Brake Problem
Banned
Joined: Oct 2007
Posts: 594
From: South Jersey
RE: Brake Problem
Hi Texas Jim,
In response to your response about not buying the air thing...
Our C3 Corvettes have fixed calipers, not floating calipers. With a floating caliper rotor runout is absorbed by the ability of the caliper to move with the distorted rotor. With a fixed caliper rotor runout can cause the caliper piston to follow the uneven surface, thus the pulsating pedal effect and possibly the air in the system. It is a theory of last resort, I do agree.
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In response to your response about not buying the air thing...
Our C3 Corvettes have fixed calipers, not floating calipers. With a floating caliper rotor runout is absorbed by the ability of the caliper to move with the distorted rotor. With a fixed caliper rotor runout can cause the caliper piston to follow the uneven surface, thus the pulsating pedal effect and possibly the air in the system. It is a theory of last resort, I do agree.
[sm=icon_cheers.gif]
Thread Starter
Joined: Aug 2007
Posts: 72
From:
RE: Brake Problem
I had to stop by the vette shop to pick up a part that they ordered for me and we got to talking about the brake light. He says its only a matter of time before the brake light comes back on and says they would check runout for the fronts. Well, there was no air in the fronts, only the rears. If the light does come on again, does it sound right to replace the rear calipers only or do all4?
Super Moderator
Joined: Jul 2006
Posts: 5,244
From: Reno, Nv.
RE: Brake Problem
I agree, unless you're doin' an upgrade.
I've already admitted that I'm no whiz on disc brakes, but it seems to me that if you can do something to improve quality, performance,and reliability, then do it.
( otherwise, I'd still be drivin' a Chevette.
I just dropped the "H", changed the "E" to an "O", and the "V" to an "R". Made a world of difference.
)
I've already admitted that I'm no whiz on disc brakes, but it seems to me that if you can do something to improve quality, performance,and reliability, then do it.
( otherwise, I'd still be drivin' a Chevette.
I just dropped the "H", changed the "E" to an "O", and the "V" to an "R". Made a world of difference.)
Super Moderator
Joined: Apr 2006
Posts: 4,213
From: KC, MO area
RE: Brake Problem
If the runout on the rears is in spec, then re-bleed the brakes.
If not, [:'(]then replace rear rotors and make sure they meet runout spec. You can check in all five locations for the best runout.
If you can't meet it, then you can get the tapered shims if they're still available.
If not, [:'(]then replace rear rotors and make sure they meet runout spec. You can check in all five locations for the best runout.
If you can't meet it, then you can get the tapered shims if they're still available.
Senior Member
Joined: Aug 2006
Posts: 1,152
From: NC
RE: Brake Problem
How much run-out on the rotor is acceptable?
If the rotor is "true" but when mounted on the hub it is out of spec, how do you correct that?
How much end play is acceptable for the front bearings?
How much end play is acceptable for the rear bearings?
dar322, I hope this second bleed solves your problem.
Texas Jim, still not convinced that"air" is a problem with our vettes,
call "Corvettes Etc" at 704 394 5150 he has repaied only vettes for the last 20 years, mabye he can convince you. PG.
If the rotor is "true" but when mounted on the hub it is out of spec, how do you correct that?
How much end play is acceptable for the front bearings?
How much end play is acceptable for the rear bearings?
dar322, I hope this second bleed solves your problem.
Texas Jim, still not convinced that"air" is a problem with our vettes,
call "Corvettes Etc" at 704 394 5150 he has repaied only vettes for the last 20 years, mabye he can convince you. PG.
Super Moderator
Joined: Apr 2006
Posts: 4,213
From: KC, MO area
RE: Brake Problem
ORIGINAL: pg
How much run-out on the rotor is acceptable?
Lateral runout TIR (65-70) .002", (71-later) .005" However total allowable end-play plus run-out should not exceed .009" on rear wheels.
If the rotor is "true" but when mounted on the hub it is out of spec, how do you correct that?
First try indexing to the other four positions. (This may require re-drilling the parking brake access hole on the rear rotors) If that doesn't work then you can either get tapered shims that fit on the bolt circle or have someone turn the rotors with them mounted on the car.
How much end play is acceptable for the front bearings?
Service manual states .001-.008" It also provides the correct procedure to achieve this.
How much end play is acceptable for the rear bearings?
Same as front. Adjustment is difficult and requires special tools. There are aftermarket companies that will rebuild your trailing arms.
dar322, I hope this second bleed solves your problem.
Texas Jim, still not convinced that"air" is a problem with our vettes,
call "Corvettes Etc" at 704 394 5150 he has repaied only vettes for the last 20 years, mabye he can convince you. PG.
How much run-out on the rotor is acceptable?
Lateral runout TIR (65-70) .002", (71-later) .005" However total allowable end-play plus run-out should not exceed .009" on rear wheels.
If the rotor is "true" but when mounted on the hub it is out of spec, how do you correct that?
First try indexing to the other four positions. (This may require re-drilling the parking brake access hole on the rear rotors) If that doesn't work then you can either get tapered shims that fit on the bolt circle or have someone turn the rotors with them mounted on the car.
How much end play is acceptable for the front bearings?
Service manual states .001-.008" It also provides the correct procedure to achieve this.
How much end play is acceptable for the rear bearings?
Same as front. Adjustment is difficult and requires special tools. There are aftermarket companies that will rebuild your trailing arms.
dar322, I hope this second bleed solves your problem.
Texas Jim, still not convinced that"air" is a problem with our vettes,
call "Corvettes Etc" at 704 394 5150 he has repaied only vettes for the last 20 years, mabye he can convince you. PG.
Super Moderator
Joined: Jul 2006
Posts: 5,244
From: Reno, Nv.
RE: Brake Problem
Parking brake light? I suspect that the switch placement might need to be adjusted. I think it only comes on when the PB is pulled. Not sure on this, but that's the reasoning my twisted mind comes up with.
