jedg

So I see this question asked every so often and haven't found a thread that was titled clearly enough for folks to find the information. This is a plagiarism of a post by SoK66 from a couple years ago, but organized for easier reading.

Measurement 1:
With the tires, springs, shocks, the yellow upper bump stops and any kit supplied bump stop extensions removed, slowly raise the axle with floor jacks on each end of the axle, like on the control arm mounts.

Raise until the first point of contact between the axle and its components (track bar, steering, etc.) and the frame.

Take a measurement on each side between the upper bump stop tube and the axle bump stop pad, add about 1/2" and that is your absolute minimum bump stop requirement.

Measurement 2:
Next, repeat with the shocks installed and stop when you have about 1/2" of rod exposed on each shock or until you reach measurement #1.

Measure the upper and lower bump stop clearance again, this becomes your new minimum.

Measurement 3:
Now install the tires, repeat the process of raising the axle and again stop at the point at which you only have about 1/2" clearance between the tire and the underside of the flare or reach measurement #2.

Then turn the tires full lock each way and lower the axle if at any point the tires make contact with anything so you can maintain that 1/2" clearance between the tire and flare/inner fender lock to lock. (Some guys will even drop one side to the max shock extension and turn the wheels lock to lock.) Take THAT bump stop measurement . This becomes your new minimum bump stop.

Measurement 1 is your absolute minimum to prevent axle and component damaging steel-on-steel axle & frame contact.
Measurement 2 is what's needed to prevent potential shock damage from bottoming out.
Measurement 3 is what's needed to prevent the tires from making contact.


The measurement that is the greatest is the bumpstop that you require to prevent damage.

This information was pulled from Post #4 (by SoK66) of this thread - https://www.jk-forum.com/forums/modi...-2-5-a-315083/

WashingtonWrangler

Also, after you've got your bumps in there, repeat the same process on the bumps to double check, as the axle can continue to articulate when on the bump stops in some instances.

OnBelay

Old thread, I know, but thank you! We need new rear bump stops and weren't sure how to determine the correct length. We were thinking along the lines of measurement #2 in your write-up. It makes sense in retrospect, but it is nice to see in writing.

TheDirtman

But it came with the lift so I installed it. It should be correct right?

EHarris

Pretty much where I'm at right now but it seems they only make certain sizes? Do people trim or cut down bumpstops?

sa29560

My impression from my build is that the fronts are much easier to find a set length that will work, especially if you have flat fenders, less bump is really needed.

In the rear I trimmed around what matched my shocks and a preset bump stop length. Meaning, I found a standard available length that kept my shocks from bottoming out and trimmed where was necessary to reach said bump stop without obstruction.

Just my two cents.

DJ1

If not making your own, you can get bumpstop extensions that are adjustable like the MetalCloaks....






.

EHarris

Thanks for this info. I just ordered new rear uppers for my replacement suspension. I was running OME and with the added weight need to move to the 618 coils in the rear. So I'm still running the teraflex in the rear and will add the new uppers when they come in. Mine were thrashed and I got some help from forum members in a recent post.

Now I'm wondering if I ordered the wrong ones or if the last ones are way off also.

EHarris

These uppers look like they need replacing.

OnBelay

Could be worse; at least you have bump stop cups and bump stops. This is what happens when you catch air in Mexico, blow out your stops, and then the axle-side pads subsequently impact your bump stop cups...leaving them unable to hold bump stops.

Mopar doesn't sell the JK bump stop cup; it's part of the frame. We've been looking for a solution DOES NOT require cutting the frame and frenching in bump stop mounts + pneumatic bump stops. My husband just ordered some TJ cups and he's going to try to install them + TJ bump stops within the rear coils. We could cut off the existing stops and weld up the TJ cups, but we're thinking that the route mentioned above might be easier than cutting, fabbing up a bracket, and then welding on the TJ cups.

If anyone has any ideas other than the route mentioned above, feel free to share LOL!