diyman25

I will start mine.

1987 FC3S TII base SCCA ITE Race car. 13BPP

Weight 2405 with 150Lb driver

LF RF

609 572


LR RR

649 615

1993 FD3S Touring, Street CAR.HKS T04R

Weight 2936 with 150lb driver.1/2 tank gas

LF RF
746 690

LR RR
779 721


I was very suprise Stock FD3s is very balance on corner weight on off 50LB at each direction. but the shop told me E36 M3 and S2000 can do a perfect balance on corner weigh. This suprise me even more. because I always thought E36 M3 is a nose heavey car......


For my FD. I install my Apexi N1 coilover. straight from BOX did not do any ADJ. the car look ok, but on the corner weight machine the spec is like this

LF RF
709 709

LR RR
6xx 8xx

so people when you buy a coilover please do corner weight other wise you are almost wast your money.....

speedturn

iTrader: (1)

I run the #79 solid blue 1979 GTU road racer. The first gens are notorius for being heavy on the left front, and a little light on the right rear. Weight with strong 13b PP carbureted engine, massive G-Force GF-5R transmission, very stout roll cage, full unibody chassis (not tube frame), lightweight glass fenders, near empty tank, and without driver is 2040 pounds. Exact corner weights are classified

Shaving weight off of a road race car makes for much faster lap times than adding more horsepower.

When a car has the soft stock street springs, which may be 150 pound per inch, if you are off 1/4" on spring preload then you are off by 150/4 = 38 pounds - preload is not sensitive with soft springs.

With stiff 500 lb/inch race springs, if you are off by 1/4" spring preload then you can be off by 125 pounds!! Preload/ride height is very sensitive with stiff race springs. With stiff race springs, a tape measure is not good enough to set up your race car.

Yes, you must use scales to get your corner weights right or else things will be waaay off.

I adjust my coil overs until my ride height is right, then I work to get my cross weights balanced.

Eagle7

86 ITS - with driver

718 665
703 643

LF/RR = 1363
RF/LR = 1368
F = 1384
R = 1345
L = 1421
R = 1308
T = 2729

cpa7man

iTrader: (2)

True, my car has never really been "set up". It's going to be a rental now anyway.

1983 ITA 05

703 540
574 515

Total with 200lb driver and 1/8 tank of gas 2332. Class min. is 2350. I need to start the races with at least 3/4 tank of gas.

RussTypeS

iTrader: (3)

ITA min weight is 2380, you need some ballast!

benny

I will ove to corner wieght my IMSA GTU RX7. If any body has scale in Los Angeles let me know.
Just done the Bump steer, toe, and camber.
Benny

cpa7man

iTrader: (2)

Yes, your right. Guess I need to eat some cheeseburgers before the race.

I took the ballast out, I'll have to put it back in. Should help the corner weights as well.

PaulyDee

Here is the setup for my ITS car:

LF 729 RF 647
LR 679 RR 613
with just under 1/2 tank of fuel and me in it. That's 2668 (12 under minimum). I have to make sure I finish a race with 1/2 tank other wise I break weight.

With those weights it comes up to a %49.7 cross weight which I think is pretty close to perfect.

RX-Heven

iTrader: (1)

Not an all out race car, but I do track it about one weekend a month...

Some basics: Battery relocated behind passenger seat under spare tire cover along with 2 amps and 1 subwoofer, spare tire removed, power steering removed, still have a/c, large fmic (front bumper support removed), Kirk Racing rollbar, full TII drivetrain. Car was aligned and weighted with the targa top removed and top down as required by any road race sanctioning body. 1/2 tank of gas. I weigh 165 lbs.

Cornerweights....with me included of course:
LF (858 lbs)_____RF (799 lbs)-------->49.45%
LR (877 lbs)_____RR (817 lbs)-------->50.55%
Crosswieghts are exactly 50/50
LS total: 1735 lbs (51.8%)_____RS total: 1616 lbs (48.2%)

Total weight with me: 3351 lbs.
Total weight without me : 3186

I do have 382 rwhp @ 16 psi to move the fat pig around.

KevinK2

tot's for driver an 1/8 tank:

1243 703 540
1089 574 515
------ 1277 1055
------ 54.76%left

diag's = /1114, \1218 .... should be closer than 104

ideal adjusted per front back tot's, and left total %

-22.3 680.7 562.3 +22.3
+22.3 596.3 492.6 -22.4
------- 1376 956

But diag's are still off, 1158.6 and 1173.3, 14.7 diff, better than 104

Could be some binding bushings, or preloaded s-bars biasing initial readings.

speedturn

iTrader: (1)

cpa7man's diagonal cross weights are waaaay off.

A note to everyone when adjusting your springs : You need to completely disconnect sway bars when setting springs to try and match cross weights.
After the spring preload is set right, then re-attach the sway bar. If you have adjustable end-links, then adjust them so that there is no preload in the sway bar at normal ride height. If your end links are not adjustable, figure out a way to shim them or change spacers or do whatever you can to ensure that there is no preload in the swaybar. This must be checked with the wheels at normal ride height, not with the chassis on jackstands and the wheels drooped down.

pedalpusher

iTrader: (1)

I recently had my '93 Touring corner weighted. It's still a street car, so no weight reduction yet (obviously) This is with a 200 lb. driver.

796 746
849 733

total: 3125

--
Rob

KevinK2

You are only 16 lbs off at each corner.

Good point by speedturn, s-bar adjusting is best done still on scales. I used levels/strings to establish 4 marked tire points where i drive my car to in the garage. I needed a 1/4" thick plywood square under the right front, to create a true planer surface. S-bars can be shimmed/adjusted there, aft corner balancing.

Also, to correct my prior post, the % method gives the exact neutral corner weights needed. The diagonals are only exactly equal if the car CG is midway between the wheels, either side to side or front to back or both.

Diagonal method is usually very close. The method assumes the diff in diag's divided by 4 is the +/- change needed at ea corner. For ROB, this method results in trivial .5 lb error per corner. For cpa7, 3.7 lb per corner error if diag's are made equal. Pauly sits well balanced, at about 3 lbs off per corner, and diag method would leave him 1 lb off.

Disclaimer: Best corner weights may not be these 'neutral' values for a specific track.

cpa7man

iTrader: (2)

Yea, I sure could use some help with this. Anyone know someone in the Dallas/Ft. Worth area that does this?

TYSON

From the 2 FD measurements it looks like they are a little rear biased stock with fuel?

Battery in stock position, front mount intercooler, A/C, etc? Anything else done that might be affecting this?

Amagi82

where do you guys get your corner weights measured? Just get a scale designed for really fat people, or is there an easy place to use for this? This thread makes me want to relocate every moveable heavy part of my car to the right side, lol.

speedturn

iTrader: (1)

There are special scales made to weigh race cars; the scales cost about $1500 a set. The cheapest thing to do is to go to a race car shop that already has the scales and pay them $25 to $50 to weigh your race car. If you already have adjustable coil over suspension, then for more $ they can adjust the spring preload until the cross weights balance out.