Replacing Rotors

[LorinD]

I have a '71 Vette , I want to replace the all the rotors and pads. Howerver I
can't get the front rotors off . I had checked the book , but the rotor will not budge . I don't want to do a pound pound number on them . I may do some damage some where else .
Thanks Lorin

 

[Eric]

Lorin,

First off, welcome to the !

Are you sure your rotors aren't still riveted to the hubs. If they have been turned on the car and the car has low miles, this is a possiblility. If this is the case, you will have to drill them out to remove the rotors.

You can give them a tap with a rubber mallet if necessary.

Also, once you replace the rotors be sure to check for run-out. Even new rotors may need to be turned on the car so that they are true to your car.

Good luck!

 

[Vettehead Mikey]

I want to replace the all the rotors and pads.

AGGGGGGGHHHHHHHHHH! WHY? It's highly unusual to NEED to replace just ONE rotor, never mind all four! Most rotors outlive the car they're attached to.

Are you sure they need to be changed?

 

[Zixxer]

What? I just had all four on my 96 replaced....clearly below specs and while I guess I could have just turned them again I would have always wondered if they would warp or fail. My Dodge Ram 1500 has 32k on it and I can already tell the rear two rotors are going to be replaced. Pulling a boat and warping have taken there toll. I don't think I've owned a car yet that the rotors have lasted more the 100k.

I washed a car the wrong way for years (dishwashing soap) so I'm willing to learn if you have a good source to support the statement about rotors outliving a car.

 

[Vettehead Mikey]

I washed a car the wrong way for years (dishwashing soap) so I'm willing to learn if you have a good source to support the statement about rotors outliving a car.

We're talking a C3 here, not a C4 or any other car. Completely different braking systems, with completely different design heritage, nothing in common. I've replaced rotors on everything else I've ever owned too. C2/C3 are a different animal.

I've got two of my four original rotors on my 125,000+ mile '73, the other two were replaced due to my own ignorance and should have stayed.

If the rotors are not heavily scored, don't have them turned. Leave them alone. If you must turn them make sure they are done while still attached to the hubs (both front and rear). Only change them if they are below service limits (extremely rare).

If you do change them, have the new ones turned while attached to the hubs. This is essential to avoid problems with runout of the rotor surface.

You CANNOT service rotors on a C2/C3 like any other car- just look at the number of posts here and every other forum about rotor runout and brake loss.

 

[Zixxer]

Thanks, makes me feel a little better.

Now is it common practice to turn a rotor while on the vehicle? I always remember them being pulled off and turned on a machine. Seems to make sense, just like I believe a tire should be balanced on the car....never understood why it's taken so long to adopt that as a practice. Cars should be treated as an entire system when it comes to balancing anything.

 

[MaineShark]

Thanks, makes me feel a little better.

Now is it common practice to turn a rotor while on the vehicle? I always remember them being pulled off and turned on a machine. Seems to make sense, just like I believe a tire should be balanced on the car....never understood why it's taken so long to adopt that as a practice. Cars should be treated as an entire system when it comes to balancing anything.

The fixed calipers mandate the rotors being turned on the car. In other words, it really doesn't matter whether the rotor is true to the hub - it matters whether the rotor is true to the caliper, to avoid problems with runout.

Joe

 

[Vettehead Mikey]

The fixed calipers mandate the rotors being turned on the car. In other words, it really doesn't matter whether the rotor is true to the hub - it matters whether the rotor is true to the caliper, to avoid problems with runout.

Joe

Afraid I must disagree Joe. Having fixed calipers is a factor in the equation, but only in the sense that they are more sensitive to disk irregularities that a floating caliper.

The principal reason that the rotor must be turned on the hub (and this may be unique to C2/C3 Corvettes) is that the hub was not machined true to start with. The hub and rotor were attached together with rivets in a semi-finished form, and THEN machined as a pair. Once the machining was finished and the hub installed on the car, the rivets became superfluous. This means that swapping rotors in the field became a hit-or-miss proposition with respect to maintaining the original intended runout limit. GM did not plan for having disks replaced in the field and I believe never sold them without the hub as a unit.

