Acceptable ride height | FerrariChat

Acceptable ride height

Discussion in '308/328' started by Jasonious, Aug 7, 2020.

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  1. Jasonious

    Jasonious Rookie

    May 13, 2018
    42
    PNW
    Well I'm happy to say that after a year plus on stands, my 79 GTB is ready to hit the road. I completed all sorts of tasks on the car that hadn't been serviced in 12 years. One of the more entertaining jobs was to change the stock Koni's and springs out for some Bilstien B14 PSS adjustable's and Eibach springs. The car is now on its wheels but is simply too low. Looks awesome, but I want to drive the thing, not just look at it!

    Can someone tell me what the "stock" tire to wheel arch measurement is front and back? I've seen threads mentioning 3.5 & 4 inches front and back. Others mentioning 2 inches all around, etc. I'd like to know what the stock height should be and what an acceptable drop should be. 1/2 inch? 1 inch?

    Also, my Porsches are all a rear to front rake of between 1 and 2 degrees. Does the 308 have any rake back to front or should I aim for level?
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    Thanks so much for the help!
     
  2. Crowndog

    Crowndog F1 Veteran
    Rossa Subscribed

    Jul 16, 2011
    7,042
    Fairfield,Pa
    Full Name:
    Robert
    Shop manual has height from road to car front and back. Sorry no longer have mine.
     
  3. Jasonious

    Jasonious Rookie

    May 13, 2018
    42
    PNW
    Thanks for the reply.

    I have never seen a manual for a 79 GTB. I have the GT4 manual, but I am assuming the suspension specs are different?
     
  4. Brian A

    Brian A F1 Rookie

    Dec 21, 2012
    3,079
    SanFrancisco BayArea
    Full Name:
    1983 US 308 GTS QV
    There are probably Factory ride height specifications somewhere. There may be differences between the various markets due to bumper and headlight height requirements.

    From a practical perspective -- bumper and headlight height aside -- the issue for an owner is whether or not the car bottoms on bumps either by hitting the damper bump stops or scraping the bottom of the car. There is a theoretical benefit to a lower center of gravity, but practically speaking virtually none of us can notice. Other than that, its an aesthetic issue. I would say, adjust it the way you like it.

    For what it’s worth, on my US-spec GTS QV the highest point of the front wheel well is 26 ¼” off the ground and the highest point of my rear wheel well is 26 ½” off the ground. I have lowering spring perches which have dropped the car 1” in the front and ¾” in the back. My goal in lowering the car was to make the distance from the tire at the top of the wheel well equal to the distance of the tire to the front and back of the wheel well. I have hit the bump stops a few times and have scrapped lightly once. It was at speed over very rough roads. I have not encountered a speed bump or hump that I could not get over.
     
  5. Jasonious

    Jasonious Rookie

    May 13, 2018
    42
    PNW
    Thanks @Brian A.

    I'm just looking for some kind of benchmark to use as a starting point. As you point out, it's ultimately a practical matter of how much scraping you can tolerate.
     
  6. ferrariowner

    ferrariowner Formula 3

    Feb 21, 2014
    1,109
    Mansfield, TX
    Full Name:
    Ron
    I think the most obvious Limit to lowering the car is the type of front spoiler. It looks like your car does not have the euro spoiler and can therefor be somewhat lower. I do not have a dimension for you. Driveways and speed bumps tend to define how low you can realistically lower the car for street use.
     
  7. Miklas

    Miklas Karting

    Dec 10, 2018
    79
    Luxembourg
    If you go too low I assume that the roll center will move below the car and then you can end up with some funky handling. When I had my Lotus you couldn't go below 110 mm ride height (ground to frame) without starting messing up the handling.
     
  8. thorn

    thorn F1 Rookie
    Silver Subscribed

    Aug 7, 2012
    3,322
    Tallahassee, FL
    Generally, to find the body height - one measures from the ground to the top of the wheel arch; not from the top of the tire to the arch.

    My 308 Euro has stock springs... I can take measurements if you like.
     
  9. 4right

    4right F1 Rookie
    Rossa Subscribed

    You will also need to be concerned with the tires rubbing the inside of the fenders if the suspension get adjusted too low. I am having mine adjusted back up this week as the fronts are rubbing in turns or over bumps. Image Unavailable, Please Login
     
  10. AZDoug

    AZDoug Formula 3

    Jun 17, 2009
    1,606
    Along the Verde , AZ
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    Doug
    No rubbing over bumps, etc. Tires are 245/45-17, and are wider than stock, wheels are 8" wide, IIRC.
    The pic below is "about" stock height.

    Doug
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  11. AZDoug

    AZDoug Formula 3

    Jun 17, 2009
    1,606
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    Doug
  12. GordonC

    GordonC F1 Rookie
    Owner Rossa Subscribed

    Aug 28, 2005
    4,119
    Calgary, AB, Canada
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    Gordon
    Not quite - Doug's post below illustrates the problem with this measurement:

    Doug's tires are taller than standard 308 tires - which raises the height of the body relative to the ground, but doesn't raise the height of the car/chassis relative to the suspension.

    The height measurement that takes tire variations out of the equation is to measure from the hub center to the fender lip - that's the actual suspension height, independent of the tire height. Using hub center to fender lip, you can compare ride height measurements from one 308 to another, no matter what tires each car has mounted
     
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  13. AZDoug

    AZDoug Formula 3

    Jun 17, 2009
    1,606
    Along the Verde , AZ
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    Doug
    Those tires I have are about 1/4" taller than stock, which is about 1/8" raise in theoretical ride height, but having adjustable spring height with the QA-1 shocks in front and adjustable height modified Konis in back, that is easily compensated for.

    The slightly larger tires would be about 1/8" closer to the fender lips, at stock lower arm inner pivot point height.

    FWIW, the hub centerline to fender lips appears to be about 13.5" in front and 14.5" in the rear with my vehicle.

    Doug
     
  14. Jasonious

    Jasonious Rookie

    May 13, 2018
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  15. Alex308qv

    Alex308qv Formula Junior

    Jul 1, 2016
    378
    PA
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    Alex
    This is what I plan to do with my US '85 QV, which were higher than earlier years and have a top gap noticeably wider than the front and rear fender gaps to the tire. I think "equal gap all around the tire" is the absolute best looking appearance on a 3x8, and my sense is the way it was originally intended. OP's car looks a bit "slammed" esp in front and it's right for him to raise it.
     
  16. Jasonious

    Jasonious Rookie

    May 13, 2018
    42
    PNW
    Well having spent the last few days on this with a tape measure and a Hunter rack, assuming stock wheels and tires, zero degree rake front and back gives you about a one inch gap difference between the front and the back. If the gaps are all equal, you may wind up with a motorboat look with the front higher than the back. Looking at contemporary 308 photographs from the factory appears to show this difference, although it is hard to really tell.

    Anyway, YMMV.
     
  17. Alex308qv

    Alex308qv Formula Junior

    Jul 1, 2016
    378
    PA
    Full Name:
    Alex
    Jasonious, thanks and after rereading your post #14 that makes sense.
     
  18. bill308

    bill308 Formula 3
    Silver Subscribed

    May 13, 2001
    1,160
    Windsor, CT
    Full Name:
    Bill Sebestyen
    I think a good starting point for ride height is to set the front and rear, lower A-arms, parallel to the road. More specifically, inboard and outboard, lower, pickup pivots, should be the same height above the ground, at your desired driving condition (occupants, luggage, fuel, spare tire, etc).
    Bill
     

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