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Ride Height Adjustment

Bruce Anderson in the July, 2000, issue of Porsche Panorama recommends an alternate to the factory method (described below) which is to measure from the ground to the top of the fender lip. He recommends 25 inches for the rear and 25.5 inches for the front for the best ride height. He says the the car should have a slight nose down attitude (about one degree). The fender cut out is flattened on the rear which explains the the additional distance on the front measurement above.

My car as received measures 27 3/8 in. at the front and 26 in. at the back. The front should be lowered nearly an inch to achieve the desired nose down attitude. I plan to restore the front pan in the next couple of months. A four wheel alignment will be done at the time which may include lowering the car.

Front Ride Height



Here's the factory method.
  1. Make dead center mark on dust covers of front wheel hubs.
  2. Depress front of car several times, by pushing down on the bumper horns and allowing the body to come up by itself on the rebound, to set the suspension at proper attitude.
  3. Measure the vertical distance between the front wheel center and a level part of the level floor (see dimension "a" in the following diagram.

    frontheight.gif
  4. Value "a" minus 104 mm equals value "b". A height marker adjusted to value "b" can be effectively used for taking measurements at the torsion bar center.
  5. Remove torsion bar dust cover at the adjusting lever to gain access to the torsion bar centering mark which should be used as a reference point.
  6. Loosen or tighten the torsion bar adjusting screw until value b is obtained at the torsion bar center.
  7. Depress the front of car, allowing it to come up by itself, and recheck height of both sides for value b, correct if necessary.

    Note!

    Even though a plus/minus 5 mm deviation is possible for value b on either side, difference in height between right and left sides must not be more than 5 mm.


Example


Value a = 315 mm
- 108 mm
----------------
Value b = 207 mm +/- 5 mm (- 202 to 212 mm)


Based on the above example where value b measures 207 mm with permissible deviations anywhere between 202 and 212 mm, the following adjustment possibilities become evident:
  • If value b on left side is 202 mm ( = 207 minus 5 ), then value b on right side can be 202 to 207 mm (up to +/- 5 mm difference.
  • If value b on left side is 207 mm ( = 207 +/- 0), then value b on right side can be 202 to 212 mm (up to +/- 5 mm difference).
  • If value b on left side is 212 mm ( = 207 plus 5), then value b on right side can be 212 to 207 mm ( up to - 5 mm difference).


Rear Ride Height



  1. Depress read of car several times by pushing down on the bumper horns and allowing the body to come up by itself on the rebound to set suspension at proper attitude.
  2. Measure the vertical distance between the rear wheel center and a level part of the floor ( see dimension "a" in the diagram below).

    rearheight.gif
  3. Value "a" plus 12 mm equals value "b"; however, value "b" cannot be measured since the torsion bar is off center due to mounting in a rubber bushing.
  4. Value "b" less bushing-cover radius ( 1/2 diameter) equals value "b1".
  5. Measure height of vehicle (value "b1") with the help of a height marker or similar device. The actual value b1 should not differ from the calculated value b1 (pts 3 and 4 above) by more than +/- 5 mm; in addition, the height difference between the right and left side should not be more than 8 mm.


Example:




Value a = 315 mm + 12 mm ---------------- Value b = 327 mm Value b = 327 mm - Bushing - cover radius = 30 mm --------------------------------- Value b1 = 297 mm


Permissible tolerance for Value b1:
  • If value b1 on left side is 292 mm ( 297 minus 5), then value b1 on right side can be 292 to 300 mm (up to + 8 mm difference).
  • If value b1 on left side is 302 mm (297 minus 5), then value b1 on right side can be 294 to 302 mm( up to - 8 mm difference).


If proper suspension adjustment values cannot be achieved, proceed as follows:
  1. Check height adjustment of front suspension and correct if necessary.
  2. Check rear torsion bar adjustment and correct if necessary.
Last modified: Mon, 17 Oct 2005

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