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Bump stops

Retoohstyoh

Jr. Member
Joined
Jun 29, 2018
Messages
111
I’m in the process of installing a 2 1/2” sl on my highway only rig. My bump stops are shot. Do I even need them? If so, do I replace with stock or taller ones to match the lift?
 

NC-Fordguy

Bronco Guru
Joined
Jan 30, 2006
Messages
1,317
Loc.
Bethel/Greenville NC
This is where a RTI ramp will tell you what you need. I added the James Duff long travel lift a couple years ago to replace the one from 20 some years ago that was worn out.

The axles did not get into the bump stops as I discovered the front brake lines need to be extended. Still plenty of room to flex test farther once I address the brake lines.
 

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Apogee

Contributor
Bronco Guru
Joined
Nov 26, 2005
Messages
6,033
Bump stops are a good idea, but they don't really matter if you're not going to adjust them to account for your lift height. I have a 3.5" lift and didn't do anything about the bump stops when I installed it, and so far it's been fine, but I don't jump it and have taken it relatively easy off-road. I don't love bottoming against the shocks, but I'm pretty sure I've done that at least a few times. That said, some proper bump stops are in the works with the new F150 axles...and possibly some limit straps for the front, as I'm binding my drag link ends at full shock droop, and I'm pretty sure I could get more droop with a longer shock. We'll see what I end up with there.
 

Broncobowsher

Total hack
Joined
Jun 4, 2002
Messages
34,834
Bump stops are good. Unless your suspension is way too stiff you get into them more then you think. Even if you don't get into them that often there is always that chance for an unexpected impact with something that can bottom out the suspension.

Do you need taller ones? Depends on your tire clearance. Really sucks to smash a tire into the body when a taller bumpstop could have prevented it. Also sucks to be hitting the bump stops all the time because you got them way too tall.
The amount of lift really doesn't matter. It is the size of the tire and how much clearance you have with them. For a typical rubber or poly bumpstop I try to figure in a 50% squish factor. That is if they are 2" tall, they will squish down to 1". Poly is less forgiving (it hits harder when you bottom out). The next suspension I plan on doing I am keeping the rubber bump stops. Going to mount everything up, compress the suspension (leave the spring out) and see what hits and what doesn't. Expecting to build a spacer to set the bumpstop height right. I won't know how much until I mock everything together. That will also be when I measure for shocks, to make sure the compressed length is short enough.
 
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Retoohstyoh

Jr. Member
Joined
Jun 29, 2018
Messages
111
I just installed new shocks with a 2 1/2” lift. There is about 3 1/2” of travel left in them. There is a little over 8” of space between the bump stop bracket and frame. My question is how much space should I have after the stops are installed? Not sure what size stops to get.
 

Broncobowsher

Total hack
Joined
Jun 4, 2002
Messages
34,834
My suggestions, and I have done this, Put the Bronco on jackstands on the frame. Take the front springs out and put the tires and shocks back on. Now take a floor jack and run the suspension up. At some point you will run into a limitation. Tires into the body, shocks bottom out, axle into the oil pan, driveshaft into the exhaust, etc.

Now measure the gap. You want a bumpstop taller than the gap, they do have some squish to them. Solid poly is generally the least squish (10% maybe?). The new foam rubber cellular factory stuff has a lot more squish factor (maybe 75%?). No solid numbers here, lots of SWAG as for how much it will squish.

This gets into every Bronco is different. What works on one may work on yours, or be completely wrong. You have to figure what works on yours.
 

Apogee

Contributor
Bronco Guru
Joined
Nov 26, 2005
Messages
6,033
X2...or if you're a wealthy fabricator type, go air bumps and have some adjustability.
 
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