Rubbing sound
Thread Starter
Racer
Joined: Feb 2012
Posts: 421
Likes: 27
From: Harrisburg PA
Rubbing sound
I have a serious rubbing sound/groaning sound coming from the right rear (most noticeable when making a turn in EITHER DIRECTION).
255/60/r15 COOPER COBRA TIRES on original rally wheels.
I have check the tire extensively, and there are absolutely no signs that the tire is rubbing anything.
It does sound like rubber on metal, but not always...kinda hard to describe (i know--very helpful).
Replaced the shocks last year (have been hearing this for a couple summers now, and has gotten progressively worse--very bad now. No issues at all in a straight line drive.
My thoughts are, in no particular order:
Spring?
U Joints?
Trailing arm/bearings?
Before I just start replacing parts, wanted some advice from the experts!
Thoughts?
255/60/r15 COOPER COBRA TIRES on original rally wheels.
I have check the tire extensively, and there are absolutely no signs that the tire is rubbing anything.
It does sound like rubber on metal, but not always...kinda hard to describe (i know--very helpful).
Replaced the shocks last year (have been hearing this for a couple summers now, and has gotten progressively worse--very bad now. No issues at all in a straight line drive.
My thoughts are, in no particular order:
Spring?
U Joints?
Trailing arm/bearings?
Before I just start replacing parts, wanted some advice from the experts!
Thoughts?
Thread Starter
Racer
Joined: Feb 2012
Posts: 421
Likes: 27
From: Harrisburg PA
I only notice it at low speeds, and only on turns...
It's not a squeal like a belt, as the speed is significantly lower...Today, for the first time, In noted "clunking" sound with it...that's what made me think it might be a U joint on the half shaft on the passenger right.
It's not a squeal like a belt, as the speed is significantly lower...Today, for the first time, In noted "clunking" sound with it...that's what made me think it might be a U joint on the half shaft on the passenger right.
Thread Starter
Racer
Joined: Feb 2012
Posts: 421
Likes: 27
From: Harrisburg PA
replaced ujoins on the passenger rear, where it sounded most like the noise was originating...
Over the last couple of weeks, the noise has gotten progressively worse, and seems ot be much more noticeable after a long driver.
I noted earlier it was a "rubbing" sound...might be better described as a groan. only really noticeable when turning...
Gear oil or posi additive?
Thinking of trying a fluid change--what gear oil is recommended--I have some sta lube 85w90 and amsoil limited slip additive I can use... Is the 85w90 an appropriate gear lube (it is a GL4)...
Over the last couple of weeks, the noise has gotten progressively worse, and seems ot be much more noticeable after a long driver.
I noted earlier it was a "rubbing" sound...might be better described as a groan. only really noticeable when turning...
Gear oil or posi additive?
Thinking of trying a fluid change--what gear oil is recommended--I have some sta lube 85w90 and amsoil limited slip additive I can use... Is the 85w90 an appropriate gear lube (it is a GL4)...
Drifting
Joined: Nov 2013
Posts: 1,806
Likes: 258
From: Dublin Ohio
I know you said you checked to make sure the tires weren't rubbing, but I had a similar rubbing sound, and I checked to make sure the tires weren't rubbing - but I had a tire rubbing.
On the actual fender, in front of the rocker panel.
On the actual fender, in front of the rocker panel.
Drifting
Joined: Jul 1999
Posts: 1,542
Likes: 43
From: Plano TX
What year car?
The mid to later 70s cars could have softer stub axles. When they wear against the diff pin it allows the stub axle to move in towards the housing causing the u-joint strap/bolts to strike the housing causing a clunking sound. This can also show up as having to max out camber adjustment (pull in bottom) to correct for the top of the wheel tilting in. May not be this but it can be a cause for the noise you described especially when turning.
The mid to later 70s cars could have softer stub axles. When they wear against the diff pin it allows the stub axle to move in towards the housing causing the u-joint strap/bolts to strike the housing causing a clunking sound. This can also show up as having to max out camber adjustment (pull in bottom) to correct for the top of the wheel tilting in. May not be this but it can be a cause for the noise you described especially when turning.
