Final Weight-Fender height discrepency question-Solved

[F500guy]

I did a weight check with all the car basically done. Numbers are fine, maybe a little tweaking to get the left side a little lower so when the driver loads up, it is balanced. But, the fender height has settled a bit since last time I checked and Passenger side rear is +1.25 inches, and passenger side front is +.75 inches. was hoping to keep both within .75 all around. I think I can make the numbers, but may not make my weight ideal if I jack the spring perches. Other option is at final body work, tweak the rear body mounting holes to drop the rear passenger side or lift the driver side. Is this a common thing to do, my bulb seal is not fully compressed on either side and previous body fitting post indicated if you got the rear holes to align as delivered, it should be good.

Good or bad?

210877

[rich grsc]

DO NOT adjust ride height to try adjusting body height. You are about as close as you can get on weight, no need to compensate for driver weight. Leave that as it is, thats a good job

[Jeff Kleiner]

I've said about 100 times that these cars are not symmetrical side to side---you have a left side and a right side and they are not the same so as Rich said, you DO NOT adjust springs based on fender to tire distances. If you do you'll end up with your corner weights all jacked up (to use a technical term ;). No, it is not common to try to twist the body at the rear to match tire to fender gap and if you do you'll probably affect the fit in other areas.

When you change spring adjustments it affects the diagonal corner therefore the fact that your RF and LR are light indicates that if you tighten the adjuster on the RF (or LR) you can get them closer; i.e. increasing the RF will also increase the LR. As is I wouldn't be shocked if you have RF wheel lockup when braking since that corner is light and will be more so with a driver. A little surprising that the car is almost 2,500 pounds!

Jeff

[rich grsc]

Jeff you are correct. I was looking at left-right percentages. :( It doesn't show a cross weight percentage, I missed that point.

[Jeff Kleiner]

Jeff you are correct. I was looking at left-right percentages. :( It doesn't show a cross weight percentage, I missed that point.

Cross weight is ~48% as it is.

Jeff

[F500guy]

Thanks for the in put, yes I was going to tweak to get more LR and RF, which will improve the difference, I know the most important is the cross weight, but life is a bucket of compromises! I plan to track the car, not sure I will get enough seat time to really dial in weight biases, I am winding down my "Racing for every bit" life. At Portland, I would weight bias my formula car for 3 right hand corners that were heavy breaking, with a bit of trail braking to rotate the rear, will not be driving this car on that edge...

[F500guy]

So, trying not to be to dramatic, I found that the driver side rear spring perch had backed off, probably after endless raises and lowering the last few months, that is why the driver side rear had dropped about 1/2 inch, leading to the large side to side discrepancy (it was less than 3/4 inch last I set it up) I did not use a set screw, as is conventional wisdom, but that corner must have been providing very little compression when wheel was in full droop, and ended up with the spring sliding up and down significantly when the wheel was in full droop since I last played with it. I adjusted the ride heights a bit higher to ensure all springs had a small pressure when the wheel is in full droop. Not fully satisfied, but it is good enough on the cross weight for most driving applications:rolleyes: Amazingly, the fender heights are back to being pretty good, front with in 1/2 inch and back with in 3/4 side to side.

Morale of this story, if you think you have an issue, dig in because there is probable something there, or something you did not know about or have experience with, even when Rich tells you to leave it alone! (Sorry Rich, had to get that in!)

210910

[MPTech]

Is the frame height the same side-to-side for front & rear?

Also, are you corner balancing it with you in the car??

[CraigS]

I think you need to adjust more. You now have a LR that is almost 100# heavier than the RR and the RF is about 75# heavier than the LF. I agree w/ MPTech, you should have your body weight, or close, in the driver seat while measuring. I was never able to come up w/ 190# of weights but got to about 150# which is a lot better than zero.

[F500guy]

Agreed it is not great, I am going to get some miles on it then re-visit. My scales have a weight readout that I can put in my lap. With a little more work,I am sure it could be improved and make my determination for front/rear bias, which I think I may prefer more rake to get that rear number up, initial concern was keeping the pressure on the springs at full droop and solving the wonky side to side that developed. That solved, move on to get some miles on it!