996.1 GT3 Brake Upgrades

[Jmracing66]

Hi all,

Can any one give me an idea of what it costs to replace mk1 calipers with mk2 calipers and discs ?

Cheers.

[keep it lit]

best part of a couple of grand including decent pads & fluid plus fitting.

edited to add you'll get 300-400 back for your four pots & 330 discs if you wish to punt them on.

Edited by keep it lit on Sunday 24th February 22:05

[marky911]

Yep, what Ade said. More for Alcons. Here's the bill for mine from 2007. JZM supplied. No fitting on there.





PS. Lovely car. An identical twin to mine.

[fioran0]

Not directly relevant i know but im not convinced the upgrade is such a slam dunk..
Theres still plenty stopping power with the smaller setup and you get less weight and better balance from that setup than you do with the larger fronts.
On wider wheels with slicks and very hard springs you can start to find a mismatch between brake power and grip but i know plenty of folk who still prefer the 330mm F/R setup with a good race pad and rotor.

Edited by fioran0 on Monday 25th February 01:45

[Jmracing66]

Thanks for all the info, it does seem that most mk1s are now wearing mk2 fronts.

Marky911 - cheers, can't be too many guards clubsports around !

Edited by Jmracing66 on Monday 25th February 18:51

[Slippydiff]

fioran0 said:

Not directly relevant i know but im not convinced the upgrade is such a slam dunk..
Theres still plenty stopping power with the smaller setup and you get less weight and better balance from that setup than you do with the larger fronts.
On wider wheels with slicks and very hard springs you can start to find a mismatch between brake power and grip but i know plenty of folk who still prefer the 330mm F/R setup with a good race pad and rotor.

Edited by fioran0 on Monday 25th February 01:45

Agreed, even the standard set up in tip top condition, large (consumable) wishbone/diagonal arm air ducts AND the Mk2 ducts (both opening up the arch liners, blocking off the exhaust in the undertray and fitting the ducts to the outside of the inner flitches)makes for a setup that I never found wanting on the road.

If the discs are in any way below par (ie corroded inner faces) or the fluid old, they'll wilt under duress.

[jackal]

Do you actually get any more stopping power or is it just better heat dissapation for any given amount of abuse ?

Having gone from a 993 C2 std. brakes to RS calipers/discs front and rear I would say think carefully before adding unsprung weight. It makes a huge difference IME.

[Slippydiff]

The six pot pads are much larger (and pricier) than the four pot items. Both they and the discs have the ability to manage heat far better than than 330mm standard items. However the standard set up suffers from very poor air flow around the front brakes. The Mk2 addressed the perceived weaknesses of the earlier car by using bigger diameter discs with an increased annulus size and larger pad area, in addition the airflow was increased massively on the later car by the modifications I highlighted in my previous post.

I suspect that the standard set up in very rude health with the mods I mentioned above, and the addition of some RS29 pads in the front calipers, braided lines and SRF or similar fluid, would survive ANY amount of hard road use and most track use. You'd possibly want to experiment with different (upgraded) compounds in the rear calipers for track use to balance things up.

I found the original set up a little wooden when cold (moreso after I'd done the ducting mods), but once warmed up, they provided some of the most easily modulated, feelsome, powerful brakes I've experienced on any 911 ever.

[marky911]

Jmracing66 said:

Thanks for all the info, it does seem that most mk1s are now wearing mk2 fronts.

Marky911 - cheers, can't be too many guards clubsports around !

Edited by Jmracing66 on Monday 25th February 18:51

Yep, there aren't many GR Clubbies about JM. My mate was told 3 when he owned my car, but there are at least 4 on here so I'd say 6 or maybe 7. Rare either way.

I can see what the other guys are saying with regard to the unsprung weight etc. If my car didn't have the upgrade already done I certainly wouldn't be rushing to pay £3k for it, but having said that I don't intend to really track my car apart from the odd special occasion maybe.

