Caster angle questions

[day215]

While I wait for my FXR to arrive from a recent trade that I made, I thought I might add a little caster to my front end. Here my question, what is the degree of caster measured off of? I set my pinion to point at the tranny, when I measure the angle of the chub in relationship to the ground, it comes in at about 60 degrees. I see people talking about running 15-20 degrees, am I measuring wrong?

[highlandcrawler]

You look closer to about 30deg. You measure with the pinion level

[TSK]

Originally Posted by highlandcrawler

You look closer to about 30deg. You measure with the pinion level

False. When you measure caster for alignment or caster measurement, you measure perpendicular to a level surface (table top, work bench, etc)

Everyone's pinion angle varies, so there would be no way to get an accurate caster angle from that.

So on the Day215's caster gauge, 90* would actually be zero caster. 80* would indicate 10* of caster, 70* would indicate 20* of caster.

If he wants 15-20* of caster, his gauge should read 70*-76*

[day215]

Highland Crawler, Thanks for the suggestion.

I'm going to have to side with The Scorpion King though, I did a Google search and it shows an imaginary verticle line that passes through the center line of the axle. If I based it off of a level pinion, it would be very close to stock. Basing it off of the imaginary line, I could raise the pinion to gain clearance while still adding caster to effect steering.

Here's by issue, the 20 or so degrees that most seem to run, just doesn't seem like enough. With a level pinion, it darn near stock. I keep looking to around 27-30 degrees, with a raised pinion or a level pinion, it seems to look best. Notice I said look, as I haven't tested it yet. What degree should I be shooting for?

Originally Posted by TheSCorpionKing

False. When you measure caster for alignment or caster measurement, you measure perpendicular to a level surface (table top, work bench, etc)

Everyone's pinion angle varies, so there would be no way to get an accurate caster angle from that.

[TSK]

Originally Posted by day215

Highland Crawler, Thanks for the suggestion.

I'm going to have to side with The Scorpion King though, I did a Google search and it shows an imaginary verticle line that passes through the center line of the axle. If I based it off of a level pinion, it would be very close to stock. Basing it off of the imaginary line, I could raise the pinion to gain clearance while still adding caster to effect steering.

Here's by issue, the 20 or so degrees that most seem to run, just doesn't seem like enough. With a level pinion, it darn near stock. I keep looking to around 27-30 degrees, with a raised pinion or a level pinion, it seems to look best. Notice I said look, as I haven't tested it yet. What degree should I be shooting for?

I too, have to side with myself on this one

Point your pinion towards your trans, and attempt to get 20-25* of caster in realtion to the imaginary line (imaginary line being perpendicular to level ground).

You don't want TOO much caster, as the tire will flop over onto it's sidewalls and you will ultimately lose traction and steering.

[Manning]

Caster is measured from vertical.

Pinion angle has exactly nothing to do with caster.

Aim the pinion at the trans output (least stress on the ujoints for RC crawlers), and then lean the knuckles back ~20 degrees from vertical, or whatever angle you feel like.

[day215]

Theoretically I could pound the pinion straight to the sky and 20 degrees would still be 20 degrees, right? When I aimed the pinion at the tranny, it cocks the front servo plate down at such an angle that the steering linkage issues seems almost impossible to work around. I'm prepared to mod my steering around the raised knuckle arms, but the steeper the plate gets the worse the clearance becomes.

I'm using a VP 4 link servo mount/ venom standard clearance knuckles/ standard front side draglink setup. Any suggestions on linkage issues?

[highlandcrawler]

I see. How is it measured with the axle off the vehicle?

[day215]

I suppose you could mock it up with the desired pinion angle and go from there.

[highlandcrawler]

Originally Posted by day215

I suppose you could mock it up with the desired pinion angle and go from there.

I mean just in general for an Axial axle.

[Manning]

The VP mount wasn't well thought out. I'm running one, but there's not much left of it. I had to move the servo back quite a bit to help with linkage interference, but they got so hole happy there isn't much room to move it. I'd like the servo another 1/4" further back. You might as well start with a blank piece of aluminum.

[TSK]

You don't have the have the pinion pointed straight at the trans. A little off is still ok.

But eah, high clocking provides a lot of issue. You just have to ge really craetiive with it. All standard servo/battery/4 link plates are gonna have the servo in a poor position relative to highly clocks knuckles.

[day215]

Originally Posted by Manning

The VP mount wasn't well thought out. I'm running one, but there's not much left of it. I had to move the servo back quite a bit to help with linkage interference, but they got so hole happy there isn't much room to move it. I'd like the servo another 1/4" further back. You might as well start with a blank piece of aluminum.

Yeah, I started cutting the plate up long ago. I thought about moving the servo back a few millimeters, or possibly fabbing up some wedges to tilt the front of the servo up and possibly back.

[TSK]

Originally Posted by day215

Yeah, I started cutting the plate up long ago. I thought about moving the servo back a few millimeters, or possibly fabbing up some wedges to tilt the front of the servo up and possibly back.

There are angled servo mounts available from numerous manufacturers. You;d probably just have to cut the rear of the plate to allow the servo to drop down in the back though. But ultimately, you may run into different clearace inssues.

I think that's why Chris the battery man is using a standard axle mounted servo setup. Much easier to come up with a linkage soluition.