Corner Balance

[Blue Streak 21]

I took the car to a friends shop to corner weight it today. The car had it's ride height previously set at 3 3/4" in the front and 4 1/4" in the rear. The corner weighting process included setting the four scales on perfectly level patches of floor, zero the scales, then drive the car onto the scales.
The car weighed 2750 lbs when first placed on the scales. I then added 5 gal of gasoline, and 200 lbs balast in the driver seat. I could have sat in the driver seat, but I wanted to check out the measuring, so I used balast. The car weighed 3003 lbs with gas and balast.
Initial cross weight was 51% RF to LR and 49% LF to RR - pretty dam close for starters. Usually on street cars +/-1% is all they adjust to, but since we started within this tolerance, we figured we'd try and get it dead nuts. I adjusted the RF and LR to remove a little bit of weight equally off of each corner. I rotated each collar on the shock one full turn CCW to remove some weight. I could have raised the opposite corners to accomplish the same result. We selected the highest corner and lowered it.
This got the cross to be 50.2% and 49.8% respectively. One third of a turn on the RF got it to cross at exactly 50%.
Final numbers are:
Front: 1438 lbs (48% of weight)
Rear: 1566 lbs (52% of weight)
LF: 735 Lbs
RF: 703 lbs
LR: 800 lbs
RR: 763 lbs
51% left bias
I was blown away with how easy this was. I had heard all kinds of stories about people chasing their tails while doing corner weighting. I thought that this would take several hours to complete. I was done 60 minutes after I pulled the trailer up to my friends garage. The key was that the adjustments were minimal and they could be done with the car left on the scales. I didn't have to take off tires to adjust the collars.
This car has great geometry!!! The cross weight was close with a decent ride height adjustment. The front to rear weights are great with 52% on the rear wheels. This means that the car should have awesome mechanical grip. To have the left bias to be only 51% with 200 lbs of balast in the drivers seat is also incredable. The car ought to be very netural.
Off to get it aligned. Then it's ready for the track. Man am I excited.

[btwog]

Great stuff! Thanks for sharing.

It is interesting that the car is rear-biased and with only 5 gallons of gas. With 20+ gallons it will be interesting to see the numbers.

[Cobra4B]

Awesome... surprised the car is so heavy.

[panoz302]

That is right where mine weighted too. The car where often corner balanced by the race school, I have a few worksheets on my car when the school did it. I redid my to get a base to work off of. I am running the bbs wheels ( by the way bss will sell you a new set for this car for $500 for all four), with pirelli d3 slicks from the panoz series. The car handles excellant.

[Blue Streak 21]

Originally Posted by panoz302

By the way bss will sell you a new set for this car for $500 for all four), with pirelli d3 slicks from the panoz series. The car handles excellant.

That's a great price for 4 ea wheels and tires. Are they 18"?

[Blue Streak 21]

I trailered the car to my local Firestone today, and had the alignment done. Firestone offers a lifetime alignment for ~$150. Since this will be a regular adjustment made to the car, I'm sure I'll get my money's worth out of this service.
It took a couple of hours to complete the alignment because the camber adjustment on the driver side was a bi%$&!!! On the lower control arm the spherical end joints are threaded into the rod, and the ajm nut locks them in place. To make the adjustment the spherical end joint has to be pulled out of the mount, adjusted for length, and then reattached. The driver side is complicated by the mount for the rack and pinion steering being right in the way. It took over an hour to get camber set on the driver side. It's trial and error figuring out how many turns per degree. Many, many iterations. The other settings, caster, toe and camber on the passenger side only took 45 minutes.
I set the car with 6 degrees caster, -2.7 degrees of camber, and 1/16" toe out. We'll see how these settings work at the track. First track day next weekend. It's an auto-x, but at least I'll be driving the car. Feb 17th is a HPDE track day. More to my liking. I'm sure I'll burn a full tank of gas!