LegendsRacer - Legends & Bandolero Racing Forum
LEGENDS => Setup and Handling => Topic started by: canadianwheels on November 07, 2007, 11:33:37 pm
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hi guys, im a newbie to this forum, and have found it an excellent source of information. my question is this, is there a crossweight % maximum, in the inex rule book there are left weight and front to back maximums but nothing is said about cross weight, thanks for any and all info guys.
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I dont believe there is a rule on it. But if you have too much cross you'll rely on the RF tire too much, where as too little relies too much on the LF. Cross is all about finding the happy medium that gets all 4 tires to do equal work and not working one tire more than another. Dont know if that helps or not. ???
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Hey Canadian Wheels...where are you located?
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in alberta canada
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"The basic idea of cross weight, is to get enough weight on the left rear tire to obtain proper traction coming off the corner. If the car is loose, add cross weight. If the car is pushing, reduce cross weight. More cross weight also tightens the car on entry into the corner.
Another thing to consider is stagger. Tire stagger works closely with cross weight. As a general rule, the more cross weight a car has, the more stagger is needed. Adding stagger to the rear decreases cross weight."
To calculate cross weight:
1. Weigh all four wheels ( be sure to weigh with driver in car, or similar weight)
2. Add totals together to get Total Vehicle Weight
3. Add left rear weight and right front weight to get Total Cross Weight
4. Total Cross Weight divided by Total Vehicle Weight = Cross Weight Percentage
There is a lot more info in Steve Smiths', "Dwarf Car Technology" book.
Hope some of that helps.
Steve
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I do not think cross should be thought of as a major tuning tool. Cross is about timing of weight transfer more than anything, and it is a coarse adjustment. Timing is effected by weight, vertical center of gravity, speed, turn radius, and track grip. Think of those factors as components of G forces. More cross will resist full transfer longer, and rebound transfer sooner. This transfer is mainly off the left rear and your adjustment is the dynamic distribution of transferred weight between the two RS tires. As the components of the G forces combine to create higher G's, you will need to raise cross to preload the suspension to resist transfer more, otherwise it will transfer to a greater degree, sooner, and take longer to rebound. If cross is too low, you will be loose just after entry and remain loose through the apex and into the exit because there is not enough resistence at the RF to keep the car from transferring too much weight from LS to RS too fast. If you have too much cross, the car will not transfer enough weight off the LR soon enough or long enough and the car will push from just after entry until, through the apex, and on exit.
Spring weights also effect amount of transfer and speed of rebound, as do shocks.
I try to keep my cross as low as necessary and work to get my handling with springs, radius rod lengths, camber, caster and brake bias. Cross does bind up the car and it will slow you down.
Good rule of thumb. Provided you don't have something way out of whack, entry problems are fixed with front end adjustments and exit problems are fixed with rear end adjustments.
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If I get my ride heights where I want them, it will change my numbers drasticly. For example I went from 50% to 38% . What kind of trouble is this going to cause me? JRTeam
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38% won't work. As I don't know any details on your set up; It is hard to give you much information. As Scott and Vern are racing in your area, perhaps they can be of more help.
Steve
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Steve what info do you need?
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Steve Why wont this work? what will the car do?
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Track info... size, banking, paved or dirt...
Current ride heights, shocks, springs, tires, caster, camber, toe, etc...
Jeff has some good information as to set up for dirt and asphalt on his site. Might give you a good start. Check this link:
http://www.jeffsteenbergen.com/setup.htm
Steve
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Steve Why wont this work? what will the car do?
Improper weight transfer. Car won't handle properly.
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Scott or Vern,
Can you help get him in the ball park for the tracks out your way?
Steve
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Set your ride heights first off. If you are at 38% cross, its too low. You have to adjust all 4 adjusters at the same time to maintain ride height and change the cross weight. Its really easy to do.
to lower the cross weight To increase the cross weight
1) Compress the right rear and left front. 1)Decompress the right rear and left front
2)Decompress the left rear and right front 2)Compress the left rear and right front
a 1/4 turn on all four will increase or decrease cross by almost 1% and the ride height will stay the same.
If you are on asphalt a starting spot would be 48%, depending on the rest of your set up.
Dennis Knox
Buckeye Legends
330-310-9212
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Dennis beat me to that Steve but he is right. 38% is way to low and the car would be SOOOO loose. I have heard that you have to loosen up the car a bit with the new tires but until I get out the sand box I will just have to read about it for now.
Scott