[fairwayhit]

I took the lemans out for its first test drive and about a half mile down the road the rear right side started smoking. After everything cooled off I cracked the bleeders in the rear and was able to get the drums to release. I thought maybe the pushrod in the booster was too long. So I put a washer under each side of the master cylinder

I still has the rear up on stands so I turned it on, put it in drive and tried the brakes. The first 4-5 times everything seemed fine and the the pedal went hard. I turned it off and the rear brakes are locked up again.

I’m thinking something either the combination valve or master cylinder. Not sure where to go from here?


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[BB70]

I would start by suspecting the flex hose for the rear. To check it get the brakes to lock up on the stands and break loose the fitting at the flex hose and line that goes to the front of the car. If that line connection is shady looking like rusted or hard to get to, try the other end of the line at the combo valve. A good flare nut wrench is highly suggested. If they stay locked its a bad flex hose or the steel line pinched. If it unlocks the brakes move up to the front and try to break loose the line going into the combo valve.

[fairwayhit]

Well I spent all day testing different parts of the brake lines. Finally I put a second set of washers under the master cylinder and that seemed to fix it.
It seems like if the rod gets pushed too far into the master cylinder it locks up.


I took it for a test ride and it was ok. Unfortunately I also have some issue with the atomic EFI cutting out so I was only able to do a short test drive.

I’ll have to sort out that issue and then do a longer test to see if they drag at all.


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[Rachelsdad]

If that is the correct master for the booster (read: the rod isn't too long), there ahould be no need for washers. The washers are a kludge when the real problem is that the rest of the parts are not right. That's not saying that your workaround shouldn't be fine, just that it should not be needed if the right parts are in place.

Just another two cents to add to the mix.

[fairwayhit]

Thanks. The booster is a repo supposedly for a 1971 lemans. The master was one I had purchased for my 74 firebird. Since I upgraded the lemans from front drums, I thought the master cylinder would be the same.

I can’t remember if I used the rod that came with the repo booster or the one out of my old 71 lemans.

I’ll have to do some measuring and see what is going on with that.

Appreciate the input fellas. Sort of worried about making sure I can stop the car reliably


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