Big brake conversion rx8?

[pbmr2]

i've got the RX8 discs (front) on the rear, spaced out stock rear caliper. Front is running Supra discs and 996 Porsche calipers. Car doesn't want to swap ends, stops fine, no more sticking front calipers every six months. Run stock pads and doesn't squeal or eat wheels with the dust and yeah stopping power is there. Brake bias pretty much standard by intention and careful caliper choice. It can be done but a very emotive topic.

How did you workout the bias based on the caliper choice?

The 996 caliper uses 2 opposing large pistons and 2 small pistons so the clamping force is greater than the stock caliper with a larger pad area too.

The rear rx8 setup uses the stock caliper on a 20mm larger diameter disc yet 4mm thinner. same clamping force as stock and same pad area.

The Porsche calipers look great and fill the wheel well, shame the branding conflicts with the car IMO.
Not saying the system doesn't work for you but it's not going to be stock bias is it?
Do you have ABS on your car?

[yokomomr4bx]

So I've got standard rear callipers with a bracket that pushes them out to accommodate the rx8 discs, standard everywhere else, been running this setup for 3 years with no problems at all. Oh and you can fit 16" wheels fine, my r32 gtr wheels actually have the same amount of clearance to the calliper as my set of 17". Not running any bias at all. I need to change my rear discs soon so if anyone is desperate for the rx8 rear bracket then send me lots of money as it's clearly desirable for some reason!

Edit: if the op does want larger rear discs you're more than welcome to my entire setup, discs and brackets, discs will probably need changing in I guess 6 months to a year depending on how many miles and driving style etc.

[Gullzter]

Gary England is the one who does the brackets I believe, last time I spoke to him I'm sure he said he would require a group buy to make it worthwhile though i.e. 5+ orders

[raptor95GTS]

i've got the RX8 discs (front) on the rear, spaced out stock rear caliper. Front is running Supra discs and 996 Porsche calipers. Car doesn't want to swap ends, stops fine, no more sticking front calipers every six months. Run stock pads and doesn't squeal or eat wheels with the dust and yeah stopping power is there. Brake bias pretty much standard by intention and careful caliper choice. It can be done but a very emotive topic.

How did you workout the bias based on the caliper choice?

The 996 caliper uses 2 opposing large pistons and 2 small pistons so the clamping force is greater than the stock caliper with a larger pad area too.

The rear rx8 setup uses the stock caliper on a 20mm larger diameter disc yet 4mm thinner. same clamping force as stock and same pad area.

The Porsche calipers look great and fill the wheel well, shame the branding conflicts with the car IMO.
Not saying the system doesn't work for you but it's not going to be stock bias is it?
Do you have ABS on your car?

You know you're the first person I can remember that's actually questioned BBK kits with some sensible questioning instead of just saying it's wrong and death follows when you change the calipers. I hope my answer below makes sense and more importantly is correct.

First off, my brakes wont stop me quicker than a stock car with stock brakes with stock pads. Tyres have a huge influence in that equation. They will however allow me to resist brake fade longer than stock discs and at the same time use stock caliper pads that dont eat the wheels with the dust. I dont have to worry about the sticking pistons or carriers on the front (still have that option on the rears!) When I did my BBK my front calipers were shot so there was a refurb cost there to consider. My pads dont cost 150quid+ an axle so ongoing costs are less.

brand of caliper isn't a problem for me but I can see how the purist might complain. Appreciate your compliment on the looks, I like it though it needs a damned good clean

The bias change towards the front is less than 2percent from all accounts however I cannot take credit for the caliper choice as it came to me from an American forum member who had done a huge amount of work around this topic, even sourcing a rear opposed piston caliper that had an integral handbrake mechanism

996 caliper is 40mm x 1 and 36mm x 1 piston per caliper side which isn't far away from the 36.5mm x 2 of the stock caliper. The pad area from my understanding doesn't affect the braking force* as friction co-efficient of the material makes the difference
* pad area does however made a difference in the pad depth however since the 996 front pad is tall in comparison to the rear stock mr2 pad it actually reduces the braking torque v the rear as the centre line of the pad is nearer the hub spindle in relation to the rear pad centre line and thus balancing the bias.

The 4mm thinner disc in the rear isn't a problem (25mm wider), just means the rear caliper piston has to move further than a stock disc but that's not an issue once it's seated correctly.

If I'd fitted 315mm lexus discs the bias would have hardly changed from stock but hey ho 2percent in my driving style isn't going to make a difference.

I have ABS and on a dry road with me taking the p1$$ on the brake pedal I can get the ABS kicking in but it takes a heavy foot to do it, you know the kind of foot you have in an OMG moment.

When I hit the brakes, they work well. The harder I push and more often I push, the better the braking gets as everything gets up to temperature. Honestly, it's eye poppingly hard but none of that makes any difference if you run ditchfinder tyres.

Hope this answer helps and feel free to shoot me down, my brakes work and so far the car hasn't tried to swap ends on no matter how ham fisted I've been

[Gullzter]

Cracking response, couldn't agree more

Moral of it I guess, run good tyres and brakes (as well as suspension set up amongst other things) if you want the car to stop to its best ability