Good morning everyone, I just finished a weekend of racing at Thunderhill with PRC. The air temperature nudged close to 100. I had my PRC GTS/PCA spec 911 car built by a very well respected local company. The car uses 964 front calipers and Carrera rear calipers clamping down on stock Carrera rotors. I use Hawk Blue pads front and rear and ATE brake fluid. The front bumper is from Getty Design and the brakes have the standard brake cooling modifications. PRC runs 20 minute practice and qualifying sessions and a 30 minute race. I experienced no brake fade during the weekend. I had the car out the previous month at Laguna Seca, runing 4-30 minute sessions on a rare hot day with track temps over 100 and experienced no brake fade issues. This set up works. I can't argue the fine points with you folks. I just drive the darn thing.

The spec 911 racers were running in a tight bunch with most of us within a second of 2:04.xx. A very good driver with good track conditions can pull off 2:02's. The tires are the limit for these cars, not their brakes.

The car weighs 2350 lbs with driver and gas. The transmission has a Guard LSD. We run RA-1's on 16 inch wheels, 225/50 and 245/45.

I wonder why we do not see Wilwood Superlite Calipers on our cars. A brand new caliper is about $160, comes in many sizes, and only weighs about 4 lbs?

Eric,

Is there any brake limits on a Spec car?

Also, can you say how they fit that caliper to your car? Did they redril the holes or machine off the mounts and make an adapter?

Thanks!

From Appendix A of the spec 911 rules:

"Any brake caliper, pad and rotor combination are legal as long as they fit inside the
required wheel size and the rotors are made of steel."

I used to run 930 calipers and custom rotors. The set up was on the car when it had turbo flares and 18 inch three piece wheels running Hooser R6 or Hankook Z214 tires. It was very difficult to modulate the brakes with the brake booster connected. We disconnected the brake booster and I immediately was able to modulate the brakes better. We wanted to remove as much unsprung weight as possible so we switched to the current system. I need to apply a firmer pedal pressure, but it is still very easy to modulate the brakes on the track. I've experienced no brake fade during 30 minute sprint races and stop better than most of my competition. You basically need just enough brake to slow your car down and not a bit more. There will be no one right answer for everyone.

I don't see many Wilwood calipers on P-cars. There's more to caliper choice than weight though.

I have Wilwoods on my 914/6... the older Superlites are flexible.. They apparently stiffened up the new ones

There was a period of time years ago where you saw Wilwoods on maany of our track cars....I think when Big Blacks and Big Reds etcs became easily available the need to adapt the Wilwoods was reduced..

Bolt on a set of Big Reds that fit, or make a set of Wilwoods fits....


Having said all that Wilwood makes some awesome calipers that would work.. The Superlites are old tech

Good stuff guys, thx.

Steve,

I meant to thank you for the help. I took you commeant out of context bit after reading through this post a second time I see you Bill and Spuggy made a point about brake balance that I should not let slip by.

I do have a LSD.

I also like that the C2's have 30% more pad area so they should last longer. KTL notes lower cost of 930 pads which could be a plus.

Still learning. Thx all.

Thx

Jeremy,

My VCI brakes are from Chris Streit. He and I exchanged brake systems because his full-on race car benefits from the 993 setup much more than I did. You are correct that the wheel bearing/spindle spacer effectively reduces the offset of your wheels. For instance, your 16x8 951 Fuchs with a +23mm offset become a +18mm offset and fender clearance is definitely an issue without a lot of neg. camber and rolled/shaved fender lips. I am lucky that I have a set of BBS RS 16x8 front wheels with a +28mm offset. So with my 5mm spindle spacers, that makes my wheels effectively a +23mm offset, just like the Fuchs, and I don't have any fender clearance problems.

