Van

I still don't think I buy it... let's say that a compressed spring is 10" long. And the distance from the spring perch to the spindle (wheel center) is also 10". This puts the camper plate (top of the shock tower) at 20" + wheel radius above the ground.

If you lower the bottom spring perch 1 inch, there is now 9" between the spindle and the perch. The loaded spring is still 10", so your ride height will be 1" *lower*.

What actually happens is this corner of the car will come down *less* than 1" - because the wheel on the other side will help hold the car up some. So, the diagonal of the wheel you lowered the perch on will be supporting *less* weight. And the diagonal of the other wheel will be supporting *more* weight.

If you lowered that spring perch all they way so the spring no longer had *any* compression, then that wheel would not hold *any* of the car's weight. You would be able to press down on that fender and get the car to see-saw on the other diagonal.

Make sense?

PorscheDoc

Raising the spring perch in the RF is going to raise the height of that corner of the car, but lower the weight on that corner, and also lower the weight on the diagonal corner (in this case the Left Rear), while raising the weight on the left front and the right rear.

theedge

Heres the spreadsheet Van has, right click save as to download.

http://thedge.info/rennlist/cornerba...lculations.xls

johntorg

According to the spreadsheet, my corner weights were within 10lbs of being optimised for the current Left/right weight distribution, before I "adjusted" them.

Left Front Right Front

734.6 678.4



Total Weight
2866




Left Rear Right Rear

755.4 697.6

Thanks for the spreadsheet.

johntorg

Raising the LF spring perch actually raised the weight on the LF and RR.

Van

That's what I'm saying!

jerome951

John,

Did you remember to disconnect the sway bars?

The only concern I would have is there is a 22# difference in your before and after weights. Assuming you didn't remove anything from the car, it's hard to feel confident when you're trying to adjust to within 5# or so when your scales vary that much.

Anyway, as you found out, raising the RF perch put more weight on that wheel. You went the wrong way. I usually get to within ~5# and call it a day.

A setup tip for you. Get the rear as low as you can then start corner balancing. If you look at the front running Cup cars, it looks like spare tire well is almost dragging the pavement.

johntorg

Thanks for the advice. I'm pretty sure the weight difference is just in the amount of fuel onboard. My next step is to reset the camber and toe.

Lemming

Van, you might be right, will have to look at my coilovers and check my notes when I get home.

Jerome - are you suggesting negative rake for the car setup, or just getting all 4 corners as low as possible?

jerome951

Not sure if the cars I've seen actually had negative rake, but they were very low in the rear. I've got the rear of my car as low as it will go. I could probably drop the front a little more but want more weight in the rear since my front end is heavy.

TF

Is it pssible to come close to a corner balance, for a mainly street car, by adjusting the ride heigth. I have a Bilstein coil over setup without torsion bars, I weigh 180#. If I set the driver's side 1/4 " higher will I be in the ballpark or am I wasting my time trying to savemoney

THANKS

jerome951

If the coilovers are height-adjustable, then, yes, you can corner balance it to within a fair degree of precision.

The main question then becomes, is it worth the cost and effort for a mainly street-driven car? My response would be 'no'. Set the ride heights to be fairly even side-to-side and drive it...

Van

TF, without scales, I think you're just wasting your time.
A) you don't know how the car is balanced before starting
B) ride height isn't the dictator
C) depending on spring rates, 1/4" could mean something totally different

Either do it right, or don't do it at all. Just blindly messing with an unknown setup won't make it any better.