Removing brake booster, for race?

[Jonny Rochester]

I am looking at the TRD Levin Bible. For the AE86 N2 spec cars, they just removed the brake booster and proportioning valves. They still use the same 13/16" master cylinder, but just bolted to the firewall with a adapter. The actual brakes only changed slightly. Front caliper has a 57.2mm bore now, stock is 50.8mm. And front disks are 248 x 22mm rather than stock 234 x 18mm. And they use "Ferrode DS11" pads front and back.

I have also seen some D1 cars with the booster removed, like Ueo's car I think.

Does anyone recomend this booster removal? My 86 will be built as a race car, but will be on the street also. With stock "JDM" brakes.


The Group A AE86 has a more complicated setup, with duel master cylinders and balance bar. No booster.

[EVOSTi]

no its not reccomended you remove it for street, its possibly illegal also. if you want better brakes get better calipers, m/c, lines, pads etc. just cause some drift car has it doesnt make it good.

[Cool1]

I'll be removing the booster in my car. Mainly because its something that needs to be connected to the engine(which I dont want to do) and it takes up space.
Go leg press 215kgs at the gym for a few weeks and you wont notice the booster is missing!

[takai]

The next question on the agenda i guess is how do you actuate the brake master without the booster there. Simply make up an adaptor with an attachment for the brake pedal and a rod to push the master?

[Cool1]

On my car I hope to be using 2 master cylinders and a bias bar!
If you choose to mount your master cylinder directly on the firewall, you will probably have to get a new master cylinder with a ball joint in the piston. Most oem master cylinders will not like the plunger shaft pressing the piston on an angle which is what will happen if you mount it on the firewall.

[roadsailing]

running a car with no booster isn't a problem on the street, at least for a light car lightish car like a sprinter.

i'd just make damn sure that you were doing it for a good reason, if you have a basically stock brake setup, then i would reccomend leaving the booster there, heavier brakes aren't a problem on the street, but are they necassarily better on the track?

and be careful when you get in a car with boosted brakes after getting out of one without them, i have nearly had my head through a few windscreens like that.

takai, as far as i know you dont have to do anything to the brake system to actuate the brakes, to prove this try this coast in your car (or get pushed with the engine off) or blank off your booster vacuum line and try the brakes - they are harder to push but still work fine, after all, you couldn't have your brakes fail if your engine stalled now could you?

edit on above pint:

i see what you mean now, one of the reasons to get rid of the booster is reduced weight and more room for inlet gear, but i think it may be as simple as just pulling off the booester as from memory it is basically an auxiliary system.

[takai]

Aye, but getting stuff like pressure angles right can be a pain. Im wondering if there are any generic adaptor plates out there.

[Jonny Rochester]

EVOsti: Ueo has won a few times in drift, people notice his setup. Also note I was mostly talking about the TRD N2 cars, meaning probably ALL of them ran no booster as the TRD Bible specs say.

I like the booster. But I know at the race track once you heat the brakes a bit they can get a bit spongy (even good ones) and you are not sure how hard to push. Maybe with better pads the feel improves.

[Jonny Rochester]

The TRD Bible show pictures of all the parts needed. It looks easy to make.

[takai]

The booster actually reduces the pedal feel which you get. For now im going to run it, mainly because i just went to all the effort of designing a plenum which gets around the brake master, and i think it will work ok. But inevitably down the line somewhere ill ditch the booster.

Jonny: ill have to take a look at the Levin/Trueno bible tomorrow at the shop. I think there is one there.

[JustCallMeOrlando]

I like the booster. But I know at the race track once you heat the brakes a bit they can get a bit spongy (even good ones) and you are not sure how hard to push. Maybe with better pads the feel improves.

If the brakes are going spongy, as you suggested, it's most likely to do with them not being able to get rid of enough heat for the pads to cope. What you're feeling is probably the precursor to fade.

[45aken]

alot of the car's that we used to go down on track days with (racing alfa's etc) didnot run any boosters, they said it reduces pedal feel (like takai said).
with out the booster, you have much better control over lock on the car, and a 'directer' feel with the brakes.

[Blown86]

Before you remove the booster try the car as it is, IMHO you don't need to remove the booster on an AE86 for the track using stock brakes.

I've run a couple of different 86s on the track with different brake setups all with boosters and haven't had a problem with pedal feel.
Many times I jumped from a Formula Ford straight into an 86 and never noticed a problem with brake feel, just lack of brakes using stockies.

Plenty of guys I know run with them and don't have a problem.
Choice of pads makes a big difference to pedal feel.
If you have any decent power you'll find JDM brakes are a too small for the track.

Be careful removing the proportioning valve if it's a stock setup, tends to lock up the rears.

[Blown86]

If the brakes are going spongy, as you suggested, it's most likely to do with them not being able to get rid of enough heat for the pads to cope. What you're feeling is probably the precursor to fade.

Exactly, you'd only just get by with JDM brakes and a stocky engine even with good pads.

[takai]

Yeah, im up to using a 17/16th master though, and the booster is frankly pissing me off and getting in the way. Going up to Revos to look at pedal boxes tomorrow. Then again, im using 4spot calipers