So, long story short I have about a 2.5-3" lift and the normal Bilstein 5100 rear shocks which are only meant for 0-2" of lift.

I noticed a thud when going over speed "humps" at over 20mph when the rear of my vehicle is bouncing up in there air.

Anyway, I can deal with this... the shocks are cheap at $75 each, I think if one breaks I can then replace with them longer shocks, maybe Dobinsons or something. Don't need to go crazy and rip them out and replace them now, hell I'm happy I just put them in a few weeks ago. I just need to go over speed humps slower. I figure also, when offroading, I tend to go slow anyway when there's lots of articulation.

But, I searched and I've seen failures of the 5100's possibly from overextension. This is the one thing I'm worried about - this happening if I'm out wheeling on a road trip.

Is it really that bad to overextend them sometimes? Does anyone else overextend their shocks frequently (5100's or otherwise - I mean, basically this happens at full droop right? Or why does my sway bar not limit it? Hmm)

That would annoy me far too much to keep like that… plus from what I read, is that those shocks also don’t really preform that great too far past their lift specs either…

If it was my truck, I would change the shock.

easy trick to confirm bottoming out on speed bump. put small dab grease on your bump stop. hit your speed bump and If your bottoming out it'll be easy to see the grease transferred over.

Great tip! I think I’m bottoming out my front suspension. I will try this trick tomorrow. Thanks!

Are you sure you are not just hearing the thud from the tires hitting the speed bump or landing after being airborne?

Pretty sure, this is a big round speed hump not the small harsh ones.

It kind of propels your car into the air. Don't think it's landing, either, that should be silent because of the coils right....also think the timing is wrong.

Either way I looked more into it and it seems bottoming out from compression seems more dangerous than overextending? Probably because bottoming out usually has more force? That makes me feel better, I think..

Can't wait to trash these Billie's then I can just get Icon's/King's. LOL

That's a good trick! But I think I'm overextending, not bottoming out..

To find out you can either measure your shock length at rest, or jack up the rear from the frame and see how much droop you have.

I’ve been bottoming out my shocks all week just going in and out of parking lots, but I also have the stock shocks on there right now with ~4” of lift.. my radflo’s are off getting rebuilt right now. I have maybe half an inch of down travel before they bottom out.

Are you talking about topping out or bottoming out? I am confused.

Both are not good for your shocks, that is why we have bump stops. Granted some might have top out bumps.

I was topping out on my old coil overs and was annoyed as all hell. So I went long travel and now don’t need to worry.

I wouldn’t go beyond the lift specs of the shock.


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hummmm,,, your thread title says 'bottoming out". Ooh well its an easy way to rule it out.

Right, topping out.

pretty sure i blew mine out by doing this... I was at 3" in the rear and like you said only ment for 2" - cant really blame them if im pushing them beyond the specs...

Im tearing them out and going a different route come spring when the salt is gone as they sound like they are loose and falling apart.

i remember the "thud" phase... only gets worse.

So I found the Bilstein 5125, which has multiple options. Bilstein 33-230375 seems to be what I need, but I wanted to double check.

Bilstein 5125 33-230375:

Collapsed Length (IN) - 17.11
Extended Length (IN) - 28.33
Mount Type - Stem-to-Eye


VS the popular Bilstein 5100 (0-2"):

Collapsed Length (IN)14.91
Extended Length (IN)23.50

Does this look like the right part? I know I might need bump stop extensions now to prevent it from "bottoming out" now, but at least it won't top out from overextending...

Again, this is to accommodate about a 3" lift.
Bilstein 33-230375 Rear B8 5125 Shock Absorber - Shockwarehouse.com

Careful, I’d cycle your suspension to see what your max extended length is before your coil starts dropping out. I’m working on a write up, but I just installed OME 899’s which are a 2-3” linear coil, and I can only go to 26” before th coils start coming loose. You’ll need a dual rate/progressive coil, or an incredible amount of lift, to fit a 28” shock.

I’m working with a company to have custom 10” travel shocks made to be used with 2-3” linear coils and 2” bump stop extensions, topped out at 26”. I can keep you posted on what I do.

You're probably right. I found another 5125 shock model - this one seems about right. 3" longer than the 5100, but not ridiculously long. I don't know how the compressed length can be similar though if the extended is longer.

Bilstein B8 5125 33-230351

Collapsed Length (IN) - 16.13
Extended Length (IN) - 26.38

UNFORTUNATELY, it does say the lower mounting eye is 5/8", compared to 19mm for the 5100's. So, I'm assuming it's not a direct fit for the rear?

Anyway, I just jacked up one side of my car and realized I only get about 3" of droop in the rear, compared to sitting height at rest.

My questions:
1)Is that low? Or normal for a lifted vehicle?
2)What normally limits downtravel? I heard it was shock length? Or could it be my rear KDSS sway bar or lower control arm?!
3)I saw in another post that other common rear shocks including Fox, OME, Icon, etc., all have an extended length of about 23.5-24". Does that mean that the shock is probably NOT the limiting factor of droop? Lots of people running around w/ 3" lifts with these shocks but I'm sure they are getting more travel ..

Copied from another post:
Bilstein 5100 Rears.....0-1" Lift 23.5" Extended
14.91" Compressed

Bilstein 5160 Rears.....0-2" Lift 23.62" Extended
14.84 Compressed

Fox 2.0 Rears............0-1.5" Lift 23.55" Extended
14.95" Compressed

(Funny that if these work for 1.5" the Bilsteins should also ???)

Fox 2.0 Rears.............2-3" Lift 24.65" Extended
15.55" Compressed

Icon 2.0....................2-3" Lift 24.3" Extended
14.8" Compressed

Old Man Emu..............60080 23.75" Extended
14.48" Compressed

Old Man Emu..............60004 22.83" Extended
14.01" Compressed

(Both of the OME's are confirmed by ARB USA to fit the 5th Gens mounting)

King 2.5" Rear......with Resi......... 24.29" Extended
15.58" Compressed