Weighing the 4 corners

[MY 401K]

I need an education. I was told to weigh the 4 corners of the car with me in it so that adjustments could be made to the shocks which affects weight transfer so that I would hook better.

Is this so ??? Thanks.......John

[Bob In Ct]

Do you weigh the car before or after breakfast at the Snakepit?

Bob

[Wayne Maybury]

While I am certainly not an expert on this subject, I have weighed all 4 corners of my car and I was surprised to see a rather significant difference in the numbers. With adjustable suspension, it is quite easy to have too much weight distributed diagonally, that is left front/right rear or vice versa. The car will be sitting perfectly straight but the weight will not be evenly distributed.

If you decide to weigh the car this way, make sure that the floor is level since any variation in the floor will have quite an impact on the weights.

Wayne

[Junket]

John the shocks has little to do with the corner weight they limit the weight transfer but it is good to have the front half way close and the rear close to one another.I have seen on the front load & unload each side as mutch as 25-40# just by turning the wheels lock to lock.But what I belive is to have the diagonal % set a 0. This transfers equal weight to left & right turns.
Ken

[scottj]

John,
Yes, you should scale the car with the driver. Most likely you will be left side heavy. To get L to Rt bias equal you will have to move or add weight since spring adjustments wont change L to R or F to R bias, only cross-weight.

To get cross-weights equal, I would again move or add weight. If you adjust the coil-overs to change cross weights, you will have unequal ride heights from one side to the other and that will affect suspension and steering geometry.

When circle track guys make adjustments to corner weights (wedge), they typically do it on the left rear and maintain the ride heights on the other corners.

My Cobra, with with the driver, has the ride heights equal across the front and across the rear with no preload on the swaybars, the LF-RR and the RF-LR cross weights within 5#, and Left to Right within 5#.

Scott

[CCX33911]

You want the cross weight to be the same so that the car turns equal left and right.

What you want to do is this:

1.) Disconnect the sway bars so they are not loading the system. Hopefully they can be adjusted at the end so that they do not torque the chassis at normal ride height (no load).

2.) adjust all coil over settings to get the proper ride height at all four corners. Now suspension is physically where you want it to ride.

3.) Check and adjust all alignment settings at this ride height. Camber caster and toe in front. Camber and toe in rear.

4.) Re-adjust ride height if #2 caused it to change.

5.) Recheck #2.

6.) Ok car is riding at the height you want with the geometry alignment that you want. Now scale the car. You have little control over the L vs. R weight and F vs. R weight. You can move things arround in car to change this if desired. You DO have control over the cross weight (percent of weight on RF and LF compared to LF and RR). VERY IMPORTANT: If you adjust all four corners each time you make a change you can change the cross weight without changing the ride height.

Example: your RF and LR add up to 48% of the total weight (and thus the LF and RR are 52% of the weight). Then you would screw down on the RF and LR springs a certain amount each and screw up on the LF and RR springs by the same amount. Start with 1/2 turn and go from there. Check your cross after adjustment and make sure your ride heights are not creeping on you.

7.) Adjust and reconnect the sway bars such that there is no load at ride height.

Detailed Geek Description:
The above discussion is not totally correct, but simplified for general use. What actually should happen is each corner is adjusted by the same FORCE (not number of turns, e.g. 1/2 turn). The adjustment by 1/2 turn, etc. will work if the springs have the same spring rate. If the spring rates are drastically different then the adjustments should be scalled appropriately. For example lets say the front springs are twice as stiff as the rear springs. Then in the above example, you would screw down on the RF 1/4 turn, LR 1/2 turn (making same force adjustment in those corners). Then adjust the LF 1/4 turn up and the RR 1/2 turn up (making the same force adjustment in those corners). This will keep the ride height constant while adjusting cross weight.

Hope this helps.
Gary

[Excaliber]

Don't be fooled by appearance of fender to tire clearance either! My Excal body was "off" a little and one rear tire had less clearance than the other. So I went after the screw jacks to adjust ride height to make it "look" even. Big mistake! Eventually I jacked it up, took off all the wheels, measured the frame with a "plumb bob" to check for twisted or bent frame. How to measure for that and where to take the measurments is critical.

Bottom line. The frame was true, the glass body was not. Adjusting for body "appearance" really screwed up the weight bias. Eventually this was a major factor in WHY I sold the Excal, it was hard to "see" the problem, but I knew it was there. And it bothered the hell out of me. NEXT Cobra, I will measure EVERYTHING before I buy. Straight frame and straight body will be top of the list!

Ernie