Will Ferch, are you out there?

moneymanager · 10-02-2009, 04:56 PM

Have tried to contact you at two email addresses both of which seem to be dead. I need to know what the measurements that go with "race" height in your ride height calculator are...expressed as the distances from the ground to the wheel center and the torsion bar center if possible. Thanks, [/B][/B]

cmonref · 10-03-2009, 04:26 AM

His Pelican name has only one "l" in it, if that helps.

moneymanager · 10-03-2009, 05:36 AM

Thanks, yes, I've seen that. Both of the (old) email addresses I have use only a "W".

aston@ultrasw.c · aston@ultrasw.c's Garage

does this make sense?

2522lb car at 60/40 gives a rear wheel load of 756 lbs

a TB of 31mm has a stiffness of 332

race setup

compression will be 756/332 = 2.28"

If total droop is 5.28"

loaded droop will be 5.28 - 2.28 = 3"

i think i have that right!

moneymanager · 10-03-2009, 01:29 PM

Makes perfect sense, except the car weighs 2250 and the torsion bar is 26mm! But thanks.
Actually Wil's race setup exactly matches my lowered setup with stock bars. So my assumption is that I have the race setup he was modelling, I just need to plug in my new bigger bar diameter and his calculator spits out the answer...24° in this case. If I can ever get the thing back together, I'll be able to test his math. It's been a fight all day and the car is winning.

Wil Ferch · 06:15 PM

Hey...sorry for being away. Its been such a long time since I noodled the numbers on the calculator...but I don't recall the starting point as being relevant to the calculator. Meaning?.... the calculator was meant to "take what you have" in the first place....and then tells you the spring plate droop angle necessary to regain your starting height when plugging in other TB diameters....OR.....what new droop you would need to either raise or lower from where you began with the same TB's you had. I don't recall ever specifically mentioning "Race" or other settings like stock or not. I do know my partner in crime Thom Fitzpatrick took my calcs and made a nice and easy to use spreadsheet ( the "calculator") and may have entered stock vs race settings from that.

I will say this from memory....the Porsche specs that related TB centerline heights and wheel centerlines...never did make any kind of sense to me as it usually ended up with a setting that seemed higher than we all took to be "Euro".....plus at times the numbers just flat out didn't make sense. I always wondered if they were mis-prints that never got edited as the pocket tech books were printed year over year ? Anybody else care to guess?

Does that help? If not....shoot me a specific question to---> ferch dot wil at gmail dot com. I'm doing this phonetically here for obvious reasons.

moneymanager · 10-07-2009, 08:22 PM

Wil, thanks. I'll get back to you when my head is clearer!

moneymanager · 10-08-2009, 12:57 AM

Again, thanks. I was using the calculator. It asks you for one of four different ride heights (stock, Euro, race, and really low) but doesn't tell you what they are. As my ride height was not stock, I didn't know which (if any) of the specified heights I was at, in order to figure how that would change when I changed bars.
Finally it dawned on me that I had to measure my droop angle to see if it corresponded to one of your categories, with my t bar and my weight. Lo and behold, I was at the race height. Then I could change the t bar diameter to find out what the new droop should be with that bar. I used that answer. Got one side very close, the other was about 1/2" too low. But all in all it worked pretty well.
Hope this explanation helps. To sum it up, the calculator wants you to tell it which of four heights you are starting from but doesn't tell you what they represent in inches of ride height. So if you know what your ride height is, but don't know how that height is described by the calculator, you don't know where to start. I hope this makes some sense. Anyway, I got an answer and it saved me a great deal of aggravation! Thanks again,

Wil Ferch · 10-10-2009, 08:10 PM

Well....in reviewing the math I did so many years ago...as recounted here--->

http://tech.rennlist.com/911/pdf/settings.pdf .....

.... I now see that I used a value of about 3.8" as the "at rest" spring plate droop when the car is on the ground and apparently at "stock" ride height. I also now see that Thom Fitzpatrick amended the calculator at some point and now shows 4 different ride heights. I don't know what the "other" 3 settings are, to alter the "core" 3.8" number I showed in my original work.

Thom.... if you are out there .... please comment. I know you and I talked about this some years ago when you so kindly asked me if you can enter these 4 ride height values.....but I never took notes on what these other 3 values were.

Just to complicate this even further.....the 911's of the 70's for USA were indeed raised over the Euro cars....so 2 of these 4 numbers make sense. But even here....keep in mind that for 1983 and later....the torsion bar cars were all set at approximately the same "Euro" ride height, even the USA cars.

moneymanager · 10-11-2009, 06:03 AM

Thanks Wil. I'm glad you were able to understand my feeble explanation. Anyhow I'm now lowered and corner balanced and pretty happy!