Majoho

I've read a lot of conflicting info on removing brake rotors. Yeah, go ahead no problem, yeah go ahead but you'll need to shim them to eliminate runout, no, you only have to do that if you install new rotors, no don't EVER separate your rotors from the hub...

I need to replace my parking brake shoes and hardware (seized solid) so I guess I need to pull the rear rotors. My question is, if I replace them in exactly the same orientation as they were in before I removed them (rotor holes back to same studs), will it be necessary to adjust the runout?

My car is a '70 and the rear rotors have already been removed at some point because the rivets are already drilled out.

I'm a newbie to Vettes but I'm learning fast, thanks to all the great members on this forum. Maybe someday I'll be able to answer some questions instead of just asking them...

MelWff

If you currently have no issues with air getting into the rear calipers and you replace the rotor into the same position, you should be fine.

lionelhutz

I would check the runout if the rotors have already been replaced. Chances they were replaced properly are rather slim.

Easy Mike

Check, yes. Adjust? Possibly not. Mic them now and check the run out. Index them before you remove them.

Majoho

The brakes are working fine now. No air in the system, pedal is nice and firm, brakes grab nice and progressively. I know this has been asked many times, but if I did need to adjust runout, is it a big, i.e. time consuming job? Not looking for a how to, just an idea of the possible scope of the job. I'm sure there's lots of 'how to' posts on shimming out rotor runout here on the forum. (anybody with links to such already bookmarked feel free to post them here)

SIXFOOTER

Shimming the rotors isn't all that hard or time consuming. Basically what you have to is put shims behind the rotor to true it up on the rotational plane of the hub. Might take 1, might take 3 or 4.
You could spend a couple hrs checking and a half a day doing.

MotorHead

Yeah seems to run hand in hand the more confuseder I get the more preterbreated I get. Hope you get er running gooder

lionelhutz

Assuming you do need shims, NAPA sells the shims in varying thicknesses. You can either use them and a dial indicator or you can find a place with an on-car rotor lathe and get it done that way.

The fronts can be done by bolting the hub and rotor together and then machining the whole assembly. Just make sure the rotor stays indexed with the hub.

Majoho

With me, getting preterbreated usually goes hand in hand with getting inebriated. Confusion? My Corvette does that to me all time, and I love it for that. Makes me think.

Majoho

Do you mean regular shim stock, or are there special shims?

wombvette

Hell of a lot easier to work on those hand brakes with the axle out too. So, if there is any chance the bearings need servicing too, it is easier to remove the whole thing and do it all at one time.

Peterbuilt

Majoho

Great video! Thanks for posting it, Pete. Are these shims readily available? I guess I'm gonna have to buy myself a dial indicator. With a C3 I'll probably need it more than once...

Mike Ward

+1.

If you don't know how many miles are on the bearings, or you know it's over 40K, they're due.

Mid-Years Forever!

Thanks for posting--I've been curious about these "shims" for some time.

Having said that: wow...that seems pretty crude to me, in that the increments (at least for that car) are .003, .006 and .009.

And what if there's more than one location or "wave" to the runout?

While it seems like an economical (potential) solution, it just doesn't seem like an equal substitute to on-car machining. But I could be wrong....

noonie

Sometimes the're close, sometimes not.

Best is to bolt rotors back on using the original rivet holes and no shims, then turning them.
On the front, mounted on the hub on a regular brake lathe.
On the rear, using a good on car brake lathe with someone that knows what their doing, but only with proper bearing specs.

Not mine, but here are some pics of how to mount the rotors properly, then there is no chance of crud falling inside. You can shim or turn, your choice, but turning is best.





For instructions, google "Rotor replacement and Dial In"

Majoho

Sheesh. This is starting to sound like a home improvement project. Start out to repair the parking brake, and 'while your at it...' turns it into a full frame off project!

So, next question(afraid to ask): is it a 'big' job to pull the axles and check/replace the bearings?

Peterbuilt

A couple of questions:
Have you tried adjusting the parking brake first at the star wheel and then at the cables?
Whats wrong with the rotors that you have? New they measure 1.250 with a minimum at 1.230. Measured yours yet?

Pete.

Majoho

Nothing wrong with the rotors. I just need to remove them to replace the parking brake guts. Rotors are in spec and in very nice condition. Rear brake cable is seized up on both sides. Star wheels are seized. Brake levers(the ones that the cables connect to) are seized. I'm replacing the entire park brake system. Got to have a functioning park brake to pass inspection.

So, how about rear axle bearing replacement? Is that a big deal?

jotto

Replace the parking brake assembly and cables. Have a beer. Then use the can to shim the rotor. Job done!