Newbie here - this is my first post. I got my first Corvette a few days ago. It's a 1976 L48. It's my first Corvette, but I've been working on cars for about 15 years, and have probably done 100 brake jobs in my life.

When I first got the car it had a light squeak/squeal only when the brakes were applied coming from the rear passenger side.

I bought some pads, popped the tire off, and was delighted to see that the calipers were already upgraded at some point and not leaking(as well as some relatively new suspension items, etc.). I popped in a new set of pads on the rear (those 4 calliper pistons are fun to deal with, by the way - I used a flat spackle knife to compress them), and took it for a test drive.

Now I'm getting what I can only describe as a rotational rubbing sound all the time , once per rotation, - even when the brakes are not applied.

Reading through the forum, looks like it could be a few things:

1. The odd ebrake / shoe system is gummed up (i'd be surprised, because it wasn't doing this before, and i haven't touched it)
2. Ebrake could be stuck on engage. I notice very little resistance on the ebrake when I engage it (engaged it before jacking up car)
2. Bulging Calliper hose

Any other ideas? Anything I should check first? Is there anything else commonly missed / messed up when doing a brake job on these C3s? I noticed, unlike any other car I've ever worked on, that the pistons on these calipers naturually pop out (which made it hard to get the pads in, hence the spackle knife). Is this normal? Every other brake job that I've ever done has involved pushing the piston back with a C clamp, and that's where it stays.

Thanks for your time, and patience with a newbie!


Jim in PA

 

As a general maintenance thing, as well as trouble shooting your problem, maybe you might want to try bleeding the brakes, and getting new fluid, as well as any air, through the system. If you choose to do this, keep in mind that the rear calipers have two bleed screws.

 

Thanks for the response. Yea, I bled them both. I had initially thought that the callipers were bad when I cracked the bottom bolt and fluid started flowing out. I have never seen a design like that before ever in my life. It's probably worth doing a second bleed just to be sure. Thanks.

 

On my 73 I have the slotted aluminum wheels , the mickey mouse clip on the park brake cable is really really close to the wheel, if not positioned correctly it could easily come in contact with an inside wheel weight.

 

"Bottom bolt"? What bottom bolt? The bleeders are on the top so you must have loosened the bottom plug on that one half. If you are hearing a scraping noise once every rotation there should be a "witness" mark (a shiny spot) on the inside of your wheel and on the caliper. Are you running aftermarket wheels?

 

I was talking about the caliper bolt. When I cracked the one on the left, it broke the seal of the tunnel or whatever that pumps fluid from one side to the other.

Also, just noted that braided calliper hoses were already installed by previous owner. Do those bulge?

 

Thanks, I'll check it out now.

 

Lets see. There are four pistons per caliper X 4 = 16 pistons. I bet one of those 16 is cockeyed in its bore and refusing to let the pad return to neutral. Sometimes after somebody works on them, they get a little rust corrosion behind the seals.

 

Thanks for responding.

Well its definitely coming from the wheel I just worked on...and I definitely didn't hear it before. I just went out and tested the emergency brake...that doesn't work at all. I haven't touched the emergency brake, so I'm less likely to think that's causing the rubbing. I've only had the car for 2 days, so far all I know, the e-brake never worked. How much of a pain is it to disassemble?

 

Just re-read your post. Probably worth taking the calliper apart again, and checking it out. Ugh I dread it. I hate the fact that I have to bleed the brakes every time i look at the pads!

 

"I noticed, unlike any other car I've ever worked on, that the pistons on these calipers naturually pop out (which made it hard to get the pads in, hence the spackle knife). Is this normal? Every other brake job that I've ever done has involved pushing the piston back with a C clamp, and that's where it stays."

If your calipers still have the original piston lip seals, vs aftermarket o-rings, there's a light spring behind the pistons pushing them out so they make light contact with the rotor at all times. That shouldn't be enough to cause an audible noise though.

 

Yes, that is how I would describe it. Makes it annoying to get the pads on. Now I know the calipers are original, and i'll put that on my list of things to replace. Fortunately, someone swapped out the hose for a braided steel one. I'm going to run out to the garage now and disasseble the caliper to check things out. Maybe one of those pistons got bent out of whack, or a pad isn't seated right.

 

It's potentially a PITA, depending on the current condition of your car. What I'm getting at is, the e-brake is a "drum style" deal, located inside the rear brake rotors. And, the brake rotors, from the factory, are riveted to the spindles. If somebody has already removed the rivets, that's one thing. If not, then you face a choice.....

You car drill out the rivets, and remove the rotors from the spindles, exposing the e-brakes, but that might create run-out issues, upon re-assembly. The other choice is to disconnect the half shaft from the retaining flange on the rear of the spindle, remove the retaining bolt, then remove a few other things, which will leave the rotor and spindle intact, but expose the e-brake assembly.

I apologize for being a little vague, but the last time I worked on a C-3 e-brake, was about 20 years ago.


That shouldn't really be necessary, as long as you don't dislodge the pistons.

 

Hah - don't worry, you're not the one to break the bad news - I knew about the riveting thing. It looks like mine was already drilled out. I'll take a picture when I go out to the garage. I came across a stainless steel rebuild kit at zip-corvette. I'll put that on my list of things to do, since my ebrake isn't working at all...still don't think that's whats causing the rubbing. The brakes work great, I can stop on a time, but dull rotational rubbing coming from that wheel.

 

If you followed all the other advise and you still have a noise then remove the caliper and the rotor and inspect the parking brake parts.

If you just remove and replace the same caliper then you don't have to bleed the system again.

There are two bleeders on the rear and they should both be at the top of the caliper.

 

I'm going to preface this by handing you guys my man-card. I've never done something so embarassing.

In my defense, I blame the unique calipers on this car, as well as the acrobatics that I had to perform to get the pad pas the 'springy' piston.

I cracked a beer, jacked up the car, pulled off the tire, and started staring blankly at the brakes. I took a picture to show you guys, to see if you could spot something wrong...and then I saw it.

I installed one of the pads BACKWARDS. Yes, ladies and gentlemen - metal side facing rotor....so....if I didn't need new rotors, I probably do now.

Thankfully, I only went 2 or 3 blocks like this. Some scoring on rotor, and just enough friction to almost wear through that 1mm thick clip thing on the back of the pad.

I walk away disgraced.

While I have this thread open, I'm assuming the attached picture means that the rivets have already been drilled out on this wheel, no?

 

Like underwear, you can put them on inside-out. Will they fit? Yes. Will it look right? Yes. Will it work? Yes. Is it desireable? No.

 

You can keep your man card, you're not the first or last one to put a pad in backwards.

 

And this is why we always double check things before we button things up. I always carry a "StreamLight" in my front pocket that uses three AAAA batteries and has a clear LED bulb. It's really bright and with it I'm able to see things I wouldn't normally see. About $13 to $15 thru E-Bay and Amazon

 

Yes, rivets have been removed, they were in each hole between the lug nut studs, rivet heads almost the size of the recessed area around each hole. I was not overly impressed with the stainless p-brake kit I got from a local vette parts supplier (not Zip), the shoe actuator was not notched deep enough and would bind on itself. I just cleaned the GM one and reinstalled it, also the pins and spring retainers were cheap attempts at the real thing. Examine what you get, just because it's new doesn't mean it's better. Some of the other guys may have had better luck than me.