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Ginetta G40 Wheels, Tyres & Brakes (Description)

The GRDC and G40 Cup car uses 12-spoke 7.5 x 17" wheels manufactured by Rimstock / Team Dynamics for Ginetta but similar to the Pro Race 1.2. For the GRDC race series, the regulation tyres are Michelin Pilot Sport 3. For GRDC+ / G40 Cup, the regulation tyres are Avon ZZR (and Michelin PS3 for wets).

  • Rim size: 17" x 7.5"
  • Offset: approx. 33 mm positive
  • PCD: 5 x 110
  • Wheel bolts: M12, head 17 mm, thread length 30 mm
  • Centre caps: 54 mm inside / 60 mm outside
  • Colour: Anthracite grey
  • Tyres Michelin PS3: 205/40 17 - permitted in list 1a MSA rule book
  • Tyres Avon ZZR: 215/40 17 - compound AT64 - permitted in list 1c in MSA rule book and list 1b if marked with 15156 & 15157 (normally for OEM fitments), see below for more on this.

The Michelin tyres last at least one season of track days and racing, after which they are probably reaching the limit of heat cycles. A Porsche 911 997, for example, at 1600 kilos and 350 BHP, will probably use a £900 set of tyres in three track days.

The Avons are road-legal semi-slicks and much grippier on the circuit, if it's dry, and not bad in the wet. These tyres have the (E) marking, meaning they are road legal in the EU. They also come in different compounds and construction. For racing in G40 Cup, you will need to check if the tyre should belong to MSA list 1b (ZZR tyres marked with 15156 & 15157) or list 1c (all other ZZR tyres). As far as I understand, G40 Cup uses ZZR tyres from list 1c.

Most UK race tracks are clockwise, and the passenger-side Avons tend to wear more quickly than driver-side. You cannot switch wheels from passenger to driver side because the tyres have a rotate direction, only resolved by turning the tyre on the rim or having two spare wheels and tyres. You may want to buy six rims and tyres when converting from GRDC to G40 Cup (where the two extra rims / tyres are configured for the left side of the car).

Brakes

Brake discs / rotors are vented 279.8 x 25 mm, the same front and rear, manufactured by Borg & Beck (BBD4074), with minimum thickness rating of 22 mm. This part is sourced from Vauxhall / Opel Astra and, presumably could be replaced with grooved discs such as MTEC925 or Brembo 09.7629.11. For Ginetta racing, however, grooved discs are not permitted and pads tend to glaze quite quickly under track conditions. For serious racing, pads would probably need replacing every race when the regulation discs are used.

Brake pads are PFC 77x51mm (part no. 7705.11.14.54) carbon metallic, and the same front and rear.

Front brake calipers are four pot, rear brake calipers are two pot, both manufactured by Hi Spec Motorsport of Dartford exclusively for Ginetta.  I have had some information from Ivano Cimaglia, G40R owner in Italy that AP5000+ calipers will also fit. For more information, see Ginetta G40 Parts (Reference).

The handbrake works on the rear discs with a separate, cable-operated caliper.

The recommended brake fluid is Sunoco R600+. Rear brake bleed screws (8 mm head) tend to seize up, so be aware of over-tightening, and check regularly. There are two bleed screws on each caliper; inner and outer. The front brakes get much more use than the rear, and I find that the front fluid needs changing every track day, ideally, whereas the rear fluid looks in reasonable condition after many track days (i.e. front fluid is black and rear fluid is clear).

There is no anti-lock braking system (ABS) on the G40 (or on most Ginetta race cars).

Ginetta G40 brake rotor

See also