70454Convert

I just tried to install a new set of brake calipers on the back of my 70. The drivers side fits fine. The passenger side does not have enough room between the caliper and outside of the rotor to install a brake pad. I measured the gap between the inner pad metal backing and caliper surface and the clearance at the front of the pad was 0.152" and rear of the pad .132".

I have read an online article with the following advice:

"If a rear caliper is off-center or angled to the outside or a front caliper of is off-center or angled to the inside, simply remove it and add flat washers between the caliper and caliper mounting bracket such that the problem is eliminated. Special washers, in .015-, .020-. .025 and .030-inch thicknesses, are made by Global West to solve caliper position problems.

If off-center or angling of a rear or front caliper is opposite to that listed above, you have two choices: you can fix the angling with Global’s shims then, if the remaining off center is small enough to allow the brake pads to fit and not drag; live with the problem or…you can measure the off-center and angling then fix it by milling the caliper mounting bosses a corresponding amount. "

Should I have a machine shop mill the caliper mount bosses? If so, how much? ).076 front and 0.066 rear?

Any suggestions from those of you who have dealt with this in the past are greatly appreciated.

mrvette

The rotors themselves look identical but they are NOT, the thickness of the mounting face/flange is thicker in front than back....so you have the rong thickness rotor....they got switched somehow.....

front is thicker mounting face/flange....

70454Convert

Thanks for the reply but I wish it was that simple. The rear rotor is the original and the only one on the car not riveted. It has the correct holes for e-brake adjustment. So it's not the rotor. I also checked to make sure the rotor was fully seated on the spindle.

The right caliper is a new GM casting, the left was a rebuilt unit (I guess they were out of rebuilt rear rights). Could it be that the "new" casting has different mounting bossess?

70 LS1

If you got them locally, I would swap it out for a different one.

If not, you could buy one locally and if it fits, return the bad one locally.

Or if you are too honest for that... then it sounds like you will have to have the caliper machined.

Double check that the rotor is fully seated and use lugnuts to hold it in place.

70454Convert

Got it mail order. VP&B. First caliper had a helicoil sticking out of a bleed seat. Returned it and it took >1 month for the replacemnt which ended up being a new casting.

The right rear rotor is not riveted. At some point, bubba removed the e-brake shoes. I will be doing the trailing arms next year but would like to get it on the road for a short fall driving season. If I exchange it (may take weeks) how do I know the replacment won't be the same?

70 LS1

you answered while I was editing. You are on top of it tonight.

GaryS

Pathetic statement. I am guessing you aren't too honest for that?

...Roger...

Its possible the mounting bracket is bent.

There is a tiny bit of fudge room in the mounting of the caliper...try putting the pads in the caliper before putting the caliper on the car and then tightening everything up.Then check to be sure its not binding up.

If your wanting to try another caliper just go to Autozone and tell them the problem and that you are buying the caliper to use as a tool to check the clearance and then return it unused...they will be fine with it.

You could remove the opposite side caliper and use it to measure...im pretty sure it will fit...I've never tried to do that but it should work to measure off of.If its the same then its the mounting bracket thats bent.

70 LS1

I didn't say I would do it. Just throwing out options, but thanks for the judgement.

70454Convert

Good suggestion. I'll try flipping left to right.

Greg73convertible

I know vbp has gone downhill .. but they won't help ?

0Willcox Corvette

Dwncchs is right!

It really sounds as if you have a bent caliper mounting bracket. This can and most often is caused by someone prying on it, or removing the trailing arm from the car and pressing the spindle out on a bench press.

When a trailing arm is put in a bench press to remove the spindle, the full pressure is put on the caliper mounting bracket. It is more common for the bracket to break than to be bent since it is a cast part.

This is a real common problem when customers take their cars to shops that are not experienced in rebuilding the trailing arms. Bubba will remove the arm and just press away. These shops are the same people that re-use the bearings, or will replace the bearings and think the shim is just a spacer. They will not set up the clearance on the trailing arm; they just re-use the same shim.

In all my years of restoring these cars, I’ve never had to use a shim washer to center a caliper.

IMHO,

Willcox Inc.

70454Convert

I know that a bent mount makes the most sense, but the old caliper fit fine and I removed it myself. The trailing arm has never been off the car (Rusty original 1970 shims prove this).

I tried flipping the caliper from the drivers side and this fit better. Not perfectly centered but enough to get a brake pad in.

Sooo... I put on my Bubba costume and broke out the file and dremel. I used a vise grips as a "caliper" to measure the thickness of the mounting flange on the rebuilt "good" unit. The thickness was greater on the new casting caliper. Using a drum shaped grinding head, I carefully "milled" the inner mounting surface of the mounting flange and used a flat file to make sure I kept the face flat. Took about 1 hour of grinding/ filing/ trial fitting but I got it centered enough to put in the outer pad with enough room for the installation tools to hold the pistons back. The mounting surface is nice and flat and it mates up well to the caliper bracket.

GaryS

It was a guess formed in the manner of a question - not a judgement.