'68 Camaro disc swap issue

[Back N Black]

I would go ahead and double check the preload/adjustment on the plunger that come out of the booster into the master. I bet it is too far out.

This! I had a very similar issue with a swapped mustang many years ago, and it was this very thing

[SSMAN]

My BIL has been having an issue with his front disc break swap on his Camaro. Car is an original 6cyl car with four wheel drums. It now sports a 350 with a Muncie 4spd. Basically he's thrown everything he can at this car. The break swap is recent, maybe has 15-20 miles on it and has had nothing but trouble since. Problem is the front and rear breaks pretty much lock up 5 or 10 minutes into a drive. Well, I guess they don't completely lock up as it can still move. A few minutes ago we took it for a drive and on our way back from what seemed to be a drive without incident, it begins to nose dive in between shifts. It dives quite noticeably BTW. A few more minutes and you can start to smell the breaks. We make it home and park in the garage, almost immediately the heat and smoke coming from the front breaks is evident. We quickly jack the car up we can't even turn the wheels by hand. And yes, it's in neutral. The fronts seem to lock up more than the rears, but nonetheless there is resistance.

Can anyone give me a starting point here?

You need to adjust the rod that pushes the piston into the master cyclinder. It's keeping pressure on the master cylinder piston causing the brakes to stay engaged. Should be able to adjust it under the dash. I ran into the same thing when I installed my disc brakes. But mine are manual brakes.

[kobuzz]

The booster pushrod should be about 5 3/4" to 5 7/8" long from booster upper mounting hole to clevis pin hole center. You also need to switch where it attaches from the bottom hole on the pedal assembly to the top hole.

[kobuzz]

http://www.pozziracing.com/brakes.htm

[projectPONY]

Ok, I think I understand, but to make sure. Under the dash I unhook the rod from the break pedal and I turn the rod counter clockwise, unscrew, to release pressure on the master cylinder. Is this correct?

[NoClassic]

In order to access the booster plunger you would have to pull and drain a majority of the fluid from the master cylinder.

I really doubt the issue is with the pedal side rod unless you are having to compress it in order to get the cross pin through the pedal arm.

[projectPONY]

Ugh, I was trying to avoid that.

[NoClassic]

Yeah it sucks. I went through the same deal on an f100 with discs.

One thing you can try in diagnosing the issue is put some shims(washers cut into a U shape) between the booster and master. If that solves the problem you will know the master needs to come off to adjust the plunger.

[projectPONY]

I try that first, I guess.

[projectPONY]

Are we certain that the plunger is adjustable?

[NoClassic]

The few I have installed all have been. Did the parts not come with any kind of instructions?

[SSMAN]

U can adjust it under the dash.

[NoClassic]

Yes you can adjust the pedal rod under the dash but not the master cylinder plunger. If the master side is too far out nothing you do to the pedal side is going to solve the problem.

[projectPONY]

The few I have installed all have been. Did the parts not come with any kind of instructions?

I didn't do the swap for him. He had a friend who, supposedly, knew what he was doing. It's been back to him several times to diagnose and fix the issue but they never seem to duplicate the problem. IMO, they're not driving it enough to duplicate it. A trip to the corner and back will not do it. Like I mentioned in my original post, it doesn't do it right after start up. Takes a few minutes of driving.

[NoClassic]

That is the same way the f100 I had issues with would behave.