kdf1986

I have been living with bad brakes on my 72 for a long, time, and just have not had time to find out what is wring with them. I bled them when I first got the car because the brakes were so bad, I thought is was just air in the lines. After reading several of the recent posts about bleeding procedures, master cylinders and brake boosters, I thought I would post my progress along the way so I could get comments, suggestions and tips on what to do next.

Here is what I have done, and my current problem area.
Problem: too much brake pedal travel. Poor brake performance, and pedal goes all the way to the floor when trying to stop.
1972 L-48 with power brakes

1. Check the brake booster valve/diaphragm. - good. air will only flow one way.
2. Check vacuum to the brake booster - Good- I have 18 inches of vacuum.
3. Check brake booster holds vacuum- good. Motor off, 3 pumps an brake pedal is hard. Turn on the car, and brake pedal depresses some.
4. Remove master cylinder and bench bleed - Completed. no air in the lines after bench bleeding.
5. Install m/c unit - complete
6. Jack up car and remove all wheels. Prepare to bleed brakes- Done. SEVERAL PROBLEMS FOUND

At the left rear I found signs of the brake caliper leaking at the inboard brake pad. I took off the caliper and found the brake pad was so saturated with brake fluid you could crumble it in your fingers. I decided to look at front calipers, and they looked ok at first, but found the outer seals were disintegrated into the piston area.

So now I am in the process of rebuilding all 4 calipers.
A. left rear caliper and brake pad


b. front brake caliper piston and seal residue.


c. Close up of piston and residue.



Hopefully I can get these rebuilt over next weekend.

kdf

mds3013

Well I think you have found some of your problems. Are the calipers original to the car? If not, have they been sleeved with stainless steel? If not sleeved clean the bores and see if they are rust pitted. Pitting means you should have them sleeved or replaced. If they are original to the car I might ck. into having one of the supporting vendors sleeving them and get them back on the car. Good luck with it, mike...

kdf1986

I tore into them more tonight. They have been resleeved, so I dont think they are original. The bores look good with no pitting, and only a marginal amount of rust at the bottom from where the car may have sat for a long time. I cleaned up the calipers, degreased them, cleaned and painted them silver tonight. I used a VHT brand caliper paint and they are looking good.

I ordered more of the caliper rebuild kit, so I will clean and install that this weekend I hope. My plans also include installing the braided steel brake lines.

Then its back to testing the brake booster and m/c again to check that this also doesnt have a problem.

kdf

sly vette

Were you not concerned with the loss of brake fluid???
Glad you are fixing them now...They look like an accident waiting to happen!
Good Luck. I'm sure you will see a noticeable improvement!

noonie

With that much corrosion in the system, I would also replace the master with new, rather than trying to rebuild it. I would be very surprised if it wasn't pitted.

MrJlr

New (rebuilt) calipers are realitivly cheap....like $69 each at autozone....

I wouldn't even mess with the old ones...get 4 and a M/C and be done with it...and new pads for sure !

Also check your rotors for runout so you're not "pumping air"...
.005" max with a dial indicator...

C3 brakes - when working correctly, are a wonderful thing !

Keep us posted...


EDIT: A motive brake bleeder is a C3's best friend !!!!!

redvetracr

and the pistons, those are most likely junk from all that corrosion

mikejpss

http://www.vbandp.com/Sales/discounted-items.html

Don't fight it. With prices like this, good brakes are easy.

MrJlr

And here is the exact product...
http://www.vbandp.com/C2-C3-Corvette...Ring-Calp.html

Awesome prices...

kdf1986

This was a strange thing. They were not leaking brake fluid. It appears that the one caliper had been leaking and saturated the brake pad. Maybe there was enough build up of dirt in the area to plug the leak area.

kdf

kdf1986

When I bench bled the master cylinder I drained all the fluid and the inside was very clean, with no pitting. It looks like the previous owner replaced the master cylinder and the brake booster at the same time. The brake booster looks brand new, so I know it was replaced. I guess they replaced these parts and didnt bother looking at the calipers.

But this is still on my check list after I get the calipers rebuilt. I couldnt tell if the m/c or booster was good or bad because of all the problems with the calipers.

kdf

C3 4ME

I second the suggestion of buying or borrowing a Motive Power Bleeder. Best $70 you can spend on your brakes. It made my brakes work the best they have ever worked. It was also very useful in flushing out all the old brake fluid in the process.

kdf1986

Update on my brake project.- Tuesday 3/22/10

Here are the freshly cleaned and painted calipers waiting for assembly. I am going to clean the pistons tonight and try to get these installed. Some of the pistons have pitting on them, but they are at the angled part of the piston, above the seal, and do not contact the sleeves.

Painted front caliper halves


damaged brake pads from front brakes.


It would be easier to buy a set from a vendor....but then I wouldnt gain knowledge and experience from doing it this way. I am learning a lot as I go.

kdf

Chromie69

This is fun isn't it..rebuilding my calipers was the first project I did to my car when I got it..I did exactly what you did..cleaned up and painted..new seals..one thing that you may run into if you haven't done lip seals before is how to get them in without messing up the lip seal..I use a few trans rebuild tools I have but a feeler gauge will work..thin one..use some brake fluid of the type you are going to use in the car..I used a seal tool to install the outer seals..you want to look for something that will seat that seal with one or two whacks of the hammer..once its messed up its done..I had to buy one extra rebuild set because it took me a few tries to find the right setup..have fun.


Oh..you can air check when you are done..just stick some blocks of wood inside where the pads will go..leave a little room..then tap it with some air pressure..I am sure a bike pump could be made to work if you don't have an air compressor..It should hold air pressure if done right..

kdf1986

Thanks for the tips. I finished three of the 4 calipers tonight. I ended coating the sleeves and the seals with brake fluid then placed the springs and upper seal on the brake piston and centered it into the bore.

I used a .020 feeler gauge and used the blunt end to work the seal into place around the bore while gently pushing down on it. Everything went in smooth. I only had one of the 12 outer seals give me a problem with getting it in place. I had to pull it out and reseat it.

I hope I can get to the last caliper tomorrow, then do the final assembly on Sunday.

One more item came up. I decided that while the front brakes were off the car.....I might as well replace the wheel bearings. Hmmm. I wonder this is leading.

kdf

Chromie69

Glad to hear it went good..I didn't replace my wheel bearings because they looked ok..I repacked them and that's it..I would do either though since you are only a castle nut away from having it apart!

kdf1986

Update 3/23/11
I have completed rebuilding 3 out of 4 calipers. I hope to complete the last one tonight.
The assembly of the seals and pistons to the bores went very smooth. Heres a photo of the three cleaned, painted and assembled calipers. One more to go, then I can change the wheel bearings, check rotor runout, install the braided steel caliper lines and back to bleeding the brakes.

Chromie69

I don't say this to often but they look perfect..I like the silver paint too..can't buy that in a store.

kdf1986

Update 3/25/11
Ok so I slowed down on my original project, and it has morphed into something more. I figured as long as I have the brakes and the rotors off, I might as well replace the front wheel bearings. And of course as long as I have the hub off and the wheel bearings, I might as well clean up the upper and lower control arms.....

So that is where I am now on this project. I have been scraping off 30 years of accumulated dirt and grease on the control arms for the past week.

Before and after photos to come later.

kdf

mikejpss

to your rebuilt calipers. There's NOTHING like doing a rebuild job yourself and having the satisfaction of knowing YOU did it. Great work. They look good!