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-   -   Looking for input on track ride height. (http://forums.pelicanparts.com/porsche-911-technical-forum/209868-looking-input-track-ride-height.html)

chrisp 03-07-2005 01:42 PM

Looking for input on track ride height.
 
It's an SC with:

23/31 t-bars
22/22 sways
8x9x17 on dot-r rubber
Full race set up (track only car)

I'll take it in fender to ground, torsion bar to ground, or any other measurement you may have.

Thanks!

lally911 03-07-2005 02:38 PM

My 85 with 23/31 t-bars and Michelin cups on 7,9x16 fuchs sits about 24.25 in the rear and 24.75 front - fender to ground.

cstreit 03-07-2005 03:16 PM

Chris,

Your perfect ride height for a race car is really dependant on several things... Your optimum suspension angles, spring rates, and right balance.

You MUST understand your spring rates and what the suspension does under full "normal" compression. Placing a zip-tie over the shock tower, then driving a few laps, and seeing where the zip tie ends up is a good way to get an initial measurement. I start there.

Ride height in a track car should really be set based on where you want your suspension angles. For example, I've got a somewhat customized suspension. During the travel your geometry changes. You want your OPTIMAL geometry to be reached when you are under cornering load (when grip and angles are MOST important). For example, once your suspension angles get "below level" the geometry can start changing in a sub-optimal manner. I set my rear ride height so under full corner compression the suspension swing goes just below level.

So lets say under a good corner your rear compresses about 2 inches. You then know how much your rear will pivot. Make sure that the center of your normal travel has the suspension angles approximately flat.

The front is then set at rest based on where I want my balance, say 60/40. That gives you the rake as well.

This gives you a good starting point for a good racecar setup.

smestas 03-07-2005 04:20 PM

Quote:

Originally posted by cstreit
Placing a zip-tie over the shock tower, then driving a few laps, and seeing where the zip tie ends up is a good way to get an initial measurement.
Can you comment a bit more about this test CSTREIT? I tried to picture it in my head and dont understand exactly where you would put the zip tie.

ted 03-07-2005 04:31 PM

Quote:

Originally posted by smestas
Can you comment a bit more about this test CSTREIT? I tried to picture it in my head and dont understand exactly where you would put the zip tie.
He might be trying to estimate the wheel travel on compression only. If the dust cover is off, with the wieght of the car on the shock place the tie wrap around the shock rod so it rests on the shock body. As the shock colapses the tie wrap is pushed up, measure how far it moved and you'll know how far your suspension is compressing.

cstreit 03-08-2005 05:22 PM

Ted is on the money. This will measure your compression. What you want to avoid is banging off racing curbs when you do this so you get an idea of what your "normal" compression is. This gives you a good baseline.

Extension is much more difficult and requires Data aquisition devices designed to measure compression and extension...


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