SledgeHammer 2.0

Okay guys, I got a small "oh my rotor is warped barely applying the brakes" grinding sound coming out of the passenger rear of my 66.

A long time ago I had a noise coming from the right side of the car and I pulled the right side of the car apart and found that I had a rear spindle that had stripped threads, I changed all that but the car still had a noise, but not as bad.

Flash forward 7 years and I have got a noise coming back again, actually two of them I think. I have got a grinding-scraping noise when I barely apply the brakes in a rhythmic pulsation (the pedal does not pulsate). If you apply the brakes a little harder the noise goes away.

I pulled both sides down again in the last couple of days just to do maintenance and check everything, and I replaced the left spindle to match the right side. I can see on the rotor where it looks like it was dragging like the rotor is warped.

To shorten the story, two new rotors, bearings, set the end play of the bearings and a new spindle, checked the half shafts etc. cleaned and adjusted everything ... and I still got the noise. At first it was even worse making the scrape-scrape-scrape noise without applying the brakes, That lasted less than a block. Now that is gone but I still got the scrape-scrape-scrape noise when I barely apply the brakes.

I also got a suspension clunk-thump going from forward to reverse like something is loose but nothing is. I checked the parking brake to make sure it wasn't dragging and making the noise but it isn't.

I don't know what else to check. Is there some secret to the Independent Rear suspension to get them set up right that I am missing?

Other notes The front rear end bushing is new(ish), the upper bar big rubber bushings look okay but are probably original to the car. I haven't hit anything to bend the spindle.

Any ideas?

62Jeff

Classic symptoms of a bad U-joint. Check the U-joints on the driveshaft for too much play. Check the ones on the half-shafts as well.

It may very well be something else too, but start with the U-joints.

Frankie the Fink

Its ALWAYS a good idea to check U-joints whenever there are rear drive train symptoms...the 'clunk' on engaging the drivetrain is usually a dead giveaway...this can be dangerous and deal with it ASAP...

You could have two problems and the other may be a sticky caliper giving you the scrape-scrape sound and the pattern on the rotor. Sometimes the accumulated crud or wear on the pistons in the caliper keep them from retracting completely....

I don't see where you changed them in your original post...

SledgeHammer 2.0

I didn't change the U-joints but checked them, they were in good shape, no pitting on the shafts. The Calipers I rebuilt myself, they don't stick, it doesn't make the noise going down the road, only when you lightly apply the brakes.

Frankie the Fink

I'd find somebody with a frame, post lift and get the car up on it and simulate shifting and light braking with somebody in a safe spot under the car observing and listening. If nothing else that shift-engagement clunk should be a no-brainer to spot... If you get an abnormal 'clunk' on engaging the drive train then there is too much lash ('play') somewhere from the flywheel rearwards...

SledgeHammer 2.0

Well I officially give up. I am going to name this car Christine,

I have tried everything and it's only gotten worse. The rotor hits the caliper body,

The spindle had about .005 run out so for giggles I took the spindle off the D.s. and swapped it with the passenger side. The D.S. still runs straight and true and now the passenger side probably has .05 run out. I out the old rotor from the D.S. and it's just as bad.


I give up...........back to storage it goes.

Mike Ward

This is the rear suspension, right? You're swapping spindles side to side? Wow.

The noise you describe sounds like the brake pads moving back and forth in sympathy with rotor runout with the sound is generated by the pads and the retaining pin.

What have you done to eliminate rotor runout?

Tampa Jerry

Before you put the car in storage, try to eliminate the runout. Make sure everything inside the rotor is very clean. Snug up the rotor to the spindle with at least 3 lug nuts. Use a dial indicator to determine the low spots. I would first try changing the "clock" of the rotor on the spindle. Measure each time for the least amount of runout. If the runout is still too great, try shimming the inside of the rotor with shim stock. Usually .005 is OK. I try to get them to within .002 and .003. Lastly, remove your pads and put a slight bevel or chamfer around the outside edge of the pad. I do this with a file and always use a mask. If you are having problems with air pumping in the calipers, rebuild with O-rings instead of the usual seals. Good luck. Jerry

Lee H

Maybe one of the pads are cracked and tries to move around a little when pressure is applied?

SledgeHammer 2.0

No It;s the actual rotor hitting the Caliper. It's the outer edge. I have tried everything I know to eliminate this problem. One thing I have also noticed is that the trailing arm actually moves slightly in and out when I have it on jacksstands with the wheels off running it in 2nd gear.

I have tried swapping the spindle from the Drivers side (not the whole trailing arm), swapped half shafts, bought a new flange, new rotors, and then taking the old rotor from the Drivers side and putting it on the passenger side. Trying the old spindle that was on the drivers side. New bearings (?) every thing I could think of that would cause run out.

This car is my Christine and we have a love hate relationship going on. It hates me. I have been working on cars since I was 12, I feel comfortable working on any aspect of any car ever made.I have even been trusted to rebuild drive lines on One Lap of America cars, but this car has fought me for 21 years. Everything I do to it is a hassle.

I had vintage air put in and while I am alone in the car, the air will dump water (the condensed water) on the passenger side floor. Got a passenger in the car? Never leaks. I have a list so long of everything I have tried to do to this car and the work turn to crap. Had the rebuilt numbers matching motor blow up at an idle, after thirty minutes of running something gave way and upon tear down it had a HOLE in the cylinder wall (don't know where it came from) water locked the piston, bent the rod, another tear down and sleeved the cylinder and it;s held together. I got 21 years of stories. It's my Christine.


I called a guy today named Vinnie, who owns Muscle Cars of Texas, and also has about 20+ years experience rebuilding Corvettes, He gave me some ideas, but I think I am just taking him the whole car. If I went and bought a new loaded trailing arm, it wouldn't fix it, but maybe if he looked at it, Christine would let him repair her.

If she doesn't straighten out I am going to sell her and get another Vette. Maybe I will get EHarmony to find her for me.

Mike Ward

That's not surprising-you shouldn't run it with the suspension just dangling. The u-joints are binding due to over extension of the suspension.

Putting that aside, find out where the runout is coming from and correct it. I'll ask again: What have you done to eliminate rotor runout?

SledgeHammer 2.0

Didn't leave them dangling...With my car on those jackstands which I jammed in between the leaf spring and control arm to give the most leverage for weight on the suspension to emulate real road ride height. The D.S. did not have the in and out movement, just the P.Side.

That's what I tried to figure out where the run-out is coming from. ......If the D.S. has minimal run-out and I switched the moving parts to the passenger side, one would think the run-out would follow the parts. They didn't. I don't know what else to do to eliminate the run out of the rotor that I believe is caused by the run-out of the spindle. Which measures bad but only on that side. I put that spindle on the d.s and it doesn't have enough run out to make the rotor move any measurable amount.

MikeM

[QUOTE=Pugly;1573831501]No It;s the actual rotor hitting the Caliper. It's the outer edge.

Is the caliper mounting bracket bent causing the capliper not to be square with the rotor?

Your AC leak problem sounds like the drain hose is in the wrong place.

SledgeHammer 2.0

MikeM, I am thinking "maybe" but that still would not explain all the run out and trailing arm movement.

I am going to run it over to that shop tomorrow and have another set of 'eyes' look at it. Maybe he can see something I am missing.

MikeM

Mike Ward explained the trailing arm movement in post #11 when he said the U joints were binding while you had the rear suspension dangling. That will kick the trailing arms ib/ob while the wheels rotate. Depends on shock extension length but that's what can happen.

It's easy to see if the caliper bracket is bent, just look and see if the capliper (not pads) is square to the rotor. Eyeball it.