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What to do when the parts aren't available?

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  • #16
    The base rack and Z51 or "quick" rack had the same respective ratios, regardless of early (84-87) or late (88-96). I suspect your supercharged 85–at least the way I remember it from our telephone conversations about it back in the day–is capable of higher speed than a stock 85 (150-mph top speed). One reason the "quick rack" disappeared after about 1990, was that during the ZR-1 development in the late 80s, John Heinricy felt the quick rack made the car too sensitive to steering input once the car got up to 140-150-mph. Needless to say, because their top speed was about 180-mph, all C4 ZR-1s had the base rack. With any C4 after MY90 or so being capable of over 150-mph, GM did away with the quick rack. I think your 85, which with that blower ought to be able to run 160-170 or so–not that you'd ever drive it that fast on the street (giggle)–you're likely better off with the base rack. If you had been able to find a quick rack, you took the car to a track like, say...VIR or something and you were running, like... 175 down the straight, that steering would require "pixie fingers" for sure. Add a little front end lift due to aero and you'd really hate a quick rack.

    While C4 autocrossers liked the quick rack for obvious reasons, there were those who road raced the C4 platform and preferred the base rack. The last successful C4s in road racing at the professional level–one of which is the old #75 "Pirate Racing" ZR-1 which is now in the NCM–used the base rack. I know because I helped build that car.

    While you solved your problem by finding that early rack, I think there is a heck of a business opportunity for someone who develops either a fix for that shaft wear problem or develops a "kit" to easily put a late rack in an early car.
    Hib Halverson
    Technical Writer for print and internet

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    • #17
      Hey Hib!

      Yes, you are right. And I think that there will be someone come forward to start producing these racks (flaming river?) but also, there should be a FIX for them as well. It'd be hard to repair the aluminum-cased ones, but the later, cast housing ones should be prone to less wear on the housing. Hoping someone does come forward.

      We tried fixing my rack's shaft, but the hard part was getting someone to take the necessary time to put the right finish on the shaft so it doesn't tear up the seals. That's what mine did. They CAN do it, but it would take a lot of units to make it worth their while.

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