85 Hot Air Powermaster question

[stmello]

I have a 85, mostly stock, just some minor upgrades (cold air intake and such). The brakes are stock, though the calipers are upgraded to larger ones (i believe 4 piston's, and the name escapes me right now.) The question i have is the Powermaster brakes work fine and normal feeling all the time EXCEPT when turning the wheel hard to pull into a parking spot. You can see why this would be a problem. The pedal goes almost to the floor, and i have to do a couple panic pumps to get it back up. Once the wheel is centered again, all is normal and i can drive traffic no problem. Anyone have any thoughts? Fluid in power steering is fine it has new belts on the pump.

 

[corsair231]

Your system should not be a powermaster. You should have a hydroboost system. It works off of the power steering system to build brake assist pressure. When you have the wheels cranked all the way over and at slow speed like pulling into a parking space you don't have enough fluid flow to boost the brakes like usual. I don't know if falling off that much is normal though.

 

[NCTyphoonKid]

Your system should not be a powermaster. You should have a hydroboost system. It works off of the power steering system to build brake assist pressure. When you have the wheels cranked all the way over and at slow speed like pulling into a parking space you don't have enough fluid flow to boost the brakes like usual. I don't know if falling off that much is normal though.

I thought 84's had the hydroboost brake system

 

[kh440]

85 was actually a split year between the two systems, the powermaster was a mid-year switch. As far as what you can do to fix it you have two options (presuming it is the powermaster and not the hydroboost): either replace the accumulator ball and do a thorough and I mean thorough brake fluid flush. The other is to convert to a vacuum system.

 

[stmello]

It looks liek i first need to look to verify what i have. From looking at it, it looks like the powermaster with the ball and everything, but i could be wrong.

 

[kh440]

if you see the accumulator and a 3 wire switch on top of the cylinder than it's definitely the pm system-hydroboost will have extra lines running to the power steering

 

[corsair231]

I thought 84's had the hydroboost brake system

Sorry, he said he had new belts and the power steering was full. I thought he was talking about hydroboost. I didn't think that it could be a late '85 with a PM. If it's a PM then turning the wheel should have no effect on the brakes unless you are crimping a hose.

 

[kh440]

Sorry, he said he had new belts and the power steering was full. I thought he was talking about hydroboost. I didn't think that it could be a late '85 with a PM. If it's a PM then turning the wheel should have no effect on the brakes unless you are crimping a hose.

That's making me wonder also-