Matty's first 1st Gen

Hey Guys,

I bought a turbo conversion off a guy. He put on the 88 Turbo brakes, but did not switch the booster or MC. There was also no check line installed from the manifold to the booster. I had assumed that the booster had one built in. Anyways, My brakes feel terriable. I mean the pedal feels rock solid. I just installed Hawk HP pads and SS lines and changed all the fluid. but at speed alot of pedal effort is needed to bring it to a stop, and at any high speeds the pedal feels great, but the car just doesn't stop fast at all. Its actually scarey at high speed. I didn't have much info on the car. and I knew it sat for about a year. The 4 piston calipers were not seized, while 2 out of the 8 expanded slower than others. Is it possiable all the boost could have damaged the booster? It would have seen up to 22 psi over the last few weeks, and who knows what kinda boost before that. The brakes have never felt decent, and the pedal doesn't fade so it makes me think the booster is the problem? Do these symptoms sound correct?
I was thinking about replacing the front calipers, or at least trying to rebuild them, but if it sounds more like a booster problem maybe I'll tackle that first.


Thanks Guys!

clokker

iTrader: (2)

The brake "booster" operates on vacuum, not boost.
The valve in the line is a one-way check valve which maintains the vacuum when the car is off.

The symptoms you describe sound like you're not getting any vacuum to it.

RandomHero

iTrader: (2)

gotta have that check valve in there. that way you always have vacuum assist even when your under boost.

Matty's first 1st Gen

Right, My question is that since the check valve normally dissallows boost from reaching the booster, could this pressure damage the booster? cause even off boost brake performance is terriable.

RandomHero

iTrader: (2)

I dunno, 20 psi is a good deal of pressure when we are talking about boost, whether it would be enough to damage the diaphragm in your booster im not sure of.

iamcountersteer

It's possible the diaphragm in the booster was damaged/blown out- that would explain the lack of power assist off boost. I looked at the booster on my FC (NA) and I don't think it's rebuildable- replace the booster and you should be fine.

RandomHero

iTrader: (2)

Unfortunately wikipedia is of little help this time.
http://en.wikipedia.org/wiki/Vacuum_servos

Do you have a check valve in that line yet? If not I would try that out before changing out the booster all together. Maybe the vacuum just isn't being stored in there properly.

Matty's first 1st Gen

What are the symptoms of a busted booster valve. I know sometimes when they fail they act as a vaccume leak, I don't think thats the case here, but i'll check tonight with a vacumme pump on it.

SirCygnus

iTrader: (1)

well


lets just say, you dont wanna find out when you suddenly need to step on the brakes right after boosting.


be safe and dont kill yourself. its a 1 dollar check valve.

KhanArtisT

iTrader: (2)

Remove the line, blow in it to see if the check valve is in and working right. Then check your vacuum source.

Matty's first 1st Gen

I just connected my vaccum pump with gauge to my brake booster, and when pumping i wasn't able to build any vaccum. This means the booster diaphram is bad right? the booster should hold vaccum while not in use right?

thanks guys, i think i'm getting closer to feeling better about going fast. I will certainly be getting a check valve while i wait for the booster.

One more question, do the boosters often go bad? am i better off getting a Junk yard one for 10 bucks right away, or getting a new one for 120 online and waiting a week?

thanks!

pistones

iTrader: (5)

where did you hook up the vacuum pump? it matters what direction you are pumping.

Matty's first 1st Gen

blowing into the booster with my mouth there is slight resistance, but i can hear a leak. This prob shouldn't happen right?

Matty's first 1st Gen

hooked up a vaccum directly to a sillicone hose that goes to the booster. no check line interferes with it