Rear wheel wobble
Thread Starter
Instructor
Joined: Nov 2013
Posts: 166
Likes: 8
From: Acworth GA
Rear wheel wobble
Ever since I got the car, 6 years ago, I've noticed a squeak coming from the back brakes while rolling out of the neighborhood. It's kind of a squeak, squeak, squeak. I finally gt tired of it and decided to fix it. I supported the rear wheels on wooden blocks about 3 inches off the floor and started the car. I did find out that both sides squeak, but I also noticed that the drivers side tire wobbled about a 1/2 inch and the other side wobbled about a 1/4 inch. I thought that I must have bent rims. So I removed the tires and started the car again. I saw that the rotors wobbled, not as much as the tires but they had definite side to side movement. So I thought that I must have warped rotors, so I removed the rotors and started the car. The thing the rotors mount onto also has a wobble.....gulp....what now?
I don't know what it's called or why the surface wobbles but I'd sure like to know. Anyone have any ideas about this???
I don't know what it's called or why the surface wobbles but I'd sure like to know. Anyone have any ideas about this???
Last edited by Rich123; Nov 16, 2019 at 04:15 PM.
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,810
From: Cool Northern Michigan
You should never do that to a Independent Rear Wheel Suspension vehicle. The outers U-Joints must have been screaming at you: let me down!
I bet the squeak is the rear parking brake innards that have been ignored for, how many yrs?
I bet the squeak is the rear parking brake innards that have been ignored for, how many yrs?
Thread Starter
Instructor
Joined: Nov 2013
Posts: 166
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From: Acworth GA
Not sure why the u-joints would scream but they didn't. I suppose that would depend on where you assumed I rested the weight.
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,810
From: Cool Northern Michigan
Anytime the tires are off the ground it puts the half-shafts, the inner U-Joints, outer U-Joints and to some degree the trailing arms in a awkward angle and stresses these parts.
Just like using a two post lift on a C3. Not recommended, but do-able especially when running the drivetrain.
Seems to me, as much run-out as you have at the rims, you would feel that going down the road. That's why I question if the half-shaft U-Joints awkward angle are what's really the wobble.
Just like using a two post lift on a C3. Not recommended, but do-able especially when running the drivetrain.
Seems to me, as much run-out as you have at the rims, you would feel that going down the road. That's why I question if the half-shaft U-Joints awkward angle are what's really the wobble.
Last edited by HeadsU.P.; Nov 16, 2019 at 07:49 PM.
Pro
Joined: Mar 2014
Posts: 529
Likes: 113
From: Texas
Anytime the tires are off the ground it puts the half-shafts, the inner U-Joints, outer U-Joints and to some degree the trailing arms in a awkward angle and stresses these parts.
Just like using a two post lift on a C3. Not recommended, but do-able especially when running the drivetrain.
Seems to me, as much run-out as you have at the rims, you would feel that going down the road. That's why I question if the half-shaft U-Joints awkward angle are what's really the wobble.
Just like using a two post lift on a C3. Not recommended, but do-able especially when running the drivetrain.
Seems to me, as much run-out as you have at the rims, you would feel that going down the road. That's why I question if the half-shaft U-Joints awkward angle are what's really the wobble.
Thread Starter
Instructor
Joined: Nov 2013
Posts: 166
Likes: 8
From: Acworth GA
Anytime the tires are off the ground it puts the half-shafts, the inner U-Joints, outer U-Joints and to some degree the trailing arms in a awkward angle and stresses these parts.
Just like using a two post lift on a C3. Not recommended, but do-able especially when running the drivetrain.
Seems to me, as much run-out as you have at the rims, you would feel that going down the road. That's why I question if the half-shaft U-Joints awkward angle are what's really the wobble.
Just like using a two post lift on a C3. Not recommended, but do-able especially when running the drivetrain.
Seems to me, as much run-out as you have at the rims, you would feel that going down the road. That's why I question if the half-shaft U-Joints awkward angle are what's really the wobble.
I don't know what your talking about with awkward angles, etc. I don't know what you envision as the lift point so here's the story. Jack the whole back of the car up until the wheels are off the ground. Place either 3 or 4 (I don't remember how many) 2x4's stacked, 1.5 inches each, under the point where the full stress of the body against the shock absorber meets the rear wheel assembly. The same point that the strut attaches to the wheel assembly. This puts the weight of the car through the rear spring to rest on the wood blocks which are about 1/2 inch from the tire so there is little if any angular stress on the assemblies.
Now, back to the question, "what makes the whole brake disk wobble? Not just the braking surface as in it's warped, but the whole thing.."
Last edited by Rich123; Nov 16, 2019 at 09:15 PM.
