So - got into the car last night and at the end of the driveway I noticed that the brake pedal had turned into an immovable object and my brakes now need five times more effort than before. (Car was fine 2 days ago).

I checked a number of things - engine vacuum is fine (via boost guage), car idles great, therefore no obvious air leaks.

Fluid level is fine. Booster inspects out OK, no whistling noises.

Since it was raining, I went out to a parking lot and tried the 'stand on the brakes to invoke ABS' trick. I can lock up the front wheels and had several ABS events, but no improvement overall in brake performance and pedal feel.

Interestingly, when the ABS kicked-in the brake pedal softened up a little (i.e. to 'normal') but returned to extra hard.

So... I plan some more detailed diagnotics this weekend using my shop manuals.

I will keep you all posted..

I would check by cylinder #7 and see if there is a crack in the booster, other wise it could be check valve in booster.
I wrapped my booster with heat deflecting stuff, as i have headers and it was found by Guldstrand years ago while testing for GM/Goodyear that the headers can crack plastic boosters

More than likely it is the booster. Mine never had any signs of anything wrong on the outside, and the last time one went bad I really couldn't hear it either.

If yours needs replacing order one for a 1984 Corvette. It will be metal. They withstand excessive heat much better than the plastic aftermarket ones. It seems the stock plastic ones hold up pretty well but once they go only the metal replacements hold up well in extreme heat (such as headers, etc.)

Make sure the check valve going into the booster is working - I had one of those fail on me years ago on another car. Cheap fix if it's the culprit.

I went the throw parts at it route. Did the check valve first. No difference. Ended up being the booster. Threw $32 out the window.

Replacing the check valve isn't a bad idea, regardless. If the booster has failed, I can't beleive the check valve is too far behind.

My new booster came with a new check valve.

Update:

It did not take long with some decent lighting to see that the booster itself is cracked - at a place closest to the headers.

Took the booster out last night (royal PITA working under the dash) - considering my options today...

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What options? Replace it or not If you don't care about NCRS get a metal booster.

Matthew

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Hey Matt - do you have any part numbers / vendors for the metal booster?

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I got mine from Piratejack.net. I looked but I don't see 92-96 boosters from them? And I honestly don't know the difference between the early and late versions, sorry.

This is the one I purchased:

http://www.piratejack.net/Power-Brake ... tte-1985-91-9-Single.html

Andy, I don't think you're going to find a metal one for a 92. I looked around last year and couldn't find one.

The metal boosters came on 85-91s.

The plastic AC Delcos are $330!!!!!!!!

I just looked at RockAuto, they have a KelseyHays one on close out at $99. Only 2 left they say, 30 day warranty.

With headers, I'd be looking at fabing a heatshield for the booster.

Metal boosters came stock on 1984 corvettes. 1985 to 1996 were plastic. You can go into any Autozone, Advance Auto, etc. and order a brake booster for a 1984 Corvette and it will be metal and it will fit. Tell them to pull up a picture of the 1984 booster and another picture of a booster for your year of car, and you will see the difference.

My car is a 1989 and the metal booster I ordered for a 1984 fits and works perfectly.

Here is the link to one at Autozone. It is metal. Be sure to paint it black before installing it or it will look rusty brown in about a week.

http://shop.advanceautoparts.com/weba ... %7CGRPBRHYAMS_49957739___

Wierd. I've never had an issue and my engine temps are hotter than most.

Too bad you can't wait til spring, I'm pulling the booster out of the '93 then. You could have it cheap.

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Duals w/o booster finally?

I'm not sure but.........I think the Brake Booster for the '84 is the only thing FROM the '84 that is recommended as an upgrade to anything on the later cars.....

Go '84s!! We got the Booster, oh yeah !!

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That's nice, but are the 84 and 85-91 boosters interchangeable with 92+ or not? There is conflicting info here.

Stick that p/n into AC-Delco's database and that'll tell you what years used what.

They do interchange. I'm pretty sure the number of vacuum ports on the check valve is the only difference, and you can add a vacuum T if you need more vacuum ports.