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Author Topic:   scaling basics
neil rucker
posted March 13, 2003 10:18 PM
need help with scaling car. what precentages am i looking for? what mathematical formulas are used to figure left, rear, cross etc? ideal set up for 1/4 mile to 3/8 mile banked dirt? (starts fairly good then goes dry slick) 2800# car hoosier d55 tires 620/650 gear. as always, thank you

posted March 14, 2003 07:35 AM
Here's your formula's:

Left Side = LF + LR, then divide that by the total weight.

Rear = LR + RR, and then divide that by the total weight.

Cross = RF + LR, and divide that by the total weight.

Example: LF = 750, LR =750, total = 2800, so left side % is 750 + 750 = 1500, 1500 divided by 2800 = .53571, so your left side percentage would be 53.6%

posted March 14, 2003 10:41 AM
This is to 34 you can hide weight if you can but i would try softer spring rates on the rear if you cant get weight. it wont help with percentage but it will help you with forward bite if you use 13 inch springs

posted March 19, 2003 11:32 AM
34racing, I would think that the output of your motor may have some bearing on your question. Is this a hight output motor? If it isn't then you could get by with a low rear %, but if your pulling a lot of torque off the corner then your car will more or less just spin the rear wheels. If you have a reasonably strong motor than you should probably shoot for a comprimise between raising your rear % by adding weight to the car or just running the car at the minimum weight limit. I'd say run the car like it is now and then gradually increase your rear % and record your lap times. Basic trial and error.


[This message has been edited by justin (edited March 23, 2003).]

posted March 26, 2003 11:10 PM
[Pure and simple ADD WEIGHT till you get a lot further along with setup and handling
Thats my opinion anyway We weight 3450 in a 3200lb class and are hard to beat. We also run pump gas on hump heads and only have 9 to 1 compression

[This message has been edited by bobaluuu (edited March 26, 2003).]

posted March 27, 2003 10:53 PM
this is to 34,all the motor in the world does not do any good if you are spinning the need to get at least 51% rear in a street stock,no matter how much lead you have to add.were I race at are min. weight is 3000pds.My car weighed 2770 pds. with no lead,and only had 48.6% rear.I added 320 pds. of lead to the car,it now weighs 3090 pds. and has almost 54% rear when the fuel cell is full.I like a tight race car,I like to be able to bury the car in the corner,and bury the car out.I am starting out the season with these %. rear-54%,Left-55%,and cross is also-55%.I also run between 320 - 400 pds. of bite in the car.Alot of people don't like the way the car feels but there again I out run them on a regular basis.

posted March 29, 2003 09:51 AM
Hey Guys,
I was able to get the car up to 49% rear weight I have 53% left and 49% cross. Car ended up weighting 3350 lbs. so I was 200 lbs over weight. Practice is today so I'm going to see how she feels and then adjust from there.

posted March 29, 2003 01:57 PM
You might see if there are any components you can move to the trunk. I don't know what your rules on the batter are, but if you are able to move that to the trunk it would help a little.


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