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Visitors since March 2003. Page update v8.73
Please visit www.highgatehouse.co.uk to see our range of Vehicle, Circuit & Track decals and a lot more ! NEW! We now have available Coffee Mugs printed with your car pictures from our events pages. See SHOP for Details!
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Brakes Porsche equipped the 944 with 4 wheel disc brakes, ventilated all round, with the handbrake operating conventional brake shoes within a drum that is part of the rear disc. 944 S2 BRAKE SPECIFICATIONS STANDARD FRONT BRAKES: The standard front brakes on the 944 S2 are taken directly from the '87 and on standard 944 Turbo. They use Brembo 4 pot calipers with 36mm and 40mm piston sizes. The brake pad width is 98 mm. The front rotors used with these standard calipers have a diameter of 298 mm (11.73 in) and a thickness of 28 mm (1.10 in). M030 OPTION FRONT BRAKES: A 944 S2 equipped with the very rare M030 Sports Suspension option uses the same size front brakes as those used on the 1988 944 Turbo S or 1989 944 Turbo. These larger Brembo calipers first appeared on the 928 S4 so are routinely referred to as the "S4 brakes." The piston sizes are 36 and 44 mm and the corresponding brake pad width is a very substantial 132 mm. The front rotors used with these "S4" calipers have a diameter of 304 mm (11.97 in) and a thickness of 32 mm (1.26 in). M030 cars use different steering knuckles and hubs. Different knuckles are required because the S4 caliper attaches using a radial mount as opposed to the axial mount for the standard caliper. Different hubs are used to accommodate the 4 mm increased thickness of the M030 rotor. REAR BRAKES: The rear brakes on the 944 S2 also came from the 944 Turbo. The
piston sizes used in these 4-piston Brembo calipers are 28 and 30 mm in
diameter. The rear brake pads are exactly the same size as the standard front
"930" pads. The rear rotors have a diameter of 299 mm (11.77 in) and a thickness
of 24 mm (0.94 in). -------------------------------------------------------------------------------- 928 GTS BIG BRAKE UPGRADE
When it comes to brakes, bigger is generally better :-) Fortunately, 944 Turbo and 944 S2 owners need only search as far as the factory parts bin for something that's even larger than the M030 S4 brakes. Note: this brake upgrade requires the use of 17" wheels or special modular 16" wheels to clear the larger calipers. Non M030 cars also require caliper mounting adapters to convert from axial mount calipers to radial mount calipers. I purchased mine from Broadfoot Racing. 1986 944 Turbo cars require modifications or a specially engineered adapter kit because of their different offset requirements. BIG CALIPERS The famous Porsche "BIG RED" Brembo calipers from the late model 911 C2 Turbo or 993 Twin Turbo work well on late model 944's. These are again 4 pot calipers with piston sizes of 36mm and 44mm . The pad width is 132mm, but depth is greater than on the S4 calipers due to the bigger disc size used. Big red calipers were originally made to mount in the leading position (in front of the axle). They must be rotated around for use in the trailing position on the 944. Mounting the calipers in this location has two minor problems. Firstly the location of the bleeder fittings and cross-over tube must be swapped (the bleed nipple should be uppermost, the crossover tube lower down). Secondly, the brake pad retention spring hinge is at the top instead of at the bottom of the pad area. An alternative is to use BIG BLACK calipers from the 928 GTS. These are physically the same as the big red's, except that they are designed to be used in the trailing position, so the fittings are already in the correct places. BIG DISCS Three factory front disc types are available for big red / big black calipers. All are 322mm (12.68") diameter and 32mm (1.26") thick. a) 928 GTS.1 piece. Solid surface. b) 911 C2 3.6 Turbo.1 piece. Cast-in ventilation holes. c) 993 Twin Turbo. 2 piece. Separate disc and mounting hat. Cast-in ventilation holes. The Twin turbo (c) types have 5 mm less offset, so custom alloy spacers (or
hats) are required to provide correct spacing. There is a weight advantage of
approximately 4 Lbs over the larger solid one piece items. DUST SHIELDS / BACKPLATES If you fit larger front discs / calipers, you will also have to remove the backplates. Although these can just be discarded, it is better to modify them by cutting them down so that they can protect the ABS sensors. BRAKE BIAS This is a safety feature designed to prevent premature rear brake lockup. A 5/18 brake bias valve is used on the 944 Turbo. The '18' designates the pressure in bars where the slope of the pressure curve changes. Thus, when the pressure in the rear brake line reaches 18 bar, the slope of the pressure curve flattens a bit and any further increase in pedal pressure will result in less increase in rear brake line pressure. Unfortunately, it also limits the effectiveness of the rear brake circuit. I replaced my stock bias valve with a 5/33 and this works well with the larger front brakes. Two additional brake bias valves are available from Porsche: 45 and 55 bar (see parts list below). I would be extra cautious about using the 45 or 55 bar valve on a street car, especially one not equipped with ABS.
contact: rick@cannell.co.uk |
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