precision adjustment of caster

[mayuri]

Through the mathematical model got the caster as 1.18 degree(say)....now how can u have such precision till minutes of degree in adjusting caster...see especially if u want ur vehicle to follow straight line the difference between left and right caster should not be more than 0.25of a degree(sae paper by hunter) if the difference is more than that the vehicle will swivel to side with more caster...SO i wanted to know how u do the precision adjustment of caster?

[mayuri]

Through the mathematical model got the caster as 1.18 degree(say)....now how can u have such precision till minutes of degree in adjusting caster...see especially if u want ur vehicle to follow straight line the difference between left and right caster should not be more than 0.25of a degree(sae paper by hunter) if the difference is more than that the vehicle will swivel to side with more caster...SO i wanted to know how u do the precision adjustment of caster?

[exFSAE]

Racecars don't always follow the same rules of thumb as passenger cars.. as I'd imagine this 'Hunter' paper is about.

Make your top a-arm adjustable. Only real quick and easy way of adjusting caster... if you're really interested in it. Few FSAE cars have this feature.

[Mike Cook]

Most A-arms feature either rod ends on the inboard side or shims (for camber adjustment). If you use rod ends you can thread one out and the other one in (this kinda stretches the a-arm, but it is prob ok) or you can do the same thing with shims.

I have never actually adjusted the caster to get the car to ride straight. If we were driving down the highway this is probably pretty important but on the race track I would tell your drivers to man up and hold on to the damn wheel tight http://fsae.com/groupee_common/emoticons/icon_smile.gif

[mayuri]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Mike Cook:

I have never actually adjusted the caster to get the car to ride straight. If we were driving down the highway this is probably pretty important but on the race track I would tell your drivers to man up and hold on to the damn wheel tight http://fsae.com/groupee_common/emoticons/icon_smile.gif </div></BLOCKQUOTE>

okay regarding FSAE it is pretty clear.Thanks!!

just out of curiosity , do Baja ATV's go for this?

[TorqueWrench]

I have done toe adjustment on our school's Baja SAE car before and we did it with two pieces of string and a tape measure. Get your wheel alignment straight and then turn your toe links even amounts until the desired angle is reached. You can calculate how far apart the centers of the tires should be on the front and back edges from some simple calculations. A more accurate way would be to make plates that bolt on to your spindles and measure off of them.

Is it going to be accurate to the .01 degree, no. Is it going to be accurate enough for all intents and purposes, yes.

[mayuri]

Hey thanks TorqueWrench!!!

[TorqueWrench]

Haha. Just realized I posted how to set toe, not caster. Our team had the measurement built into our adjustability, so we never actually had to measure it by hand.

I would think you could make a jig that bolts up to your upper and lower ball joints and you could just stick a dial indicator on it. I am sure it would take a bit more design work than what I just said, but i would think that would be pretty accurate.

I am waiting for someone who actually does suspension (engine idiot here) to come up with a better way.

[MalcolmG]

you have a surface parallel with the kingpin axis machined into the upright, then you measure the angle relative to vertical with a digital level.