Le Mans Master
Joined: Sep 2003
Posts: 8,812
Likes: 2,029
From: eastern NC
Keith, there really are any number of things in the C2-C3 IRS that could be responsible for the noise you are hearing. Things such as E-brake internal parts that have come loose or failed; rear wheel bearings that need servicing; rear control arm bushing that allows the control arm to move about when under acceleration or braking or just turning, etc. Others have already been mentioned, but it may be time to seek the help of someone nearby who is familiar with these cars and has gone through the process in the past to help you narrow it down.
Another option is to mount a GoPro under the rear of the car (securely...) and take it for a drive. This could be quite revealing and entertaining.
One thing you haven't really provided is information related to the age and condition of the car. On a high mileage car it could just be time to go through everything and refresh it, on the other hand if it has had work performed on it recently that could help narrow it down. A bit of history can help us to help you here. Throwing parts at the car is a good way to add frustration to your life and loose enthusiasm for the car.
Good luck and do let us know what you discover... GUSTO
Another option is to mount a GoPro under the rear of the car (securely...) and take it for a drive. This could be quite revealing and entertaining.
One thing you haven't really provided is information related to the age and condition of the car. On a high mileage car it could just be time to go through everything and refresh it, on the other hand if it has had work performed on it recently that could help narrow it down. A bit of history can help us to help you here. Throwing parts at the car is a good way to add frustration to your life and loose enthusiasm for the car.
Good luck and do let us know what you discover... GUSTO
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Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,754
From: Charlotte NC
^^^^I agree with GUSTO14.
Also..does the noise occur when you are turning to the left and right...or only one side when turning.
Even though I use Amsoil oil in my shop. I am still only use GM's additive in the differential. 2 bottles. And depending on the roads and if they are really hilly . I might also switch to the Lucas 85w140 gear oil with 2 bottles of the GM additive like I do for some of the Corvettes in my area that run some of the curvy roads in the mountains around me. I cannot afford to have problem in the rear differential by trying out another product when for 30 years....I have not had a problem at all when I change out rear differential fluid.
Possible rear wheel bearings....but guessing where due to more information from you is needed.
DUB
Also..does the noise occur when you are turning to the left and right...or only one side when turning.
Even though I use Amsoil oil in my shop. I am still only use GM's additive in the differential. 2 bottles. And depending on the roads and if they are really hilly . I might also switch to the Lucas 85w140 gear oil with 2 bottles of the GM additive like I do for some of the Corvettes in my area that run some of the curvy roads in the mountains around me. I cannot afford to have problem in the rear differential by trying out another product when for 30 years....I have not had a problem at all when I change out rear differential fluid.
Possible rear wheel bearings....but guessing where due to more information from you is needed.
DUB
Thread Starter
Racer
Joined: Feb 2012
Posts: 421
Likes: 27
From: Harrisburg PA
honestly, it is probably about time to go through the whole rear half.
Was hoping to push it at off as long as possible, but the trailing arms need to be re-done at some point--it's a '77, and still has what appears to be the original riveted rotors. Spring also has quite a bit of rust on it...the parking brake has never worked since I've owned it...cables are stretched and frayed--and I'm pretty sure the hardware inside the rotor is frozen up (thankfully not frozen in the braking position)...
Just replaced the passenger U joints on the half shaft...did not help the issue.
Anyone recommend a good rebulid service for the trailing arms? I'll do the R&I, and can send them out. Heard good things about a place in Erie, PA www.bairs.com they are at the Carlisle Vette show every year, too.
Figure I'll end up doing the trailing arms, the spring, and diff oil all at the same time...
what should I expect to pay for the trailing arm rebuild service?
Was hoping to push it at off as long as possible, but the trailing arms need to be re-done at some point--it's a '77, and still has what appears to be the original riveted rotors. Spring also has quite a bit of rust on it...the parking brake has never worked since I've owned it...cables are stretched and frayed--and I'm pretty sure the hardware inside the rotor is frozen up (thankfully not frozen in the braking position)...
Just replaced the passenger U joints on the half shaft...did not help the issue.
Anyone recommend a good rebulid service for the trailing arms? I'll do the R&I, and can send them out. Heard good things about a place in Erie, PA www.bairs.com they are at the Carlisle Vette show every year, too.
Figure I'll end up doing the trailing arms, the spring, and diff oil all at the same time...
what should I expect to pay for the trailing arm rebuild service?
Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,754
From: Charlotte NC
Contact Bairs if that is who you choose to use about the price.
