Brake upgrade questions.

[callum]

I'm in the process of upgrading the front brakes on my ae92.
I'm fitting some 4 pot brembo calipers which have very similar piston size to the standard single piston ones. However since you need to double the area for the single pot calipers (cheers to bazda for explaining this to me) I will have twice the fluid I need going to new front calipers.
So I have a few questions.

1, will I be able to fit the front brakes then somehow modify the bias to even the front and rear brakes?

2, will fitting a smaller mastercylinder help?

Cheers for any help on his one.

[strx7]

you'll probably need a larger master cylinder, st202 curren/celica run 15/16ths ones, a trip to pickapart will find a cylinder that will fit your current booster and displace more fluid

[callum]

Since I now need less fluid to the front calipers I was picking a smaller one would be more appropriate.

[wde_bdy]

You sure you have calculated the piston area correctly? I would expect your 4 piston Brembo's to have the same or more piston area per side. Got some dimensions so we can confirm your calcs?

Callum

[callum]

Piston sizes are 2x 26mm and two times 24mm. But each piston has to move half as far as the single since they are opposing.

[wde_bdy]

Pistons seem very small, what size was the standard piston?

Callum

[callum]

Yeah there not very big. I can't remember exactly but when worked it out they were very similar areas. The main thing I'm worried about is how easily a cars brake bias is changed.

[Bazda]

Stock ones are 50mm = 1963.5mm^3
x2 = 3927mm^3

Your Brembos are
26mmx2 = 1062mm^3
24mmx2 = 905mm^3
Total = 1967mm^3

So basically half the area. The fronts will work alot earlier than the rears so you can do stand stop wheel stands

I don't think there is an easy way out of this, the master would need to be alot smaller, and remember a fwd master cylinder is a dual thing with a spring inside, also the way the brake lines are hooked up is REALLY funky. One lines comes off and goes straight to one of the front brakes, the other line goes into the little bias valve box which distributes off in 3. 1 to the other front brake, and 2 to the rear.

Ideally you need 35mm pistons and the minimum in a 4 piston caliper. This is what I run, if they made 36-37mm this would be even better as I still had a bit too much front bias so I changed the rears brakes to make my bias better.

[gasman]

wait what? im confused, does the brembos have a 24mm and a 26mm piston on once caliper?

[wde_bdy]

It's not uncommon to run staggered pistons on high performance calipers, so will run a 24mm and 26mm on each side of the caliper. Personally to me though with those piston sizes the calipers aren't suitable for mixing with factory brake components. You really need to go all out to use them, no booster and dual masters probably with a rear caliper change too.

Callum

[neo]

does it need to remain road legal / does it have an authority card?

(cant remember if its my cert of auth card that covers the adj. prop. valve) however, on my 101 I threw out the factory prop, run the front line to the front brakes and just have the prop. valve inline with the rear ones, so simply resisting how much goes to the rear. they can shut down a huge % of the pressure so it might cut it..

lol and with this and the factory master cyl, a feather landing on the pedal should stop the car in its tracks :p

[Leon]

(cant remember if its my cert of auth card that covers the adj. prop. valve)

It's the cert, not the card.