GC8 GPA Front Wings

Discussion in 'Projects, modifications & how to guides' started by Craig_F, Dec 10, 2017.

  1. 2pot

    2pot V-Limited Member

    What tyre size?
    What suspension?
  2. Craig_F

    Craig_F Type RA Member

    Sorry 2pot, I've only just seen your reply.
    The car is on its original Prodrive Bilstein GPN suspension. I've been using Hankook Z209 Tyres 647mm diameter by 228mm wide.

    We've been looking at the front in more depth today and have been trying the car on full locks but can't see anything touching and there isn't much in the way of witness marks on the bodywork on the front. There are kind of some lips/centre seam in the centre of the wheel arch behind the wheel which protrudes quite a way and could be the culprit. Front wheels are running spacers which I know one of the previous owners didn't run but then he was on 7.5" wide wheels rather than 8" wheels I'm running.
  3. Craig_F

    Craig_F Type RA Member

    I think removing front spacers is a first thing to try and see if the wheel still clears lower arms etc. Rear wheels try a narrower spacer like one of the previous owners did as current one is a fair but wider than he ran.
    We set up the Geo as close as we could to the above settings which I've posted.
  4. asperformance

    asperformance Site Supporter

    oop north
    Has been asked a few times now but if you can check the spec of the wheels, exact width and ET (normally stamped into he rim at the rear) then a few suggestions could help......

    What size spacers??
  5. Craig_F

    Craig_F Type RA Member

    Definitely 8" wide and I believe ET48 as per the Revolution wheels website for the Millenuim wheel, will check the ET tomorrow for definite.

    Will also check wheel spaced width.
  6. Gloremir

    Gloremir Type RA Member

    Dont be to sure that they are 8" wide before you check. Mine are 7.5" wide.
  7. 2pot

    2pot V-Limited Member

    Your effectively running a 225/42 x 18 tyre (210mm tread).
    215/40 x 18 et48 7.5" is on the limit with no arch modifications and a compliant suspension - street tyres rarely measure the sidewall width.
    225/35 x18 et 51 7.5" (the P1 wheel/tyre size) sometimes needs arch adjustment.

    I don't know why you're running spacers? Unless you wanted to intentionally widen the front track, in relation to the rear?

    For next to no road use, you'll need to adjust the arches and run camber plates at neg 2.5 to neg 3 deg front camber. With neg 1.75 to neg 2.25 deg rear. With very stiff suspension.

    What are your wheel centre to metal arch measurements?
    Last edited: Dec 19, 2017
  8. Craig_F

    Craig_F Type RA Member


    I wanted to thank you with your help on the above. The arches had already been rolled so there wasn't much more for us to do there. We removed the wheel spacers front and back and appeared to have plenty of clearance.

    Went and ran the car today on a rally test session on an airfield we rally a top and all good. Car didn't touch any bodywork at all. We had some brake issues before which we now know is where the pedal box was built by a total pikey so my brother who is a top race car engineer has rebuilt that with correct master cylinders and they now perform quite well.

    Couple of further questions.....

    Car is running Gold Brembo on front and two pot Subaru caliper on rear. I think we have Mintex F four pads but anything anyone can recommend that will stop the car better?

    Also we have a JDM Six speed box which I find a long throw and vague compared to dog box and sequential boxes I'm used to. Anyone know of a decent short shifter or modification to make the throw shorter or more positive?
    • Like Like x 1
  9. tekkerchrede

    tekkerchrede V-Limited Member

    • Like Like x 1
  10. Burnsie

    Burnsie V-Limited Member

    North west
    Hi Craig @Craig_F

    Glad you’ve sorted your brake and wheel rubbing issues mate.

    I’ll get back to you regarding your gearbox.

    Your Brembos should be good enough with a good bleed through using Castrol SRF and decent master cylinders I.e. AP. If you want to stop better buy AP calipers, Discs and bells. Or if you want an even firmer pedal go hardline.

    Kind regards,

    Last edited: Jan 14, 2018

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