Coilover track suspension

[merl]

Can you guys with experience in the coilover department give me some more info on how exactly to choose a starting point on this stuff. People that run them on the track but all info is welcome. 

 

1987 535is

 

Current - Spax springs with Billy sports and 22-front (set middle) / 16 rear (set stiff) sway bars. I have camber plates on the front but I am not able to get anywhere near the camber I need. I like this setup although it is a bit soft. 

 

This has come up as I have some new wheels and tires I would like to run next year (see pic below) which will require more negative camber in the front.  

 

The spring chart below shows popular aftermarket springs for the e28 (I currently run the Spax SSX). 

 

I would like to go with a fairly aggressive coilover setup specifically for the track (the car gets very little street time). But, the car won't be trailered to the track all the time. I will need to be able to drive it to the track as well. 

 

I would like to try to understand a starting point for spring rates and how that relates to the shocks (adjustability) as well as sway bars. I will be running race camber plates as well as strut braces. 

 

Thanks !!

 

 

 

[B C]

Dive into some theoretical calculations to arrive at some spring rates to try. When you decide that it just isnt feasible to acquire some of the data you need to complete the calculations or you actually do come up with answers,  then compare this with what you know about your current setup and spring rates and make a Scientific Wild Ass Guess (SWAG)

Then when you purchase them and find they aren't what you were hoping for, adjust/try again. 

 

Please understand that this reply is intended to be informative and not a jackass type reply. Its very fascinating stuff but when I went through the calculations years ago I came to the determination that I dont have some of the data I need (or accurate enough data) to make solid calculations and that there are numerous small factors that equations do not account for that are going to cause theory to differ from reality. In this case, decisions are made off of informed personal experience and continually adjusted upon. Hopefully some of the information will help steer you closer to a starting point. 

 

 

 

http://www.optimumg.com/docs/Springs%26Dampers_Tech_Tip_1.pdf

 

http://www.optimumg.com/docs/Springs%26Dampers_Tech_Tip_2.pdf

 

http://www.optimumg.com/docs/Springs%26Dampers_Tech_Tip_3.pdf

 

http://www.optimumg.com/docs/Springs%26Dampers_Tech_Tip_4.pdf

 

http://www.optimumg.com/docs/Springs%26Dampers_Tech_Tip_5.pdf

 

http://www.optimumg.com/docs/Springs%26Dampers_Tech_Tip_6.pdf

[HipMF]

Another good resource:

 

http://farnorthracing.com/autocross_secrets5.html

 

GLHF

[merl]

@nap -- Your post is informative and I took it that way ... no worries

 

Thanks to both of you, I think these resources along with what others have done on the e28 chassis will help a lot. 

[Rowleym]

at least common sized coilover springs and cheap and easy to replace! 

[merl]

Agreed. Just trying to narrow down my starting point and learn a bit more about them.

[Brian.]

Theres a few more coilover setups past these. That are way more then just a different strut and spring combo. 

[merl]

@Brian - The chart is for non-coilover springs. I was trying to show my current non-coilover spring rates (Spax SSX) for comparison. Sorry if I was not clear there.

 

An example I found from someone running slicks on the track for the e28 - 7 inch springs front and rear, 650lb front and 550lb rear with Koni race single adjustable shocks.