The 24 Hours of Lemons Forums → Lemons Tech → power brake boosters?
Do most racers run their Lemons cars with them? Since there is so much time spent under low /no maniforld pressure wouldn't they be pretty worthless? Then coming off throttle cause braking issues of added brake boost at exactly the wrong moment?
If it has power assist brakes leave them, our Pontiac never has had an issue with low vacuum. Even on the Snoopy van with the turbos working there was never an issue, there is a 1 way check valve on the booster that prevents + (atmospheric/ boost) pressure from entering the booster as well as not letting the - pressure (vacuum) to escape. If you want to remove the booster to remove weight I would get a master cylinder and possibly the brake peddle and linkage from the same type of car with out the power assist option to maintain proper brake peddle geometry.
When I was driving the old farts 64 buick special, the booster failed in practice and it was fine unboosted. Disconnected the vacuum line, good to go.
A good rule of thumb is going down one master cylinder size, like from 1 inch to 15/16 or 7/8.
This means a slightly longer pedal, but decent power. Plus a lot less bulk and plumbing, which with some of our engine swaps is vital...
No problems with our brake booster. Lifting throttle cause huge vacuum reserve to be stored in the booster, which is supposed to be good for a couple of brake applications, even if the car wasn't coasting in gear & making more vacuum.
Brake systems with boosters were designed to use them, travel, applied force, bias, master cylinder volume, caliper sizing, even compounds are designed around the OE system. You can add more grip but idiotically removing the booster does nothing but make it harder to apply, the bullshit nonsense about 'feel' is stupid, and lots of race car don't have boosters because they have huge master cylinders and gigantic pedal ratios.
"lots of race car don't have boosters because they have huge master cylinders and gigantic pedal ratios."
And a booster won't work in a race car w/ a race cam and no manifold vacuum.
But that doesn't apply to CrapCan racing.
We've been running without a booster for two races now. . . .We did an engine/tranny swap with a newer car and had to convert to a hydraulic clutch. There was no other place to put the clutch master cylinder since the booster was taking up most of the firewall near the pedals. So we cut that sucker out and haven't missed it. Yeah, braking effort is significanty increased, but it's not that bad if you just remember to stand on the pedal. I'm not sure if we actually are getting more feel or not, but it seems like we do. . . .personally, I like running without it. The amount of effort to brake the car seems very proportional to the amount of adrenaline running through your body. . . .
It should be noted, that we do have a very light car (86 prelude) that is super easy on brakes, so the experience may be entirely different in a heavier car that requires a sh1t ton of energy to bring to a halt.
"lots of race car don't have boosters because they have huge master cylinders and gigantic pedal ratios."
And a booster won't work in a race car w/ a race cam and no manifold vacuum.
But that doesn't apply to CrapCan racing.
All gasoline engine make vacuum on deceleration, you could have 361 degree cams (ha!) and when the butterfly closed you'd make vacuum. Boosters are a reservoir by design with a check valve and I've never seen problems even with the most nasty drag cams. Its pretty rare to actually make *NO* vacuum, ususally its low inHg but boosters store a lot of vacuum and still function fine with 5-6inHg. Anytime you are on large decel (you make more vacuum than you use when braking) you store its energy.
Anyone who worries about weight from a booster has never handled one and would lose more functional weight by removing some undercoating or pooping before the race.
Sometimes it's just a packaging issue. My Z600 Honda had a crazy separate booster system because a conventional booster would put the master where the engine lives.
My crazy postal Jeep project I had to pull the booster to make the supercharger plumbing work.
I downsized the master and it worked fine, but there was a bit of master swapping to get the ratio right. If you don't have any problem with packaging, there's no reason to remove your booster.
If the booster is broken, disable it (cut the vacuum) - removing it is extra wrench-turning that you could probably use somewhere else. If it works, leave it the hell alone.
This is generally a good policy on any not-strictly-essential component on any crapcan, whether for the road or for the racetrack.
Brake systems with boosters were designed to use them, travel, applied force, bias, master cylinder volume, caliper sizing, even compounds are designed around the OE system. You can add more grip but idiotically removing the booster does nothing but make it harder to apply, the bullshit nonsense about 'feel' is stupid, and lots of race car don't have boosters because they have huge master cylinders and gigantic pedal ratios.
Actully to use less effort to apply the brakes easier you would go smaller not larger on the master cylinder size. More travel= less effort..
What's the old addage about parts left off a race car never break down ?
A brake booster is simply one more item to leak/fail.
Factory brake boosters usually work pretty well. At Stafford we always had power brakes. Just rebuild it if you're unsure
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