # Travel Valving Extended Compressed Mounting
BE5-6252-H5 8.13 255/70 21.54 13.58 14mm eye/eye
BE5-6253-H5 8.60 255/70 22.50 14.06 14mm eye/eye
EDIT just found this one...might be a little short for the front even with the BPE?
BE5-6526-H5 7.62 224/100 20.45 12.83 14mm Stem/eye

All shocks come with 5/8" hourglass bushings

Would need the BPE front & rear and the Stem to Eye front. I would love to find a suitable 5100/5125 with eye lower and stem upper for the front, but the only one I found in an appropriate length has VERY stiff valving and I think will ride terribly.

I am still open to other shock suggestions, but admittedly I am partial to bilstein, which seem to consistently get high marks across almost all different brands of vehicle (and are highly regarded in the Toyota world...where I came from).

The Jeep will likely be more than 80% pavement use, so road manners are very important, but It will run beach, fire roads, and trails (disconnected) whenever possible!

Other shocks I've heard good things about:

Edelbrock Monotubes
Rubicon Express Monotubes (I think these are the same as the edelbrocks)
BDS (not sure if the hydros or nitros are recommended here)
Skyjacker (have heard the hydros are a good cheap option)
Rancho 9000 (I like that they are adjustable, but think for this kind of money bilsteins are higher quality)
OME (Even though they are pricey for a twin tube, I hear nothing but good things, these are popular with toyota guys too)
Monroe Reflex and/or sensatracs (good cheaper option?)
Stock JK rubicon shocks?
Doetsch (don't know much about these but they have come up a few times. They have good lengths)

Sorry for the lengthy post, I'm new to Jeeps but not to forums and I know it's frowned upon for a newbie to come on and just start asking questions without searching, so I have searched, I have learned, I have EVERYTHING listed above in my garage ready to install...I'm just having some trouble finalizing the shock decision, and this thread seems to have some really good contributions to it. Thanks in advance for any advice you can offer! Once I learn a little more I hope to be able to offer some back!
Forget about the bpe/conversion stuff and use 5100's for 0-3" lift with proper bumpstop extension....

the conversion/bpe stuff takes away valuable uptravel and isn't a good idea unless you have over 4.5" of lift.... if you want to use 5125's and elimiate bpe's outboard mount the rears and relocate the lower front mounts using 10" travel shocks. See the other links in my sig.
 
#100 ·
Thanks for the advice mudb8. I understand that BPE's can take away uptravel, but only if the shock isn't sized with the additional length of the BPE in mind. That being said, the difficulty is in finding an ~8" travel shock with a shorter overall (and compressed) length, to accomodate the extra 1/2" or more of length that the BPE will add. I got my hands on some Monroe Reflex Monotube JK shocks for stock height that were taken off after only a month of use when the jeep was lifted, and my initial measurements look promising. We'll see how difficult it will be to make them work. If they don't work well, no big deal since the investment was very low. I can always go back to my original plans and get the 5100 (if I can find them in stock) That was actually the first problem. I ordered them in September from shockwarehouse.com and they kept pushing the date that they would be available. Finally I called Bilstein who told me shock warehouse won't be getting any until next year! Too bad too, because they were a good price, especially after the promo code. Anyway...I'm gonna try these shocks and see what I come up with. They will at the very least get me by until Jan if I decide to re-order the 5100's. Thanks again for the advice. This forum has been invaluable in educating me about my options. I'm very much looking forward to the install...if only it were warmer here!!
 
#101 ·
I have been reading all these posts and I still have a question about shock relocation brackets and bumpstop length.

I bought a set of RE 3.5 inch springs and a set of shocks.
BILSTEIN Front 5100 Series Gas Shock Absorber
For 97-06 Jeep® Wrangler TJ & Unlimited with 4" Lift
Quadratec Part No: 16070.202
Manufacturer Part No: BE56241H5

BILSTEIN Rear 5100 Series Gas Shock Absorber
For 97-06 Jeep® Wrangler TJ & Unlimited with 4" Lift
Quadratec Part No: 16070.203
Manufacturer Part No: BE56242H5

Im ordering a Rock Krawler TB and Tie rod, but im unsure of what length bumpstops I will need inorder to keep the shocks from bottoming out?

I currently have a 2" teraflex coil spacers and 2" shocks, but Im wanting to get rid of the coil spacers...

Any help would be appreciated.
 
#102 ·
the 6242 rear shocks won't give you much uptravel as listed @25.50" / 15.49"
you'll need around 3.5-4"+ bumpstop extension.
a better fit for non relocated rear shocks is the BE52732H5 @23" / 14.5" (actual measurements.... q-tec's lengths are wrong.)which will need around 2.5-3" bumpstop extension....

up front since you'll be needing 2" extensions to keep the track bar off your diff cover, the 6241's will be fine.
 
#103 ·
thanks mudb8, after doing some measuring and looking at some of your past post about shocks and bumpstops I have a better idea of what its gonna take to get a good setup..

From me to you, I think you really know your stuff when it comes to the ins and outs of jeep mods....
 
#104 ·
Let me see if I'm getting this before I order another set of shocks (1st set don't fit right):

From the center of shock mount to mount with no shocks installed, I have 16 3/4"
From the base of the spring to the very top of the bumpstop (like it was totally collapsed) I have 6".

So my collapsed shock length needs to be 10 3/4"? Seems logical.

I have a 3.5" lift and can't find shocks that short. :confused: Why can't I wrap my head around this?
 
#106 ·
I am really new to this but I have recently fallen in love with my jeep and can't stop adding stuff and working on it. My latest endeavor is putting in a bb lift. I have been doing research and reading up on tons of threads trying to figure out what works and what doesn't. Now I'm just hoping someone can check my work and offer some suggestions to tie up loose ends. :)

I want to install 3" bb lift with perf. 8000 shocks. I plan on switching the front coil springs to the back and installing 3" lift front coil springs. I got 15" soft 8's and 31" tires. I do not know if I will need a steering stabilizer or bump stop extenders or anything else however.

This is my daily driver so I would like a smooth ride. I do not go offroading much but I would love to start, nothing crazy, just wanna try something new.
Any help would be much appreciated. Feel free to point out good ideas or erroneous errors.
Thanks much.
 
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