Need new rotors for S4 calipers

[sjanes]

I have an 87 911 with S4 calipers on the front and I'm using Coleman rotors with VCI hats. With Pagid black pads, the rotors (slotted, not drilled) crack to the point of replacement within 14 track days. I tried a PFC 97 pad, but it cut through the rotor like a lathe. I would have been done in 5-6 days. So now I'm looking for sources for something better that would fit my application. I'm thinking a good Brembo rotor/hat would be nice and last a while.

So, for those of you that use 930 or S4 front capliers on these cars, what are you using for rotors, how may track days do they last, and were do you get them? Cost? Do I go floating?

[jester911]

You need to get with Bill Verberg. He is the Porsche brake guru. He is a member on this board and is a wealth of info and he is always willing to help.

Do a search for info in his name and you will get a ton of info.

[Bill Verburg]

Best i've ever seen in the 304x32 2 piece size is the oem '78 930
they are expensive, and you will need the hats/hardware to go w/ them

Pelican Part #s
right 930-351-048-00-M136
left 930-351-047-00-M136



here

[hmd]

I use ProBraking (I think they are Wilwood) 2 piece rotors with Hawk Blue have lasted more than 12 track days and still going. The replacement outer rotors are also supposed to be inexpensive.

[sjanes]

Originally posted by Bill Verburg
Best i've ever seen in the 304x32 2 piece size is the oem '78 930
they are expensive, and you will need the hats/hardware to go w/ them

Pelican Part #s
right 930-351-048-00-M136
left 930-351-047-00-M136



here

Bill,

you aren't kidding on the expensive part. It will be $1200 + shipping for rotors and hats (assuming VCI floating hats).

How many days are people that use OE rotors get (using what pads)? I'm not a big fan of drilled since they crack (although my slotted Colemans also cracked).

[Bill Verburg]

Jack O's are several years old(last I heard)

Several local guys in PCA GT classes have tried the Wilwood and Colman alternatives but have all gone back to the oems.

[sjanes]

well, considering how much driving Jack seems to do, several years is pretty good. I'm supprised PFC or stoptech doesn't make a 78 930 replacement, or at least one that I've heard of.

[JeremyD]

I've got about 10 track days on Wilwood rotors

Wilwood Rotors HD
12.19" (309,7) 1.25" (31,8) 8 x 7.00" (177,8) .313" 8.41" (213,6) 6.53" (165,9) 12.7 RH 160-3870
12.19" (309,7) 1.25" (31,8) 8 x 7.00" (177,8) .313" 8.41" (213,6) 6.53" (165,9) 12.7 LH 160-3871

Wilwood Directional GT
12.19" (309,7) 1.25" (31,8) 8 x 7.00" (177,8) .313" 8.41" (213,6) 6.53" (165,9) 12.7 RH 160-2526
12.19" (309,7) 1.25" (31,8) 8 x 7.00" (177,8) .313" 8.41" (213,6) 6.53" (165,9) 12.7 LH 160-2527

The HD's are about 100 a piece. The hats I got from probraking

[Steve@Rennsport]

Originally posted by Bill Verburg
[B]Best i've ever seen in the 304x32 2 piece size is the oem '78 930
they are expensive, and you will need the hats/hardware to go w/ them

Bill:

Indeed, thats good stuff but these Zimmermans are rather soft and any race pad will really decrease their lifespan.

FWIW,..our modified non-floating Brembo's have held up exceptionally well as long as one has effective brake cooling. My only caveat is against using Hawk Blues due to how abrasive they are. Considerably less $$$ than the above option, to boot.

Just another choice.

I'd also recommend using 322mm rotors with S4 calipers if possible.

[Bill Verburg]

Steve's got a good point, as long as you have 8x17s, the 2 piece non floating, 993tt 322x32 rotors are useable.

They are very resonably priced and are excellent choices.

You would need a hat which Steve can supply, and also new caliper adaptors that space the caliper 9mm further out from the axle

Alternatively, new calipers w/ the existing caliper adaptor can be purchased.

The calipers that have the proper built in spacer for 322x32mm rotors are the early 964t/964RS versions of the 993/S4 calipers that you now have. They use the same pads and caliper adaptor but have the mounting boss built up the correct 9mm.

part #
left caliper 965.321.423.01
right caliper 965.321.424.01

[Jack Olsen]

I posted this on Rennlist, but I'll repeat it here:

I have the factory 78-79 ones. At $400 a pair, you wouldn't think they're cheap.

But I've been using the same rotors now for over five years.

And this is with at least one track event a month, and three week-long Open Track Challenges, and one full season of wheel to wheel plus a lot of other racing -- and about 10K/year street use. I've used everything from Pagids to Porterfields. The factory rotors have pretty amazing durability, relative to a lot of the aftermarket ones. I bought two sets initially, thinking this would be a regular replacement item. I'm still waiting for my cracks to exceed factory specs, and we're talking over 100 track days so far.

Maybe I need to brake harder?

(Full disclosure: my car is only 2400 pounds.)

[sjanes]

I'm not sure I need such a big rotor though. My car is only 240hp and 2700lbs, so the bigger rotor may be overkill. I do have brake cooling to the front airdamn, and my brakes don't fade.

If I could pay $400 for a pair of front rotors every 2-3 years, I'd be more than happy.

[JeremyD]

That is impressive Jack -

[armandodiaz]

Originally posted by JeremyD
I've got about 10 track days on Wilwood rotors

Wilwood Rotors HD
12.19" (309,7) 1.25" (31,8) 8 x 7.00" (177,8) .313" 8.41" (213,6) 6.53" (165,9) 12.7 RH 160-3870
12.19" (309,7) 1.25" (31,8) 8 x 7.00" (177,8) .313" 8.41" (213,6) 6.53" (165,9) 12.7 LH 160-3871

Wilwood Directional GT
12.19" (309,7) 1.25" (31,8) 8 x 7.00" (177,8) .313" 8.41" (213,6) 6.53" (165,9) 12.7 RH 160-2526
12.19" (309,7) 1.25" (31,8) 8 x 7.00" (177,8) .313" 8.41" (213,6) 6.53" (165,9) 12.7 LH 160-2527

The HD's are about 100 a piece. The hats I got from probraking

Jeremy can you elaborate on your system? Are you running 930 calipers? What about the rear?

[JeremyD]

rear are 993 calipers on 930 rotors with the throats opened up to accomodate the larger rotor.

Fronts are custom hats and caliper adapters from probraking.net

I don't even wear out brake pads anymore

[armandodiaz]

Yes, I'm working with David about an alternative braking solution. I still want to keep the 15" wheels so I'll probably go with 930 rear calipers. But I would like floating rotors all around.