For the past few weeks I have noticed a very odd Loose tin sound when I drive over bumps. They checked (Warrenty since these are BRAKE NEW Brake pads installed by them less than 1 month ago) the rear rotors, sanded them down and it disappeared for 1 day and came back the next day (COURSE IT RAINED THAT DAY SO perhaps the rain had caused it to disappear.. or was merely coincidental).

I figured out WHERE it is coming from. REAR DRIVER WHEEL.

I shake the rear driver wheel and it KNOCKS. The rims appears to be SOLID and TIGHTLY bolted on. It seems the sound comes from BEHIND the rotor..

I describe the sound as a Shopping Groccery cart where if you were to kick it.. the sound it would make...

Symptoms:

* Appears when you go over rough bumps (not speed bumps, and not pushing shocks down)

* STOPS when you apply brakes. (Brake OFF.. Loose Tin sound,Brakes ON.. Disappears completely).

I took 3 video's.

SAVE AS Because some are large

1. Video of my shaking the wheel - www.camarosource.ca/temp/100_8012.MOV (2.9M)

2. Video of my shaking the wheel - www.camarosource.ca/temp/100_8014.MOV (2.9M)

3. Video of me driving by over a bump in alley. You can CLEARLY hear it the SECOND time I drive forward (0.52secs - 0.53sec) - www.camarosource.ca/temp/100_8015.MOV (Large 17.6M)

I have taken it to 2 different shops.

They both claim that they could not get it to do it for them nor when they did road test. (Rediculous cause it does it for me the MOMENT the car moves).

THe last shop took apart the rear differential and said everything was perfectly fine. Both checked the brakes and they appear fine. The last one also checked the supension and tranny..

Remember the sound DISAPPEARS when you BRAKE so it seems to be related... HELP!

 

The differential shop I took the car to said that movement (like 1/4" play back and forth) is COMPLETELY NORMAL.. Sorry but that seems like bull...

Anyone here please do an experiment.

1. Park car on FLAT surface
2. Put car into NEUTRAL
3. Emergency Brake OFF (in other words, make sure the car is secure and flat or it will coast away) :-)

4. Kneel to the side of your rear driver wheel.
5. Reach over the very TOP of the tire and grab a deep tread with your fingers.
6. HANK back and forth (towards the SIDE of the vehicle) (in otherwords, in line with the axle.. I want you to try and slide the axle back and forth)

Basically you're doing the EXACT same thing I am doing in video 1 (http://www.camarosource.ca/temp/100_8012.MOV)

Please tell me if that noise happens to you?

THANKS!

 

Take the wheel off and see if the pads are loose.

 

They said the brakes are brand new and all brake components are tight and secure.

I am under the impression the AXLE you hear is the cause but the diff shop claimed that 1/4" back and forth in the axle housing is completely normal??

 

Actually the wheel moving back and forth as you describe is normal, how much is the question, GM manuals give you a spec for different rearends. It varies but slight movement using your hands is normal. You would have to use a dial indicator and see just how much you have and check the manual for the specs,,,,usually when the C-clips get worn the play is excessive, simply replacing the C-clips may tighten it up slightly.
My Iroc has the same noise in the right rear. I also had it in the right front and found that to be the brake pads, the inboard pad did not have the anti rattle clip installed, replaced the clip and no more rattle in the front. I have not check the rear one yet. Although mine has the Aussie 9 bolt rear so it probably is not axle related as these do not use c-clip axles. I have yet to take the rear disc pads off and see if they use anti rattle clips like the front. I do know the noise goes away when the brakes are applied just as you decribed. One of these days I will get the time to check it. Larry.

 

in the last vid i heard what sounded like a brake pad shifting around due to worn or missing hardware (sounded like a few clicks fast in a row), can ya take some pics of the brakes with the wheels off? What rear end is this? On a side note, GM pads some with new installation hardware, most aftermarket pads don't.

