The 24 Hours of Lemons Forums → Lemons Tech → Removing Power Assisted Brakes
For those of you that your Lemons chariot had PB, do you keep them or remove the power assist unit? We flat spotted some tires, I think, because the power brakes were just so touchy. When you race and get all pumped-up I find it hard to be "a wuss" on the brakes. PB like PS just doesn't have the feel that non PB/PS cars have, I find it difficult to threshold brake with PB. So do you keep the power assisted brakes or take them out?
Maybe try a brake pad with a lower coefficient of friction?
We kept our stock power assist brakes. New Bosh pads. Well used rotors. Drum brakes in rear. Never had an issue. The car is so slow you want to use the brakes as little as possible.
This just seems like a bad idea.
Yea I think you would be better putting in a proportioning valve or may be restrict the vacuum that goes to the booster a bit . I would not remove the booster. Have you ever had a car with full maunal brakes.. you end up with a really strong right leg.
So there is a method to "reduce" the boost then? A boost or assist reduction would definately work, Hmmm.
Our Z had been in a barn for a few decades and among the things that didn't work was the brake booster. We didn't find this out until just before we left for the Lamest Day since our car moved under its own power for the first time onto the trailer. Even though it is a light car, it was not easy to stop it. We swapped the booster as soon as we got to the track and they worked great. Without power assist, I think it would be undriveable and very unsafe.
What brake pads were you using? My guess is that they were too aggressive. Like EvergreenDan said, try pads with a lower friction coefficient.
I used Hawk DTC-60. The stopping was great and no fade the whole time, I just couldn't get a good threashold braking feel because they were so sensitive. I guess I'll just have to deal with it or find a way to "reduce" the power assist.
I used Hawk DTC-60. The stopping was great and no fade the whole time, I just couldn't get a good threashold braking feel because they were so sensitive. I guess I'll just have to deal with it or find a way to "reduce" the power assist.
DTC-60s are kinda touchy no matter what. we run HT-10s. i love a Hawk pad but i have my reservations about the DTCs. they need a heavy car and constant heat i believe.
as such i supposedly put some flat spots on the tires. but that wasn't the fault of the braking system or the pads. don't mess with the OEM system.
and no i am not admitting to anything here. 
I used Hawk DTC-60.
Bar Patron: I ordered 200 proof grain alcohol last night.
Bartender: Uh huh.
Bar Patron: I got stupid drunk, kept falling off my bar seat, and slept with my sister the hooker.
Bartender: Uh huh.
Bar Patron: You need to widen the bar seats and fire my sister.
Bartender: <facepalm>
Mole, I thought 4th gen Maximas had ABS.
Larger tires will dial out brakes.
A tire with more grip will counter act the brakes more too. Don't know if you can do much in this area.
Finally, push on the brakes less.
In the '64 Buick, we had a blown booster that we didn't find out about until the night before- turns out it didn't do a hell of a lot. With the booster capped off to prevent vacuum leaks it would still lock the wheels with a bit of effort. And there were some good braking needs at Fernley.
With ABS all bets are off, but otherwise just find a master cylinder that is 2mm-ish smaller and run it with no boost. If you can find a master that'll mount up... Slightly longer pedal, but should still be powerful enough without the 'bite' overboosted feel that some systems have.
Perhaps some other models of the Gen 4 have ABS but the GXE doesn't. I'm sure it's just the driver (me) I just need to be a wee bit less aggressive on the brakes cuz after all this is enduro racing not a friggen sprint race with every lap on the edge. Sounds like don't to the power unit and just reel back some on trying to threshhold brake. Sounds like a plan.
Perhaps some other models of the Gen 4 have ABS but the GXE doesn't. I'm sure it's just the driver (me) I just need to be a wee bit less aggressive on the brakes cuz after all this is enduro racing not a friggen sprint race with every lap on the edge. Sounds like don't mess with the power unit and just reel back some on trying to threshhold brake. Sounds like a plan.
Perhaps some other models of the Gen 4 have ABS but the GXE doesn't. I'm sure it's just the driver (me) I just need to be a wee bit less aggressive on the brakes cuz after all this is enduro racing not a friggen sprint race with every lap on the edge. Sounds like don't mess with the power unit and just reel back some on trying to threshhold brake. Sounds like a plan.
Or maybe you have an electrical issue in the abs system (start by checking the fuse). If you want to see what it would be like with out power assist, point it down a (straight) hill and roll it without starting the car...then try to stop it.
IMO, the larger master cylinders required to compress the larger pistons in heavy, modern cars just aren't usable without a booster.
Going w/o the booster is definitely a BAD idea. I agree the DTC-60's are way too agressive for the tires that we are allowed to run as well. The amount of boost is determined by the amount of vacuum so reduce the vacuum and you will reduce the boost.
I wouldn't pull the power assist...the pedal will be SO heavy without it....we ran a stock brake system on the 928 with Raybestos ST43's (very aggresive pad) and I LOVED THEM.....excellent brakes....sure they would lock up pretty easy in 10 & 14, but I'd rather have too much than not enough!!
In theory you could run a smaller brake booster to increase the pedal effort? I don't know about Maximas but 928's came with 9" and 10" boosters depending on model year
Our car came stock with manual brakes and it is staying that way. Next question is do we do with manual steering? It's all well and good in a 2200 pound Miata but a 4,000 pound C-Body with 245 tires? Hmmm...
So there is a method to "reduce" the boost then? A boost or assist reduction would definately work, Hmmm.
yeah. it's called your foot. 
Buzz - EUREKA!! Why didn't I think of that, so profound in its simplicity, thanks Buzzman.
We had anti-lock brakes on our e-30 and needed to pull the brake booster and abs-controll crap out for our engine swap. I had a Wilwood 3/4" master cylinder for a sprint car that we used. The brakes have a very nice firm feel to them now and it cleaned up our engine compartment alot and left more room for our okied exhaust. They are about $65.00 new or you can find them on ebay for less. they are very easy to mount in any type of car as they have two different ways to mount them.
Buzz - EUREKA!! Why didn't I think of that, so profound in its simplicity, thanks Buzzman.
no problem, chap. happy to help.
Our car came stock with manual brakes and it is staying that way. Next question is do we do with manual steering? It's all well and good in a 2200 pound Miata but a 4,000 pound C-Body with 245 tires? Hmmm...
If you swap to a manual box, it won't be too hard to steer, but you'll be turning the wheel a dozen times to get around the corner.
That just ain't right... just change pads... OTOH, when I was a foolish youth, I put dual tilton masters with a balance bar in my street Celica, and it worked ok, but you had to push like a mutha to slow down!
So there is a method to "reduce" the boost then? A boost or assist reduction would definately work, Hmmm.
Use a master cylinder with a larger bore diameter....less mechanical advantage and a shorter pedal travel...
The 24 Hours of Lemons Forums → Lemons Tech → Removing Power Assisted Brakes