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Setting up Bump Stops and Limit Straps?

BarrelRoll

Well-Known Member
After beating on my '97 4 runner without limit straps and bump stops I have 2 blown front shocks and cracked coil buckets. Now it's time to do things right and avoid this carnage in the future. I have some limit straps with clevis and air bumps on the way.

What's the right way to set them up? I'm assuming install my shock without the coils, drop the suspension to set the limit strap and stuff it to set the bump. How much shock shaft should I have showing at full bump and unused down travel at full drop? Any other tips to get it right?

Thanks,
Andy
 

shock pros

Well-Known Member
There's ac couple of things to look out for when setting up limit straps. I'll TRY to keep the explanation real simple to keep this post short.

First, limit straps will stretch over time, so take that into consideration when mounting the clevis. Just say that your limit strap will stretch an inch over time, so leave some room for that and some threads on the clevis to adjust that extra inch or whatever it stretches over time. If not, the strap wont stop your arms from over-extending and damaging any other components.

Second, make sure to mount the straps so that when the arms open up and stop on the strap, the tabs and the clevis are in line. If you imagine the threaded bolt
on the clevis as an arrow, you want it pointing directly to the tab on the arm where the lower part of the strap is bolted to. The tab should be the same way. You don't want any lateral load on the tab or it will most likely break off and bend your strap tab as well. Mount the tab so it's standing up and pointing to the clevis. You want everything in line when it's being pulled tight at full droop.

Now onto the bump stops. Too many times I've seen bump stops mounted inside on the lower arm and it's engaging about 3/4 of the entire travel. Your riding on the bump stop and it's actually working as a shock for most of the time instead of just the final inches of travel. 4-runners don't have very much room to work with for this, so just do the best you can as far as mounting the bump stops as far outside as possible and only engaging at the very end of your travel. What kind of bump stop are you getting? Just for example, if your getting a Fox 2.0 bump stop, the standard size will be 4" travel. Depending on your arms, your 4-Runner probably has what, 10" of travel? I'm just guessing about your 4-Runner travel, but what I'm trying to explain is that the bump stop is going to work almost 50% of your travel depending on where you mount it. You want that bump stop to work just the last few inches. If you get it shortened to a 3" or a 2.5" bump stop, it might be better. Again, just using that Fox 2.0 as an example.

Now as far as actually mounting the parts, you will always have a limiting factor for bump or droop. Most likely for droop it will be the shock, so open it up and measure the shaft at full droop. I would leave it about a 1/4" from fully opening the shock. Just because the shock is such short travel to begin with. The bump stop you are going to depressurize completely so you can collapse it to full bottom. Compress your suspension to wherever you want the final stop to be, then mount the bump stop where it touches. Remember that most bump stops have a pad that will compress a little bit over time, so give it an extra 1/4" for that too.

Before we get into more details about mounting everything, let's get some info on what you're getting and we'll figure out what to do then. Keep us posted, I want to see what we can do.
 
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loufish

Well-Known Member
Now onto the bump stops. Too many times I've seen bump stops mounted inside on the lower arm and it's engaging about 3/4 of the entire travel. Your riding on the bump stop and it's actually working as a shock for most of the time instead of just the final inches of travel.
Well said...my pet peeve when looking at front suspension systems...
 

BarrelRoll

Well-Known Member
Shock Pros thanks for the really helpful reply.

It's a pretty darn stock 4 runner. It works pretty decent but I'd like to not destroy shocks and have a little better ride in the rough.

Front Suspension: TC uca's, bilstein adjustable height 5100's, 2" travel bilstein 2.0 bumps

Rear Suspension 2-3" lift coils, bilstein 5100's, after market track bar and lower control arms, these http://www.polyperformance.com/shop/Synergy-Suspension-Budget-Bump-Stop-p-25577.html in air bump cans with poly bumps till I can afford 2 more bumps.

What's the trick when welding the cans on? Should I leave those aluminum "budget bumps" in the cans when I weld them on?

Thanks for the help
 

BarrelRoll

Well-Known Member
I did some measuring and got my shock mounted. I have 9" of wheel travel without completely maxing out the shock (about 1/2" of shaft on stuff and drop before maxing out). The best spot/ farthest out practical spot to mount the bump travels 4 1/2" shortening my bumps. total and has around 2 1/4" from ride height to bump. How much of this travel should be in contact with the bump? If I keep them as 2" travel bumps They would engage 1" over ride high or roughly through 40% of my suspension travel. I'm thinking I need to look into shortening them. If I limit them to 1" travel bumps they would engage in the last 2" of travel and if I limit them to 1.25" travel bumps they would limit the last 2.5" of wheel travel.

Disclaimer all these measurements are dark drive way measurement and might be off slightly.
 
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Dezertbronco

Well-Known Member
dont Bilstiens have an internal stop? have you looked into Light Racings Jounce shocks? they may have a direct fit application?

I could be wrong.
 

shock pros

Well-Known Member
The street going shocks usually have a rebound cushion to prevent noise but its not intended to take repeated full droop yanking.
Exactly, and believe this guy, he knows a thing or two about shocks.
Even race shocks shouldn't be the limit strap. Save the shock.
 
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