8Pot + 356Mm Front Brakes/ Rear Brake Upgrade Needed? R32Gtr

[geetea-are]

I'm just about to gain ownership of the d2 8pot 356mm big brake upgrade on the front of my r32 gtr, with the increased piston surface area at the front i'm guessing it will largely change the brake bias in my car? I understand that my gtr has 38mm pistons in the rear, and the (r32vspec, 33, 34) are an amolst straight bolt on with a larger 40mm rear pistion and slightly larger disc.

Would the larger brembo plus larger disc be worth my time or should i opt for some thing else, my car will see a fair bit of track work.

Also an upgrade in the master brake cyclinder would greatly help?

Thank you Elliot

Edited February 1, 2013 by geetea-are

[GTSBoy]

Piston area has little to do with it. In fact, given that these calipers are intended to be put onto cars without any changes to the master cylinder (or necessarily any change to the rear brakes), I think you'll find that the 8 little pistons don't have a very different total area than the 4 bigger ones in your existing calipers.

The difference in braking power comes simply from the extra torque created by moving the contact circle radially outward from the hub. The same braking force applied to the disc multiplied by the longer lever arm = more torque.

On that basis, given that you are increasing the front braking ability by quite a reasonable amount, then yes, putting at least the 330mm kit on the rear would probably be a good idea. If you were to look on D2's site, you would see that they do mildly recommend that you match upgrades at both ends.

Do not consider the Vspec rears to be an upgrade that you would notice the effect of. The changes are really too small, and they were intended to work with 324mm front rotors. Hence why I suggested you would go for at least the D2 330 rear equivalents if you were to do anything.

[djr81]

Rather than speculating you should find out from D2 what the area is. Some manufacturers use smaller areas than Brembo do and all the balance issues come out in the wash. But find out first.

[R31Nismoid]

If you are just aiming for your club level track day

Front Upgrade

Stock rear

Stock Master Cylinder

It's what most people do, and it works fine.

Rear upgrade isn't required unless you need more heat dissipation capacity from the larger rotor etc - only needed in a totally dedicated track car that's aiming for LOT of laps and 15mins+ running time (which is well over & above your club level sprint days).

[beenowened]

The D2 calipers have 4 x 26.4mm and 4 x 31mm diameter pistons compared to the 4 x 40.4mm pistons.

So there is a significant increase in surface area.

[geetea-are]

awesome thank you very much, i'll just leave it for the time being unless that rears become an issue.

[GTSBoy]

The D2 calipers have 4 x 26.4mm and 4 x 31mm diameter pistons compared to the 4 x 40.4mm pistons.

So there is a significant increase in surface area.

Ahhhhh.......1.5% is "significant"?

[beenowened]

i

[GTSBoy]

You're doing it wrong. Very very wrong. You have to square the diameters to compare them. Area is not the same as sum of diameters.

Area = pi*(d^2)/4

4 x 40.44mm pistons has total area = 5127.582mm2.

4 x 26.4 + 4x 31 mm pistons has total area = 2189.564 + 3019.071 = 5208.635 mm2 which is 1.5% more than the original calipers.

[beenowened]

yeah my bad i realised that after i posted lol

[Duncan]

ahh that's what I was about to say D2 piston area is almost identical to standard although the disc and caliper is much larger. So they are a great swap with no impact on front/rear bias

I wouldn't bother changing the rears in any case, you just change the pads to be more or less aggressive if you want to change the front/rear balance a little. No need to change the caliper and disc they are already adequately large in almost all use

[geetea-are]

thank you I got paranoid today that I would have to change my rear brake setup to accomodate for the new fronts !