GT3luvr

Great forum - looking for some help.

I've been taking repeated damage on the inside of the front wheels due to gravel lodging between wheel & calliper causing a significant and repeatable score / groove. As many of you know the clearance in this area is minimal (perhaps 3 to 4 mm) and doesn't seem to tolerate any form of road debris. My brakes are PCCB and I'm not sure if similar clearances apply to steel brakes.

In about 900 km I've been able to identify at least 4 incidents. Roads are clean and free of debris but from what I've seen it doesn't take much. Easy to see the damage on black wheels ... but those of you with platinum might want to take a closer look. A friends 991 turbo S has the same PCCB brake system but clearance must be better as the wheels aren't taking damage.

I haven't found any comments on this forum but did find reports of the same issue with BMW owners :

http://f80.bimmerpost.com/forums/sho....php?t=1107233

While it's painful worrying about wheel damage every time I take the car out, an even more serious concern is that this issue could cause damage to the calliper and a stress point on the inside of the rim as the groove becomes deeper.

Comments appreciated.

ipse dixit

https://rennlist.com/forums/991-gt3-...ed-remedy.html

mwar99

I can't imagine it would do enough damage to be an issue. For the iron brakes there is more clearance. On my S6 I have almost no clearance and there are a lot of scrapes. I just chalk it up to something that is going to happen and there is nothing I can do.

thxbuff2001

Battle damages. Gives more character to the Car.

GT3luvr

From the Racing Brake web site, looks like the stock front steel rotors / calipers have 30mm (1-3/16" inch) more clearance (380mm vs 410mm).

I've emailed them to ask if they can offer a solution - perhaps a different caliper design or a deflector (presumably a deformable piece so as to avoid damage) that could be clamped to the leading edge of the caliper.

Other solution is aftermarket wheels or the turbo wheels which might provide additional clearance.

GT3luvr

Looking at the Racing Brake web site, I note that the factory ceramic fronts have 30mm (1-3/16") less clearance than the steel brakes 410 vs 380 mm).

I've also emailed racing brake to see if they can offer a solution. perhaps a different caliper or a deformable deflector that could be installed on the leading edge of the caliper.

An aftermarket (or perhaps the Porsche turbo wheel) might also solve the problem.

mwar99

I would think that the only way to get more clearance would be to go with a larger diameter wheel.

ZZinger

Same thing happened to my titanium colored stock wheels. I have PCCB also. It happened in my neighborhood when I was making a turn. The area had some light gravel and a small gravel piece got lodged between the wheel and made a awful sound. It scratched the area all the way around the wheel, I was pissed they got damaged. No structural issue but it looked bad.

I since sold the wheels and my black wheels have no marks yet...

GT3luvr

So here's a my idea for a cheap fix using a flexible bristled deflector clamped to the leading edge of the caliper. Same would be set to clear the wheel by approx 2-3 mm.

Let me know what you think.

note - this mockup uses a photo of a 997 GT3 as I couldn't immediately find a 991 picture but the idea is the same.

bronson7

How are you attaching it? I've had one instance on my front wheel. Stone fell out before the wheel went all the way around.

SmokinGTS

The deflector/sweeper needs to be on the Bottom of the caliper, flexible and extreme heat resistant.

2016RS

interesting

GT3luvr

Still working on engineering a solution. Also waiting for more comments from racing Brake.

As silly as it sounds, I believe it might be possible to attach a flexible sweep to the protective brake tube block but this will need more study as the deflector must be designed to fail well in advance of causing any stress on the tube or caliper. While this is not as good a solution as wheel replacement, it might offer an opportunity to at least reduce damage events at significantly lower cost. For those with an RS, wheel options are even more limited, hence additional impetus to seek a solution.

Interested in hearing from people on this as I don't believe it to be a trivial or cosmetic issue. Additional stress associated with stones pushing against the caliper are not insignificant and I am unsure how much design focus Porsche or other manufacturers place on this item. I've experienced what appears to be 4-5 incidents in less than 900km and that seems significant. Either way it would be nice to avoid where possible.

mwar99

I would expect that everything is engineered strong enough to handle the issue. I would expect it to be a cosmetic issue only. I have had no issues in three years with the S6 other than it being cosmetic.

FLT6SPD

I would use flat spring steel about ten thousandths thick at the top. Taller towards the front of the caliper, lower towards the inside to deflect toward the inner barrel.

How is the brake duct designed on the 991? Is it possible to debri is coming through the duct through the center of the rotor, through the veins? Or is air forced directly on the rotor?

Either way you could also explore screening the inlet duct.