How to Choose Shock Lengths

BrianJr said:

I am trying to determine what length rear shocks I need.

I tested the rear flex using two ramps on opposite wheels. I left the front sway bar connected to try and force more load to the rear. At the point just before I lost enough traction for the wheels to grab the shocks went from about 15.5 compressed to 20.5 extended. The 20.5" is the same length I saw when letting the axle hang, unsupported, below the XJ.

The Doetsch Tech 3163's will go from 13.0" compressed to 21.5" extended. So they are long enough for what I am seeing...

As loading changes, and the springs settle (weaken) how will the range of motion change? Am I better off, in the long run, going with a shock that allows more of an extended length, or less compressed? Should I be going with a longer shock? For example the 3231 goes from 13.5" to 22.5" and the 3265 goes from 14.5" to 24.5".

Also, the bump stops was still about 6" from the axle on the compressed side - so it does not seem like the springs would ever let them hit. Do I need to do anything about the rear bump stops or are they basically out of the picture now because the spring limits upward travel?

Thanks,
-Brian

BTW: I'll get some pictures up soon - you guys have been a great help figuring all this out. This has been my first lift and things are coming out quite nicely. Thanks.

Click to expand...

small pederson said:

dont let 4wheel parts do it

Click to expand...

Matt99XJ said:

It looks like you have the shock length measuring down but, you should get some bumpstops to limit your uptravel. If you keep letting the spring stop it then your springs will start to sag pretty bad and you risk bending them. You need to measure for shock lengths without any shocks on there at all. That way they aren't limiting your down or up travel. Then take those measurements and add about 1" to each end to have a little bit off slack so they don't bottom out.

Click to expand...