Method to tell torsion bar dia. while still in car
01-09-2004, 09:18 AM
#16
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To calculate the diameter could you not just wrap a piece of string around the bar, make a pen mark across both end of the string where they cross, remove string from car, measure distance between pen marks and divide by Pi (3.14ish)?
Neil
Neil
01-09-2004, 10:39 AM
#17
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rates
Charlie,
Did you read my method? If you have race scales, it's easy. First, if your arms are approximately parallel, the error is smaller than the differences between the rates of the bars.
Put the car on the scales.
Note the weight on each rear wheel.
Measure from the center of the wheel to the top of the wheel well.
Raise the rear of the car until the measurement increases 1 inch.
Note the weight on each rear wheel.
Simple math: subtract the second weight from the first, this is the wheel rate of the torsion bar.
Consult the chart at Paragon. If it's 220lbs for example, you have 27mm torsion bars. 26 is 189, 28 is 254, hopefully your error is less than the difference between bars.
Measuring
Did you read my method? If you have race scales, it's easy. First, if your arms are approximately parallel, the error is smaller than the differences between the rates of the bars.
Put the car on the scales.
Note the weight on each rear wheel.
Measure from the center of the wheel to the top of the wheel well.
Raise the rear of the car until the measurement increases 1 inch.
Note the weight on each rear wheel.
Simple math: subtract the second weight from the first, this is the wheel rate of the torsion bar.
Consult the chart at Paragon. If it's 220lbs for example, you have 27mm torsion bars. 26 is 189, 28 is 254, hopefully your error is less than the difference between bars.
Measuring
01-09-2004, 11:45 AM
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Originally posted by Charlie944
Adam, sounds like a good method, I have access to a set of scales for racing to figure out the weight and acheiving full droop can be done. I guess what I can do is compare my result and match up a torsion bar rating that has been confiugured to how a coil spring rating is measured for ex: X amount of pounds moved it one inch...BUT that is a linear compression....the spring is roughly square to the movement. A torsion bar has a mechanical leverage acting on being the rear spring arm...so can a ONE inch moved at X pounds be accurate when the torsion bar is converted to a poundage rating like a coil spring??
Thank you again for all your responses!
Adam, sounds like a good method, I have access to a set of scales for racing to figure out the weight and acheiving full droop can be done. I guess what I can do is compare my result and match up a torsion bar rating that has been confiugured to how a coil spring rating is measured for ex: X amount of pounds moved it one inch...BUT that is a linear compression....the spring is roughly square to the movement. A torsion bar has a mechanical leverage acting on being the rear spring arm...so can a ONE inch moved at X pounds be accurate when the torsion bar is converted to a poundage rating like a coil spring??
Thank you again for all your responses!
01-09-2004, 12:00 PM
#19
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Torsion bars are linear rate. If a 100lb weight on the end of an arm moves the bar 1 degree, a 200lb weight will move it 2 degrees, etc.