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Thread: short wheel base alignment

  1. #1
    LG
    Guest

    short wheel base alignment

    My 67 911 is very low and has 205/50-15" tires, bigger 21mm front and 26mm rear t-bars, yellow koni's, stock sway bars, and shock tower brace.
    I have been having trouble finding the right alignment for high speeds. What kind of toe front and back will work ?

  2. #2
    ttweed
    Guest
    For street use and high speed stability, you want a little toe-in on the front wheels (10-15 min.), lots of caster (6+ degrees), and not much negative camber (0-.5 deg.). For track work, you want crisper turn-in and better cornering, so a little toe-out in the front, less caster, and more camber (1.5-3 deg., depending on tires) works better, but makes the car more darty at high speeds. It's all a compromise, according to how you will use the car. Keep the rear toed-in slightly (10-15 min.) in either case.

    If you have lowered the car a lot, you need to put spacers on the steering rack to prevent bump steer.

    HTH,
    TT

  3. #3
    67eSse
    Guest

    Wheel alignment

    LG: the spec TT gives is good for both the short wheel and long wheel base cars.

    There are three things to address for an alignment: Ride height, Corner balancing and Alignment.

    For corner balancing making the torsion bar adjustments will also set the ride height. Bruce Andersons Performance Handbook gives wheel openings heights, something like, 25" front and 24" rear. In setting up my 1965 911 for high speed drives I ran at 24 1/8" front and 24" rear. Corner balance weight measuments (with driver weight in the front seat) came out to Front L/R 131, 132, Rear L/R 186, 189 - that equates to 41% front weight and 59% to the rear.(And the diagonals were pretty good). After changing out to a Sparco light weight seat and install of the roll bar, no drivers weight and removed the front bumper weights the balance shift came to 35% front and 64% rear. Yikes - need bigger rear rubber. (Lowered the front by a little over 1/2" and pounded out the Red Konis after one weekend -there is a point where too low is bad). I drive to the track at the 24 1/2" front and lower the front torsion bars by 6 flats of the flan block bolts (one rotation).

    Setting the 1965 are unique as the front top shock mounts are non-adjustable (No caster /camber adjusments) and there is no cam adjustments to the rear alignment bolts. (you lossen -strong arm the wheels - retighten and measure. Pain in the butt.) After marking, moving and measuring we was able to get to:
    Front:
    7 is ideal&nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp
    (6 degrees caster)
    Camber L/R: ideal is -1&nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp
    ( -1.3 -1 )
    Toe: ideal is 0 (this is with the tie rods loaded)&nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp
    ( .00 .00 )

    Rear:
    Camber L/R: ideal is -2 degrees &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp
    ( -1.4 -1.4 )
    Toe: ideal is toe-in 15 to 20 min.per side (can anyone chime in on how that converts to a decimal reading on the Hunter alignment machines ?)
    (.00 .05 )

    With the vented rotor hubs on front and 1/4" rear wheel spacers the rear track is still narrower than the front.
    Torsion bars are 23mm front, 27mm rear. (On most race tracks this would be a little stiff for the front and light for the rear). Your 21 and 26mm should be good for spirited driving.
    Adjust the front shocks light and the rear toward firm.
    Front Bar 19 mm, rear bar 16mm (unattached at Mid Ohio and set light at Heartland)

    This set was for high speed drives and tracks like Brainerd, Road America and also worked well at Mid-Ohio and Mosport.

    The only time I tried a slight front toe-out was for parking lot auto crosses, Yup - way too darty on the road, and very fast tire wear. Only ran the 19mm rear anti-roll bar on tight auto crosses. TT is also right about the bump steer, if you can't get the 1/4" spacers under the steering rack (mine wouldn't raise that high) use washers to raise it some.

    Bob

  4. #4
    67eSse
    Guest

    65 911 at Mid Ohio


  5. #5
    67eSse
    Guest

    test for image

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