Pushrod between brake booster and master cylinder??

Both the primary push rod and the master push rod need a slight amount of free play to insure "A" the vacuum valve closes on the booster and "B" the fluid return ports in the master open to release fluid pressure and allow the free flow of fluid back to the reservior for heat expansion purposes.


Your problem sounds like an internal booster problem. I have had a number of problems recently with new OE boosters. They have all looked as though they have been on the shelf since the 80's when the cars were built and required repair before use.

Be sure you have a good, leak free vacuum hose and a good vacuum check valve etc.

 

The boosters I have had trouble with have not been from my suppliers shelf either but they were sitting somewhere.

Without doubt White Post would be my last choice.

I do not send boosters out. Do a quick search. Several well regarded rebuilders have been mentioned in recent threads. If that doesn't work out let me know. I will come up with a name.

Also, just in the name of covering the bases you should consider taking the pedal box out and apart. They were lubed from the factory with white lithium grease and at this point in their life that stuff has turned to epoxy. I do lots of those from cars of the 80's for sticky pedals. I just did our 90 TR pedal box about a month ago. Big difference.

 

I have always have had very good results from Power Brake Exchange in San Jose, CA. They have always done a good job, even on some real oddballs.

 

Power brake exchange is the way to go. I could not remember their name but they have had a good reputation around here for a long time.

PM sent

 

We have also had very good work done by power brake exchange. Whatever you do, don't send anything to Whitepost.

Brian Brown
Patrick Ottis Co.'

 

The clearance between the brake pedal linkage and the pedal side of the booster should be .3mm with brakes released. The pushrod at the master cylinder end of the booster should have a very small clearance between it and the master cylinder piston, just enough to let the master cylinder return to the full rest position when the brakes are not applied. The manual does not give this clearance, I can't recall, does this rod have an adjustment? If it is adjustable, I would guess that .2 or .3mm would work

 

I just called the 408 number and they answered right away.

 

If the rod is too long, you can look down through the primary fill port on the brake master cylinder as you bolt the master to the booster (this is with the booster already installed and pedal adjusted correctly). If you see the primary piston move, then the rod is too long, as it should not be contacting the piston. I always blow backwards through the output ports, with the master in place. There should be no restriction. If there is no flow, then you are going to have problems with the brakes sticking on.

 

Good luck Mike,

Here is a stainless pushrod i had made to adapt a larger mc to the stock booster. We made it to have the same dimensions, particularly the projection from mc mounting face to the end of the foot. works fine.
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I came across this thread tonight and you guys may have saved me a lot of grief. I am new to the Ferrari scene. I acquired my first Ferrari a few weeks ago [84 308 GTS QV] and am going through the car restoring things in order of importance.

I have a hissing booster and leaking master so I was searching around for a reasonable place to do a rebuild. I had pretty much decided, in my ignorance, on White Post Restorations but noticed several posts here suggesting that route as worse than a last resort.

Can someone clue me in as to why to avoid them. Feel free to e-mail me off chat if you don't want to pollute this thread with that information.

I'll certainly look a little further now and will check out the other shops noted here.

Paul