setting caster; normal caster sweep method vs angle finder on spindle

[johnny v]

I have always used conventional magnetic caster/camber gauge , used per the instructions.... place on hub, turn tire out 20*, level gauge, zero caster bubble, turn tire past center, in 20* and read caster......
I recently went to help a friend setup a Harris..... in reading all the Harris info I could find, Harris is selling a new front end package up-date that gives the instructions on setting the caster with a small digital angle finder that you just attach to a flat machined on the spindle and directly read the caster.....
I just can't grasp the 2 are the same...... sweep vs direct reading? Could someone explain the math here so this will quit bugging the heck out of me!!

And don't tell me they are talking about Camber..... yes, it does say put the angle finder on the rotor to read camber... that is easily understood.....no problem with that.... they say use the same magnetic angle finder to do caster....... its the caster sweep deal that has me scratching my head!!

[stockcar5]

caster is a calculated measurement not a direct reading. it basically is the change in camber when the wheels are turned. more camber change=more caster. my guess is they are measuring camber change and converting that into a caster number.

[jsf74]

Awesome idea I'm gonna use this.

[johnny v]

Caster is the difference in the lower ball joint and upper relationship as in the upper is xxx degrees behind the lower.

You can measure it by putting a piece of tubing thats notched on the ends over your ball joint studs and put a angle finder on that and read it directly..

Ive always carried a cut piece of tubing and used this method while on the road racing out of town if needed. Ive also double checked it in my shop.

Yes, I know what caster is....now how does a direct reading compare to a caster sweep of a conventional gauge reading... that is the question.....

[BigBlueFord]

Caster is the difference in the lower ball joint and upper relationship as in the upper is xxx degrees behind the lower. You can measure it by putting a piece of tubing thats notched on the ends over your ball joint studs and put a angle finder on that and read it directly.. Ive always carried a cut piece of tubing and used this method while on the road racing out of town if needed. Ive also double checked it in my shop.

On our mod the upper and lower balljoints studs are different diameters. Do I have to compensate for the diameter difference or just read directly. Do you use this method as your primary method for setting caster or just a quick setup/check at the track.

[HEAVY DUTY]

Caster

You can check caster by putting an angle finder on the machined surface where the top brake caliper bolt goes thru the spindle on a PINTO spindle. The machined surface is parallel to the balljoint axis.If you are using a metric spindle you need a tool that goes over the balljoints or a sweep type caster guage. The T type tool is far more simple to use but is only accurate if your spindles have been reamed straight. Caster is a vertical line thru the center of the 2 balljoints.( like Jeff said) 0 caster would mean that the line would be plumb (90 degrees to the ground) 5 degrees positive means that the line is leaning back 5 degrees from plumb.It has nothing to do with turning the wheels (turning the wheels is just one method to check caster) We make a caster checking tool that we use on our cars that allows you to check caster on both wheels in less than a minute.

[let-r-eat]

All you're doing on a sweep test verses a static situation, like using a tool to measure it directly, is to compare the reading at 20* left turn and 20* right turn. The difference is the caster.The smart level works in the static position only if the chassis is level. Picture having the car setting on a up hill or down hill. The smartlevel on the balljoint doesn't work so well.Always need to keep in mind what we are leveling to. If you're NOT on a level floor the sweep test will work while the static test won't without a little more maneuvering.

[wideopen]

no sweep

GRT sell a NO SWEEP caster/camber gauge,that requires no turning of the front wheels,, it comes with a tool to cut a keyway inline with the upper & lower ball joint,on the spindle snout.

in circle track mag. Sleepy Gomez show's you how to make the t-bar type like DON at lightning chassis uses. DON also made a slick but simple bumpsteer gauge.

i made a caster gauge using the adjuster bolt out of a drum brake setup,one end has a hole that fit the lower ball joint ,,i added a short piece of tubing to the top end that fit the upper ball joint,, the adjuster bolt will spread between the balljoints to keep it centerd ,,i squared off that with 1/2 x 1/2 squared tubing at 90 degree to set my angle find on. works great,,can check both sides in two minutes

[Lizardracing]

Whats a low buck but accurate way to measure a 20 degree sweep of the front wheels?

[johnny v]

Whats a low buck but accurate way to measure a 20 degree sweep of the front wheels?

you can eyeball the edge of your caster/camber gauge... It has a cut on it for that.. ( or at least the one I use has it )

the other guy I help has a lift.... the car is always in the same spot.... he takes an angle finder and a board and paints a white strip 20* out and in right where the tires sit....then just turn it to the painted line on the floor...

or you can spend $$$$$ on a set of turntables with the angle measurements on them...

[washeduptoo]

Harbour Frieght used to have them for about 100, thats where we got ours and they're heavy.