Need fresh ideas/help on suspension noise diagnosis

einreb · 05-11-2005, 05:51 AM

I have a noise coming from my left rear torsion tube and cover. The suspension was recently 'refreshed' with new t-bars, polybronze and monoballs in the trailing arms. The noise location is pretty obvious, but I went ahead and disconnected the sway bars and shocks and the noise persists when bouncing the bumper. I can also sometimes get a slight noise/movement when I push hard on the torsion bar covers.

I've pulled it all apart 4 times and reshimed the bushings and relubed. I also replaced chuck's thick spacer with 2 smaller washers to 'compress' the polybronze assembly better (while still getting free play with no t-bar). The noise will go away briefly, but then return.

I'm about at wits end. Any fresh ideas?

-Bernie

Mike Bonkalski · 05-11-2005, 06:29 AM

What kind of noise is it? Squeak, groan, click, etc...?

Chuck Moreland · 05-11-2005, 06:48 AM

What kind of motion are you getting when pushing on the tbar covers?

I assume you have the bolts loose when you are doing this pushing?

Have you carefully inspected the area around the torsion bar tube for cracks? There are 4 mounting bosses that accept the mounting bolts securing the cover plate. Look at the base of each of the mounting bosses. That is a very common area for metal fatigue and cracks to develop. Also check at the weld around the torsion tube itself.

einreb · 05-11-2005, 07:06 AM

Mike - more of a 'click' than anything else.

Chuck - First... I don't think its a problem with the polybronze.

I get the noise when its all tightened up and I push pull on the cover. I thought the same thing and cleaned the area completely and didn't spot any obvious cracks or points of failure.

My latest suspicion is the actual torsion bar. They are sway-a-ways and the tolerance difference at the splines between the left and right was ridiculous. I had to remove a decent bit of material from the right side to get it to fit. Its snug... but not noisy. hmmmmm.

The left side fit in easily... maybe too easily. Maybe there is play in the x-y plane at the spline interface thats giving me the noise.

If one side was off that much too big... maybe this side was off too small.

-Bernie

Chuck Moreland · 05-11-2005, 07:15 AM

Quote:

Originally posted by einreb
I get the noise when its all tightened up and I push pull on the cover.

Okay, somethings not right here. If the bolts are torqued down, there is no way the cover plate should be moving.

Is it possible the 4 bolts securing the plate are bottoming out?

Did you install longer bolts or omit the washers under the botls?

Either the bolts are not cinching that cover down, or the mounting bosses are torn away. I can't see any other way the cover plate could move.

Chuck Moreland · 05-11-2005, 07:19 AM

Just to clarify, along with the click you are seeing visible movement of the cover plate?

Mike Bonkalski · 05-11-2005, 07:27 AM

Could the sound be coming from the trailing arm monoballs? How is the torque on those bolts?

einreb · 05-11-2005, 08:14 AM

Quote:

Originally posted by Chuck Moreland
Okay, somethings not right here. If the bolts are torqued down, there is no way the cover plate should be moving.

Is it possible the 4 bolts securing the plate are bottoming out?

Did you install longer bolts or omit the washers under the botls?

Either the bolts are not cinching that cover down, or the mounting bosses are torn away. I can't see any other way the cover plate could move.

Chuck,

I think I misspoke by saying that the 'cover plate' moved and made noise.

When everything is tightened down and I come back from a test drive... I can pushpull at the outer torsion bar tube (what you can set the jackstands under) and i can replicate the noise once or twice. the movement is very slight if any.. but i get the click.

I just got back from redoing it again... and verified some slop in the torsion bar spline interface. with it all assembled, but not attached to the trailing arms, i got a little play when i pushed up and down on the spring plates.

To test this theory, i took two long 1/4' strips of the thinest shim material and made an x at the bottom of the torsion bar and ran it allong the splines and taped it above the splines. the tbars slid in snug. I've reassembled and there was no noise... but this has happened in the past. it sometimes takes a couple drives for the noise to show back up. I'll drive the piss out of it today and see what happens.

I don't like this as a long term solution if it stays quiet, but at least I'll know the reason.

Mike - its definately not at the monoballs. I can tell by feeling the different points when someone is jumping an the bumper. Also, the di/reassembly of the spring plat bushing makes it go away for a day or two.

thanks guys...

-bernie

Chuck Moreland · 05-11-2005, 08:24 AM

I see.

Yes, it sounds like the loose fit of the torsion bar is the culprity. The sway-a-way/Welteister bars are known for fitment issues.

MotoSook · 05-11-2005, 08:35 AM

Even with a loose fit of the t-bar splines, won't the "spring tension-compression" maintain contact between the splines of the t-bar and the cover plate? The t-bar would have to be unloaded, then reloaded for it to make the clicking sound that one might expect from contact to no-contact....

At the track the car was on the ground (t-bar loaded) the car was clinking while Bernie pushed on the bumper.

einreb · 05-11-2005, 10:19 AM

Quote:

Originally posted by Souk
Even with a loose fit of the t-bar splines, won't the "spring tension-compression" maintain contact between the splines of the t-bar and the cover plate? The t-bar would have to be unloaded, then reloaded for it to make the clicking sound that one might expect from contact to no-contact....

At the track the car was on the ground (t-bar loaded) the car was clinking while Bernie pushed on the bumper.

Souk,

I had been thinking the same thing, but I was running out of possibilities. Exagerate the looseness and think about what is going on... the rear half of the car is being supported by the two outer points of the t-bar. chucks bushings are solid, but its not tied to the t-bar at that point. you've got 2 feet of leverage at that outer spline connection to get a fractional bit of movement and some sort of creaking.

-bernie

MotoSook · 11:33 AM

I feel your pain Bernie, and I'm not making any statements regarding the merit of the bushings. But, if you are able to make the noise by pulling or pushing on the t-bar carrier (the tube that the cover plate slides over), then the carrier is hitting something. I am more inclined to believe that the carrier and the bushing are moving (or carrier is moving relative to the bushing) rather than the idea that you can rotate the loaded carrier such that the t-bar and carrier are creating contact noises at the splines.

If the carrier is pivoting about the splined end of the t-bar, then the bushings are not fitted well (fitment allowances are covered with the shim design/provide by Chuck). Unless I misunderstand Chuck's design, the carrier should ride in the bushing such that their axis are always the same. If the bushing and carrier are not fitted to prevent a pivoting motion, then the carrier will pivot such that the end of the carrier that is inside the chassis and the t-bar (not the spline contacts) are making the clicking noise (the spline end would be the pivot point...sliding movement) The same may be true if the bushng to chassis fitmet is not per design. The bushing AND carrier would move.

Additionally, if the cover plate to bushing fitment is not proper, then the carrier and bushings maybe move and clicking against the cover plate or chassis.

Shimming the splines may be a bandaid that [causes] less movement of the carrier, bushings or all of the parts.

einreb · 05-11-2005, 11:29 AM

I was incorrect when I said it was 'supported' at the outer points... that makes no sense. I had reshimmed both the inner and the outer quite tight and reinstalled without the tbars to check for free play. (per instructions and some previous emailing with chuck)

Again, I'm grasping at straws at this point. I took the car out for a couple miles and hit some potholes... came back, bounced on the bumper and no serious noises. (of course i'm over paranoid about any sound at this point).

Ah, self employment... I've got a crapload of work to do and i'm wrenching on the car.

its not even fun wrenching... its WTF is up with this crap... wrenching.