walfran

I think I know what the problem is but I thought I'd ask the experts. With the car running, when I press the brake pedal, there is a loud hissing noise. The car will stop, but it does take a lot of pressure. I have replaced the front calipers and bled the whole system. I believe the problem is the brake booster. The noise is down by the brake pedal.

Any ideas? By the way it's an 81.

Thanks

jnb5101

booster. one of the more fun jobs

75 Red Vert

Take a look around your booster. Get someone to step on the brake with the engine running (emergency brake set and in neutral). You may be lucky enough just to have a leak from the hose going into the booster, but in any case, you should find the noise when you have someone step on the brakes. Good luck and be careful.

Duke94

Hissing noise=booster kaput.

ShinodaVette

I just pulled the booster out of my '81 and I was thinking how bad it would suck to have to replace one with the dash and steering wheel in the car. I'm in the middle of a body off resto. It will be tight but I'm sure you'll get it with a little patience.

pbcanney

I cant think of one job I've done on my 81 that svcked more

however, had I removed the dash... it wouldnt have been so back breaking

walfran

There are 4 bolts that are very difficult to get to right? I assume removing the seat is a must, but the dash too?

Will I have to bleed the brakes when I'm done?

No leaks at the hose so I did think it was the booster.

Thanks for all the help.

stock76

It is a lot easier if you remove the seat - gives you some more working room. You do not have to remove the Dash, you can get at it from underneath, it is just an awkward position to work in and a real PITA to remove and replace two of the four bolts.

If you unbolt the MC and carefully pull it forward off of the booster studs you won't open up or disturb your brake lines so bleeding the brakes won't be necessary. Make sure you support The MC somehow. I used a piece of 2X2 spanning across the engine and wired the MC to it to hold it up and keep the lines from kinking.

Make sure you get the clevis pin reattached to your brake pedal correctly. Again, another minor PITA - you'll see why.

Someone posted on here a couple of weeks ago that they replaced their booster in 30 minutes working under the dash. Either a product of a very faulty memory, pure BS, or they know something I don't and I'd sure be willing to learn.

Replacing the booster is going to take you a little while, be patient. It's not technically hard to do - just hard to get to. Best of luck.

walfran

OK I've done a few other tests and it's definetly the booster. One last question.
Is it safe to drive? Have to save up money to buy the new booster. Just got laid off last week. The last thing the wife wants me to spend money on is the vette.

Thanks

7T1vette

Have you checked the floor for any loose snakes??? (Sorry, I couldn't help myself. Besides, the other posts have given the right advice.)

Duke94

I'd be careful with this one. When the booster leaks to the point where it will no longer supply boost, you will have to push REALLY hard on the pedal to stop. To find out how hard, disconnect and plug the vacuum line to the booster and go for a short slow drive.

m and t's77

Do you have cruise control?Double check your brake light switch.On my '75 Cutlass it was making a hissing noise that sounded like the booster and it was actually the switch.A vacuum hose runs to it on cruise control cars.

7T1vette

An excellent suggestion!!

walfran

OK everything removed. New booster and master cylinder installed but the damn clevis pin. Does it really matter which way in goes in? I can't get it back in the way it came out. Then the clip..... who the hell ever thought of that!!!!

7T1vette

Needle nosed pliers....