992 C4S- underbraked?

[Deep]

I eventually got around to test driving the C4S. It was equipped with sports PASM, RAS and PDCC. On the whole it drives really well, changes direction nimbly, steering has a nice weight about it and the whole car feels planted on the road.

And for once (imho) the vanilla 911 has enough poke to make it feel properly fast. The thing that shocked me was that the brakes didn't seem to match up to the other abilities of the car. I'd say the lack of stopping power was hindering how fast I was confident to drive.

I have to qualify this by saying that I've got used to the PCCB brakes in my TTS. I can stop the TTS from any speed with complete confidence, the stopping power is brutal.

However (due to my ignorance) I always thought that PCCB brakes didn't actually help the car stop quicker but were just less likely to fade on sustained heavy use.

I was considering ordering the C4S to replace the TTS and then perhaps trading up to the new TTS in a year or two if funds allowed. However if I have to spend £6k on PCCBs as well the haircut I'll take will just be too much.

Did anybody else find the brakes a bit lacking for such an otherwise sorted car?

[Cheib]

If you were driving fast enough to need the full braking of a Porsche I’d say you’re on the limit of what’s feasible on a road to drive safely. Porsche’s braking benchmark is a car has to stop in half the time it takes to accelerate....so will be less than two seconds to stop from 60mph.

[Kawasicki]

I'm guessing here, but are you sure you are not confusing braking effort with braking performance?

[Twinfan]

Like for like, as on GT models for example, PCCBs will potentially have better fade resistance than steels and will be a bit lighter. However, PCCBs on vanilla models are generally larger than steels and therefore have increased stopping power but the weight difference becomes negligible.

EDIT: The 992 C4S has 350mm front and rear steel brakes, PCCBs are 410mm front and 390mm rear (same as your current 991 Turbo S).

Edited by Twinfan on Thursday 2nd May 14:07

[anonymous-user]

Porsches are generally not massively over servoed like other cars, so the braking performance is there but involves more use of the foot.

Initially it'll feel wooden, but you'll rapidly get used to it and feel the braking effort is far easier to modulate. Not to be confused with outright lack of stopping power.

[Deep]

bgunn said:

Porsches are generally not massively over servoed like other cars, so the braking performance is there but involves more use of the foot.

Initially it'll feel wooden, but you'll rapidly get used to it and feel the braking effort is far easier to modulate. Not to be confused with outright lack of stopping power.

Thanks. I did mention to the SE that the brakes felt disappointing and he just said that it was because the PCCBs in my TTS were better. So you think I just needed to apply more pressure with my foot to get them to work at their best?

Cheers

[IanJ9375]

Deep said:

Thanks. I did mention to the SE that the brakes felt disappointing and he just said that it was because the PCCBs in my TTS were better. So you think I just needed to apply more pressure with my foot to get them to work at their best?

Cheers

Try braking with your left foot, that should do it!

[IREvans]

Deep said:

I eventually got around to test driving the C4S. It was equipped with sports PASM, RAS and PDCC. On the whole it drives really well, changes direction nimbly, steering has a nice weight about it and the whole car feels planted on the road.

And for once (imho) the vanilla 911 has enough poke to make it feel properly fast. The thing that shocked me was that the brakes didn't seem to match up to the other abilities of the car. I'd say the lack of stopping power was hindering how fast I was confident to drive.

I have to qualify this by saying that I've got used to the PCCB brakes in my TTS. I can stop the TTS from any speed with complete confidence, the stopping power is brutal.

However (due to my ignorance) I always thought that PCCB brakes didn't actually help the car stop quicker but were just less likely to fade on sustained heavy use.

I was considering ordering the C4S to replace the TTS and then perhaps trading up to the new TTS in a year or two if funds allowed. However if I have to spend £6k on PCCBs as well the haircut I'll take will just be too much.

Did anybody else find the brakes a bit lacking for such an otherwise sorted car?

I'm 500 miles into a 992C2S, and find the braking performance great. If I was being slightly critical, it's a little over servoed at light pedal applications (compared to 991.2), but at medium to high pedal pressure, the feel is great. In the wet, you can modulate the pressure right up to the point at which the ABS intervenes.

You are correct, PCCB doesn't help stop the car any quicker, the braking system is just more resistant to fade under heavy use.

I actually prefer the feel of the PCCB brakes - the feel under the initial application is nicer.

[MeisterH]

IREvans said:

I'm 500 miles into a 992C2S, and find the braking performance great. If I was being slightly critical, it's a little over servoed at light pedal applications (compared to 991.2), but at medium to high pedal pressure, the feel is great. In the wet, you can modulate the pressure right up to the point at which the ABS intervenes.

You are correct, PCCB doesn't help stop the car any quicker, the braking system is just more resistant to fade under heavy use.

I actually prefer the feel of the PCCB brakes - the feel under the initial application is nicer.

Can Echo the above, 800 miles the braking feel on 992C4S is awesome, as usual, slight over servo but very pleased. Ironically back to back the other day with my 991.2 GT3RS with PCCB's down b road heavy braking into hairpins could not tell them apart, id go a far to say the new setup on 992 feels like a PCCB on initial bite.

[IREvans]

MeisterH said:

Can Echo the above, 800 miles the braking feel on 992C4S is awesome, as usual, slight over servo but very pleased. Ironically back to back the other day with my 991.2 GT3RS with PCCB's down b road heavy braking into hairpins could not tell them apart, id go a far to say the new setup on 992 feels like a PCCB on initial bite.

