Apex Late

I wanted to ask those who have lowered their cars for track purposes to post their ride heights (front and rear) and offer comments on the results that they have had on the track. This is an extension of an set-up thread that Bob has going right now but I'm very interested in only the height issue for this thread.

Thanks guys.

porkernut

WHY, unless you NEVER use it on road???????

Porsche997gt

Why not, it will make the car lower therefore the mass of the car will be closer to the ground allowing it to less move its weight around And I don't think he'll drop the car 2"!

CWay27

Read the other thread mentioned above and you'll understand and like 997gt said, he did not lower it 2".

Apex Late

As the boys said earlier it is not being lowered for "road driving" purposes and we are likely talking about 12mm which is really not that much at all.

Unitah

pokernut, there are great benefits to lowering the car slightly. I think you should research this issue a bit and study those benefits...

Unitah

Apex Late,
I see why you started a new thread on ride heights, getting a bit off topic on the other thread... So, lets restart...

Here is a repost of my ride height data:
-Measurements taken inside perfectly flat and level garage.
-1/2 tank of fuel
-no driver
-GT3 seats (-about 50 lbs) + 997 RS Cage (+ 37 lbs)(for weight and balance purposes)

Left Front: 25 5/8"
Right Front: 25 7/8"
Left Rear: 26 1/8"
Right Rear: 26 3/8"

Carrera GT

You're going to need to work from the chassis, not the body panels. And you have to compensate with driver weight.

There's a factory spec -- going much lower will "invert" the steering control arms (aka tie-rods, track rods) and begin to introduce bump steer. In terms of ride height 12mm is significant. The spec is something like +/- 5mm range.

You might research the new RSR and any of the Cup cars to see what's required to get the GT3 to the lowest possible useful level (and retain adequate compression travel, aerodynamics, cooling flow etc.) There's some low-hanging plastic on the 997 that would need to be considered.

doc2s

fwiw stock tolerance is +5mm only.

Apex Late

Thanks for your comment. Firstly ride height is taken without the driver in the car. I got this information from the factory yesterday as there seemed to be some confustion around this fact. Next the +/-5mm is the "factory tolerance" and is used by the dealer to determine if street adjustments are necessary. I'm told that it is not a figure that is based on optimum suspension performance. I'm only giving you the information I have received so if you are sure I'm incorrect here I would honestly like to hear how you have come by your information.

I've been informed that the optimum number is 10-15mm lower before the benefits of the lower center are outweighed by the negative aspects of reduced travel.

I'm open to correction here if my information is in fact flawed.

Carrera GT

Everyone (else) is open to correction. : )

As for ride height, if you set ride height without the driver (assuming you're setting up for the track) what's the point?

How can you get ride height and corner balance correct if the driver weight is not included?

Anyway, what factory? Are you talking with a factory engineers? Kussmaul? Was this a visit?

Apex Late

Although I understand your point and it seems VERY logical this is what I was provided from Porsche through a contact that I have there. I don't think this is any big secret but I don't know if he should have provided it to me so I won't post his information.

WM 4400TW Adjustment values for suspension alignment Technical values

Location Description Type Basic value Tolerance 1 Tolerance 2
Front axle height Adjustment value 108 mm + 5 mm - 0 mm

Rear axle height Adjustment value 133 mm + 5 mm - 0 mm

Vehicle height

Note

The following values relate to the empty weight, i.e. full fuel tank/fluid reservoirs, vehicle with tools, but without driver or additional weights!

Vehicle height 911 GT3/911 GT3 RS (997) RoW/USA

Front axle

Height with 19-inch wheels
→ Adjustment value: 108 mm+ 5 mm- 0 mm → :

From road contact surface to lower edge of hexagon-head bolt of cross-member threaded connection to the body.

Rear axle

Height with 19-inch wheels
→ Adjustment value: 133 mm+ 5 mm- 0 mm → :

From wheel contact surface to the locating bore in the rear-axle side section (between toe and camber eccentrics).

Permitted transverse inclination of the vehicle: Max. difference in height, left to right = 5 mm.

Max. wheel-load difference from right to left on front and rear axle is 15 kg.


Wheel alignment values
Note

The following values relate to the empty weight, i.e. full fuel tank/fluid reservoirs, vehicle with tools, but without driver or additional weights.
The toe-difference angle value is also influenced by the vehicle height. For this reason the measured result must be evaluated accordingly. No action is necessary in the case of small deviations from the toe-difference angle’s required value as long as the value to the right and left is almost the same.

Wheel alignment values
911 GT3/911 GT3 RS (997)
RoW/USA


Front axle

Toe unpressed (total)
+ 6' ± 2'

Toe difference angle at 20° lock
- 1° 50' ± 30'


Camber (with wheels in straight-ahead position)
- 1°20' ± 5'

max. difference, left to right
10'


Caster
8° ± 30'

max. difference, left to right
40'


Rear axle

Toe per wheel
+ 13' ± 2'

max. difference, left to right
5'


Camber 1)
- 1°40' ± 5' 1)

max. difference, left to right
10'


1) Altered camber value on the rear axle which is also valid retroactively (from start of production). Previous value: - 2° ± 5'.

doc2s

apex,

thanks for providing the info. it is available for techs at the dealer through porsche's online system.

Unitah

Apex Late,
Since I posted my ride height information, please post yours so we can compare... Thanks