mk's78

To my fellow C3 panel of experts...

I am considering removing the rear rotors on my 78 Vert. Initial inspection with the wheels removed show that the rivets were drilled out by the PO.... My question is: I am assuming that the caliper(s) have to be moved out of the way and would appreciate it if the experts could tell me how they are removed and can they be reinstalled without the calipers trying to close the brake pads.

Any and all help, tips & guidance etc. as always is greatly appreciated...

mk's78 Mike

jdunfee

There should be two bolts on the back of the calipers that are holding them in place. Once the bolts are removed you should be able to pull the caliper off the rotor. The rotor shouldnt close the pads unless you press the brake pedal. I have had them close a little bit but you can usually open them back up easily enough with a c-clamp or a caliper compression tool.

briankeery

Two bolts hold rear caliper on, make sure you remove the larger bolts, as the smaller ones hold the two caliper halves together.
If concerned about the reassembly, place a piece of wood between the pistons to keep them stable.
The rear caliper has the hard line attaching it to the rear brake hose, be careful not to bend this once the caliper is off.
If you're going to be reinstalling the rotor, make sure it's indexed to the hub before removal.
A dial indicator gauge would be useful to verify run out when you reinstall the rotor.
I replaced calipers at the start of this season, along with the rubber lines and the two rear hard lines and master cylinder. My rotors were fine, as were the pads.....so a brass wheel on my cordless drill cleaned all the mating surfaces.
I bought a clamp on dial gauge and was able to get run out down to .002 and .003 respectively on the rear rotors.
The tricky part will be keeping the lines attached (if indeed this is your goal) and not bending/twisting the hard lines.
Good luck.

Easy Mike

Why are you considering removing the rotors? Do you need to remove the rotors?

mk's78

Thanks for the info..It seems as though removing the rotor attach bolts is reasonable/doable and my guess is that the caliper can be moved slightly at the rubber line end but I'd have to remove the SS line and go through with bleeding etc.....

mk's 78 Mike

Kevin68

Where did you find a 78 vert?

mk's78

online 5 yrs ago, went to look at with my wife and had it shipped a week later............

mk's78 Mike

mk's78

...next to last post regarding the hard line with respect to moving off the rotor without disconnecting it..............Are we talking bleeding the whole system here???

mk's78 Mike

Mike Ward

No reason to remove them unless you're servicing the parking brake ***'y.

Ontario73

Ummmmmmm, they never produced a convertible in 78! Records show the last C3 vert was 75?

The photo in your profile is a 78 Coupe....

mk's78

done by my NCRS specialist.......when all was done and said I hear a slight sorta like a rubbing sound at low speed even through my loud mufflers and I was trying to have a look in there myself trying to maybe find the noise and acquaint myself with what's behind the rotor assy....He told me that it was because the PO had the rotor rivets drilled etc and that is what's causing the noise....Just sounds a little strange too me........I just wanted to take a look myself.....

And yes he did a complete parking brake installation and adjusted it three times and it just barely holds....Of course his response was that it was a poor GM design.....The PO had the whole PB assy removed for some reason I just don't understand to this day..

mk's78 Mike............

mk's78

I used the term vert because I thought that it meant any and all Vettes...Sorry for the miscue...........

mk's78 Mike

Mike Ward

WTF is that?

No need to disassemble the rotor ***'y to isolate a rubbing noise. It's probably rotor runout causing the surface to rub on a pad. Does it go away when you touch the brake pedal?

Roozstr

A little trick on removing the calipers. Go through your sockets and as you take the caliper off slip a socket the same size as the rotor in. Makes it easy to re install.

Brcmpbl

You don't have to remove the hard brake line going to the caliper to remove the caliper from the rotor for the purpose of removing the rotor. Just be careful and rest the caliper, with the line attached, somewhere close to it's normal position on the car (I rest them on the rear sway bar attaching point - your car may not have one of these though). The hard line will have some give. That is less likely to be true if they are stainless lines, however, because that is a much more rigid metal.

The sound you are hearing is very likely rotor runout or related to it. Once the rotor rivets have been drilled out, the rotor is usually just held in place by the caliper and the wheel lug nuts. This can cause the rotor to not sit properly on the hub to the tune of a very few thousands - enough to cause runout sounds. If you have runout, you can shim the rotor on the hub to lessen it (some disparage this, but I've had good luck in the past, just takes patience).

mk's78

One reply suggested shimming....what's your take......mike

briankeery

You can buy shims through Rock Auto, I believe in .003 and .006 thicknesses. They have a 'wedge-like' cross section; actually pretty cool idea. My advice would be to verify with a dial gauge what your best runout measurement is through indexing the rotor, before worrying about any sort of shims.

Mike Ward

You didn't answer my other question about the noise disappearing when you touch the brake pedal. Have you measured the runout?

Brcmpbl

You really should get a dial indicator on the rotor to determine if runout exists. In the US, they can be had from Harbor Freight for relatively cheap.
With runout commonly the squeak or rubbing sound will go away when the brakes are applied. If the runout is bad enough, the sound may just change in pitch rather than disappear on light braking.

You might have a look to see if the "NCRS expert" installed the rotor indexed away from having the parking brake adjustment hole lined up. The rotor and spindle were installed as a unit (hence the rivets), so if it is in the wrong position it might be creating a high spot that otherwise wouldn't exist.