Today's cars have the hubs machined true, meaning that swapping disks around does not affect runout.

 

[LorinD]

The right front is the only one that Ihave removed the caliper. The rotor is score on the
inside . It may not be as bad as I think . But it does feel rough . The the inside pad on that rotor worn down . Last summer I had to bleed the brakes about every two or
three weeks , to keep a desent pedal . I was told if the rotor are bad that maybe the cause of my problem. Thank all you guys for your quick replies.

 

[mvftw]

I haven't cut my Vette rotors yet, but I would take them off for 2 reasons...it's cheaper to bring them somewhere and get machined and second the inside bearing should be cleaned & greased which is offen forgotten about.

 

[MaineShark]

Afraid I must disagree Joe. Having fixed calipers is a factor in the equation, but only in the sense that they are more sensitive to disk irregularities that a floating caliper.

The principal reason that the rotor must be turned on the hub (and this may be unique to C2/C3 Corvettes) is that the hub was not machined true to start with. The hub and rotor were attached together with rivets in a semi-finished form, and THEN machined as a pair. Once the machining was finished and the hub installed on the car, the rivets became superfluous. This means that swapping rotors in the field became a hit-or-miss proposition with respect to maintaining the original intended runout limit. GM did not plan for having disks replaced in the field and I believe never sold them without the hub as a unit.

Today's cars have the hubs machined true, meaning that swapping disks around does not affect runout.

Sorry for the delay in replying...

Many modern cars are still requiring that the rotors be machined while on the car, so I doubt that it is a matter of modern machining practices vs. older machining practices. If that were the case, I would also expect to see aftermarket upgrades with properly-machined sets of hubs and rotors.

Joe

 

[JohnZ]

Unless your rotors are badly scored or measure below minimum thickness, leave them alone, and leave them indexed EXACTLY the way they were on the lug studs. Brake shops just LOVE to "turn the rotors", but none of them understand the C2/C3 fixed-caliper brake system, nor do they understand that the rotors must be turned ON THE SPINDLE, IN ITS BEARINGS, to avoid getting more than .003" total lateral runout, which will pump air past the caliper piston seals.

With stock pads, stock rotors will last 100K miles with no problem at all, and don't need "turning" when pads are changed; Billy-Bob's discount brake shop (the one in the old converted gas station on the corner) doesn't know squat about C2/C3 brakes, but they LOVE to "turn them rotors" :eyerole

 

[LorinD]

The right front rotor is scored bad on the inside , the side facing out wasn't bad . I am going to remove the left caliper tomorrow to check the condition of rotor . I have been
told if you replace one , you must do both .
Thank you guys for all your help, I do appreciate it .

 

[Vettehead Mikey]

I have been told if you replace one , you must do both .

Bull poopie. Must have been Bubba the paid-on-commission parts sales guy. No technical foundation to changing out a goor rotor just because it's distant cousin isn't is good shape.

 

[LorinD]

The right front was the only bad rotor . It is so bad that it can not be turn down and
still be legal . It is the inside surface that was torn up . The out side surface was in good shape . The inside pad was worn down , but that may have come from the rotor .
This has become a major operation , I was figuring a few problems , I have asked a
couple machanics what may have been the cause . I got the feeling they don't like
working on Vettes .

 

[Flared69]

i had my rear rotors and discs replaced at a shop...

$1600

make sure you know what really needs to be replaced.

 

[Vettehead Mikey]

The right front was the only bad rotor . It is so bad that it can not be turn down and
still be legal . It is the inside surface that was torn up . The out side surface was in good shape . The inside pad was worn down , but that may have come from the rotor .
This has become a major operation , I was figuring a few problems , I have asked a
couple machanics what may have been the cause . I got the feeling they don't like
working on Vettes .

There must be a Vette friendly place somewhere nearby. Just remember to measure runout as soon as you install the new rotor. If over max. have rotor and hub machined as a pair.