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Last Post 17 Jul 2011 10:21 AM by  lost87
C4 Corvette set-up/mods advice
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New Member
New Member

11 Jul 2011 01:55 PM

    I co-drive my street-driven 1987 Corvette coupe (automatic with Z52 package) with my son in BSP with street tires (put on 17" wheels this year which bumped me into prepared). This is our second season. Car was originally purchased as daily driver/restoration project until I discovered my son was interested in autocross. I have done some work to the car (see below). Car is run on a hobby budget (read low $)

    I am looking for advice from other C4 owners who autocross.

    1. Am I on the right track? With limited budget what should I do next? G-force tires are new so they'll stay on until they wear out (although advice is that they were not a good choice). I was thinking Hawk street brake pads and slotted rotors.
    2. Last year with old shocks car was called "tail happy". This year gas shocks and G-force tires were added before first event. We noticed a huge improvement. Car was driven this past weekend by a driver who had been to SCCA Nationals who still described it as tail happy. He suggested that I go back to a smaller rear sway bar. Any thoughts appreciated.

    Work done

    new polyurethane bushings all-around, 30 mm front sway bar, 24 mm rear sway bar, adjustable camber struts (originals damaged), fabricated X brace (original missing), 17"x 9.5" wheels (with correct offset for an 87), 27540ZR17 BF Goodrich G-Force Sport tires (run at 37 psi front and rear), Bilstein Z51 gas shocks (correct for car), alignment front camber -0.5; rear camber -1.0, front toe 0.0 and rear toe -1/16". Everything else is stock.

    Advanced Member
    Advanced Member

    11 Jul 2011 08:10 PM

    absolutely on the right track. depending on how serious you want to get you can go a long way. great car. fun car.

    make sure you have good brake pads that work right out of the box cold but don't fade; leave the small brakes on. Lots of threads on pads.

    you will have a lot higher potential with MUCH more negative camber up front, -3 degrees or so, with all the caster you can get; go for 7 degrees. toe it out about an 1/8 inch for starters.

    At the rear you'll want about -1.5 degrees negative camber and zero toe.

    Once done, you will likely find you want a smaller rear bar.

    these changes will get you much more stability in transitions where you want it, but the ability to point the car into and out of corners the way you want, without unnecessary wheelspin and without push.

    next thing in the high returns department is some light 17 or 18x12 inch wheels all around with good tires.

    if you have trouble keeping it balanced, shocks could be next but are expensive.

    weight is next; take out everything you can under the rules; though I would not go with a mini clutch if you still want to street the car.

    next is gearing, you want to be able to run all courses in 2nd gear. I think the car is good stock.

    finally, and maybe most fun, is power. Ultimately an LT4 long block with good headers and intake is what you'll need.

    the biggest things of course is seat time and good instruction; i'd put really bad tires on it and find a place to drive them right off the car. ride with good people. go to the Evolution schools.

    put all that together and you have everything you need to win BSP and have a blast.

    New Member
    New Member

    12 Jul 2011 10:50 AM
    Thanks very much for the advice!

    I had seen the alignment numbers before but wasn't sure how much they affected street driving and tire wear so I arbitrarily made some choices.

    Our club offers basic and advanced schools and we have taken both.

    When I bought the car the front seemed low but seems to have stock suspension parts. I have now lowered the rear. The front frame rail at the jacking marker is 7.25" while it is 7.5" at the rear jack point.

    Thanks again.
    New Member
    New Member

    17 Jul 2011 10:21 AM

    This question was also posted on Corvette forums

    Thanks to everyone who posted. I have a clear plan for this year.

    The car will be aligned with more front camber (shop will work with camber, caster and toe to give me the best compromise) and a little toe out 1/16th(to see how it feels)
    The shop will also scale the car for me to see what the balance is now and what can be done.
    I will try the car with the new alignment and see how it feels.
    I have the 22 mm sway bar with urethane bushings and i'll try it, after trying the alignment, to see how it feels. Easy to change.
    Brake pads need replacement so I have ordered HAWK HPS pads.
    Will try 36 psi front and 34 rear
    Get as much seat time as possible

    Next year a set of grippier tires!

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