Le Mans Master
Joined: Sep 2003
Posts: 8,812
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From: eastern NC
Rich, I think what you're being told is that if you lift the back of the car and the trailing arms reach full droop, it is possible to get the U-joints into a slight bind. When this occurs it can result in the spindles 'wobbling' as the joints try to align themselves. To see how this occurs, the next time you lift the rear of the car with the wheels off the ground, put the trans in neutral and turn one of the tires by hand. As the joints approach the bind you will immediately feel it and notice the spindle try to rise and relieve the bind.
If you do want to run the driveline with wheels off the ground, its best to support the trailing arms (near the spindles) and then lower the car down until the half shafts are closer to horizontal. This will prevent the joints from entering a binding situation and allow a more unfettered diagnosis.
Good luck... GUSTO
If you do want to run the driveline with wheels off the ground, its best to support the trailing arms (near the spindles) and then lower the car down until the half shafts are closer to horizontal. This will prevent the joints from entering a binding situation and allow a more unfettered diagnosis.
Good luck... GUSTO
Last edited by GUSTO14; Nov 16, 2019 at 09:56 PM.
Intermediate
Joined: Sep 2014
Posts: 45
Likes: 9
From: Queensland
Hi Rich, From what I have read in this thread you have jacked your car up at the end of the trailing arms and the half shafts are strait and are not at an excessive angle.
Now to a possible answer to your question.
When you have checked the wobble on the rotor. I assume you have bolted the rotor firmly to the hub.
Can you check for movement in the rotor by trying to move it side to side or up and down?
Make sure it is only the rotor that is moving and the half shafts are not moving.
If you have movement only at the rotor then there could be a problem with your rear wheel bearing setup. I think you may need thinner shims to tighten the axle in the hub and remove the wobble.
I am not an expert here and could be wrong. I look forward to better experts on the forum commenting on this issue and not about jacking points in this thread.
Now to a possible answer to your question.
When you have checked the wobble on the rotor. I assume you have bolted the rotor firmly to the hub.
Can you check for movement in the rotor by trying to move it side to side or up and down?
Make sure it is only the rotor that is moving and the half shafts are not moving.
If you have movement only at the rotor then there could be a problem with your rear wheel bearing setup. I think you may need thinner shims to tighten the axle in the hub and remove the wobble.
I am not an expert here and could be wrong. I look forward to better experts on the forum commenting on this issue and not about jacking points in this thread.
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Thread Starter
Instructor
Joined: Nov 2013
Posts: 166
Likes: 8
From: Acworth GA
Rich, I think what you're being told is that if you lift the back of the car and the trailing arms reach full droop, it is possible to get the U-joints into a slight bind. When this occurs it can result in the spindles 'wobbling' as the joints try to align themselves. To see how this occurs, the next time you lift the rear of the car with the wheels off the ground, put the trans in neutral and turn one of the tires by hand. As the joints approach the bind you will immediately feel it and notice the spindle try to rise and relieve the bind.
If you do want to run the driveline with wheels off the ground, its best to support the trailing arms (near the spindles) and then lower the car down until the half shafts are closer to horizontal. This will prevent the joints from entering a binding situation and allow a more unfettered diagnosis.
Good luck... GUSTO
If you do want to run the driveline with wheels off the ground, its best to support the trailing arms (near the spindles) and then lower the car down until the half shafts are closer to horizontal. This will prevent the joints from entering a binding situation and allow a more unfettered diagnosis.
Good luck... GUSTO
Thread Starter
Instructor
Joined: Nov 2013
Posts: 166
Likes: 8
From: Acworth GA
Hi Rich, From what I have read in this thread you have jacked your car up at the end of the trailing arms and the half shafts are strait and are not at an excessive angle.
Now to a possible answer to your question.
When you have checked the wobble on the rotor. I assume you have bolted the rotor firmly to the hub.
Can you check for movement in the rotor by trying to move it side to side or up and down?
Make sure it is only the rotor that is moving and the half shafts are not moving.
If you have movement only at the rotor then there could be a problem with your rear wheel bearing setup. I think you may need thinner shims to tighten the axle in the hub and remove the wobble.
I am not an expert here and could be wrong. I look forward to better experts on the forum commenting on this issue and not about jacking points in this thread.
Now to a possible answer to your question.
When you have checked the wobble on the rotor. I assume you have bolted the rotor firmly to the hub.
Can you check for movement in the rotor by trying to move it side to side or up and down?
Make sure it is only the rotor that is moving and the half shafts are not moving.
If you have movement only at the rotor then there could be a problem with your rear wheel bearing setup. I think you may need thinner shims to tighten the axle in the hub and remove the wobble.
