beyond fricking PREPOSTEROUS
11-21-2018, 08:42 AM
#21
Drifting
My 88 coupe is on it's ORIGINAL booster with probably 40k miles on it, and it sat outside its whole life, some of which was with the hood off.
in addition to that, I autocross the car and now run half mile stuff.
ABS is deleted. M/C was replaced with dorman reman like 3 years ago.
silicone dot 5 fluid.
it also has the original vacuum check valve that gets abused with more than 15psig boost.
I sold an 89 coupe last year that needed a booster at 120k miles, and I replaced it with a dorman reman. Worked like a champ.
Pretty sure my dad's 87 vert is still on the original booster.
What I am trying to say is that there must be something else going on. Quit your whining and go find a competent mechanic or even one who specializes in the braking system of cars.
There's a saying down here in the south,
"fool me once, shame on you. Fool me twice, shame on me."
Go find a new mechanic.
in addition to that, I autocross the car and now run half mile stuff.
ABS is deleted. M/C was replaced with dorman reman like 3 years ago.
silicone dot 5 fluid.
it also has the original vacuum check valve that gets abused with more than 15psig boost.
I sold an 89 coupe last year that needed a booster at 120k miles, and I replaced it with a dorman reman. Worked like a champ.
Pretty sure my dad's 87 vert is still on the original booster.
What I am trying to say is that there must be something else going on. Quit your whining and go find a competent mechanic or even one who specializes in the braking system of cars.
There's a saying down here in the south,
"fool me once, shame on you. Fool me twice, shame on me."
Go find a new mechanic.
Johno504. I would ask if they are checking the distance the rod is traveling. Also, has anyone checked the vacuum the engine is pulling. Not sure what would cause it, but too much vacuum may be over stressing the diaphragm. A brake booster being as simple as it is. It seems something has to be causing the diaphragm to break down or be over stressed.
As quick as some of the failures, I would go with over stressed and tearing it. I would be nice to brake one open and confirm it is a failure on the diaphragm.
Last edited by KyleF; 11-21-2018 at 08:42 AM.
11-21-2018, 08:58 AM
#22
Melting Slicks
Member Since: Sep 2008
Location: Cherokee National Forest TN
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Change the vacuum hose to the booster the hose will look perfect on the outside however they will fail internally.
Use 11/32 vacuum hose not 3/8 fuel hose.
To test a booster: Rig AC gauges & a vacuum pump to pull a vacuum. Check later to see if it holds vacuum.
Vehicle should stop even if the booster fails if no brakes at all there is a hydraulic issue.
Use 11/32 vacuum hose not 3/8 fuel hose.
To test a booster: Rig AC gauges & a vacuum pump to pull a vacuum. Check later to see if it holds vacuum.
Vehicle should stop even if the booster fails if no brakes at all there is a hydraulic issue.
11-21-2018, 09:00 AM
#23
Safety Car
Is your engine boosted (supercharged or turbocharged)?
How are the brake boosters failing? Have you pulled any of them apart to see what failed?
It's not likely to be the master cylinder. If the diaphragms are failing ('blowing out'), then it's either a bad check valve or something causing pressure to reach the thing. If your engine is boosted, then you need a very good check valve (strong enough to stop any boost pressure from going through). If your engine is stock(ish), then check for any backfiring in the intake. That will blow a brake booster out.
With the luck you're having, hydro boost might be worth looking into. 1994-1995 Chevy Astro is the unit that is most commonly used. There's another (larger) one available as well, from the 1991-1996 Chevy Kodiak/GMC Topkick medium duty trucks, but I'm not sure it fits the Corvette. There's some difference in the pushrod length for the hydraulic boosters. Most of the time, you have to shorten the master cylinder pushrod. The hydraulics is a minor plumbing issue. You need fittings and lines to connect it in parallel with the power steering gear, and run it off the power steering pump. Most pumps have adequate capacity to run both power steering and the hydraulic booster.
How are the brake boosters failing? Have you pulled any of them apart to see what failed?
It's not likely to be the master cylinder. If the diaphragms are failing ('blowing out'), then it's either a bad check valve or something causing pressure to reach the thing. If your engine is boosted, then you need a very good check valve (strong enough to stop any boost pressure from going through). If your engine is stock(ish), then check for any backfiring in the intake. That will blow a brake booster out.
With the luck you're having, hydro boost might be worth looking into. 1994-1995 Chevy Astro is the unit that is most commonly used. There's another (larger) one available as well, from the 1991-1996 Chevy Kodiak/GMC Topkick medium duty trucks, but I'm not sure it fits the Corvette. There's some difference in the pushrod length for the hydraulic boosters. Most of the time, you have to shorten the master cylinder pushrod. The hydraulics is a minor plumbing issue. You need fittings and lines to connect it in parallel with the power steering gear, and run it off the power steering pump. Most pumps have adequate capacity to run both power steering and the hydraulic booster.
Last edited by C6_Racer_X; 11-21-2018 at 09:01 AM.
11-21-2018, 09:29 AM
#24
If you read the thread, he has been to a few different places. To be honest, this is a pretty harsh statement to make to a guy who isn't healthy and just wants to enjoy his car. Your post provided zero insight or help.
Johno504. I would ask if they are checking the distance the rod is traveling. Also, has anyone checked the vacuum the engine is pulling. Not sure what would cause it, but too much vacuum may be over stressing the diaphragm. A brake booster being as simple as it is. It seems something has to be causing the diaphragm to break down or be over stressed.
As quick as some of the failures, I would go with over stressed and tearing it. I would be nice to brake one open and confirm it is a failure on the diaphragm.
Johno504. I would ask if they are checking the distance the rod is traveling. Also, has anyone checked the vacuum the engine is pulling. Not sure what would cause it, but too much vacuum may be over stressing the diaphragm. A brake booster being as simple as it is. It seems something has to be causing the diaphragm to break down or be over stressed.
As quick as some of the failures, I would go with over stressed and tearing it. I would be nice to brake one open and confirm it is a failure on the diaphragm.
I stand by what I said, FIND A NEW MECHANIC.
One that specializes in the braking system would be ideal.
I have been wrenching on cars for a while, and I've NEVER heard of something as crazy as this without there being something else causing it.
He mentions "his repair shop", and one that replaced a booster while he was stranded from home.
I would get away from that repair shop.
11-21-2018, 11:14 AM
#25
Racer
Thread Starter
Thanks for all the input gentlemen. I am going to put this ongoing problem on the back burner for a few weeks . I have to start a new series of chemo Monday , and know I won't be up to dealing with a "simple" car repair. Enjoy the holidays all . RUNNING TO LIVE , LIVING TO RUN
11-21-2018, 12:40 PM
#26
Drifting
11-21-2018, 01:40 PM
#27
Melting Slicks
First off Johno504 hopefully your upcoming Chemo dosn't knock you back too far. But this is a question that Will be met with probably a scoof by few but needs to be asked. When your brakes fail do you hear the ABS pump running. I had a car come in with a complaint of no brakes got into to the car and it had brakes but then the ABS pump started to run and poof brakes gone. It turns out it had a bad wheel sensor
Last edited by s carter; 11-21-2018 at 01:53 PM.
11-21-2018, 01:47 PM
#28
Race Director
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