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Description: Ginetta G40 Wheels, Tyres & Brakes

Wheels

The GRDC and G40 Cup car (up to 2018) use 12-spoke 7.5 x 17" wheels manufactured by Rimstock / Team Dynamics exclusively 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 (to 2018), 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
  • Team Dynamics colour: Anthracite grey

For 2019, G40 Cup is adopting the 15" wheel and Michelin P2A race tyres.

Tyres

Michelin Pilot Sport 3 for 17" wheel

  • Michelin PS3: 205/40-17 (inflated diameter 588 mm) - permitted in list 1a MSA rule book

The Michelin tyres last at least one season of track days and racing, after which they are probably reaching the limit, even if hey have tread left. The car weighs about 1050 KG with driver and fuel.

Avon ZZR for 17" wheel

  • Avon ZZR: 215/40-17 (inflated diameter 590 mm) - compound AT64 - permitted in list 1c in MSA rule book and list 1b if marked with 15156 & 15157

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.

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.

Alternatives for 17" wheel

I haven't tried these but I'm told the following are used:

  • Nankang AR1 215/40-17

For racing wet and slick tyres, the following are the closest fit but may be too big on inflated diameter, so would need confirming for the 7.5" rim (and comparing the inflated diameter to the Avons at 590 mm):

  • Michelin Pilot Sport GT Rain P2G 20/61-17 (inflated diameter 604 mm on 8" rim)
  • Michelin Pilot Sport GT Slick S8L (Medium) 20/61-17 (inflated diameter 604 mm on 8" rim)
  • Michelin Pilot Sport GT Slick S9M (Hard) 20/61-17 (inflated diameter 606 mm on 8" rim)

Michelin P2A for 15" wheel

  • Dry: Michelin Slick (Hard) 18/58-15 S9AL (inflated diameter 588 mm)
  • Wet: Michelin Rain 18/58-15 P2AL (inflated diameter 588 mm)

Michelin P2 Race Slicks Ginetta G40 Cup Tyres

Michelin P2 Race Wets Ginetta G40 Cup Tyres

Brakes

The G40 uses a dual-circuit brake system with separate master cylinders for front and rear brakes as part of the pedal assembly. There is no anti-lock braking system (ABS).

You can adjust brake balance with the adjustment bar on the pedal assembly. From factory setting, we adjusted approximately two turns to rear bias due to rear waver on corner entry.

Discs / Rotors

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, grooved discs are not permitted and pads tend to glaze quite quickly under track conditions. Pads may get replaced every race weekend (but see my notes below on brake cooling).

Pads

Ginetta brake pads are PFC 77 x 51 mm Carbon Metallic (Ginetta part no. 7705.11.14.54), and the same front and rear.

For non-Ginetta racing I've been told that alternative brake pads will fit, but I've never tried them. The types mentioned are as follows:

  • Carbon Lorraine CL6 used with MTEC grooved discs (reported as good for sprints). See here for a diagram of the CL6 pad shapes. I'm not sure which model number matches the Ginetta size, if any, but you can contact CL Braking (Birmingham, UK) and quote the PFC pad dimensions given on this page.
  • Ferodo DS3000 used with MTEC hooked discs (but reported as not fully spreading across the disc face, resulting in warping). Ferodo DS pads are specified here, and are not suitable for road use. Ferodo do specify a specific pad (front FCP399, rear FCP408) for the Ginetta G40 (see the PDF catalogue from the link above, page 1100), so the report of the pad not fitting the disc would need checking.

Calipers

Front brake calipers are four pot, rear brake calipers are two pot, both manufactured by Hi Spec Motorsport of Dartford exclusively for Ginetta.

For alternatives, AP5000+ calipers may also fit. For more information, see Ginetta G40 Parts (Reference).

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

Brake fluid

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 fluid needs bleeding every track day. At the very least, bleed the front calipers.

Ginetta G40 brake rotor

Brake Cooling

Due to issues with brake pads glazing, we decided to add some cooling ducts onto the brake calipers. These would have to be blocked off for racing in G40 Cup, but are valid for championships such as 750 MC Roadsports and MSV-TDC.

The following photos show our brake cooling ducts and a standard method to test the temperatures with heat paint. We tested the brake temperatures after fitting the ducting and they were within an acceptable heat range, so we now have less of a problem with glazing.

The heat paint turns white when it's reached its indicating temperature, where: green turning white is cool; orange turning white is medium (acceptable to hot); and pink turning white is hot (overheating brakes).

Brake Cooling Ginetta G40Brake Cooling Ginetta G40

Brake Cooling Ginetta G40

Before use (above) and after use (below). The green paint has been activated and turned white, but the orange and pink are still intact after three track days. The brakes are now cool enough and working well.

NOTE: On the bottom photo you can see the new cooling pipe that goes to the caliper. On the top photo, this is the front brake, but the coilover was removed at the time, and it was before we fitted the cooling pipe.

Ginetta G40 brakes - activated heat paint

See also