I'm trying to verify that I do/don't need bump stops on my RK 2.5" flex mod lift (I have them but am now wondering if I don't need them). So I'm trying to measure how much clearance I have between the bump stop and the frame and compare that with how much travel I think I have left on the shocks. I can look up the compressed shock length from the shock specs (Bilstein 5100s model 24-186872 front and 24-146715 rear) and compare that to the current length of the shock. But when measuring my current length, what are they measuring from? I'd hate to be off an inch, think I have room to spare, and then over-compress one of my shocks. On the other hand I've got plenty of room between my tires and fenders (chopped flares) so I'm not worried about rubbing.

 

Factory shocks have a compressed length of about 15" up front. So by that train of thought, for every inch of shock length (compressed) over stock, you need an addition inch of bump stop.

NOW.... That's only a ballpark and is not necessarily true for every rig. Ideally, you should remove the springs and cycle the suspension with shocks installed to properly set everything.

 

Ugh. After the hours it took me to wrestle the springs into position the last thing I want to do is pull them back out again. I understand the logic, just don't want to do the work

According to the Bilstein specs I've found the front shocks are 16.41" compressed and the rears are 15.39" compressed.

 

Just measure the gap between the front bumpstop pad on the axle to edge of the metal cup that holds the factory yellow or white bumpstop.(that bumpstop will compress completely flat with the metal cup). Then measure how much shaft of the front shocks are showing. If theres a 4" gap in the bumpstop and 5" of shaft on the shock showing then when fully flexed, you won't bottom out your shocks.
If its the other way around, 5" gap for the bumpstop and only 4" of shaft showing, then u will have to add an additional 1.25"-1.5" of bumpstop to the lower perch on axle

 

Well, I hate to break it to you but you're going to need to pull the springs anyway to install at least front bump stops. I would guess you need about 1-1.5" up front.

Rear I'm a little unsure. Usually you can get away with none in the rear and stock brackets on shorter lifts.

 

Here's my setup-
tf 2.5" lift with 2.5 rk coils in the front.
1.75" front bumpstop
2.5" rear bumpstop
Front lower spring retainers
Rear lower and upper spring retainers
Trimmed frenders,pinch seams and rubi sliders
11" long front sway bar links
9" long rear sway bar links
Bilsteins for 4" lift up front
Bilsteins for 2" lift in rear
EVO rockstars lower shock mounts
1.25" rough country body lift
37" BFG km2's on stock wheels
1.5" spidertrax wheel spacers

 

Lol, I did install bump stops on the front and back originally. But then as I looked at them I started thinking maybe I didn't need them and might get more flex. But you guys have talked me out of it.

 

I completely forgot that the factory bumpstop thing would compress. Now I feel better that I'm not missing out on some flex.