 

yep the pads jiggling is kind of what I was eluding to. I was not sure if the rear pads on a disc brake car would have the anti rattle clips or not, I know the front do on the standard D52 pads.
There should be clips that snap onto the pad that attaches to the piston side of the caliper, that clip will slip inside the piston and hold the pad still from jiggling, the outer pad on the front (D52 pads) also has tangs that fold over the caliper, these are supposed to be tapped down so the pad stays still and tight to the caliper, may people that do brake jobs do not do this and therefore you will have an outside pad that also jiggles slightly and also causes squeaking issues.
I am just not too sure about the rear discs on these cars, I would assume the pad on the piston side of the caliper would have an anti rattle clip also just like the front, and if it is missing you will here that rattle sound over bumps until light brake pressure is applied which in turn squeazes the pads and no more jiggle. Make sense? One of these days I will pull mine apart on the right rear and check the pads for a clip and find the reason why mine is rattling, since a long weekend is coming I may find the time and answer my own curiousity. Hope I explained it well enough, Larry.

 

I have the exact same sound coming from mine. Yours looks to move a little more than mine, but it's the same sound and it drives me up a wall! Were you ever able to determine if it is a problem or not?

 

Yep. It was the driver side rear disc brake pad moving around in the caliper. They put a shim on each end and fixed it.

 

I can definitely say that's not my problem since I have drums. I am one of the lucky ones in 91 who got a Z28 with all the bells and whistles. Then they must have run out of rear disc setups!

Mike

 

I consider you one of the lucky ones Mike with those rear drums. I hate rear disc brakes. I would much rather have drums, they are much simpler, cheaper, and easier to work on and rarely ever give you a problem unlike these stupid disc brakes, calipers are expensive, the e-brake system sucks in my opinion, and GM didn't design a simple way to remove them with steel lines going to the caliper you risk bending and kinking the lines every time you do a brake job (my vette is the same way) and the one caliper that GM did put a hose on, the stupid hose is not long enough to move the caliper around and get it off You would think GM would make it a little more user friendly. Of course I am old school and not much for technoligy,,,,in my own opinion I prefer the rear drums, but thats just me, okay sorry for the rant, I am done now, Larry.

 

Well I get a "ting" <--kind of like a bag of loose change, pennies, dimes and nickels) when I go over a bump from the rear. I too thought it was a loose tire/hub and I have aluminum drums, and I removed the tire and looked at the sway bar end links. Well needless to say the bottom bushing was completely dry-rotted off. The source of my "tinging".

 

Just installed new Spohn rear swaybay and end links as well as Spohn panhardbar, LCAs and torque arm. Have checked and rechecked ALL torque values and even called Spohn to confirm they were all correct. I can grab the tire with the car on the ground and pull it out/push it in and I get the "clunk". I jack it up and removed the tire and drum and the axle actually moves in and out between 1/8 and 1/4 inch. I would point to the c clips being worn, but I also installed a TA cover and found nothing out of the ordinary in the gear oil.

firebirdjones - I may be lucky, but I'm still going to install a 4th gen rearend with disk brakes. This noise is going to drive me nuts!

Mike

 

You can also get a hollowy sound when going over bumps from the emergency brake cable hitting the Driveshaft. (the bracket it sits in) if it comes out of place over the driveshaft. Another possible cause is a loose brake line or whatnot...

 

I pulled the wheels and brake drums off again just to make sure I wasn't seeing things the first three times. I can physically move the axle shafts 1/8 inch in and out on both sides. I do have spacers for the aftermarket wheels, but like I said, it makes the same noise with the wheels and drums off. I am looking for a fourth gen rear end now. I am pretty sure my Spohn LCAs, Track Bar, torque arm and sway bar will work, but will call Spohn next week. Any ideas on what a fair price is to pay for a rearend? I have access to one without brakesbut has everything else with 3.42 gears. Can I transfer my drums over until I get ahold of some discs???

Mike