Joe,

We do not use any blockoff plate on the Wilwood rotor and use the same hat as you show. That's not to say it wouldn't be worthwhile to do it for reasons you mention- avoiding loss of cooling air thru the gaps instead of thru the rotor vanes. Chris' brakes get seriously hot on his race car and he goes thru a set of rotors maybe every two seasons?. He probably could get much more life out of them by improving his cooling. He has the AJ under-the-A-arm funnels like you mention. On his race car, I think he'd be better served by pulling air from the front bumper. But doing that would steal some of his downforce. Still, I think it'd be better for brake cooling because I suspect he's not scooping much air with the AJ funnels due to a big front bumper splitter he custom made from scratch on his 965 bumper.

These 993/Wilwood setups have so much mass (but not as heavy as many like to argue they should be penalizing you in unsprung weight) that the cooling is not as imperative as it is for the factory 24mm rotors. I only used the 993 scoops for my 993 brakes and never had concerns with heat. Still, the cooling is worthwhile because it only serves to extend the life of your consumables. The cost of providing cooling pays for itself right away.

Eric,

That's good practical feedback about how your setup(s) have performed. I'm just guessing here based on my track experience, but I think your setup proves that it works well due to the nature of your car- substantially lightened SC running with capable track tires, suitable brake cooling and a driver with some ability. I think the Brembos on the 24mm rotors are bigger concern when they're thrown on a relatively stock car. Another thing to consider is that the Hawk Blues are a very fade resistant pad. For some reason nobody ever has problems with these pads, besides them eating rotors at a very fast rate.

Agreed there's no definite answer for everyone. I too had a bigger and better setup on my car (993 caliper/Wilwood front, 993 caliper/930 rotor rear) and felt it was a bit much. I'm very happy with the smaller C2 brake setup devised by VCI, but still think there's some fine tuning that could be done with them by finding a better rotor for the rear. I'm trying to acquire some junk '86 951 or 928 S4 rear rotors (they're the same rotor) to see what kind of fit they provide.

With respect to Wilwood stuff, I don't have much experience with it other than the HD rotors which are a good quality rotor from my experiences over the last 3 years or so. There's others here on the forum that have used the Wilwoods with mixed results like Tim said. Do a search for "Wilwood" and jpahemi username and you'll see some discussion on the different setups people have tried. Seems like the newer forged Superlites would be a nice option and these calipers are actually fitted with axial mounts that fit our 911s- 3.5 in. bolt spacing. They may be old tech, but so are these Brembo C2/951 calipers! :D

Hi, I have a full set ( front and rear) of 996 calipers I’d like to fit on my 79’ RUF replica using original RUF speed line wheels. I already have the adapters but don’t know what discs to use.

Thanks for your help 😉

http://forums.pelicanparts.com/uploa...1571240930.jpg

1) Start a new thread for new questions. This thread is 9 years old, and your question is not in line with original direction.

2) Search. There's more than one way to do it - and several more recent threads specifically on using 996 brakes, which answer your exact question. If the site search function isn't working out for you, use Google - optionally with the spec "site:=forums.pelicanparts.com" to provide only answers from PP.

The Instant-G approach uses modified factory (non-911) hubs and provides kits (including all fasteners of the correct length/hardness) which are not expensive. These are intended for use with stock 996 rotors, front/rear. Expect to spend time fitting (in the original sense of the word) the rear adapters.

I used Bolo rotors (OEM for MB, BMW rotors). Set of 4, drop-shipped (in Sachs packaging - think they must be a subsidiary), were ridiculously cheap. Still have the original rotors/pads; they're barely stressed at all - getting them hot enough to bed in/gas off new pads takes a visit to the track...

996TT certainly won't fit up front behind Ruf Classics without spacers. Regular 996/Boxster S fit like they were made for it, with ~4.5mm clearance on the diameter of the wheel barrel, and behind the spokes. The modified hubs seem to fit slightly more inboard than stock, perhaps 8-10mm (my fenders already rolled, but I have more clearance now with 225/45/17).

http://forums.pelicanparts.com/uploa...1571242318.jpg

You will probably need to go twin M/C in order to get enough rear bias for the most effective braking.