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Author Topic:   Modified weight
ronnypete
Member
posted July 08, 2000 11:08 AM
We are running a Pro-Chassis Modified converted to a wissota superstock.Last year we had a problem with bite coming out of corner and a mod driver and chassis builder advised us to add 200 lbs. to the rear.We can run as light as 2800 lbs. and adding the 200 put us at 2992. The car had better bite and runs quite well but was still loose. We checked the 4 link rear and found we had 7/8 inch LR lead. changed that to 1/4 inch RR lead and the car handles much better. Now the Question?? Our weights with the 200 on the back end are LF 656 RF 632 LR 982 RR772 54% left 58% rear and 53% cross Do we or can we take 200 of and run.It seems that without it we had only 51% rear and had trouble setting the correct per-centages. Also the track we run on gets very dry and dusty making it very hard to run without spinning out. any help on either of these Thanks


jammin
Administrator
posted July 08, 2000 12:26 PM
The total of the weights you gave me come out to 3042 and the rear is 57.65....What part of the car did you add the lead to? If It was over the top of the rear end, I would probably leave it there. That rear percentage will help you keep the car's rear tires on the ground. But I bet if you took about 1/2 of that off of the car and increased your cross by about 50 lbs, you would be better off. This will put you closed to the weight limit. I think that it would be possible to run about a 53.5 or 54 rear weight percentage on this car and get away with it, simply because the car's weight is greater. This means that your still putting a certain amount of weight on the contact patch per square inch so as to hook the car up. When you get into heavier cars, from my exeriences, the less rear percentages you have to run for this reason. Tires are a factor too, but overall this is what I have come up with. This is generally why imca's and some of the other lighter cars have to run more rear, because the weight is lower and you still have to get the same amount of weight on the tires for them to work correctly. The lead that your running will hurt you also, if you run straight up, it will also tighten the car up more if you remove the lead.

Just a thought, hope it helps.

jammin

[This message has been edited by jammin (edited 07-08-2000).]

ronnypete
Member
posted July 09, 2000 10:24 AM
Thanks for the help Jammin. I would like toadd that the lead is a 200 lb.hunk mounted behind the 22 gal fuel cell not above the rear end. we can take it off and mount a coupe of 50 lb. weights. Would you suggest placing them above the rear or elsewhere. Also with the 200 which is shifted slightly to the left side we now have very little adjustment left rear coil adjuster. I also woud appreciate your advise as to how much cross to run. Thanks


jammin
Administrator
posted July 09, 2000 12:43 PM
What I would do is add the weight over the rear....try to get it in the centerline of where the top spring mounts are. What this accomplishes is that it will allow you to run a tighter(faster) car without the front end washing out on you. If you add the lead on the very back of the car, it tends to take weight off of the front wheels(I have played with this on the scales). When you take weight off the front wheels, you have just made your car less steerable than before. You want to be able to run your car as tight as you can without pushing, this will make you faster. If you take away your steerability, then the car could push easier with less weight on the rear tires. This is one of those small things that can make a big difference in a race.


jammin
Administrator
posted July 09, 2000 12:45 PM
Sorry, as far as the LR lead, I would leave your crossweight the same and straighten the rear up square and see how it acts before I would change the cross.


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