Chasing clunk in rear suspension

Bluemustang · Aug 11, 2016

So a few weeks ago I posted about a clunk noise coming from my right rear. When I would take off from a stop, I could hear a loud clunk. Took it the shop that I had the work done, and it turned out to be the LCA bolt had worked its way slightly loose. Fixed. They re-torqued everything and I was off!

Now- a clunk has returned, but it's different problem now. I hear it when going over an uneven surface or I hit a bump. Sometimes I hear it when I am making a turn. I think it's caused by bumps/uneven surfaces. Even a small bump will do it. The other night I floored it off the line, wheels spinning all the way from 1st on into 2nd, no noise.

Any idea what it could be? I'm thinking maybe there is an issue with the stock shock mounts but really am out of my element here.

The mods are in my signature, all parts installed at the same time. Base GT 3.15 gears.

Dominant1 · Aug 11, 2016

Did you start hearing the noise right after you upgraded the suspension?

rvlyssup · Aug 11, 2016

Probably the Heim joints of your BMR Toe Rod Ends...mine does the same (only when making turns) but not all the time.

Bluemustang · Aug 11, 2016

Dominant1 said:
Did you start hearing the noise right after you upgraded the suspension?

No. The first issue didn't come up until about 2 weeks later. And after I took it back to them, everything seemed good. But now it's returned and it seems to be a different problem.

Dominant1 · Aug 11, 2016

Ok when the suspension was installed did you re clock your front and rear bushings?

Dominant1 · Aug 11, 2016

This is a neccessary step on the s-550's, the factory preload must be released after the car is lowered otherwise you could have noise. Its done by loosing the above bolts while the car is sitting on all 4 tires and its full weight. Then retorquing them to factory spec to set the preload to the new ride height...then you take it to be aligned!

5ABI VT · Aug 11, 2016

what kind of vertical links do you have? search a few threads down I have a post on my groaning/creaking etc.

5ABI VT · Aug 11, 2016

Dominant1 said:
This is a neccessary step on the s-550's, the factory preload must be released after the car is lowered otherwise you could have noise. Its done by loosing the above bolts while the car is sitting on all 4 tires and its full weight. Then retorquing them to factory spec to set the preload to the new ride height...then you take it to be aligned!

Interesting.. which bolts are you referring to? the lower control arms?

Dominant1 · Aug 11, 2016

5ABI VT said:
Interesting.. which bolts are you referring to? the lower control arms?

From kelly at BMR:

Many of our customers in both the GM and Ford segments of our operation, have ride height issues after lowering their vehicles.

Some very common complaints after lowering vehicles are:

-Car did not drop much in the rear

-Car is sitting lop sided

-Car is making noise now

-Car feels very unstable and floaty

-After lowering the car, some of the bushings have worn out

Many times, it is simply due to not loosening all of the suspension pivot point bolts, and re-torquing them to their specific TA values whent he car is sitting on all (4) wheels/tires - loaded.

The best way to perform this is get the car on a drive on lift, or blocks or drive on ramps. The car needs to be level and sitting on all 4.

Loosen all of the suspension pivot point bolts enough to where there is no load on the nuts.

After ALL of them are loose, go ahead and RE-torque them all to OEM specified values.

These pivot points are as follows:

FRONT: (anywhere there are rubber bushings)
Front Radius Control Arm - inner mount
Front Lower Control Arm - inner mount

REAR: (anywhere there are rubber bushings)
Upper Camber Link - inner and outer mounts
Toe Link Outer Knuckle Bushing
Rear Control Arm Front Inner Mount
Rear Control Arm to Knuckle Mounts

5ABI VT · Aug 11, 2016

Dominant1 said:
From kelly at BMR:

Many of our customers in both the GM and Ford segments of our operation, have ride height issues after lowering their vehicles.

Some very common complaints after lowering vehicles are:

-Car did not drop much in the rear

-Car is sitting lop sided

-Car is making noise now

-Car feels very unstable and floaty

-After lowering the car, some of the bushings have worn out

Many times, it is simply due to not loosening all of the suspension pivot point bolts, and re-torquing them to their specific TA values whent he car is sitting on all (4) wheels/tires - loaded.

The best way to perform this is get the car on a drive on lift, or blocks or drive on ramps. The car needs to be level and sitting on all 4.

Loosen all of the suspension pivot point bolts enough to where there is no load on the nuts.

After ALL of them are loose, go ahead and RE-torque them all to OEM specified values.

These pivot points are as follows:

FRONT: (anywhere there are rubber bushings)
Front Radius Control Arm - inner mount
Front Lower Control Arm - inner mount

REAR: (anywhere there are rubber bushings)
Upper Camber Link - inner and outer mounts
Toe Link Outer Knuckle Bushing
Rear Control Arm Front Inner Mount
Rear Control Arm to Knuckle Mounts

excellent thank you very much ! will do this asap :thumbsup:

:cheers:

Bluemustang · Aug 11, 2016

I don't think they did that when I took it back the first time. This has to be the issue I am having. I recently noticed an unstable ride feeling as well. I'm pretty confident that clocking the bushings is what needs to happen.

Unfortunately I already paid for the install and the alignment. And they use another place that does the alignment.

5ABI VT · Aug 11, 2016

Bluemustang said:
I don't think they did that when I took it back the first time. This has to be the issue I am having. I recently noticed an unstable ride feeling as well. I'm pretty confident that clocking the bushings is what needs to happen.

Unfortunately I already paid for the install and the alignment. And they use another place that does the alignment.

Do you have any tools? or ask a friend with some? some simple race ramps is what I plan to use.. just going to drive up, crawl underneath and loosen the bolts.. very very simple.. and cheaper than driving to pay someone to do it

wildcatgoal · Aug 11, 2016

Most ramps do not go high enough such that you can operate a torque wrench in the space given. Especially a wrench capable of 150+ torque-a-roonies.

Bluemustang · Aug 11, 2016

Unfortunately I don't have the tools to do this myself. I bet they will fix it up for me. They were most likely not aware this procedure is necessary. Thanks guys, I don't know why I didn't think of that, since I've seen that thread before. I never noticed an issue until some time after. Perhaps it's been degrading my performance all along without me realizing.

Dominant1 · Aug 11, 2016

Video that shows what kelly is talking about:

Chasing clunk in rear suspension

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