Ride height / corner weight

[P91176]

Hi, I will start by saying I am a noob in Porsche world. Got my first 911 1 year ago, did drive it for 3 month and then took it apart for a full respray and suspension bushing upgrade.
I am now back and have assembled the car. Added 80kg to the driver seat, added 50 kg weight to compensate for missing fuel in tank. I put the car on my corner weight (use to dragrace).


My corner weight show the car a bit heavy on rear left and front left. When I measure the car height I am about 7mm lower on rear left(to right) and 20mm lower on front left compared to front right.

If I add a degree on the rear left spring plate(lower the spring plate to raise the car) to get the car level would it not cause the weight on rear left to increase? The opposite of what I would like to achieve looking at the corner weight.

[nickelplated5s]

First question is did you weigh it empty or with a driver. Most people strip weight versus adding 286lbs.

[P91176]

I added weight for the driver and added weight to the trunk because my fuel tank was empty.
80 kg at driver seat and 50 kg in trunk

[smadsen]

I've never corner-balanced a Porsche, but have experience with many other road-racing cars. If you raise the left rear, you will throw weight from there to the right front, and vice-versa. It's a lot of trial & error, but fairly simple with a coil over suspension. Torsion bar cars are more problematic, but the principle is the same, in that you have to re-index the T-bars for gross changes. I'd start by getting the ride height even side to side, then see where you are weight-wise, and make small ride height adjustments with the front adjustment screws (because it's easier).

Try to get the fronts as close to equal as possible, it's O.K. if the rears are a few pounds off. That's probably different philosophy than a drag racing car.

[Bill Verburg]

Originally Posted by P91176

Hi, I will start by saying I am a noob in Porsche world. Got my first 911 1 year ago, did drive it for 3 month and then took it apart for a full respray and suspension bushing upgrade.
I am now back and have assembled the car. Added 80kg to the driver seat, added 50 kg weight to compensate for missing fuel in tank. I put the car on my corner weight (use to dragrace).


My corner weight show the car a bit heavy on rear left and front left. When I measure the car height I am about 7mm lower on rear left(to right) and 20mm lower on front left compared to front right.

If I add a degree on the rear left spring plate(lower the spring plate to raise the car) to get the car level would it not cause the weight on rear left to increase? The opposite of what I would like to achieve looking at the corner weight.

You want the cross weights to be as close as possible

right now you have the top left + bottom right @ 585 and BL + TR @ 616.5
Lots of ways to play it and it will never be perfect, but
2244 244
350 349
gives 594 & 593

the fly in the ointment is the ride height at the corner you adjust changes and can look a bit weird , so some compromises have to be made

given my druthers the front being closer is better

[Billiam 911 2.8]

If that is your garage, I am jealous.
I recommend Carroll Smith's book, Tune to Win.

[Magyar Kiwi]

Hi
Suggest your next step is to measure ride heights four places per Porsche maintenance instructions.
This will help you decide which corner(s) to adjust.
(Front adjustments being much easier!)
See post 2 of first link below.
Second link may also be useful.
Cheers
https://dorkiphus.net/porsche/showthread.php?t=13577
https://forums.pelicanparts.com/porsche-911-technical-forum/1044306-alignment-specs-street-de-911-a.html

[nickelplated5s]

Dump the weights and put a 1/2 tank in it then weigh it. My car, with no fuel cell, I can tell the difference between a 1/2 tank and full. Driver weight doesn't seem to matter much as it's spread front to rear. My guess is the car alone clocks in at 2,500+. BillV can give setup advice. My SWB doesn't translate to yours.

[EC900]

Off topic - wow P91176…what color is that… from the factory?

[nickelplated5s]

Nope. OP said a recent overspray.

[P91176]

Its a new respay but factory color. Continental orange, paint code 107

[P91176]

Thanks, I will try and raise rear left due to this being 7mm lower then rear right. Then this will move weight and lower the front right. Fine adjustment i need to do at the front.

[PeteKz]

Yes, 7mm is a significant difference at the rear. Typically, you want the left slightly higher, to account for the driver's weight, since that is usually the only person in the car.

[r lane]

Originally Posted by PeteKz

Yes, 7mm is a significant difference at the rear. Typically, you want the left slightly higher, to account for the driver's weight, since that is usually the only person in the car.

A 78 911 track car with torsion bars. just put her on the scales and this is close to what I generally get. I check the R ride height at the lowest bolt on the trapezoid shaped torsion bar end plate and the F height I check from the 12mm bolt that secures the front cross member at either end. The rear heights are within a 1/16'' and the fronts are off 5/16'', higher on the left. Includes driver and fuel. The ride height discrepancy bothers me, but don't know what to do about it. It is mentioned in this post that closer weight is preferred in the front. Why is that as my assumption is that on this car most of the traction and all of the drive is controlled by the rear tires. Bob

[Bill Verburg]

Originally Posted by r lane

A 78 911 track car with torsion bars. just put her on the scales and this is close to what I generally get. I check the R ride height at the lowest bolt on the trapezoid shaped torsion bar end plate and the F height I check from the 12mm bolt that secures the front cross member at either end. The rear heights are within a 1/16'' and the fronts are off 5/16'', higher on the left. Includes driver and fuel. The ride height discrepancy bothers me, but don't know what to do about it. It is mentioned in this post that closer weight is preferred in the front. Why is that as my assumption is that on this car most of the traction and all of the drive is controlled by the rear tires. Bob

Braking, you want the front to be as even as possible for safety, if you give up a tad on acceleration it's a fair trade off, plus acceleration is often employed at least a bit while is the comer, this would throw the rear balance off any way, and Your lsd is also compensating