I would advise NOT riveting the rotor back on the spindle. Reasons being it is NOT needed and IF you need to get back into your parking brakes. You are not having to drill out rivets. The wheel will hold the rotor on quite well when the nuts are torqued properly.
I would measure the thickness of your rear rotors. Do you have a micrometer that can do this??? And I also would attempt to remove them if they are good and you can have them turned down locally....or buy new ones.
Keep in mind that IF you buy new rotors that they will need to be checked for proper run-out and possibly INDEXED.
A new rotor thickness is 1.250" The MININAL thickness you can turn a rotor down to is 1.230" Discard thickness is at 1.215'' Measure about 1/2" from the outer diameter of the rotor when checking.
Also MAKE SURE that when you get your trailing arms back. That you feel and make sure that the sleeve that was used to compress your trailing arm bushing is NOT above the outer flat surface of the large special washers that are used to compress the bushings together. IF IT IS ...you need to file that surface FLAT. So your alignment shims are now laying against a FLAT surface. And not on a portion of that sleeve that is protruding above the flat washers.
DUB
I would advise NOT riveting the rotor back on the spindle. Reasons being it is NOT needed and IF you need to get back into your parking brakes. You are not having to drill out rivets. The wheel will hold the rotor on quite well when the nuts are torqued properly.
I would measure the thickness of your rear rotors. Do you have a micrometer that can do this??? And I also would attempt to remove them if they are good and you can have them turned down locally....or buy new ones.
Keep in mind that IF you buy new rotors that they will need to be checked for proper run-out and possibly INDEXED.
A new rotor thickness is 1.250" The MININAL thickness you can turn a rotor down to is 1.230" Discard thickness is at 1.215'' Measure about 1/2" from the outer diameter of the rotor when checking.
Also MAKE SURE that when you get your trailing arms back. That you feel and make sure that the sleeve that was used to compress your trailing arm bushing is NOT above the outer flat surface of the large special washers that are used to compress the bushings together. IF IT IS ...you need to file that surface FLAT. So your alignment shims are now laying against a FLAT surface. And not on a portion of that sleeve that is protruding above the flat washers.
DUB
Heel & Toe
Joined: May 2020
Posts: 23
Likes: 2
I'm getting the same thing I think. It's groaning around turns, especially at lower speeds or from a stop. I thought at first something was rubbing.
Here's what I have done recently:
-Changed the driver's rear wheel bearing
-Opened the differential to install a missing retaining ring on the yoke. And I used diff fluid with the additive already in it when refilling
-Replaced the differential mount bushing with a poly one
-Replaced both leaf spring bushings with poly ones
-Rebuilt both trailing arms with poly bushings
-Did a string line rear toe after the rest of the wheel adjustments (minus front caster) were done
It sounds like it's all coming from the driver's side, but it's not 100% for sure.
I checked the u-joints for play while I had them off and didn't notice any problems, however the caps fell off on a couple during reinstallation, but I checked the roller bearings and it appeared they were all present. Also, I did the driver's side u-joint twice, because I didn't have it on very well the first time I didn't think, and it might have been installed a little lop sided at the yoke the first time.
One thing I still have to do (again) is adjust the parking brakes as they are not working, and the actuating lever that pushes on the shoes doesn't hold the cable ball very well.
Here's what I have done recently:
-Changed the driver's rear wheel bearing
-Opened the differential to install a missing retaining ring on the yoke. And I used diff fluid with the additive already in it when refilling
-Replaced the differential mount bushing with a poly one
-Replaced both leaf spring bushings with poly ones
-Rebuilt both trailing arms with poly bushings
-Did a string line rear toe after the rest of the wheel adjustments (minus front caster) were done
It sounds like it's all coming from the driver's side, but it's not 100% for sure.
I checked the u-joints for play while I had them off and didn't notice any problems, however the caps fell off on a couple during reinstallation, but I checked the roller bearings and it appeared they were all present. Also, I did the driver's side u-joint twice, because I didn't have it on very well the first time I didn't think, and it might have been installed a little lop sided at the yoke the first time.
One thing I still have to do (again) is adjust the parking brakes as they are not working, and the actuating lever that pushes on the shoes doesn't hold the cable ball very well.
Last edited by CRobLove; Jul 12, 2021 at 10:45 PM.
