Suspension Alignment - GT3
Suspension alignment - GT3
Note: The 911 GT3 suspension alignment contains only those procedures which deviate from those for the 911 Carrera (996) suspension alignment.
Driving onto measuring platform
Due to the reduced vehicle height, additional access ramps, for example 959 access aids, are required to drive the vehicle onto the measuring platform. Otherwise the front spoiler would bottom on the platform. A measuring platform without a sloped position is unsuitable.
Tools
The special tools for suspension alignment of the 911 Carrera (996) are also used for the 911 GT3.
Additionally, a hook wrench insert (special tool 9647) is required for the 911 GT3. The special tool 9647 is required to change the vehicle height and to adjust the stabilizer mating bearing on the front and rear axle. The special tool is used together with a torque wrench to tighten the lock nuts (slotted nuts) on the spring struts. Tightening torques in Front wheel suspension, drive shafts and Rear wheel suspension, drive shafts.
Important: The stabilizer mating bearing must not be adjusted for street use.
Deviating points for 911 GT3
Only those points which deviate from the 911 Carrera (996) are listed.
- Changed adjustment values.
- For the measured-value pickups, electronic wheel alignment testers require spoiler adapters of 50 and 100 mm in length, depending on the wheel alignment tester. This is the only means of enabling data transfer from the right side to the left. The wheel alignment testers recommended by Porsche which have a spoiler measuring program require 100 mm spoiler adapters on the rear axle. Observe the operating instructions from manufacturer of the measuring instrument if necessary.
- The vehicle height of the 911 GT3 can be adjusted at the front and rear axle by means of the adjusting nut(s) on the corresponding spring strut or struts.
- Maximum wheel-load difference from left to right on front and rear axle 15 kg.
- Adjustment of wheel alignment values on front and rear axle: as for 911 Carrera (996).
Notes on front axle camber
Front axle basic camber adjustment is carried out at the factory on the lower 2-part control arm. Further notes on this topic are provided in the following text under Wheel alignment values. Camber adjustment (fine adjustment) is carried out at the spring strut mount as for the 911 Carrera (996).
- Check all wheels for clearance after adjustment and assembly work.
Important instructions for suspension alignment work - GT3
The following must be observed during suspension alignment of the 911 GT3:
Height adjustment/wheel-load change
A one-sided height change causes a wheel-load change at the same time.
A wheel-load change on one wheel also alters the wheel loads of the other wheels.
A one-sided increase in the installed spring preload (raising vehicle) increases the wheel load.
A one-sided decrease in the installed spring preload (lowering vehicle) decreases the wheel load.
A change in the wheel-load is always transferred diagonally onto the other axle side. This means that if the wheel load on one wheel is decreased or increased, the same occurs on the diagonally opposite wheel.
Example
Rear left spring preload C is increased.
In this way the wheel load:
- rear left C and front right B increases____________
- rear right D and front left A decreases_ _ _ _ _ _
The wheel-load difference from left to right on front and rear axle should be as small as possible (under 15 kg if possible).
Vehicle height 911 GT3
General
The vehicle height on the front and rear axle of the 911 GT3 can be adjusted.
Before wheel alignment values are adjusted at front and rear axles, it is recommended or necessary* that the height adjustment be checked at the DIN empty weight. The height adjustment possibility allows the wheel-load difference from right to left to be kept as small as possible, provided that wheel load weighing machines are available. The wheel-load difference is adjusted by changing the vehicle height within the height tolerance. The priority is to achieve the smallest possible wheel-load difference from left to right. after work which causes a change in height or in the event of an incorrect height
Note: The height adjustment possibility allows:
1. Differing wheel loads on left and right to be corrected. At the correct height the wheel-load differences lie within a permissible range, provided that the coil springs have the same installation position (installed spring preload) on each axle. Tolerance +/- 1 mm. Wheel-load differences can be kept as low as possible in conjunction with wheel-load weighing machines. Tolerance from right to left on front and rear axle under 15 kg.
2. Any impermissible height differences -front axle to rear axle - can be balanced out (only within the permissible tolerance).
Preliminary work
For the height check of the ready-to-drive vehicle (full tank and tools), place the vehicle on a level surface or on the measuring platform.
Front axle
Measure from wheel contact surface to the lower edge of the hexagon-head bolt of the tension-strut screw connection to the body. Measuring point as for 911 Carrera (996). Required values for front and rear axle in Wheels, tires, suspension alignment.
Rear axle
Measure from wheel contact surface to the locating bore in the rear-axle side section (between toe and camber eccentrics).
The vehicle height on the front and rear axle is adjusted by turning the adjusting nut No. 2. The lock nut No. 1 must first be loosened. Use a hook wrench or special tool 9647 (hook wrench insert) for this purpose.
Adjusting nut No. 2
- turn to the right = vehicle higher
- turn to the left = vehicle lower
After adjustment of the lock nut(s) (No. 1) on the front and rear axle, tighten with special tool 9647 in conjunction with a torque wrench. Tightening torque No. 1 = 50 Nm (37 ft. lbs.).
Wheel alignment
Notes: Adjustment of wheel alignment values on front and rear axle: as for 911 Carrera (996). Observe note on front axle camber adjustment (see following text).
If the vehicle is measured front and rear, check and adjust the rear axle first. Nominal values in Adjustment Values For Suspension Alignment. After adjustment, tighten the appropriate screwed connections with the prescribed tightening torque.
Check all wheels for clearance after adjustment and assembly work.
Note on front axle camber adjustment
Unlike the 911 Carrera (996), a basic camber adjustment is made by means of two intermediate plates on the 2-part control arm of the front axle for the 911 GT3.
A 1 mm thick adjustment plate (arrow / Figure below) is fitted as standard on the right and left in the 911 GT3 M002 and M003.
By using thicker adjusting shims, the 2-part control arms permit a correspondingly increased camber value to be obtained for circuit use.
In connection with this, observe the note on fitting the diagonal control arm on the control arm.
Camber fine adjustment
The camber (the fine adjustment) is adjusted by moving the spring strut transversely (as for 911 Carrera 996). For this purpose, loosen the three fastening nuts on the spring-strut mount and, to move the spring strut, remove the covering cap on the piston rod.
Instructions for fitting diagonal control arm on control arm - GT3
In the case of the road version of the GT3 (M002 and M003), the diagonal control arm must be fitted at the center bore (No. 1) of the control arm.
Left control arm (A)
Right control arm (B)