Binding Rear Rotors?
Thread Starter
Drifting
Joined: Mar 1999
Posts: 1,381
Likes: 15
From: Lusby MD
Binding Rear Rotors?
I've had one problem after another getting my new brakes working on the 68. Now I have a pretty decent pedal (not great) and have the whole system buttoned up, but last night I went to start the car and move it, and it was frozen in place. I checked into it some more and found that the rear pads were binding on the rotors. The pistons are all the way in and there's still contact. I removed the calipers and the wheels rotated freely.
I brough the rotors to a machine shop today and the shop manager said that the spec for the rotors was 1.230 and discard was 1.215. These were 1.259! I had him turn them down to 1.230, which was OK because, even new, there was some slight wrapage. Now I can get the wheels to turn and I can drive the car, but the rears still get hot. Its primarily the outer pad on both wheels.
Anyone else run into this???
I brough the rotors to a machine shop today and the shop manager said that the spec for the rotors was 1.230 and discard was 1.215. These were 1.259! I had him turn them down to 1.230, which was OK because, even new, there was some slight wrapage. Now I can get the wheels to turn and I can drive the car, but the rears still get hot. Its primarily the outer pad on both wheels.
Anyone else run into this???
Last edited by 69L71; Aug 24, 2004 at 07:51 PM.
Le Mans Master
Joined: Jul 2000
Posts: 6,663
Likes: 162
From: columbia city in
brakes
take off one of your wheels ,then have some one pump the brakes .look at the brake caliber ,are the pistons returning moving back and forth ,i just replaced a rubber brake line on my 82 .because the left rear brake was not releaseing ,the line would not let the fluid return .
Melting Slicks
Joined: Feb 2000
Posts: 3,052
Likes: 0
From: Vancouver BC, Canada
Originally Posted by 69L71
I've had one problem after another getting my new brakes working on the 68. Now I have a pretty decent pedal (not great) and have the whole system buttoned up, but last night I went to start the car and move it, and it was frozen in place. I checked into it some more and found that the rear pads were binding on the rotors. The pistons are all the way in and there's still contact. I removed the calipers and the wheels rotated freely.
I brough the rotors to a machine shop today and the shop manager said that the spec for the rotors was 1.230 and discard was 1.215. These were 1.259! I had him turn them down to 1.230, which was OK because, even new, there was some slight wrapage. Now I can get the wheels to turn and I can drive the car, but the rears still get hot. Its primarily the outer pad on both wheels.
Anyone else run into this???
I brough the rotors to a machine shop today and the shop manager said that the spec for the rotors was 1.230 and discard was 1.215. These were 1.259! I had him turn them down to 1.230, which was OK because, even new, there was some slight wrapage. Now I can get the wheels to turn and I can drive the car, but the rears still get hot. Its primarily the outer pad on both wheels.
Anyone else run into this???
nominal rotor thickness is 1.250". minimum is 1.215". i really doubt +.009" would cause the rotor to bind. in fact pad thickness tolerance is likely +/-1mm. do you have the correct pads?
front and rear C3 rotors have the same dimensions correct??
did they measure the total runout? where did you get these rotors? where they made in North America?
Le Mans Master
Joined: Jan 2000
Posts: 8,918
Likes: 27
From: New Hill NC
No, they are not the same. They are machined from the same blank and they are the same thickness and size etc. Some will even work. But, the flange thickness is different and it makes the rotor off center. For this reason one pad will bind. It is easy to see if it is off center.
Thread Starter
Drifting
Joined: Mar 1999
Posts: 1,381
Likes: 15
From: Lusby MD
I talked with a buddy of mine and he suggested that worn brake hoses often cause a similar problem. I have new ones so it's not that.
The Rotors are Reybestos and were marked as rear units. They have the rivit holes drilled. The fronts didn't. That was interesting. No, they are not American made. They're offshore. Its hard to tell if they're offset or not because I don't have the old ones anymore. In hindsight, I wish I'd have asked the machinist to just shave the outside surface. But before I had 'em mic'd, I couldn't get the caliper and pads on the rotor at all, even with the pistons fully compressed.
Interestingly, the latest copy of Corvette Fever, which arrived yesterday, had a tech question from a guy with a similar problem. They suggest messing with the combination valve. I'm gonna try that tonight. If it fails, I'm gonna remove the outer pad and shave it down a bit. Its very close now. A little more clearance and, even if something is a bit awry, it will drive fine.
The Rotors are Reybestos and were marked as rear units. They have the rivit holes drilled. The fronts didn't. That was interesting. No, they are not American made. They're offshore. Its hard to tell if they're offset or not because I don't have the old ones anymore. In hindsight, I wish I'd have asked the machinist to just shave the outside surface. But before I had 'em mic'd, I couldn't get the caliper and pads on the rotor at all, even with the pistons fully compressed.
Interestingly, the latest copy of Corvette Fever, which arrived yesterday, had a tech question from a guy with a similar problem. They suggest messing with the combination valve. I'm gonna try that tonight. If it fails, I'm gonna remove the outer pad and shave it down a bit. Its very close now. A little more clearance and, even if something is a bit awry, it will drive fine.
Last edited by 69L71; Aug 25, 2004 at 09:03 AM.
Premium Supporting Vendor
Joined: May 2000
Posts: 4,312
Likes: 70
From: Clearwater FL
Just because the rotors have rivit holes DOES NOT mean they are for the rears. They have to have a parking brake adjustment hole. Do you know the runout of the spindle surface? Whats the rotor run out? Did you bleed the brakes properly?
Thread Starter
Drifting
Joined: Mar 1999
Posts: 1,381
Likes: 15
From: Lusby MD
Good info VS. I can't comment on the runout and I can't remember if it has the brake adjustment holes. The car is at home. I'll check tonight.
I bought the rotors from a local parts store and the fronts are rears were definately different part numbers, and both pairs stated 65-82 corvette. However, these comments are giving me reason to doubt the correct application. Since I'll be up at Carlisle this weekend anyway, maybe I'll pick up a new set of rears and try again.
I bought the rotors from a local parts store and the fronts are rears were definately different part numbers, and both pairs stated 65-82 corvette. However, these comments are giving me reason to doubt the correct application. Since I'll be up at Carlisle this weekend anyway, maybe I'll pick up a new set of rears and try again.
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Racer
Joined: Oct 2002
Posts: 449
Likes: 2
From: Fayetteville, PA
Same problem
I thought I had the same problem. Changed the calipers and pads. No change still felt like the brakes were sticking.A friend mentioned he had the same problem and it was his posi rear. I changed the fluid and "voila"(wa-la), I haven't had a problem since. 
Thread Starter
Drifting
Joined: Mar 1999
Posts: 1,381
Likes: 15
From: Lusby MD
Thanks Blue, but that's definately not it. I took the wheels, tires, and rotors off the car and the axles spin freely. Which everything installed and I drive the car, the rear brakes get hot. You can smell them and feel the heat coming off the rim. Its definately brakes.
BTW VS, my rear rotors DO NOT have parking brake adjustment holes so I think you're onto something! I'm off to Carlisle this morning so I'm gonna look me up a new set of rears and see if that does the trick.
BTW VS, my rear rotors DO NOT have parking brake adjustment holes so I think you're onto something! I'm off to Carlisle this morning so I'm gonna look me up a new set of rears and see if that does the trick.
