Humble,

You brought up valide point about tires.. street vs race slicks.. which has to be factored into the equation.

What about pads.. I know on my street/track car I use to mix front and rear pads at times depending on the track and tire choices I had.. What is everyone using as their respective characteristics will have an impact on lock up also?


Alex

They usually are but what are they, I can't read them off the photo?

The standard 19/19 dual circuit m/c is more than man for the job. However, I have heard that they give long pedal movement with single pot 944 fronts that could be down to the anti-slide spring that gives a twisting action of the piston body. This in turn means that if you have new pad on old discs or new discs with old pads there is a little extra bedding in to do to get the best pad shape i.e. a pair of matching shallow wedges. New pads on new discs should wear together so there ought to be no problem. It sounds as though you have about the right front rear balance assuming the discs are about the same size also. Don't think that because the m/c comes from a Porsche that it is intrinsically better than the VW one. With m/cs it is all about selecting the right size. Bigger m/cs usually mean poorer braking performance.

Pad selection with full disc conversions with porsche calipers and discs will provide very high levels of performance in such a light car (around 2/3 the weight of a high performance Porsche) so the main problem will be to generate heat to get optimum friction. also, the cooling ability of the discs will quickly dissipate the heat that has been generated so it is better to select a quick i.e. low temperature pad. Any of the good quality pad suppliers such as Pagid will be suitable. I will be trying EBC Greenstuff on the front of mine.

Clive

The #'s on the MC are 26 and 20

Clive is right about the pads, on light cars it can be hard to get them up to temp. Until now I've been running PBR metal masters on the race car but it's been an autox/hill climb car. In those events you can't really get heat into them, even with left foot braking. I've still got them on the car but I won't know if they're keepers until the first track event. Performance wise they bite pretty good initially, they're easy to modulate and predictable on release.

[QUOTE=Humble;70404]The #'s on the MC are 26 and 20

QUOTE]

I too would have thought that the numbers refer to the bore but the information I have been able to gleen is that the 930 ran plain bore 20mm pistons. It maybe that my numbers relate to a different (earlier?) version of the model in the same way that the 944 m/c changed to a stepped bore from a plain bore. I presume that the #26 is at the pedal end of the bore?

Clive

[QUOTE=evilC;70407]The 930 Turbo 78-89 is a dual circuit 23,8mm MC (930 355 011 03).
AFAIK it was used with a brake booster as well (1984: 930 355 027 00, >1984: 930 355 027 02)

Actually 20 is by the pedal and 26 on the end. I thought I read somewhere that the 930 had the same 4 pot calipers all around but the piston sizes were different front to rear, the rear calipers being smaller.

Humble, The #20/26 can't be the piston sizes as the larger one would have to be at the pedal end! If the caliper piston sizes were smaller at the rear then it would have been more likely that the m/c would have the same bore size for front and rear circuit since the bias will have been controlled by the caliper sizing. It would be unusual for the manufacturer to have controlled it by both the caliper and the m/c (late 944 excepted). The 23.8mm (15/16") bore size does imply a power assisted pedal as it is quite large for non-servo assistance, which are generally </=19mm

Clive