flickroll

I started a thread to show what happened to my GTS on the very first drive I took in it. The car has PCCB’s and in the first 40 miles from brand new a rock caused damage to the front left caliper and wheel. If you have not seen the thread, here it is:

https://rennlist.com/forums/991/1037...t-so-good.html

I have talked to the dealer and they are going to elevate the issue to the regional rep about repair or replacement of the caliper, either under warranty or goodwill. The damage to the wheel can be taken care of by my tire and wheel insurance. However, I have read a lot about this problem since it happened and it appears it is a very common issue. Don’t know if it has always existed or if it’s more of a 991 problem. Anyway, fixing the caliper and wheel appears to be a futile effort as it sounds to me like it will only be a matter of time before it happens again. So rather than waiting for the other wheels and calipers to be damaged I started thinking of another alternative. I do not know if this issue is mainly for the front wheels or if it happens on all 4 corners. There is more caliper/wheel clearance on the rears fwiw. So I started looking at other calipers that would have more clearance than oem and one brand the really piques my interest is racingbrake.com. Here is a picture of their design which to me looks a lot better than the porsche caliper for a lot of reasons:



The pads are top loaded for easy pad changes and it appears they are lower profile which would result in greater caliper/wheel clearance. Racingbrake’s website even says the top loaded design will stop the road debris problem. So I’m thinking about swapping out the calipers and wanted opinions from anyone that has installed these calipers. Looking for overall opinions and also specifically has the installation of these stopped the road rock damage issue? Thanks!

Edit: Right before I hit ‘Submit New Thread’ I received an email from racingbrake saying they can’t say for sure how much additional clearance their rotors will add. But the question remains, has anyone installed their calipers only on a 991 and what was your experience? They do have a ZR1 ‘kit’ that adds replacement rotors and a lot more clearance but that is more $$ than I’m prepared to spend at this point in time. Thanks

bkrantz

What about a thin wheel spacer?

flickroll

It’s a circumferential clearance issue so spacers would not help even if I could use them. These are centerlock wheels, can’t use spacers.

LexVan

Flick, don't change out your beautiful, massive, $$$$, PCCB calipers. I hope Porsche makes good on the good-will repair.

Have you researched this much on the GT4 and 991 GT3 Forums? Some damage over there, but it's not rampant.

I think ounce you get the wheel's barrels coated (Optimum Gloss Coat or another high quality nano coating) and start using Armor All Outlast, the issue/risk will be greatly removed. Good luck.

flickroll

Lex before I do anything I’m going to run the car some more and see what happens. It could be that I was just extremely unlucky on my first ride and the problem might not surface again for a long time. If the regional guy says no I’ll ramp it up to PCNA and see what happens. Worst case is I’ll fix it myself using a high heat tolerant filler for the gouge, and yellow VHT caliper paint in my airbrush for a spot repair. But I hope Porsche steps up to the plate with this.

I’m just exploring options at present in case this happens to me a lot. I agree the Porsche PCCB’s are beautiful, and anything else won’t be as nice. Just wish there was a way to get more wheel/caliper clearance. 21” wheels would do that but I don’t think that would look right after giving that option a lot of thought.

MJG911

upsize wheels to 1" larger.

I had the same problem with some brembo brakes on my racecar. I grinded the edges down for additional clearance and refinished them. M3/m4 guys have this problem with the 19" wheels.

flickroll

That is something that is under consideration. Just wonder how 21” would look on the car and how it would affect handling. Not to mention how would ride quality be. But I do have some feelers out to HRE for 21” P101’s in centerlock. I think that would solve the problem if the things I mentioned are not a big issue. I am sure Porsche has a reason for not offering 21” wheels on these cars, but for me the option is worth exploring.

Gordon Shumway

I'd say it is probably just the front wheels. The 911 problem is the PCCB front rotors are 16.14" inside a 20" wheel, which doesn't leave much room for calipers. The rear rotors are 15.35" , which would take a good size rock to get caught back there. Compare that to the standard GTS rotors, which are 13.78" & 12.99". The Cayman & Boxster would not have the same problem with PCCB's, as their rotors are considerably smaller. Pretty sure they are the same size as the standard GTS rotors.

nxfedlt1

No way would I put racing brake calipers on my car....too many horror stories on their products. Do your own research and you'll find lots of failures.

flickroll

And the calipers extend out from there with minimal caliper/wheel clearance. A little more than 1/4” clearance between the outside of the caliper and the wheel barrel. Way too little.

4pipes

Maybe put some 1/4” closed foam weather strips on top of the calipers to repel any stones from entering the gap.

flickroll

That’s a super idea. I had been thinking about some sort of deflector there with a very close gap between the wheel and caliper, and the foam might do the trick. I had considered fabricating an aluminum deflector and attaching it to the caliper with 3M VHB tape, but I like your idea better, and for a temporary trial will try a piece of dense foam weatherstripping and give it a try. Only pitfall I can think of is calipers can get hot and the foam might come unstuck but it’s worth a try, and if foam comes loose it won’t damage anything. Thank you, I love this forum!

4pipes

When you’ve proven the idea, you can use high temperature RTV gasket adhesive to bond the foam. It’s designed to withstand engine temperatures.

flickroll

Thanks for your help 4pipes. If this works, and I see no reason why it won’t, I may migrate to the aluminum deflectors painted to match the calipers. I have some 1/4” aluminum angle out in my hangar and that might be perfect and easy. High temp RTV A great attachment solution.

flickroll

4pipes, I sent off for this from Amazon:



Looks about the perfect size and it has 3M automotive grade adhesive tape so high quality. The 1/2” width will help to keep it from getting knocked off or simply falling off, and it’s 1/4” high which will leave about 1/8” gap between the top of the foam and the wheel. I’ll put it on both front calipers and give it a try for a while. Thanks again for the suggestion.