I know ride height is measured at the torsion bar centres, but often the height is taken from the wheel arch lip to the floor running through the centre of the wheel.

So, lets have a comparison on the heights we are all running.

Here's mine:

Front Right: 25" (63.5cm)
Front Left: 25 1/4" (64.12cm)
Right Rear: 24 3/8" (61.9cm)
Right left: 24 3/8" (61.9cm)

So, if the wheel arch tops are all inline, then mine needs to drop a little at the front.  Porche recommends a 1 degree slop of the car for down force at high speed.

Will dig out my geometry settings from GTOne and measure my arch heights this eve. Should be useful comparison data.

These are mine:

Front Right:  24 1/2" (62.0cm)
Front Left:    24 1/2" (62.0cm)
Right Rear:  25 1/4" (64.0cm)
Right left:    25 1/4" (64.0cm)

Quote: hukent at Apr 19, 2010 4:52:12 pm

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These are mine:

Front Right:  24 1/2" (62.0cm)
Front Left:    24 1/2" (62.0cm)
Right Rear:  25 1/4" (64.0cm)
Right left:    25 1/4" (64.0cm)

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Hi Hu

Thats intresting.  You have two cm's lower at the front and I have two cm's higher.  I suspect this is part of the reason I have a high speed stability problem.  I've just bought a digital inclinomter so I can at least measure the slope of the car.

I would like mine to be 63cm at the back, but it handles so well at the moment,
I think I'll leave it untill after I give it the 'beans' around Spa in June.
Have you taken the whale tail off?

No, the whaletail is still on there......

your heights are very odd pete !...how can you be higher at the front than rear ? will nip to the garage and measure mine after ive finished watching my footie team get spanked by liverpool

The other oddity is your front left is higher than the right despite the heavy battery and water bottle being on the left (nearside). Strange!

heh, well i spoke too soon as mine is similar !

Front right (offside) = 61.8cm
Front Left (nearside) = 62.0cm
Rear right = 59cm
Rear left = 61.2cm

Weird huh !? Wonder if my rear left side has risen when i fitted a lighter exhaust system. The fronts are fairly even but higher than the rear. Perhaps its because of the lack of weight up front? . I have lost about 20kg out of the front plus another 35kg from the seat replacements.. Could also be fuel dependant as only have 1/4 tank of petrol left in car.
May have had a eureka moment there!...perhaps we need to measure heights with same fuel in car !

Hu your measurements seem uncannily exact all round. Did you measure accurately or do it to nearest cm ?

This is the absolute correct way to measure ride height but its a good approximation.  These cars were hand built and no two are the same.  Im not sure if you can assume that the wheel arch heights at the front and back are the same anyway.....

Hu's do look amazing I have to say.

I think you should have half a tank of fuel and the driver should be in the car....  When corner weights and balancing is done, the drive should be in the car.  This means with no driver you could end up with slightly difference wheel arc heights, so a slight difference is not too much to worry about.  My diagonal and axle weights are almost spot on, but the effect is differences in heights.

What I need to do (an didnt when I did the corner weights and balancing) is make sure the car has a 1 degree angle of attack.

Gut feel says the front arches should be lower tan the rear.

I just ne get my car to somewhere with a level and flat surface so I can use my new gagdet!

i would think damper age would affect heights too at each corner? If you have saggy old dampers its going to sit lower than some shiny new stiff bilsteins.

Thats true it could effect it.

Mine are all shiny and new, so mine is likely to be a setting issue.

Im going to get two reference blocks of the same size, place them adjacent to the front and rear wheel centres.  Pleace a straight edge along them.  Calibrate my inclinomter to zero, then measure the angle by placing the inclinometer on thye sill.

Ideally the tank should be haf full and me in the car.

With the driver out of the car te right hand side should be higher.  In an ideal world the front pair and rear pair would be the same, but if you want your corner weights to be right, then this is done by varying the height at each corner.

Great topic this 

OK, some progress.  I have managed to get a consistent reading on the inclination of my car.

I placed a block adjacent to the centre of the wheel on the drivers at both front and back.  Both blocks te same thinckness;

I then ran a straight edge from one block to the other.  The top of the straight edge now represents the angle of the car at the tyre contact points.

Next I zeroed my inclinometer on the straight edge

Then I transfered the inclinometer to to the centre point of the door sill.

I measure an inclination of 0.4 degrees (down at the front)

So, the distance between weel centres on my car is approx 231.5cm.  Over that distance at 0.4 degrees there should be a difference of 1.61cm.  Looking at my original readings of rear 61.9cm and front 63.5cm thats a difference of 1.6cm.  Coincidence - i think not....

So, Porsche recommend a 1 degree gradient.  This means I need a further 0.6 degrees or 2.42cm less onfront.  This would make my ride heights as follows:

Rear 61.9cm
front 61.08cm.

So I have some adjusting to do 

Just for reference.  A 1 degree slope over 231.5cm is 4cm.  So the front of the car needs to be 4cm lower than the rear.  So clearly the height of the arches at the front and rear of the car are not the same....

update:

I just thought.  I put 215 tyres on the front instead of my 205's.  That in itself would have raised the front of the car by 5.5mm.

Slowly Im finding out all the little things contributing to my ride height issues ..... 

pete, i have spoke to alot of people about this even though the back end of a 911 looks great when its squat on its arse
it handles shit, ask the guy from center of gravity he says it should sit slightly higher at the back than the front he has a 3.2 aswell , my handlings all over the place cos i dropped it on its tummy, but will soon get it rectified
on another note  HU, if you read this post i know you said you got the brace on ebay was it a guy selling a few or a one off?

cheers 

Yep common opinion is that there should be some rake front to back. My car sits very low with no apparent rake but must say it handled pretty well at Brands, better than i thought it would in fact, no doubt the low c of g helping, but it had some understeer i'd like to lose and a bit of height increase at the rear would help cure that a little as it should help with turn in.

My car had 4 wheel laser alignment last year so i am not going to worry too much about altering its stance etc yet as i intend to replace my struts all round with Bilsteins at some point..ie when ive robbed a bank then i can get it properly corner weighted and aligned. I think my current dampers are near the end of their working life as i notice every divut in our lovely road surfaces.

Yep, Porsche say that our cars should have one degree of rake.

I measure (with my magic tool) an inclination of 0.4 degrees (down at the front)

So, the distance between weel centres on my car is approx 231.5cm.  Over that distance at 0.4 degrees there should be a difference of 1.61cm.  Looking at my original readings of rear 61.9cm and front 63.5cm thats a difference of 1.6cm.  Coincidence - i think not....

So, Porsche recommend a 1 degree gradient.  This means I need a further 0.6 degrees or 2.42cm less onfront.  This would make my ride heights as follows:

Rear 61.9cm
front 61.08cm.

So, Ill fill the tank to half full (to represent an average) then measure again and adjust as necessary.

But I have to hope tat I dont get any tyre rubbing on the front arches.