I have had this 68 since 2005, and the brakes have never been right on the car.
Originally it was a 4 speed car. Clutch pedal and z-bar assembly long gone when I got it.
It looked to have OEM master cyl on it when i got it. It leaked didnt stop very well. Caliper seals were shot, etc. I had the calipers rebuilt stanless sleeves installed in bores, rebuilt the rear drums, cylinder,springs, etc. Purchased a new MC from Advance Auto for manual from disc 68. With all that there were no more leaks and the car stops OK. But it feels like I am pushing a 300lbs boulder with my foot when I apply the brakes. And 3 times pistons seal in the calipers starts leaking.
I believe what going on is.. The MC I purchased was for a manual all drum car. When the brakes a appplied and released the front pads do not relax enough and creates drag from the pads staying to tight on the rotor. Which is probably melting wheel seals from friction causing them to start leaking.
I bought a new MC for front disc, as the car is undergoing more mods now. This one has the bigger from resivour and 1 1/8" piston instead of 1". NOW the brake pedal push rod does not seem correct for the new MC piston.. I feel like a have 500-600 bills into the 40 year old brake technology and wish I had went with a aftermarket setup..

Can anyone give me any insight on the correct brake pedal pushrod? Hopefully some who has ran accross this problem before can share the experience.

thanks, Chad

maybe someone already got you the answer...did you look thru this thread? I think I recall they discussed the rod length in here....

https://firstgenfirebird.org/forums/ubbthreads.php?ubb=showflat&Number=257824#Post257824

Bjorn, Thanks.
That is a similar situation. The MC in his pics have the exact same issue. The one I was using just has a dimple on the end of the piston for the brake pushrod to contact. The new has a deep bore. And my brakes are manual, no booster between.
So are there 2 disc brake MC's? One power and other non?

Matter fact. Adding more info. The pushrod coming off the brake pedal assembly is at like a 30deg angle pointing upward out the hole. The MC piston is facing 90deg. (straight with the firewall.
I would thing the pushrod would go straight into the piston? Power brake cars I believe were angled, where the booster and MC pointed up a bit.
PHS says its a non power brake car, but I am thinking it may be possible someone put a power brake pedal assembly in it when they took out the clutch. (as stated above was orginally a 4 speed car)

the brake pedal has 2 holes to use for the MC rod. One for the power brakes and one for the manual. Remove bolt and move to other hole and see if it performs any better for you.

Mr Bill, thank you. I seen another hole about an 1" above it. So it has been in the wrong hole since someone removed the clutch assembly.
So, the only problem to figure out is the MC bore and depth. The new MC i have looks like its designed for a differant depth pushrod.

There are 2 standard push rod lenghts. The short one is for power brakes. The long one is for manual brakes. Never use the short push rod and M/C for manaual brakes. You could have an instance where the rod shifts out of the bore and results in either a locked up brake pedal or no brakes (depending on where the rod goes). This isn't an issue on power brakes because the m/c is bolted directly to the booster.

The pushrod on my pedal is 4". That has a rounded tip on it that depressed a MC piston with just a dimple on the end of the piston. The piston on the new MC has a 1/2"bore in the end of the piston 1 1/4" deep. The pushrod will catch the new piston, but does not seem like the right fit. The dimple sits inside the 1/2" hole and the flare around it catches the OD of the 1/2' hole. If any of this makes sense..? I am just tired of puchasing wrong brake parts for this car. If anyone has a picture of manual brake pushrod I would appreciate if they can send me a pic. My email is f68pontiac@msn.com Thanks, Chad