Glad we concur....Seems we are both comparing a 991.2 GT3 with PCCB and a mechanical vacuum operated brake servo, with the 992 with its new electrically operated brake servo.

It's therefore fair to assume the rather over servoed initial bite is down to mapping of the electric motor and control system...? I predict the pedal feel in GTS and GT3 will be different...

[Deep]

MeisterH said:

Can Echo the above, 800 miles the braking feel on 992C4S is awesome, as usual, slight over servo but very pleased. Ironically back to back the other day with my 991.2 GT3RS with PCCB's down b road heavy braking into hairpins could not tell them apart, id go a far to say the new setup on 992 feels like a PCCB on initial bite.

Thanks. I find that quite confusing though. Your GT3 RS has about the same power as my TTS and is lighter and I assume the PCCBs in the two cars are the same. But to me the brakes in the 992 didn't feel like they had anything like the stopping power of my PCCBs.

Do the steels require a lot more pedal pressure applied? I did apply more than I would usually with the PCCBs.

Trying to figure out why my experience is so different to you guys....

Thanks

[Blue62]

Maybe the pads on the demo hadn't been bedded in properly? Seems strange that it lacked stopping power, for me it's one of the aspects of 911 driving that I love, the brakes are always bang on IMO, feel, bite and sheer power are hard to beat.

[JulierPass]

I've done just over 1000 miles now in my C2s. At 800 miles I did an oil and filter change and changed the brake fluid for Motul RBF 600. Makes a big difference to pedal feel. It doesn't change the retardation, bias or the fact that you are trying to stop a 1600 odd kilo car (with fuel and driver), but it gives more confidence under braking as it firms the pedal up nicely.

[IREvans]

JulierPass said:

I've done just over 1000 miles now in my C2s. At 800 miles I did an oil and filter change and changed the brake fluid for Motul RBF 600. Makes a big difference to pedal feel. It doesn't change the retardation, bias or the fact that you are trying to stop a 1600 odd kilo car (with fuel and driver), but it gives more confidence under braking as it firms the pedal up nicely.

Are you saying you've changed nothing apart from swap one synthetic brake fluid for another type, and you can observe an appreciable difference in pedal feel in normal road driving..? Remembering that on a 992, the brake servo is electrically controlled with a fast acting high power pump which generates most of the braking force, you must have the world's most sensitive and highly calibrated toes to notice any difference....

I have tried almost every combination of brake pads, brake discs and brake fluid in many years of rallying, and on really hot long stages like in Corsica, we'd run Brembo HTC 64T, the best brake fluid there is, and there is absolutely no difference in pedal feel whatsoever - you just get a little more resistance to fade at the end of the stage, when the discs are probably glowing red hot, and the heat soak has got into the whole system.....

[anonymous-user]

You need to push the pedal harder and build up the leg muscles, Audi brakes are over-assisted beyond belief.

[JulierPass]

IREvans said:

Are you saying you've changed nothing apart from swap one synthetic brake fluid for another type, and you can observe an appreciable difference in pedal feel in normal road driving..? Remembering that on a 992, the brake servo is electrically controlled with a fast acting high power pump which generates most of the braking force, you must have the world's most sensitive and highly calibrated toes to notice any difference....

I have tried almost every combination of brake pads, brake discs and brake fluid in many years of rallying, and on really hot long stages like in Corsica, we'd run Brembo HTC 64T, the best brake fluid there is, and there is absolutely no difference in pedal feel whatsoever - you just get a little more resistance to fade at the end of the stage, when the discs are probably glowing red hot, and the heat soak has got into the whole system.....

Yes. The pedal is definitely firmer.

[Deep]

Blue62 said:

Maybe the pads on the demo hadn't been bedded in properly? Seems strange that it lacked stopping power, for me it's one of the aspects of 911 driving that I love, the brakes are always bang on IMO, feel, bite and sheer power are hard to beat.

They've had the car for a number of weeks now so it would be unlikely that the pads weren't bedded in.
But you're right, 911s are known for their braking prowess but personally I don't have a benchmark as the only two 911s I've owned had PCCBs.
Thanks

[Deep]

gottans said:

You need to push the pedal harder and build up the leg muscles, Audi brakes are over-assisted beyond belief.

If that's the case then that's not a problem, I can certainly do that and it would be preferable to spending £6k on PCCB!

[Taffy66]

Deep said:

They've had the car for a number of weeks now so it would be unlikely that the pads weren't bedded in.
But you're right, 911s are known for their braking prowess but personally I don't have a benchmark as the only two 911s I've owned had PCCBs.
Thanks

I've owned a mix of either PCCB or Steel braked 911s over the years..I slightly prefer the initial pedal response of the PCCBs for brushing off some speed when going fast..
I also drove both a 991.2GT3 Steel braked and one with PCCBs back to back at the PEC..When jumping into the Steel braked car straight after driving the PCCB car the brakes initially feel less powerful..However once you acclimatise and press the Steel braked pedal harder especially in the initial phase i don't see much difference in overall stopping power if at all.
The only benefit i find with PCCBs is when driving over badly pitted surfaces when the unsprung weight savings improves the ride..

[anonymous-user]

Deep said:

gottans said:

You need to push the pedal harder and build up the leg muscles, Audi brakes are over-assisted beyond belief.

If that's the case then that's not a problem, I can certainly do that and it would be preferable to spending £6k on PCCB!

I have a 997.2 and an S4, the 911 brakes need more effort than the S4 but perform much better, the Porsche as a car demands more from the driver.