Rotor removal

They were installed with rivets at the factory....and they must be drilled out before the rotor can be removed.... Unusual that a 78 has never had the rotors removed...BUT not unheard of...for sure...if they were removed then go from gentle to... a good wack to wacking the hell on them.....

Bob Griffiths

Hi Bob,

Wow! Thanks for the quick response! I should have been more specific but I'm sure your information is correct anyway.

I am trying to remiove the rear rotors to get to the emergency brake parts. I think they are dragging (cables are loose) and causing overheating and therefore I get rear lockup after a few miles of driving. After things cool down the car rolls easily by hand.

I can see someone has tried to drill out what appears to be large rivits or screws but without success. Some are drilled off-center and deeper than others. They are big rivits if that is what they are, probably 3/8". Does this sound right?

BTW, the symptoms you are experiencing can also be caused by a bad power brake booster.

I would have guesstimated more like 1/2" but yes, those are the rivets Bob G. was talking about - there are 5 of them. Just a tip: Some folks recommend marking the orientation of the rotor on the axle so that it is replaced over the studs in the same position as it was assembled at the factory. I don't believe Chevy specifies this step in the repair manual for that era, but it certainly would not hurt to do it anyway.

Here's waving to ya - \||||

Owen ___

'67BB & '72BB ___

"To know the world intimately is the beginning of caring." -- Ann Hayman Zwinger

Any suggestion son how to tell if it is the power booster?

I don't know a way to test it directly (although there may be a way), nor can I remember how that problem was diagnosed when I had it about 15 years ago (I may have just had the booster rebuilt on blind faith at the time).

Here's the way I understand the booster...

The booster stores vaccuum > Any suggestion son how to tell if it is the power booster?

Pump the pedal a couple of times and hold. If the pedal goes slowly down, the booster should be okay.

I have a 77 which had never had the rotors removed. I also had no emergency brake. When the rotors came off, the emergency brake shoes were broken in half and all the parts and springs were powder. Put new gear in, and like a putz, I forgot to adjust the emergency brake. Now I'm trying to find out if that can be done without removing the rotors again.

This is not an opinion, this is fact. The factory machining process was done with the hub or spindle riveted to the rotor. As such, this simplified manufacturing as any flaws in the hub surface and the inner drum of the rotor surface could be eliminated by the final machining of the rotor surface.

If you put the rotor on any position but the original, or on an different hub or spindle, you can introduce run out that exceeds the specs and which "pumps" the caliper pistons. Pumping the pistons introduces air into the brake fluid, resulting in a spongy pedal and eventual leaks.

Absolutely. There's a hole in the hub of the rotor between one pair of studs through which you can see the star-wheel - that is as long as the rotor was put back on the axle correctly so the holes line up. A screwdriver is used to lever the cogs on the star-wheel to tighten/loosen.

To resogngb: Back to the rotor rivets - you don't have to replace them when everything goes back together. The wheel lug nuts, of course, will hold the rotor securely to the hub.

Here's waving to ya - \||||

Owen ___

'67BB & '72BB ___

"To know the world intimately is the beginning of caring." -- Ann Hayman Zwinger

Well, I got the rivets drilled. It was easier than I thought it would be. I found the emergency brake shoes OK but everything else in this area is pretty much toast, either broke or rusted beyond repair. They were dragging a little and were rusted that way so this may be the problem. However, I am changing the flex hoses as well. I can blow through them both directions without any obvious obstructions. I will pick up the new ones in the morning, $19.00 each for a 10" hose. Wow! If this doesn't solve the problem I guess it will have to be the power booster. This is the only thing in the system that isn't new!

I don't think it is the problem because I can use the brakes while sitting still for a long time and nothing locks up. It only happens when I drive a few miles.

Will let you all know what happens. You have been a great help in dealing with this problem. Thanks, Tom

OK, I got it all back together but I have a question that may be obvious to some of you. This is the first time I've been into the brakes on an old vette. What keeps the pads from contacting the rotors all the time. The tension of the boots and/or spring inside the boots, if there is one, seems to apply a little pressure to the pads even before fluid is added. Could this cause the heat buildup problem? Seems likely to me but I don't know. Is there a spring , maybe, on the the retainer pin that is supposed to spread the pads apart? If so, I don't have any.

I know I should get a manul and will but right now I just want to get it together so I can drive it while the weather is nice.

The only springs on the calipers are light weight springs behind the pistons which very, very gently push the pistons to the pads which, of course, contact the rotor very, very lightly. They are only creating minimal friction so shouldn't be the source of your heat problems - though don't touch the rotors after a drive of any length. DAMHIKT.

There is nothing pushing the pads away from the rotor - if the pads are creating excess friction after your parking brake rebuild and hose replacement, then you could have a piston that's cockeyed in the bore. You might have a problem in the tubing with a crimped area obstructing return pressure or something wrong with the pressure regulator just down fluid from the master cylinder. When you bleed the brakes you might notice differences in flow between the four corners to detect fluid flow problems.

Here's waving to ya - \||||

Owen ___

'67BB & '72BB ___

"To know the world intimately is the beginning of caring." -- Ann Hayman Zwinger

Well, I got the rotors off, thanks to you help. Thank you all. I have a book now, too. I removed the emergency brake parts temporarily until I get new.

The problem (with the brakes locking up) ended up being not enough clearance between the face of the piston in the master cylinder and the face of the "piston" that holds the actuating rod in the booster. I made a 3/32" shim to space the booster and master cylinder apart a little and now the brakes release. I think the fluid was unable to return to the master cylinder after the peddle was released and that caused the brakes to stay on.

NOW! I know they are properly blead but they (the rears) only work after two or three pumps. I actually used a vacuum device attached to the bleeder, starting with the farthest from the master cylinder, kept the reservoir full and blead each point until the fluid ran without bubbles.

What have I missed now?

Since you were messing with the master cylinder, you might have to bench bleed it to get everything to work again. Certainly, there's not much doubt that you still have air in he lines somewhere. Is the proportioner valve working right?

NOW! I know they are properly blead but they (the rears) only work after

================================================================ The rear calipers have 2 bleeders each. Did you bleed both of them on each side ??? ======================================================== Remove the ZZZ from my E-mail address to send me E-mail.

NOW! I know they are properly blead but they (the rears) only work after

================================================================ The rear calipers have 2 bleeders each. Did you bleed both of them on each side ??? ======================================================== Remove the ZZZ from my E-mail address to send me E-mail.