I have just placed a non standard engine under the car and made up short struts to replicate 1/3 compression this I assumed would be neutral position. This looks too low so could some kind soul please tell me say the agreed factory hight say base of sills to ground assuming that the base of sills are supposed to be horizontal?

I think there's a diagram in the service manual that shows all the dimensions ... don't have one at my disposal at the moment.

Ground clearance at max. total weight-- 130 mm/5.11 in.

The Haynes 914 manual has a procedure for measuring and setting the front ride height in Chapter 7, paragraph 16.7. The formula is: a - b = 3.54 +/- 0.19 inch, where a = distance from centerline of front axle (wheel) to ground, and b = distance from centerline of front torsion bar to ground.

Of course, most people probably set the front lower to get the downward rake look.

The manual doesn't give a rear ride height, at least that I could find.

The info I gave was copied and pasted from the factory manual.

Thanks for the information, that will make things a lot simpler, is it safe to say sills should be horizontal? I can place solid suspension at the rear so can play with drive shafts and engine positioning, its just welding in engine mounting points once done is no fun changing.

Remember that ground clearance depends heavily on tire size, among other things. The original size was 165/80-15, unless this is an early car with the base wheels and tires, in which case it was 155/80-15. Or a Six with the 14" Fuchs, which I think held 165/80-14.

The above is one reason that ground clearance isn't often thought of as that useful. Also because the front ride height is trivial to change.

I believe that the US-destined cars came with something of a nose-up attitude to meet bumper and/or headlight height requirements. Frequently the nose was lowered down to more even with the front, or possibly lower because the 911s have a 1-degree rake and some people like to emulate that.

The rear springs, if original, are usually sagged down so the rear height is practically never the same as it was originally.

Usually we advise people to set the car to the ride height that they like, as long as the A-arms and trailing arms do not go past level to the ground at rest. (And that's rather low, trust me!)

Changing the rear ride height usually means changing out the springs, unless adjustable spring perches ("coil-overs" or the Koni Or Bilstien shocks with snap ring adjustment) have been installed. So sometimes the rear height is simply whatever it is. The front is set by turning the adjusting bolts.

I hope this helps, though likely it just muddies the water...

--DD

14" were 185.

Thanks, I had forgotten that!

--DD

Not many cars came with 155s, except for the early "base" models. The speedos were different for those cars, too. Most came with 165s. Sixers came with 15" steel wheels, 14" Fuchs alloys, or 15" Mahle alloys. Those tires were probably all 185s.

The Cap'n

If you use the formula posted above, it is always based upon your tire diameter, so you will be safe.
I do this, then measure the front of the rocker to ground and add 1/4 of an inch to the rear of the rocker to give you a very slight rake.
I have found this is a good setup that positions the rear just right for autos, and fun street driving.

Rich