I purchased my first xj (99) about a month ago and the previous owner put a 4.5 RC lift on it and needless to say the shocks aren't that great. I know their are a lot of good reviews on the Bilstein 5100s and I can get all 4 for around $260 online. However the description says for between a 3 - 4 inch lift. Will they still work on my rig even though it has a 4.5 inch lift? Thanks for any help.

 

I tried to do my research. I even went to Bilstein's website. Here's the problem as I stated above. They show shocks for: stock, 2-3 inch lift, 3.5 -4, and then it jumps to 5-6.

 

Measure your current shock length, and then either start measuring flex or doing some really good guessing. Measure from bolt to bolt, and they will give "collapsed" and "extended" lengths, and those are what you need to reference.

If they are too short, it'll pull apart on top out (wheels dropping into a hole) or explode on compression (improperly bump stopped when wheel is in wheel well)

 

The specs for the 5-6" shocks are:
Rear:
15.91 collapsed
25.93 extended
Travel 10.02

Front:
16.97 collapsed
28.44 extended
11.47 travel

Specs for 3.5-4" lift shocks:
Rear:
14.88 collapsed
23.84 extended
8.96 travel

Front:
14.98 collapsed
24.61 extended
9.63 travel

My lift is a 4.5 I won't be doing any off-roading just a daily driver. Will the 3.5-4" shocks be sufficient or do I need to go with 5-6"?

 

Go outside (I know, right!?) and measure your shocks at ride height. One from the front and one from the back.

Take that number and compare it to the extended/collapsed lengths of the two different size bilstien shocks. You want to be as close to "in the middle" as possible. In other words, have similar up travel and down travel.

The only reason I'm recommending this technique is because you won't be wheeling your rig, so chances are you wont be fully collapsing or extending your shocks ever anyway.

 

Wait, so the answer to this whole issue is to just physically measure what he has. Never would have thunk that lol

 

I guess I'm just a newb but with the shocks on my vehicle in the settled neutral position, how does measuring that help me?

 

I'm happy you asked. To measure stance, measure from the top of the shock mount to the bottom shock mount. That's your standing length.

Now if you were to off road, we would tell you to take the shocks off and flex to you max. But that's not your case. After you get your standing length. Measure the distance between your frame rails and the bumpstop, in the rear, and measure the bumpstop distance in the front. This is generally your travel. You dont want your shock to act as a bumpstop, so the travel has to be less than the travel of the bumpstops. You will see what I mean when you're out there. I can't describe it fully, brain fart moment.

There's gonna be about several other pieces advice people will post after this. The main thing is, you dont want your shock to act as bumpstops or limit straps. So you should bottom out onto your bumpstops first, and with droop, there should still be some travel left in the shock. Generally a 3-4" shock would be fine for you and you can always add a bar pin eliminator to add up to an 1" of downtravel. However, I can't see your lift, that's why you must measure and not go by what everyone else says to just buy and do.

And to just add about measuring stance. Shocks generally have a compressed and extended length. Well if those lengths are 16" compressed and 24" extended, and you're neutral stance is 20". That gives you about 4" up and down travel. Real life numbers obviously work better. I hope my rambling makes it somewhat more clear.

 

Don't be supersized to find the RC lift has settled to below the advertised height of 4 1/2" but you "MUST measure everything even when flexed with the SB disconnected to find the correct shock length I have a 4 1/2" lift on mine 3" kit with ACOS spacer and a 1 1/2" Boomerang Shackle. With it bump stopped and flexed I needed the 5-6" 5100's After buying the 3-4" ones first, I did not measure at all and could have used them but did not have all the travel that I could use.


Measure twice buy once

 

Ok so the back and front shocks standing length is between 21-22 inches as is. The 3.5-4" show 23.84 extended for the rear and 24.61 for the front. The 5-6" shows 25.93 for extended in the rear and 28.44 for the front.


Also after looking under my rig I don't see any bump stops. In the front there is a metal tube/housing within the coil spring but no rubber sticking out of it. Is that normal? In the back they have pretty much rotted off or worn away. So what should I do?

 

Sounds like you need new bump stops all around and you may need to set the bumpstops so you don't eat fenders. Once you do that you can measure to get the right shock.

 

Ok so is there a certain length bump stop I should use or do they come in different lengths???

 

They come in multiple lengths and and be adjusted multiple ways. Typically the rear is done with just a longer snubber the front can be done with a longer snubber or by adding hockey pucks to the landing pad for the bump stop.

 

So I decided to double check and make sure the rig has a 4.5" lift because to this point it was just what the previous owner had told me. I went out and measured from the center of the rim cap to the edge of the fender. Rear measured 22.5" and the front 23". Is that not a 6" lift???? I was under the impression that stock was 17"????

 

Heres a pic of the rig. Its on 31.5 x 10.5