The brakes on my car have been terrible for a while now and I finally determined that my brake booster is bad. I put a vacuum pump on it and it will not hold any vacuum. I replaced the booster a few years ago and I remember doing the same test and it having good vacuum. The booster was under warranty so I have another one coming, but the issue is it will not be her in time for this Sunday's AutoX event (which I will be running with or without a functioning booster).

I'm trying to figure out if there is any chance I can repair my existing booster for Sunday's race. There is some magic gasket that always comes loose and only takes 10 minutes to fix right? Seriously though, I would spend the time and take it all apart if there was at least a 50% chance I could resolve the issue without needing any special parts. I have looked at the diagram and I can't tell what could cause such a massive leak. Does anyone know of a repairable gasket or seal that I should check? If a repair is unlikely then I'll just wait until I get the replacement on Tuesday.

If you take it apart and try to repair it I am pretty sure the A1-Cardone or whomever manufactured it will deny the warranty claim. I am pretty sure that rebuild kits for the old and new boosters are not available. I would just wait.

John

I did it a few months and documented: http://www.atlanticz.ca/forums/index.php?topic=3010.msg16642#msg16642

I used black silicone for sealing and spark plug grease for lube. You should be able to do it today

Thanks for the link Blue. I didn't have time to attempt a repair last weekend but I did replace the booster tonight. I can hear something rattling inside the old booster so I think it must be the reaction disk. I didn't suspect that before because the symptoms didn't match what I read online, but I maybe its possible for that to also cause complete vacuum failure.

I suspect that the reaction disk fell off during installing. The booster had vacuum before I installed it, but I never checked it afterwards. I had to adjust the pin that pushes the master way out which now makes me think I was compensating for the missing disk. The car had very weak brakes before and after the 1st booster replacement but I just attributed it to a problem somewhere else in the system.

The car had weak brakes when I bought it a few years ago. It now has rebuilt front cylinders, a new master, a new booster, new rear cylinders, stainless lines, and hawk pads. I can't wait to test drive it tomorrow to see how it feels with functioning brakes for the first time.

yeah from your description it sounds like it is just the reaction disc that dropped.

Blue,

I have a bad brake booster in one of my Z's and since I have 2 brake boosters laying around I thought I would try out your repair techniques. I have been trying to get one of them open. I made a wooden pattern to grab the top side that needs to turn counter clockwise to unscrew. I have two questions how hard was it to disconnect the pieces? I have pulled very hard and they don't want to rotate. I have also tried a punch and hammer to try to make the half rotate. Also how much tension is on the large spring inside? Is it going to launch the top across the shop?

The spring is weak. No worries there. You may need a long 2X4 to get the required torque as the two halves can be tightly fastened and maybe even corrosion bonded.

Thanks,

I thought I would add some 2x4's for leverage. I was putting a tremendous amount of torque in already. We shall see...

Charles

Made a wooden block to hold the studs on the bottom in the vise so I wouldn't tear them off. Added 3' 2x4's on each side of my jig. A little PB blaster and it turned right off. Might post pictures later. The inside of the booster stinks like old brake fluid and tons of rust crumbles. I can't get the retainer off of the plunger as it is corroded into the central plastic part. Any ideas? The diaphragm is ripped at the bottom where it sat in the brake fluid. Don't know if I can seal it up with RTV or not. There must be a source for replacement diaphragms since there are companies out there reconditioning them and you know the cores we send back have torn diaphragms in them. It would be nice to find a source for those, since that is all you really have to have.

Charles