C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

Brake Booster bad? - Not sure

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Old 04-29-2016, 09:30 PM
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Scooter94
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Default Brake Booster bad? - Not sure

Ok, I have had my 94 since last summer. I always thought the brakes pushed a little too hard, kind of like a non-power brake that I had on my 69 Chevelle. If I stand on the brakes hard, it will stop, but I doubt I could lock them and the ABS start working, just too much pressure.
So for normal driving, its not a problem, but its not right either.

I can say that if I put my foot on the brake, and start the car, the brake peddle acts like the power system is working and it drops down.

I shut the car off and disconnect the vacuum hose and you can tell it is holding vacuum as it initially sucks air in.

So, now I am confused. Is it the booster or could something else be the problem?

The Booster in it now has the name "PBR" on it, so maybe it is not original. Last fall before storing it for the winter I flushed the brake lines for maintenance. No change.

Ideass?
Old 04-29-2016, 09:59 PM
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JamesThatGuyy
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I had my brake booster go out on my 91 coupe going to school one morning. And when it did, it basically felt like I could not stop the car. I had to basically stand on it to get it to actually stop (i was going 30 mph). A new brake booster is about $120 and the install involves you working both under the hood and under the driver side dash and requires a lot of extensions

I'm going to assume you have brake fluid and your brake pistons are actually getting fluid to them. If this is the case, it could also be your brake master cylinder. Does the pedal move kinda slow and push down more than you would expect it to?

If no, has the braking always been this difficult for you? If this is new, and the brake acts normally, and the braking is substantially weak, it might actually be the brake booster giving you a warning I didn't receive. I can't give you a certain answer, but I hope I at least helped
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Old 07-16-2016, 03:32 PM
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b46nelson
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I think the power booster just went out on my 94. It seems a bit different when testing as with the other threads I've read. With the engine running in park, I hear the wooosh sound when I press the brake pedal. If I continue to press the pedal toward the floor (half way to the floor) the wooosh sound stops as I continue to press the pedal as far as I can (both feet). Makes the wooosh sound just during the first half or so of pedal travel.

When I pump the brakes with the engine off then start the car the pedal doesn't drop the 1/2 inch. If I pump the brakes and hold with both feet pressing hard then start the car the pedal drops the 1/2 inch.

Pedal is very hard, it's always been kinda hard but not this hard. Brakes stop the car quickly but lots of leg power is needed.

Also I noticed the idle smooths out and increases as I hear the wooosh when in park while pressing the brakes. If I continue to press the brake pedal down till the wooosh stops, the idle lowers and is a bit rougher.
Old 07-16-2016, 07:26 PM
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Tom400CFI
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Originally Posted by Scooter94
If I stand on the brakes hard, it will stop, but I doubt I could lock them and the ABS start working, just too much pressure.
If your ABS is activating, then your brakes have the capability to lock the wheels. The ABS actuates to prevent the wheels from locking.


Originally Posted by Scooter94
I can say that if I put my foot on the brake, and start the car, the brake peddle acts like the power system is working and it drops down.

I shut the car off and disconnect the vacuum hose and you can tell it is holding vacuum as it initially sucks air in.
Sounds like the booster is working properly.


Originally Posted by Scooter94
So, now I am confused. Is it the booster or could something else be the problem?
Could be crappy auto parts store pads,

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