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308 tire/suspension upgrade

Discussion in 'Technical Q&A' started by fedev, Nov 10, 2003.

  1. fedev

    fedev Rookie

    Nov 10, 2003
    23
    I am planning stgh to improve handling of my 82 gtsi. I thought of new rubber on 16" rims (I have trx at the moment), new shocks, new springs in this order. I think tires and shocks should do the most of it, and spring could actually be ineffective, due to poor chassis rigidity.
    My goal is just to have a level of grip/hanling comparable to a modern car (road use).
    Did anybody test the effectiveness of these mods on a quantitative basis (lap times on a given track or lateral acceleration on a skidpad)?
     
  2. pma1010

    pma1010 F1 Rookie

    Jul 21, 2002
    2,558
    Chicago
    Full Name:
    Philip
    Fedev
    I ran Blackhawk and Gingerman on my carb'd 308 in the early days on the all season XWX or similar 205/70x14 tires. Lots of tire squeal, and the tires "would go away" after a couple of laps after they heated up beyond their normal design/operating characteristics. Played a lot with pressures, but they just weren't up to the use pattern on the track.

    I bought a set of BBS rims which came with Yoko AVS 225/50x16F, 245/50 (subsequently changed to 45) x16 rear. More modern tire compound, three season tire. No comparison on the track. Would "trammel" abit more in the road contours.

    I have subsequently changed the AVSs for Kumho Victoracer V700s. Same sizes (rear is 45 section). Much more grip on the track, (therefore quicker) but not a good street tire (water/hydroplanning resistance, or lack of it, and they pick up everything - you can hear stuff rattling through the wheel wells). You start to notice body roll and height of CofG much more. I'd guess 5 seconds a lap at RA for the tires, but I was also getting to know the track better (lap times fell by 12 secs over last year on the AVSs) and did a fair amount of work to the chassis (bushings, shocks, rack etc) so it is hard to isolate different factors.

    Rob S. should chime in here but my guess is you've got the upgrade items in the right order. I did tires/wheels, then shocks, bushings and rack as one winter project. I have not done springs. I am half done (R) on anti-roll bars.

    It would be interesting to hear perspectives on the upgrades required to get closer to the handling of a car of more modern design -- or even if this is feasible.

    HTH
     
  3. f355spider

    f355spider F1 World Champ
    Rossa Subscribed Owner

    May 29, 2001
    16,694
    USA
    Full Name:
    Hugh G. Rection
    There are lots of expensive upgrades one can do to the 308 suspension, such as coil overs, new anti-sway bars and such. For less than the cost of stock bushings, you can upgrade to polyurathane bushings; but the labor to do so would be very expensive, unless you are an accomplished DIYer.

    Bottom line, you have a 22 yo car, just refreshing the existing components back to stock would probably make a huge difference in the handling dept., but the tires and wheel change will likely make the most noticeable change. I know when I put qv rims on with Bridgestone RE730s in 225/50 and 245/45 the increase in corning and grip was amazing on my 78 308 GTS.
     
  4. mk e

    mk e F1 World Champ

    Oct 31, 2003
    11,428
    The twilight zone
    Full Name:
    The Butcher
    With modern tires and shocks, they drive/handle like modern cars on the street. The skidpad numbers are also compareable to modern cars, thats mostly tires and alignment. Autocross, no problem. At the roadrace track is where you'll fall a little short since chassis stiffness and suspension geometry really are important. You can make the car as good as most other car, but not as good as newer ferraris...unless you're on race tires and they aren't.
     
  5. Mike C

    Mike C F1 Veteran
    Owner Lifetime Rossa

    Aug 3, 2002
    6,061
    Southeast USA
    Full Name:
    Mike Charness
    To have my poly bushings changed, the labor was less an $400 (8 hours), though you have to add another $100 for an alignment afterwards. Did make for better cornering on my 308QV.
     
  6. rexrcr

    rexrcr Formula 3

    Nov 27, 2002
    1,572
    Kalamazoo, MI
    Full Name:
    Rob Schermerhorn
    I agree with Dave and MK here. Tires, in all vehicles, have the greatest influence on vehicle dynamics.
    One can come very close to a new Ferrari, with the caveat being horsepower. Just ask Philip (pma1010) here what he's modified and discovered on his beautiful fly 308.

    The design and geometry of the 308 is sound and quite modern. Very tunable. Lowering is always a good idea. It always comes down to compromise, though. What's your goal and what's your intended usage? What's your budget? Of course, the new Ferrari's excel in driving dynamics, but at a cost of initial investment compared to the 308.

    Basically, the in order of diminishing returns, these have the greatest influence:
    1. Tires (and a proper wheel to match)
    2. Alignment
    3. Shocks
    4. Springs
    5. ARB (anti-roll bar, a.k.a. 'roll-bar' or 'sway-bar')
    6. Bushings

    Of course, sorting the suspension system, just like one would tune an engine, is of great importance too. That's where testing and experience comes in.

    Now, if you're modifying for all-out racing, with a proper budget, you can go scary fast just like in a new Ferrari.

    Best regards,

    Rob Schermerhorn
     

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