Loud pop/clang during articulation - XJ

[rockclimber]

I
As far as the joint debate, rockclimber is right, though my 'opinion' doesn't mean sh!t.... Its relatively simple. They clamp, what's so hard to understand.

right, and the whole point of this argument is to say that it doesn't matter how much shit you weld to the outside of your mounts.

 

[chris420]

Mine makes all kinds of popping noises when I wheel. Most noises come from the springs when they are compressed all the way and then released quickly. I would worry about it it's an XJ if the doors shut after wheeling than everything is fine.

 

[blistovmhz]

Well, I couldn't find any evidence of the lower CA moving around, but I took it out and sure enough, the stock hole is lobed out.
Figured out that if I hammer on the brakes in reverse, then in forward gear, I can recreate the pop on command.

So I've been told by several people that weld washers wouldn't solve the problem, and told the opposite by many others (ie: engineers).

I figured just to be safe, I'd try two things at once.
1. Weld in some beefy 1/4" weld washers into the lower CA axle mount.
2. Applied a combination of powdered Unicorn and fair trade Mermaid tears to the steering wheel.

One of the above does seem to have resolved the issue. Haven't trail tested, but on the street, I can't make anything pop anymore. Even went and did a small jump on the road.

Given there were no other changes made, one of the above must be the resolution to this issue. As the "CA's are held in by friction" camp says the weld washers couldn't possibly work, I guess I must have got some really high potency powdered Unicorn and Mermaid tears.

 

[yossarian19]

I'd still recommend replacing the hardware & torquing to spec. The factory stuff is best, failing that, use a 9/16" grade 8 bolt and make sure *NO* threads are touching the control arm pocket. Use washers as needed (minimally, though) to take up the exposed "grip" (un threaded section) section of the bolt.
The clamping force + friction is "supposed" to keep the bolt from being loaded in shear / knocking into the bracket. Evidently, yours wasn't doing it - so two fixes: take up the space allowing the bolt to clunk and get 100% sure that your clamping force is as-designed.

 

[old_man]

Well, I couldn't find any evidence of the lower CA moving around, but I took it out and sure enough, the stock hole is lobed out.
Figured out that if I hammer on the brakes in reverse, then in forward gear, I can recreate the pop on command.

So I've been told by several people that weld washers wouldn't solve the problem, and told the opposite by many others (ie: engineers).

I figured just to be safe, I'd try two things at once.
1. Weld in some beefy 1/4" weld washers into the lower CA axle mount.
2. Applied a combination of powdered Unicorn and fair trade Mermaid tears to the steering wheel.

One of the above does seem to have resolved the issue. Haven't trail tested, but on the street, I can't make anything pop anymore. Even went and did a small jump on the road.

Given there were no other changes made, one of the above must be the resolution to this issue. As the "CA's are held in by friction" camp says the weld washers couldn't possibly work, I guess I must have got some really high potency powdered Unicorn and Mermaid tears.

When I did weld washers, I went a size down and then reamed them out to be a very tight fit over the bolts. Most washers have way too much slop. I'm and Engineer and machinist.

 

[blistovmhz]

When I did weld washers, I went a size down and then reamed them out to be a very tight fit over the bolts. Most washers have way too much slop. I'm and Engineer and machinist.

One's I used were machined specifically for the application. Precisely 9/16" ID, 1.5" OD, 0.25" thick. Bolts had to be hammered in to fit .

I'm IT by trade, but work for an engineering company as well.

If this doesn't do the trick long term, I'll just build some new lower mounts. I just didn't want to swap out mounts and discover it wasn't actually the problem. With the way I beat on things, I should have at least 1/4" thick boxed mounts anyway.

 

[rockclimber]

You wasted your time and energy by welding washers to the outside... But since you did it, it makes no difference. Keep them torqued to spec and you will be fine

If they loosen up, the same will happen again.

 

[x-jay vision]

Maybe the other theory is that the friction coefficient of the washers was much higher than that of the original bracket metal. That must be it...

 

[blistovmhz]

You wasted your time and energy by welding washers to the outside... But since you did it, it makes no difference. Keep them torqued to spec and you will be fine

If they loosen up, the same will happen again.

So what you're saying is that what I did won't work, but since I did it, I just have to keep it torqued to spec and it'll work?

Not trying to be a dick here, but the whole "friction" thing just doesn't make sense. The math proves this. Steel isn't strong enough, nor does it have a high enough friction coefficient to support several thousand pounds of truck, at upwards of 50 or 60 G's on bumps, with under 1/2" square contact patch.

