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JimmyG93

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Discussion starter · #1 ·
Rookie Question... I am currently not running any bump stops and after Saturday's wheeling trip I decided its time to get serious and put some in there (front for now). I already have extensions in place and I am only missing the rubber part. My question is, is which ones do I need or do you guys recommend? I have been doing some research and see several options and am wondering whats the best route to go?
 
Discussion starter · #3 ·
Aren't those extensions?
 
I ran the stock bumps the whole time I had springs - just kept adding hockey pucks (literally) to the base as needed.
 
The hockey pucks work great, but have to be glued together, or they can slip out when extended. I did a 1 3/4" extension and 3 pucks for a 5 1/2" lift. I don't rub at all with 33s. I'm going to take one out to see how it works.
 
I've seen the rubber part available at most auto parts stores. You should be able to press them in by hand into the bumpstop cups.

When I was at 4.5" Clayton's and 33x12.5 Trxus's on 3.75" backspacing (similar to the OP's set up but with long arms), I ran 5" of bumpstop extensions with the front limit strapped to where the coil would just barely unseat (keep in mind that limit straps can also help to reduce tire rubbing problems and prolong the life of your shocks). The extensions were hockey pucks bolted to the bottom of the spring perch. This was the minimum I needed to be able to still turn the tires while at full stuff.

For extending the bumpstop, I would recommend extending from the bottom of the coil spring instead of extending the existing post. Unlike a coilover, regular coil springs don't (de)compress in a straight line, so extending the post too far could give you rubbing issues of the bumpstop post on the coil spring.
 
Bump stopping my front end was a process of experimentation and measurement to get right.

The mystery was all over when I put it on a trailer and used my winch to suck down the front end. Standing in front of my rig and cycling the suspension around allowed me to determine the exact amount of stop needed as well as what suspension adjustment I can make to allow even more uptravel.

Also know that up front the maximum bump stop off the lower coil spring should be no more than 3 inches. All the rest of your bump stop length should be added to the unibody side. I run the RE 3 inch bump stops on the axle coil bucket. There is also a 1.5 inch spacer between the upper BS tower and the steel cup. It is perfect.
 
Also know that up front the maximum bump stop off the lower coil spring should be no more than 3 inches. All the rest of your bump stop length should be added to the unibody side.
I have no problem running 5" of bumpstop on the lower spring perch. I think it's a function of how your control arms are set up. Short arms should bow the spring more than long arms because the axle moves front to back more with short arms. An axle forward or backward of stock also affects the bowing of the coil springs.

So bottom line it just comes down to experimentation and measurement as Horus said.
 
Discussion starter · #11 ·
That's basically what I thought, and for the last wheeling trip I found that i can't even run my jeep with the swar bar disconnected due to it rubbing WAY to much. I already have the extensions in that lower the cup down, but don't have any rubber bump stops in there at all. I just purchased some of the daystar ones and I'll give em a try and see what works. I figure that if they are too long I'll just short'n them up a little... Plus I got some 1" spacers to lift it a little more since I've added the front bumper, soon will have a winch, extra battery, sliders, and rear bumper etc... With all that extra weight 5.5" will probably be more like 4.5"-5". But that extra height should still make a diference with the bump stops. Thanks guys for your answers, its good to hear from people who have experienced it and played with different varations of each individual set up.
 
Ive actually been using blocks of 2x4 glued in with "the right stuff" which is a super sealant/gasket maker glue that holds **** so strong i wont use it for sealing diff gaurds and stuff anymore.
This works just fine to get your height established. I got 2 blocks in there now for a 3" stop, which i have found to be about 1/2" too much with the setup and trimming ive done.
Im gonna sawzall off the 1/2" and wheel it some more to be sure before i build a nice little steel piece to tack in there on the coil bucket.
 
I have no problem running 5" of bumpstop on the lower spring perch. I think it's a function of how your control arms are set up. Short arms should bow the spring more than long arms because the axle moves front to back more with short arms. An axle forward or backward of stock also affects the bowing of the coil springs.

So bottom line it just comes down to experimentation and measurement as Horus said.
I guess it comes down to which problem you are trying to correct. My 3 inch max on the lowers rule has to do primarily with flex. Try to imagine your front axle and chassis flexing looking at it from the front. Generally speaking when your front suspension begins to flex the axle housing stays in the same position to the body, left to right. A result of this is the upper stops generally stay pointed directly at the lower perch. As the angular difference between the front axle and the chassis increases (as it flexes out) the lower perches have a tendency to point away from the upper perch location. The taller the lower stops are the more they deflect away from the location of the upper bump stop.

I have seen a guy post up pics of his "bump stop problem." The pics show the upper bump stop bushing contacting the side of his 5 or 6 inch tall lower stops.
 
Here is a very crude illustration....




Image




I say generally speaking because every setup is different and obviously going with a ton of upper mount will also cause a problem. When it comes down to it I guess 35 to 65 split lower to upper is probably a good rule of thumb.

Jimmy seems to want to BS out to stop tire rubbing under flex. To that I say trim dude, just trim. Look for the shiny spots inside your wheel wells and we'll show you how to pound it back or cut it out/off.:D

I tuned my bump stops because my axle and steering would smack the track bar bracket and oil pan. I still need to move some stuff around to create the opportunity for less upper BS and more uptravel. All of this has to do with running trails at speed and doing 40 mph over surfaces the zero uptravel guys do 2 mph on.

But....

Fully flexed out and picking a rear tire, neither of my bump stops are touching. In the photo I drew on? Still a finger thickness away on the stuffed side. ;)
 
Discussion starter · #15 ·
Mike, I THINK I have an understanding of what youre saying, I'm gunna have to just play with it a little and try to tune it in the way I want it. You're right about the flex issue, but right now I dont even know where to start.. I have rubbing issues in so many places its a little more difficult than it sounds. Since I'm not running any bs now I think this will deffinently really help. I'm also going to be getting my new CA installed and push the front forward a little which will also help.
 
Horus, I get exactly what you are saying about the bumpstop lining up and I agree. The 0-100 rule worked for me and the 65-35 rule seems to work for you :)

I have about 0.5" of uptravel less than stock (5" of extra bumpstop on the lower part on 4.5" lift). My bumpstops line up BOTH during flex and full suspension compression (I don't jump mine, but they line up just fine when I tie it down to the trailer). It also allows me to steer at full stuff. Less uptravel makes it easier to get the bumpstops to line up at both flex and bottoming each side out at the same time. My bumpstops were tuned for 33s, though, so I still need to tweak it with my 36s.

I'm going to somewhat disagree with the comment on just needing to trim or hammer to prevent it from rubbing. I agree that it should be done before tinkering with the bumpstops, but you can only pound the inner fender in so much. So, short of removing the inner fender, the tire will eventually rub on the inner fender (assuming nothing is binding in your suspension). Pounding it in gives you more uptravel, but the tire will still hit eventually. When your tire is stuffed into the inner fender, you can't steer. Many people have no problems with this happening, but I personally prefer to be able to steer.
 
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