I am not an expert here and could be wrong. I look forward to better experts on the forum commenting on this issue and not about jacking points in this thread.
When I removed the rotors and ran the engine, the hub seemed to have the same wobble in it. With the lug bolts spinning around and being that the diameter of the hub is so small compared to the rotor or the wheel it was difficult to tell how much it moved in and out around the face of it.
Drifting
Joined: Nov 2018
Posts: 1,752
Likes: 645
From: USA
If you have the rear tires back on, jack up the rear on one side, like you are changing the tire.... take your left hand and put on the top of the tire at the same time put your right hand on the bottom of the tire....now try to rock the tire in on the top and out on the bottom, over and over! Can you feel play? If so, how much, it should be very minimal or none at all....if there is play, like posted before, it's time for bearings! Good time to rebuild both trailing arms.....bearings, bushings, stainless e-brake hardware, etc. Good luck!
Tech Contributor
Joined: Aug 1999
Posts: 15,166
Likes: 3,967
From: Connecticut, USA
The rotors left the factory riveted to the outer axles, commonly called spindles, and stayed on until someone drilled out the rivets and replaced the rotors.
With the tires on you will have more leverage to load the rear bearings and see some play with high mileage and wear. You may also pick up inner axle endplay in the differential.
You have to get the arms to ride height if you want to power up the rear axles, otherwise you will bind the u-joints are extreme angle and break parts, I know a guy who broke a posi case doing that.
With the rotors off you will see the axle flange has runout in it, they all do and its not because the axles are bent. They were not finished machined since the rotors first had to be revited on and then machined as one. Grab a wheel stud and see if you have play in the outer axle in/out. If you see it move a lot you need to rebuild the arms and replace the bearings. If they are tight then look for movement at the axles and front bushing, If your rotor is bolted on tight to the axle flange and you see runout by eye you have issues most likely with the bearings. Make sure there are no burrs between the rotor hat and flange that could throw them out as well.
With the tires on you will have more leverage to load the rear bearings and see some play with high mileage and wear. You may also pick up inner axle endplay in the differential.
You have to get the arms to ride height if you want to power up the rear axles, otherwise you will bind the u-joints are extreme angle and break parts, I know a guy who broke a posi case doing that.
With the rotors off you will see the axle flange has runout in it, they all do and its not because the axles are bent. They were not finished machined since the rotors first had to be revited on and then machined as one. Grab a wheel stud and see if you have play in the outer axle in/out. If you see it move a lot you need to rebuild the arms and replace the bearings. If they are tight then look for movement at the axles and front bushing, If your rotor is bolted on tight to the axle flange and you see runout by eye you have issues most likely with the bearings. Make sure there are no burrs between the rotor hat and flange that could throw them out as well.
Thread Starter
Instructor
Joined: Nov 2013
Posts: 166
Likes: 8
From: Acworth GA
The rotors left the factory riveted to the outer axles, commonly called spindles, and stayed on until someone drilled out the rivets and replaced the rotors.
With the tires on you will have more leverage to load the rear bearings and see some play with high mileage and wear. You may also pick up inner axle endplay in the differential.
You have to get the arms to ride height if you want to power up the rear axles, otherwise you will bind the u-joints are extreme angle and break parts, I know a guy who broke a posi case doing that.
With the rotors off you will see the axle flange has runout in it, they all do and its not because the axles are bent. They were not finished machined since the rotors first had to be revited on and then machined as one. Grab a wheel stud and see if you have play in the outer axle in/out. If you see it move a lot you need to rebuild the arms and replace the bearings. If they are tight then look for movement at the axles and front bushing, If your rotor is bolted on tight to the axle flange and you see runout by eye you have issues most likely with the bearings. Make sure there are no burrs between the rotor hat and flange that could throw them out as well.
With the tires on you will have more leverage to load the rear bearings and see some play with high mileage and wear. You may also pick up inner axle endplay in the differential.
You have to get the arms to ride height if you want to power up the rear axles, otherwise you will bind the u-joints are extreme angle and break parts, I know a guy who broke a posi case doing that.
With the rotors off you will see the axle flange has runout in it, they all do and its not because the axles are bent. They were not finished machined since the rotors first had to be revited on and then machined as one. Grab a wheel stud and see if you have play in the outer axle in/out. If you see it move a lot you need to rebuild the arms and replace the bearings. If they are tight then look for movement at the axles and front bushing, If your rotor is bolted on tight to the axle flange and you see runout by eye you have issues most likely with the bearings. Make sure there are no burrs between the rotor hat and flange that could throw them out as well.
