Brake Upgrades

[Koffee-Black]

Hey guys,

Last night i went for a spin in a gen3 SW20, with R33 4 Pot calipers....and damn, what a difference!!!!

Im looking at the Supra 4 pot for the front, there are brackets available to bolt these on...

Thing with the car last night, it had stock rear brakes, and really hurt the stopping, as it would lock quite easy.

Whats an upgrade for the rear? Can i use the Supra 2 pots? Or is it different?? What do I need to look for to upgrade the rear?

[lexsmaz]

You said the brakes would lock quite easy, i assume you are talking about the rear's ....
If you are talking about the rear's, you would need an adjustable proportioning valve for the rear's on the one you "drove last night" , if you were to upgrade the brakes on the rear it would lock up even easier ... I would leave the rear's alone & just limit the pressure going to them ....
( Bigger callipers = more presssure = more clamping force on the pads easier lock up... Bigger diameter discs = more leverage,= easier lockup .. )

[Koffee-Black]

sorry its the front locking not rears

[amichie]

Hey guys,

Last night i went for a spin in a gen3 SW20, with R33 4 Pot calipers....and damn, what a difference!!!!

Im looking at the Supra 4 pot for the front, there are brackets available to bolt these on...

Thing with the car last night, it had stock rear brakes, and really hurt the stopping, as it would lock quite easy.

Whats an upgrade for the rear? Can i use the Supra 2 pots? Or is it different?? What do I need to look for to upgrade the rear?

You might be able to just change the front pads. Most of the basic entry level pads have very high coefficients of friction 0.5 to 0.6. Most of the premium pads are a fair bit lower 0.4 -0.45. But their tendency to fade etc is much reduced.

[IN 05 NT]

dont bother upgrading the rear, just concentrate on the front, any disc rear end is more than adequate for street under heavy braking,

only time you would take advantage of a big rear setup is if you have dirty big slicks/tyres that will actually help slow down,

but for street, leave em standard,

blake

[Billzilla]

dont bother upgrading the rear, just concentrate on the front, any disc rear end is more than adequate for street under heavy braking,

FWIW a good general rule is that the better set-up a car is, the more rear brake you can carry. Karts are a good example of that.

[Cruiser97_80]

FWIW a good general rule is that the better set-up a car is, the more rear brake you can carry. Karts are a good example of that.

SW20 = Big Kart lol

sw20's are pretty well balanced, and can run more rear brake.
Manufacturers tend not to run alot of rear brake.

[Koffee-Black]

Well driving the car hard on the street tend to make the fronts lock, but the g's i got before it locked was crazy! Better than the 4 pots on my old supra!! Maybe due to its lighter body with the supra big pots, it will be awesome.

[Cruiser97_80]

I would expect a big four pot conversion on the front and an adjustable brake bias would be a great upgrade.
There is a conversion for the rears being the later model sw20 rear callipers and rx8 front rotors, you may already know of this.

[Koffee-Black]

ahh ok, i read something like that last night, so its just the rx8 rotors used, not the calipers?

Mines a gen2 so maybe gen3 rear caliper?

[Cruiser97_80]

yeah i believe it's the geniii rear calliper and rx8 sports front rotor.

Would not be legal on the road though. Unless you can get it engineered.

[Cruiser97_80]

ok i found where i got my info from. mr2 forum

http://toyota-mr2.mine.nu/mr2/topic.asp?TOPIC_ID=7275

[Mooro]

As mentioned I think an adjustable proportioning valve would go some way to solving the problem.

[Joshstix]

MR2's really need more rear brake. The general rule of thumb for a FR or FF car do not apply to a mid engined setup. The cars weight is biased to the rear meaning there is a lot more force on the rear wheels than in a normal car.

Unfortunately people making big brake kits don't seem to be able to get this through their head and only make kits for the front.

The problem with getting decent rear brakes into the MR2 is that it runs a hand brake that actuates the calipers rather than an internal drum like most cars. My plan is to use the Gen3 SW20 calipers I have now with a spacer braket to allow me to run a lrger diameter rotor and just take advantage of the greater torque of the larger diameter and the greater speed past the pad due to the larger circumference.

Having said that this weekend I am planning on installing a brake proportioning valve on my front brakes to be able to adjust them back and get the fronts not as lock-up prone. I figure that will get me sorted for now and when I redo the brakes I'll be able to use the propr valve for either the front or rear to fine tune.

[Mooro]

Hey did you ever try using gen 3 SW20 rear calipers and the late model AW11 front rotors on the rear of an AW11...is this what you are planning to do because I heard it was a straight bolt up job but I think you mentioned you need a new caliper bracket??

[Joshstix]

Currently I am running Gen3 SW20 rear calipers with AW11 front rotors on therear of my AW11. They need a spacer between the hub and rotor.

[Mooro]

Sweet...sorry to go off topic Koffee.

[Koffee-Black]

thats cool, its all relevent!

How hard is it to hook up a poprtional valve? is thatbasically a brake bias?

[Mooro]

Yep allows you to adjust the brake bias...you still want it to be adjusted such that the fronts will lock before the rears with some margin of safety, cos a rear brake lock up can be difficult to control.

Not sure how hard it is but from reading up briefly on it it is something that should be done with care to do it correctly. I believe the factory system is setup with multiple systems so if one fails/leaks you still have some braking power but an incorrectly installed proportional valve can stuff this up which is obviously bad.

Also I believe they are illegal...well at least an in cabin one is but maybe an external one will be ok.

[Joshstix]

Just installing a proportioning valve is fairly simple, it's just a case of cutting and bending the appropriate brake line to fit into the valve then slipping on the appropriate ends and flaring the pipe and bolting it up.

Setting it up correctly on the other hand is a lot more work. Running an aftermarket proportioning valve along with the factory proportioning setup is going to lead to problems as well.

Currently my MR2 is setup with the factory proportioning valve completely removed, I have replaced it with a T piece and a straight connector. Even with this setup with no proportioning it is far to easy to lock the front brakes.