pa951

I know that they are from a 928 but any other difference? Disc size?

Darwantae951

I thought the discs and pads were slightly bigger?

Chris White

Keep in mind that there are a couple of different black calipers on 928s.
The 928GTS is the same as the 'big red' except the cross over pipe and bleeders have been swapped. The non GTS had the same caliper as the 88 turbo s and 89 turbo. the pads are the same length but not as wide due to smaller rotors.
The 'big red' mounting points are made so that the caliper is about 10mm further out from the hub center - that is why you have to use large rotors with the big red.

If you want brake info here is the place to go!!
http://www.pelicanparts.com/MotorCity/wmv/brakes.htm

Chris White

BTW - I believe that you can add a 10mm spacer to the Turbo S caliper mounts and add the 964 turbo rotors and a set of big red pads to get the same braking as the big reds.

Pauerman

Thank you for this Chris! I knew there was a way of adapting the Turbo S caliper to a 993T rotor, but I wasn't sure.

I just picked up these rotors off of a 951 guy on Facebook for $200!! I passed on the calipers since my Turbo S caliper will work, but if anyone here is interested, the seller is selling them for $800. These are Brembo GT calipers and they are brand new.

333pg333

That's a great price Vic! Wonder what rotors the hats fit though?

Pauerman

This is a LR big brake kit, so hats are meant for 951. The owner decided to go with the Brembo GT calipers as he was iformed that these calipers offered an upgrade over a big red caliper. When I asked him what the difference was he mentioned that may have larger pistons.

ibkevin

I have the 5/33 on a MO30 set at midway point on Pzero 285's, I expected them to contact better, but I'm not impressed. I can shave rubber of the rears just during street travel.

BoostBuggy

The Brembo GT BBK has either 44/38 or 44/40 mm pistons depending on which caliper it is. Technically this kit (upgrade?) will change the brake bias quite a bit based on a couple of things; (1) with the larger pistons you are changing the brake balance to have more of a front bias and being that the new rotor is larger in diameter you are again changing the balance to be more front biased due to the increase in leverage.

What appear to be simple changes in brake hardware can make rather significant changes in the brake bias. Additionally brake bias can be changed by using different compound pads front vs. rear.

Just a couple of thoughts...

Chris White is correct in that other than the position of the xover pipes/bleeder screws the 993 TT Big Reds and the 928 GTS calipers are the same in all other aspects.

Pauerman

So the Brembo GT caliper may work well with a 5/33 proportioning valve if it does in fact have larger diameter pistons.

I was on the fence about picking them up as the seller couldn't confidently explain the difference. I may get back to him and ask what the piston sizes are just to verify the difference.

sm

Chris, please share more details! Does the big red pad need to be shaved down or modified in any way? On a non-M030 944 turbo or 968, is it safe to use the 10 mm spacers in addition to the adapter that allows fitment of the Turbo S calipers?

Thanks!

Chris White

Yes, it will work out fine as long as you are using the 964 turbo or 993 turbo rotors. 'stock' big red pad will work fine.

dmcampbell

Rear lock up not only depends on PV, but also pad compound, tire size, suspension, corner balance, braking technique, etc. The 5/33 works great for me. Mike

mudbuddha

This ^ I have been running this set up for years (933TT front rotors) with great result. Braking, at least for spirited street use, is phenomenal.