I agree, that the friction does help keep things in place, but I do not agree that it is the most important factor. If it were, they wouldn't bother putting the caster adjust locker on the frame side mounts.
Friction helps keep things from moving CONSTANTLY. It'll retain the bolt and bushing sleeve relative to the mount for the trillions of tiny movements your truck makes over the course of a drive, which will absolutely keep your mounts from lobing out in 10 seconds, but adding 1/2" of extra steel to the outside will have the same effect long term. Again, this ain't my first rodeo. I've done weld washers on most of my Jeeps, and tonnes of others for friends, and not once have I seen a 1/4" washer lobe out in 7 years. Maybe the mounts will lobe out again in 10 years, but if my axles survive 10 years, I've clearly not driven the Jeep hard enough. As I said, I'll throw on some new mounts at some point, but I'm certainly not in a hurry as the last washers I installed were only 1/8" thick grade 5 steel, and they've held up to 5 years of abuse thus far and they haven't lobed out enough that I can measure any variance in the holes (I checked last night while installing the washers on the passenger side). Measured with a machinist caliper, and while there's certainly some variance in the hole, it's less than 0.002 of an inch, which could easily be accounted for by rust scale. The new washers are grade 8, 1/4".


As for "wasted my time", I'd say that if this answers my question about where the pop was coming from, with about 5 minutes of prep and welding, that's time damn well spent. Cost me 5 minutes and $4 and assuming it holds up on the trail for 10 minutes without a pop, it's proven the pop's origin. Even if the washers fail after 15 minutes, it's still time very well spent.

 

[rockclimber]

Maybe the other theory is that the friction coefficient of the washers was much higher than that of the original bracket metal. That must be it...

no. the friction is on the inner faces of the bracket. no matter what you weld to the outside, you haven't changed the inside faces

So what you're saying is that what I did won't work, but since I did it, I just have to keep it torqued to spec and it'll work?

no, what I am saying is that welding the washers on the outside didn't fix your problem.

Not trying to be a dick here, but the whole "friction" thing just doesn't make sense. The math proves this. Steel isn't strong enough, nor does it have a high enough friction coefficient to support several thousand pounds of truck, at upwards of 50 or 60 G's on bumps, with under 1/2" square contact patch.

you are completely wrong. friction of the joint sleeve on the inside faces of the mount is the ONLY THING THAT HOLDS THE JOINT IN PLACE. I don't know how else to say it. if that bolt sees any load besides tension, it WILL bend or break. the bolt is designed to be a clamp, clamping the joint INSIDE the bracket. once again welding shit to the outside of them doesn't increase that clamping power.

if you do not believe me, go crawl under the front of a TJ. they have slotted holes on the axle side LCA mounts. they use a cam washer to locate the bolt until it is tightened down. if the bolt is not tight, that washer will allow roughly 1/8" movement until that bolt is torqued. that much movement would destroy that bolt in a matter of hours, or one hard braking event. and yet, there are hundreds of thousands of TJs that have never had a failure.

I agree, that the friction does help keep things in place, but I do not agree that it is the most important factor. If it were, they wouldn't bother putting the caster adjust locker on the frame side mounts.

the only reason those guides are there is so that you get the bolt lined un in the right spot until it is torqued. its the same for the TJs cam washer

Friction helps keep things from moving CONSTANTLY. It'll retain the bolt and bushing sleeve relative to the mount for the trillions of tiny movements your truck makes over the course of a drive, which will absolutely keep your mounts from lobing out in 10 seconds, but adding 1/2" of extra steel to the outside will have the same effect long term. Again, this ain't my first rodeo. I've done weld washers on most of my Jeeps, and tonnes of others for friends, and not once have I seen a 1/4" washer lobe out in 7 years. Maybe the mounts will lobe out again in 10 years, but if my axles survive 10 years, I've clearly not driven the Jeep hard enough. As I said, I'll throw on some new mounts at some point, but I'm certainly not in a hurry as the last washers I installed were only 1/8" thick grade 5 steel, and they've held up to 5 years of abuse thus far and they haven't lobed out enough that I can measure any variance in the holes (I checked last night while installing the washers on the passenger side). Measured with a machinist caliper, and while there's certainly some variance in the hole, it's less than 0.002 of an inch, which could easily be accounted for by rust scale. The new washers are grade 8, 1/4".

if you are so confident in your "weld washers" go loosen your bolts until they are just finger tight and then drive around. I guarantee you bad things will happen.

As for "wasted my time", I'd say that if this answers my question about where the pop was coming from, with about 5 minutes of prep and welding, that's time damn well spent. Cost me 5 minutes and $4 and assuming it holds up on the trail for 10 minutes without a pop, it's proven the pop's origin. Even if the washers fail after 15 minutes, it's still time very well spent.

I say you wasted your time because all you had to do was loosen and re-tighten the CA bolts. you would have the same effect.

 

[x-jay vision]

Sarcasm is very much lost on some people.

 

[WB9YZU]

Rockclimber is 100% correct in his description of how bushings and the LCA adjuster works.

The bolt stretch caused by the bolt being torqued to spec clamps the bushing center between the brackets. This holds the control arm in place. If you did the job right, there is no sheer force on the bolt at all, just stretch.

-Ron

 

[rockclimber]

Sarcasm is very much lost on some people.

over text... usually.