Bone Stock '76 need lowering whats the specs?

[C-Pierce]

I am the proud owner of a 80k mile "S" that is so un-molested it still has the aluminum plates in the front and is still at the rediculous US Spec ride hight.
My question is, what are the right specs for this car to handle like it was built to.
Euro specs maybe??

Anyone want those plates???

HEheh

C

[Paulporsche]

I like to set the rear @ the same or maybe 1/4" higher than the calculated tire size diameter, and then set the front about 5/8" higher.

For example, if you are using 205/60/15s then your tire dia is 24.7" so I would set the rears @ just under 25". This is what was called Euro ride height by Bruce Anderson.

If you are running 205/50/16s then the rear ride ht would be about 24 1/4". Where I live, that's about as low as I figure I can go.

[Grady Clay]

C,

Yes, you can set the suspension system lower. It will look better setting in your driveway.

The issue is more complicated than just static ride height. The key word is suspension system. There are several interrelated things that need to be paid attention to. They are ride height, spring rate (torsion bar diameter), shock rate, sway bar size, tire type and size, rim diameter and width, toe & camber, caster & bump, suspension mounting & chassis stiffness and even tire pressure.

Let’s just discuss lowering a stock suspension. You no doubt realize how much your 911 leans in a corner. It uses a lot of suspension travel on the loaded side. Lowering the suspension doesn’t reduce the amount of lean or necessary suspension travel. Now the loaded side compresses the suspension enough to be riding on the bump stops in the shocks. The stops are highly progressive “springs”, perhaps 3rd or 4th order. Going over a bump with the suspension on the stops is like having no suspension compliance at all. This seriously diminishes the grip and handling.

The same is true for braking. Under hard braking the front suspension can compress the rubber bump stops. When irregular pavement is encountered, the front tires are more prone to locking up.

There are many 911s set to “European” specs and lower. Most, when they install the appropriate complete system, are ecstatic about the improved handling and ride. Some of this is because the handling and ride were degraded when lowered “to look good.”

Suspension is a compromise. A 911 set for use on a smooth racetrack would be very unpleasant and difficult to handle for normal street use. Your stock suspension and ride height would leave a lot of performance on the table when used on a smooth track. After almost four decades of people tinkering with their 911s, there isn’t too much mystery about the appropriate compromises.

At the extreme lowering look at the effort to maintain appropriate handling. The spindles are raised, the rear trailing arm mounts are raised, the shock shafts are shortened, the steering is modified and more. Much of this is to get the car low while keeping suspension travel and not ever letting it ride on the bump stops.

If you have to contend with very rough roads, snow and SUV bumpers, stock settings are best, perhaps softer and higher in some situations. If you are going to trailer your 911 to track events, the other extreme is suitable. There is a wide range in the middle where you can balance having the 911 appropriately low, improved handling yet still not too stiff and rough for normal street use. Most important is that you will have functioning suspension under all circumstances.

Best,
Grady