I was half tempted to offer you a deal on mine actually as I prefer cars to be standard especially as they get rarer, but given the amount the 6 pots cost etc, I'll probably just leave them on and source the MK1 items over time. In fact if I could be so rude, if you get sorted and want £300 for your old stuff, drop me PM. Although you'd probably be better off boxing them up and hanging onto them.

[sportsandclassic]

One of the main benefits on 6 pot MKII GT3 cars is the inserts in the brake caliper pistons which is zircon oxide inserts than insulate the heat from transferring into the brake fluid. This stops a load of overheating problems

Mike

[keep it lit]

marky911 said:

I was half tempted to offer you a deal on mine actually as I prefer cars to be standard especially as they get rarer, but given the amount the 6 pots cost etc, I'll probably just leave them on and source the MK1 items over time. In fact if I could be so rude, if you get sorted and want £300 for your old stuff, drop me PM. Although you'd probably be better off boxing them up and hanging onto them.

mark, I've got a mint front 4pot/330 set up off a genuine 6k miles car....

lmk pal

[gt3nor]

High quality aftermarket 350mm discs are usually lighter than the OEM 330mm discs, so they do not add to the unsprung mass. Actually they reduce the rotating mass.

[Slippydiff]

gt3nor said:

High quality aftermarket 350mm discs are usually lighter than the OEM 330mm discs, so they do not add to the unsprung mass. Actually they reduce the rotating mass.

I'm not saying you're incorrect, but I'm struggling to believe that. My car runs Alcon 362mm discs and six pots. I'd be amazed if that combination was lighter than the four pots and OE discs.

[marky911]

keep it lit said:

mark, I've got a mint front 4pot/330 set up off a genuine 6k miles car....

lmk pal

Yep, dead interested. I've pm'd you. Cheers.

[jackwood]

gt3nor said:

High quality aftermarket 350mm discs are usually lighter than the OEM 330mm discs, so they do not add to the unsprung mass. Actually they reduce the rotating mass.

But once you add in the additional weight of the larger callipers, spacer blocks and pads, how does the total of the unsprung mass work out? Is it still lighter to go with the the larger size set up overall? Is it only the rotating mass that makes a difference or is it just the total unsprung weight that makes the real difference?

[Slippydiff]

jackwood said:

But once you add in the additional weight of the larger callipers, spacer blocks and pads, how does the total of the unsprung mass work out?

My point precisely. The discs have to have a certain mass to allow them to function without cracking or warping. Whilst lightweight discs are available (the WRC teams used to use them) they ideally need warming up to ensure they don't suffer the effects from the thermal loads they're subjected to (check out the videos of the WRC cars of 6-8 years ago) they show the WRC cars with their lightweight discs glowing even in daylight. Not an issue then as brake discs were replaced regularly. Now the regulations don't allow it.

[fioran0]

gt3nor said:

High quality aftermarket 350mm discs are usually lighter than the OEM 330mm discs, so they do not add to the unsprung mass. Actually they reduce the rotating mass.

the discs are only part of the equation. the brake calipers themselves add significant weight.
one can also fit high quality aftermarket 330mm discs too, thus offsetting any weight saving from aftermarket 350mm discs and then some.
that argument is thus illogical. there is no way that like for like, the 350mm setup can weigh less than the 330mm one.

[fioran0]

jackal said:

Do you actually get any more stopping power or is it just better heat dissapation for any given amount of abuse ?

you get a good bit more, the downside is that it gives the car huge front bias which then requires pad splits in order to redress.

[barchetta_boy]

How can you get more stopping power, given that you can lock the front wheels with the standard setup?

[bobsan]

barchetta_boy said:

How can you get more stopping power, given that you can lock the front wheels with the standard setup?

this is the difference between a quality pad and a cheaper brand, all pads can lock a wheel, its how it does it that makes the difference, and the hefty premium.

its all about retardation v's modulation, the ability to offer massive retardation through modulation keeping the wheel rotating and under control whilst still bringing the vehicle to a standstill quicker than a locked wheel.