Ride height review

[echrisconnor]

OK. I'm trying to revise the ride height on my 911 and would like to assess how low is too low. I don't want the car to be slammed, or lowered excessively, but I'm putting on smaller wheels and making adjustments to ride height accordingly.

Ride height as described by the manual is the difference from the center of the torsion bar cover to the center of the road wheel.
What I'm interested in is simply the distance from the ground to the center of the torsion bar cover. This measurement should be a better indicator of ride height independent of the wheel diameter.

If any of you have this measurement available, I'm interested. I'm changing from a 185 70 r 15 front wheel and 215 60 r15 rear to 205 55 r15 front and 225 50 r 15 rears on 7" and 8" fuchs. This smaller diameter may affect my ground clearance which is currently set at the factory euro height.

[wckrause]

Ride height as described by the manual is the difference from the center of the torsion bar cover to the center of the road wheel. What I'm interested in is simply the distance from the ground to the center of the torsion bar cover.

I think you have that backwards. If you measure from the ground to the torsion bar, then the diameter of the tire will be part of the measurement. The first method (center of torsion bar to center of wheel) is independent of tire size.

[echrisconnor]

Bill,
You're right - the factory measurement method is independent of the tire diameter. I guess what I'm really after is ground clearance. The factory method should retain the same measurement regardless of wheel/tire diameter, while the ground clearance will be different. As I put smaller diameter tires on my wheels, the factory measurement remains constant, however the car is now lower to the ground.

[wckrause]

Sorry, I see what you're after.

You can calculate what the difference in tire diameter will be when you switch tires (or get it from the manufacturer). Half of the diameter change will be how much lower your car will be. (you probably knew that).

I run 205/55R15's and 225/50R15's on 7 x 8 rims as you are planning. My car is extremely low, probably as low as you can get and still clear the fenders. I can't say that I recommend it for a daily driver. Driveways and parking lots make me nervous.

[echrisconnor]

So, you're running the same combination of tires/wheel size I'll be using. In looking at your gallery photo, your car doesn't look too low, and the tire/fender gaps look good as well. You don't happen to know your ground to torsion bar center measurements do you? I suppose, since we're talking about the same combination of wheels/tire sizes, the difference measurement would be appropriate as well. Is it factory euro height?

My car is not a daily driver, however, I want to be sure not to lower it to the point of constantly dragging the ends in every parking lot or gutter.

[1980SC]

I have 15x7 and 15x8 fuchs off my old 944 that I plan to use shortly with the above mentioned tire sizes. I'd like to lower the car just enough so the wheel gap doesn't look stupid with the smaller tires. Is it necessary to raise up the steering rack? Did you, Bill?

Thanks,
Rob
1980SC

[wckrause]

Yes, I did. I got a lot of bump steer without it.

I don't know my heigths off hand. I had it lowered and aligned about 8 years ago, and haven't touched it much since. I can take some measurements for you, but right now it's sitting on jacks waiting for a rebuilt pedal assembly.

The trouble with 15 x 7,8's is that there's not a lot of choice in tire sizes. I'd really prefer to have 16's, have stock tire diameters, and get the car off the ground a little more.

[echrisconnor]

Do you have turbo tie rods? I've just installed them on my car and haven't driven it yet. I'm assuming that they'll get rid of a good deal of the bump steer unless the car is really low.

[wckrause]

No I dont' have turbo tie-rods. I hadn't heard that they help bump-steer before.

[Glasgow 911SC]

I installed turbo tie rods on my car and they improved bump steer no-end. Definately a must do upgrade.