Suspension Noise Help Needed
 

I've searched and found nothing quite like this:

I refreshed everything made of rubber in my 87 Cab suspension to stock specs last winter. Front A-Arms and rear spring-plate bushings were done with Elephant Racing rubber. Sway bar links and bushings and trailing arm bushings were also replaced. Front and rear shocks were replaced with stock-spec Sachs units from Pelican.

I'm very happy with the results, but I'm getting a noise from the rear when going over low-frequency bumps - like the crown of an intersecting road. Sometimes I hear it when hitting a smaller bump while cornering with the suspension under load.

It sounds like tire scrub or something metallic touching the ground but I'm at so-called euro-height, there are no signs on the tire or the fenders of any contact, and the sound is the same regardless of speed. The noise is coming from each side independently; sometimes both sides make the noise at the same time depending on the bump.

I'm guessing that the sound is stiction from a bushing that's turning in its carrier. It sounds like this:

https://youtu.be/El6yF7jXKcE

If my ER spring plate bushings were turning in their carriers, is this what it would sound like? I also replaced the trailing arm bushings, and I wondered if the sound might be the bushing flanges turning against the carriers but the noises seem further out from the center of the car.

Last piece of the puzzle - I don't hear it when my wife and I are both in the car, only when I'm alone.

Any suggestions on what this might be or how to troubleshoot would be very welcomed!

Thanks in advance,
GK

Kinda sounds like a rubber chin spoiler touching the ground but I'd ask you what kind of sway bar bushings you have. If they are the clamped rubber or urethane kind I would say that might be the noise.

Did You change the rear banana arm bushings where they bolt to the body, above the trans axle?
I replaced all the rubber bushings with ER rubber on my 1988 except for those 2 banana arm bushings, and the car creeks every time I go over speed bumps. I still regret not changing them when the motor was out.

Mike

Are you sure your rear sway bar carriers are not cracked?

I have a similar noise, but mine is nearly constant. One thing you can do is disconnect the rear sway bar, just to eliminate variables. It should be possible for someone to listen back there while you drive, to get a better idea if it's coming from the inside or outside of the trailing arms.

I think some of Elephants rubber is a harder compound than stock.

Ask her to stop talking and see if this is still true:)

This approach helped me isolate a problem once: with a wheel off, put one rear corner on blocks. Use the jack to raise and lower the suspension and listen. If you hear anything spray the hell out of it with silicon spray. If the noise goes away, you've hit it. This has worked twice for me, most recently on the hard-to-reach center control arm bushing.

noise
 

change your sway bars and your noise will vanish

I thought the same thing - they are the clamped rubber kind and I put new ones (URO brand) on. I sprayed them with silicone before today's mid-winter scoot and there was no change. I'm thinking that my next troubleshooting step is to disco the swaybar drop links and take it for a ride to see if that changes anything. Thanks for the input!

I did change those despite some advice on the forum that said it wasn't worth it. I did not change them when the engine was out (that would've been too easy!) but it wasn't impossible to do it with the engine in place.
I was wondering if these were the cause of the noise since the "cheeks" of the bushings have serrations in them, apparently to hold them stationary against the carrier. I thought they might be slipping but it makes no sense that this wouldn't occur when I have a passenger.

I don't see anything obvious but I know that these are a weak point. I suppose that if I disconnected the swaybar links and took it for a ride I'd know that this was a swaybar assembly noise (nod to David.avrahami's post.)

Tell me more! I changed the swaybar bushings and the drop links - are you suggesting to change out the bar itself?

The good news is that she doesn't talk excessively. We really have a nice time taking the car out for a weekend top-down ride. The bad news is that she scares easily and I like to DRIVE the effin' thing.

I would think that if spraying silicone on the trailing arm bushings stops your noise, that means the bushing is rotating in the carrier, and I don't think it's supposed to. It's a fairly tight fit and the torque specs are high and I thought I recalled there being serrations on the bushing cheeks which indicate to me that the rubber is supposed to deflect instead of the bushing rotating like a bearing. I could be wrong, and if so, maybe somebody here will set me straight.

?
 

Are your shocks OK?..Try checking the bottom shock(s) bolt/nut to see if they are tight.

I recently replaced everthing that you did, including the shocks, and I had a sound as if the muffler was loose when going over the odd bump...The sound was due to one of the shocks bottom nut being a bit loose. I had somehow forgot to torque it.

Re securing the spring plate's large rubber bushings...I was a little concerned about using the Crazy Glue that came with the ER bushing, as the original ones, as you know, were vucanized to the plate...To ease my mind, I ended up purchasing a 3M two part adhesive kit - 2 small tubes- that were specificially designed for bonding rubber to metal. It has a very high shear, including heat rating -expensive- $70.00 but it satisfied my mind that the bushing(s)wouldn't move.

BTW.. If you end up replacing the sway bar bushings, I would suggest that you use a better quality brand than ERO

Thanks - I did replace the front and rear shocks, I'll double-check the nuts and bolts top and bottom. Noises can be tough to trace since the sound travels through metal parts and can mislead us on the direction.

When you replaced the trailing arm bushings did you find that the bushing is held tight between the carrier flanges or is it supposed to rotate?

Tight...I assume that they are meant to function in a similar manner to that of the large spring plates rubber bushing.

Agreed, and I confirmed this with one of our forum's experts on the matter. Given that the noises seem to be coming from further left (and right) than where the trailing arm bushings are mounted I'm going to discount those bushings as the source.

I've re-read numerous posts on spring-plate bushing noises, but they are usually described as squeaks, not the quick "grind" that I'm hearing. Does this sound ring a bell for anyone?

https://youtu.be/El6yF7jXKcE

Frustrating ay. :( Being that you feel that it is a 'grind', one would conclude that some paint would be 'ground off' whatever it is rubbing on...I would suggest for you to jack it up, lay underneath it, and with a good light/ flashligh, go over every point on the complete suspension, including the undercarriage, such as the skid plate over your front crossmember. (where the fuel pump is located)...I would specially look at one point at a time...Like when you are trying to find something small in the grass. -> Focus.

BTW, kind of a long shot, but did you put the two spacers back on the bottom of your spring plates prior to reinstalling the bolts?

Spring Plate - Bottom bolts
 

As you may know, the spacers go on the bottom, at the back of the spring plate, prior to reinstalling the four bolts.


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