sportscarclassics

I have a 90 928 gt and I want to upgrade my brakes. What calipers and rotors are used on the GTS or big reds? Are they from a 911 or 993?
Thanks.

MikeN

If the picture of your GT for your post is still up to date it appears you have the stock Design 90 wheels on it. I'm not absolutely sure, but you may have to move up to a bigger 17" wheel in order for the brakes to clear. Just something to consider.

What is your reason for the upgrade? The stock S4/GT brakes are pretty stout as they sit. The GTS brakes tend to offer a little more fade resistance for track use, but I don't think they offer much of an advantage on the street.

Glen McCartney

I just upgraded to big reds on my 1985. I got the calipers and rotors used from a 993 twin turbo. The wheels have to be 17's to fit over the calipers. The spare has to be from GTS to fit also.

sportscarclassics

Thanks,
I like the look of the big reds and I want to change rims to a turbo twist II in 18's.

sweanders

Or you can put one of the rears up front and the spare on the back if you have a flat front tire.

Rich9928p

There is an issue with installing 993 calipers (Big Red or take-offs) on a 928. The calipers are situated differently, so the brake line - bleed hardware needs to be installed "as with the GTS" rather than as with the 993.

If you buy Big Reds, specifically ask the vendor if they have different versions for 928 and 993, if they say they sell only one version, odds are 99% they're set up for 993s.

drnick

part numbers from a previous post for cross drilled discs: 965.351.045.00 and 965.351.046.00 these are from the 3.6 turbo 964 and apparently will fit the 928 with big reds/turbo brakes. i am about to do this to the front of my 86, just waiting for the callipers to be refinished as i bought them 2nd hand from a breaker.

there is a general agreement that the stock S4 brakes are very good really, especialy with a tougher compound pad. however its also agreed that the GTS brakes are better in most respects!

fabric

Not if you have an LSD or PSD.

cobalt

For the most part the fronts on a GTS are the same as the big reds used on the 94 turbo 3.6. The Cast hole rotors are 94 part numbers and the GTS rotors are interchangable with the turbo 3.6. The 94 offered the Big reds painted Black as an option and were called Big Blacks. I see no visible difference between the front brakes on my GTS vs the front Brakes on my turbo 3.6 other than color.

I believe the rear brakes on the GTS are actually 951 parts. Smaller than the rears on my Turbo 3.6 The rear rotor part numbers start with 951 they in turn use a rather large spacer to accomodate the 17 inch alloys and the flaired fenders.

If the 928 is anything like the 94 turbo you can adapt the rears to accomodate the 320mm rotors and larger brakes but you will loose the handbrake in the process.

wds928

I like the Big Yellow's. From the PET program, the GTS calipers are 928 351 423 02 (Left side) and 928 351 424 02 (right side) for 1994 and 1995. My rotors are cross drilled, I believe from the Turbo 3.6 993.

The rear calipers are 928 352 421 02 (Left) and 925 352 422 02 (right).

I'd check out 928 Specialists for their GTS brake upgrade kit.

cobalt

After doing a little research it appears the calipers on the front of the GTS are a 993 part number. 993.351.425.10 & 993.351.426.10 They appear to be the same as the 94 visually but the mounting offset is somewhat different. They do however use the 94 turbo rotors.

The rear rotors are part number 951.352.041.903 but the pads are a 965 part number 965.352.930.4 sio it is possibl ethe rear calipers are from a 964 turbo.

cobalt

Sorry,

To correct myself the big reds used as an upgrade are the 993 part number not the big blacks The GTS part numbers in black are as wds928 stated. Anything pre 93 will need an addaptor kit which I believe includes some bolts.

Does anybody know the rear caliper part number used on the GTS?

Vilhuer

AFAIK '86.5 S US (all '86 S ROW's), S4, CS, SE, GT and GTS use same rear brake design and they first appeared in 928.

sportscarclassics

Thanks guys for the help and advise. I guess I will be shopping again.

Carl

drnick

are the 993 turbo discs the same as 965 3.6? hope so cause ive just ordered some..