turbobuickman
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Just like the title says, whats the highest boost you guys with vaccum brakes can hold on the line?
Highest boost held with vaccum brakes?
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Cheeseburger
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Vacuum brakes were the worst thing i ever had on my car (bought it like that).
I could not hold ANY boost at all, this is after farting around with the brakes forever.
Best thing i ever did was go back to the stock electric brake booster!
I could not hold ANY boost at all, this is after farting around with the brakes forever.
Best thing i ever did was go back to the stock electric brake booster!
EightSecV6
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2 ways to handle that....install an electric vacuum pump (from a Caddy) OR once you stage, put it in neutral and start revving the engine as you sloly push the brake pedal to the FLOOR when it wont go any farther, put it in gear and get ready to let it rip, it will hold a bunch more boost like that.
turbobuickman
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Mine had already been converted when I bought it too
Thats a neat little trick eightsecv6, I'll experiment with that this spring 
.
Thats a neat little trick eightsecv6, I'll experiment with that this spring .Vendor Defendor
Out the window
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What kind of caddys do you find these electric pumps in? I swiched over to the vacuum brakes due to the cost factor, and am a little concerned with how stiff they are, not too confident that I could do some 'oh ****' stopping
EightSecV6
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I dont remember the year or model, it is actually used for the air ride siuspension....
Vendor Defendor
Out the window
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hmm, could you come up with a guesstimation? Like, 70s 80's or 90's?
Thanks Bill
Thanks Bill
EightSecV6
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mid to late 80's
I have vacuum brakes on my 87 street car and have launched at as much as 10 lbs., but usually go 7 - 8 lbs. I probably could go higher but then I get too much tire spin. However, even at 7 - 8 lbs. of boost, over a period of time the brake shoes will bend out of shape. Up where the bar from the wheel cylinder pushes on the shoe there is a notch for the e-brake that is the weak point. The only way to avoid this is to not boost it or have a trans brake.
My friend Geno has launched at as much as 20lbs. with 1.3x 60 ft. times. But he doesn't do that any more because of bent shoes also. He also twisted after market axles as well.
I just figure I will have to replace my rear shoes from time to time. Thats racing.
My friend Geno has launched at as much as 20lbs. with 1.3x 60 ft. times. But he doesn't do that any more because of bent shoes also. He also twisted after market axles as well.
I just figure I will have to replace my rear shoes from time to time. Thats racing.
Cheeseburger
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I.M.O. i think that the vacuum brakes take away from the authenticity of the car, and if you have a big cam and make power you will always creep through the staging lights when loading up the car.........and that really makes you mad when you have done everything to try and make it work!
With s10 cylinders and using 2 sets of brake shoes to get 2 longer ones on each side my peddle would always go right to the floor when loading up the car.
As i said before, changing back to original was the best thing i did for holding boost.......went from holding zero boost to holding 15lbs with no other changes.
I am sure a vacuum pump or storage tank will work, but why have that crap under the hood when you could just go to original?
I.M.O. anyone that has vacuum brakes is just ''cheaping out'' on spending the extra $$ for the proper original unit.
Good luck on your decision, and if its a daily driver with no use for drag racing i would not worry about it and drive it as is.
With s10 cylinders and using 2 sets of brake shoes to get 2 longer ones on each side my peddle would always go right to the floor when loading up the car.
As i said before, changing back to original was the best thing i did for holding boost.......went from holding zero boost to holding 15lbs with no other changes.
I am sure a vacuum pump or storage tank will work, but why have that crap under the hood when you could just go to original?
I.M.O. anyone that has vacuum brakes is just ''cheaping out'' on spending the extra $$ for the proper original unit.
Good luck on your decision, and if its a daily driver with no use for drag racing i would not worry about it and drive it as is.
There's something to be said for original, until it breaks.
One thing I havn't heard of is the use of another booster unit. Certain Astro vans used a hydrostatic booster as well, it my be a better design then the booster used on the TRs, but now that I've said that it's probably not. (you know, murphy's law)
What about Turbo T/A users, I thought they had vacuum breaks and Sy/Ty people?
There's something to be said for original, until it breaks.
One thing I havn't heard of is the use of another booster unit. Certain Astro vans and some bigger trucks used a hydrostatic booster as well, it my be a better design then the booster used on the TRs, but now that I've said that it's probably not. (you know, murphy's law)
What about Turbo T/A and Sy/Ty owners, I thought they had vacuum brakes.
I've never seen a vacuum system fail completely and totally in one brake pedal application (booster related). My GN's PM fail completely in brake application. Luckily it was a cheap lesson, and nothing got hurt.
IMO, using a PM is just waiting for it to fail, and it can fail in one brake pedal application. Just the think you want going thru the lights, right?. Ever try and stop a PM in a worst case scenario?, ever try and stop a Vac system, in a worst case scenario?, IMO, the vac system beats the PM, in every way when there is a problem. If you want to trust to never having a problem, fine by me.
The stock brakes, IMO, are a complete joke, for the performance level that the car can achieve (rotor/ drum size). IMO, cheaping out by even trying to use them is irresponsible.
malibuick231
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I had vacume brakes on my old car and will have them on my new car.They would hold 15 psi on the foor brake for a 1.50 60ft never had a problam with them.I would roll in to the pre stage and rev the motor up and while at full vacume would stab the brake pedal.
turbobuickman
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Hmmmm... I guess vaccum brakes arent so bad after all.
Red Regal T
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Yeah right...........hey look! This guy has VACUUM BRAKES on a TR! THEY'RE NOT ORIGINAL! 
LOL!!!
Anyway, you can get those caddy electric vacuum pumps off 85 thru 87 front drive caddies, ONLY. They all have them. They are hooked to the vacuum brakes. The pump is located under where the battery is.
If you are not confident in your vacuum brakes because they don't stop adequately, there is something wrong. Go through them.
LOL!!!
Anyway, you can get those caddy electric vacuum pumps off 85 thru 87 front drive caddies, ONLY. They all have them. They are hooked to the vacuum brakes. The pump is located under where the battery is.
If you are not confident in your vacuum brakes because they don't stop adequately, there is something wrong. Go through them.
I'm just an amateur, but isn't boost level pretty irrelevant? I mean a 72 turbo at 10 lbs of boost is certainly exerting a lot more pressure on the driveline than a stock turbo at 10 lbs, right? Isn't it really the air flow at a given boost level that matters, not the boost level itself? I don't see how boost level is relevant (for seeing how much you can hold on the foot brake) unless you have the exact same combo. Someone slap me around if I'm wrong 