I think I see the reason some thought I was driving the rear wheels with them hanging down. The blocks I supported the wheels with were put on the garage floor under the point where the shock attaches to the wheel or spindle assembly and then I lowered the back of the car down until the full weight of the car was on the blocks and the axles were straight. I just did not explain it sufficiently. I can't imagine anyone trying to trouble shoot any condition, that is only experienced while driving, and doing that with the wheels hanging down unloaded.
Tech Contributor
Joined: Aug 1999
Posts: 15,166
Likes: 3,967
From: Connecticut, USA
Yes that is correct, axle flange was rough faced and most have 010" or more runout. Many have been sold new axles - being told they were bent. These are relatively strong so they won't warp, they will bend from impact such as sliding into a tee bone accident of some sort but then you would see evidence on the car as well. The rotors were riveted on and turned for -0- runout. The brakes were superior to anything offered during the run of c2- c3's and are still very good once properly set up.
If you see runout by eye you have some issues that shouldn't be too hard to pinpoint, there is only a few suspects= rotors, axles, bearings, steel wheels.
If you see runout by eye you have some issues that shouldn't be too hard to pinpoint, there is only a few suspects= rotors, axles, bearings, steel wheels.
Thread Starter
Instructor
Joined: Nov 2013
Posts: 166
Likes: 8
From: Acworth GA
I finally got time to set it up again. I jacked it up using the jack under the diff, put blocks under the end of the shocks, lowered the body down to the point the jack was free, then lifted the jack until it lifted the diff about 1/2 inch to put a small amount of weight on the jack.
The tires were about an inch off the ground, so they were not loaded. I put a 1 x 4 x 24 board under the tire and lifted and released. I could see the tire moving up and down about 1/2 inch. I had someone else do it while I looked at the transaxle. I saw the shaft at the diff moving in and out of the diff about 1/2 inch. I believe that means the spindle was moving in and out about 1/2 inch. This happened on both sides.
With the rotors off you will see the axle flange has runout in it, they all do and its not because the axles are bent. They were not finished machined since the rotors first had to be riveted on and then machined as one. Grab a wheel stud and see if you have play in the outer axle in/out. If you see it move a lot you need to rebuild the arms and replace the bearings. If they are tight then look for movement at the axles and front bushing, If your rotor is bolted on tight to the axle flange and you see runout by eye you have issues most likely with the bearings. Make sure there are no burrs between the rotor hat and flange that could throw them out as well.
The same pressure applied to the rear driver side does not show any movement.
I looked in my Haynes Repair Manual for anything to do with the spindle or rear bearings. There was nothing. I don't have any idea what the norm is or what the specs are.
I looked online for spindle replacement and saw that I need to purchase two special tools to do it. I doesn't look like leisurely afternoon job to do this. I might take it to a garage that specializes in Corvettes.
Thank you for your help here.
Tech Contributor
Joined: Aug 1999
Posts: 15,166
Likes: 3,967
From: Connecticut, USA
An 1/8" is a mile if that is correct. If that much play was in the axle bearings you would see a huge wobble all right. Sounds like inner axle endplay and possible outer axle play. If the car has not been serviced for the IRS and Diff you are probably overdue. If the axles are that loose they will crash into the housing at the seal and grind away the 1/8" lip and hit the seal. You may loose the housing at that point and have a massive oil leak.
No, this job requires time and patience from anyone working on them. A good shop that knows these cars shouldn't have a problem, an inexperience shop will break more things that you will imagine and the repair cost will approach what we used to pay for a whole car- if they even correctly set them up.
Good luck.
No, this job requires time and patience from anyone working on them. A good shop that knows these cars shouldn't have a problem, an inexperience shop will break more things that you will imagine and the repair cost will approach what we used to pay for a whole car- if they even correctly set them up.
Good luck.
Thread Starter
Instructor
Joined: Nov 2013
Posts: 166
Likes: 8
From: Acworth GA
An 1/8" is a mile if that is correct. If that much play was in the axle bearings you would see a huge wobble all right. Sounds like inner axle endplay and possible outer axle play. If the car has not been serviced for the IRS and Diff you are probably overdue. If the axles are that loose they will crash into the housing at the seal and grind away the 1/8" lip and hit the seal. You may loose the housing at that point and have a massive oil leak.
No, this job requires time and patience from anyone working on them. A good shop that knows these cars shouldn't have a problem, an inexperience shop will break more things that you will imagine and the repair cost will approach what we used to pay for a whole car- if they even correctly set them up.
Good luck.
No, this job requires time and patience from anyone working on them. A good shop that knows these cars shouldn't have a problem, an inexperience shop will break more things that you will imagine and the repair cost will approach what we used to pay for a whole car- if they even correctly set them up.
Good luck.
