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Old 01-19-2012, 07:12 PM
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32' Ford - too much caster angle?

So I grabbed my handy angle gauge and measured about 12 degrees of caster, leaned back from zero. I've done a ton of reading that suggests an angle od 7 to 9 degrees is optimal. So is 12 gegrees too much? Should I try to correct this? What would be the worst that could happen if I left it alone? I've heard that the more caster the more stable the car will be at higher speeds. I put the gauge parallel with the kingpin/pivot point of the hub. Is it possible I measured the angle wrong? I'm runnning an I beam with hair pins.

Thanks,
Jim
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Old 01-19-2012, 08:16 PM
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The "usual" caster angle is 5-7 degree's.....and yes it's possible you measured it wrong, need some pics with the tire removed to better clarify. What kind of chassis is it and who built it, a pro or a driveway job?? Too much caster can cause wheel shimmy or "death wobble" at slow speeds. I've seen drag cars do that at slow speeds because they are running a ton of caster.
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Old 01-19-2012, 09:10 PM
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Remember you have to include the "rake" of the car in the caster angle in order to get an accurate reading. If you've got big'n littles then your chassis has 2-4 degrees of rake which will effectively subtract from the measured caster.

Here's an illustration of what I mean, (not my car).



On my Deuce I have a caster of 11 degrees (measured with the chassis level to the ground), however the actual caster winds up being only 8 degrees due to the rake of the chassis with the tires and wheels I'm running.

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Old 01-19-2012, 11:39 PM
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Yes well said and illustrated, I forgot to also say that these measurements should be taken at "ride height" with the wheel/tire combo you're going to run and the car on the ground.
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Old 01-20-2012, 08:21 AM
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Increasing castor angle will increase the "effort" you put forth in turning the steering wheel and will also increase the turn radius (wider turns). Other than that, there's no real down side...

Russ
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Old 01-20-2012, 02:35 PM
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I have seen that pic somewhere before, can't remeber where. Thanks for throughing it out there. So if I understand this correctly I should measure caster angle in reference to the bottom of the frame (as shown in the pic)? So now I'm thinking I might use a floor jack to gently put a 2x4 against the bottom of the frame and then measure that angle from plum. Then subract that angle from my original 12 degrees. We'll see where I end up.

Thanks guys,
Jim
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Old 02-06-2012, 06:12 PM
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Well I finally made my adjustments to the front end. I was a little nervous about taking the rear of the hair pins loose from the frame. I wasn't sure how much tension would be there. I slowly and gently took everything loose and whala... no sweat. I noticed the bottom cleves on the bat wing had way more threads showing than the top cleves. Also the front spring looked like it was tweaked due to the excessive caster angle. I turned it in a little more each time until I ended up at 7.5 turns on each side. I then needed to adjust the rear hair pin bushing where it connects to the frame so it would line up with the holes and made the same adjustment on the other side. Bla bla bla. Now the caster measures in at 8.5 degrees, minus the 2 degrees of rake which puts me at 6.5 degrees of caster. That puts me somewhere in the middle of the recomended 5 to 7 degrees. Cool.

Thanks guys
Jim
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