Caltrac info set up" hypothesis"

[thunder550]

So what happens when the caltrac bar and spring line diverge towards the front of the truck? Here is what mine looks like. Is the instant center behind the rear axle? How does this orientation affect things?

 

[IdahoRob]

Instant center is the center of the truck if you could balance it from that point, front to back and side to side. If your bars point below this point, then you will have the front lifting placing more weight transfer on the back tires. If the bars point above this point, you have what is called anti-squat, basically lifts the rear up and keeps the front end down.

My set-ups seem to like bars pointing close to the instant center point. Too high and the truck seems to bind up on itself. Too low and unloads the front tires too much.

 

[thunder550]

Right, I understand that concept, when the spring line and the bar line intersect in front of the rear axle. I can't wrap my head around what happens when they don't, like in the drawing I posted.

 

[IdahoRob]

Don't worry about the spring, think of the traction bar as a big lever being applied by the rear axle twist. If the bar is pointing low, it picks up the front, if pointing high it pushes the front down.

 

[thunder550]

Ok I think I get it. So in the pic below, if my instance center were the red dot and my bars are pointed as drawn in blue, they will act like a lever arm pivoting around the red dot and will try to lift the front of the truck in up as indicated by the blue arrow. If the bars were angled up like the green line, they would still act as a lever arm pivoting around the red dot but would try to push the front of the truck down, as indicated by the green arrow. Correct?

If that's right, then even if I can't get the bars to point up enough to push the front of the truck down, then moving them up into the higher holes would shorten the lever arm that was pushing the front of the truck up, giving them less of an ability to do so, which would help.

 

[minerigger]

I'm gonna have to remember this drawing for future reference

 

[Chevy1925]

Ok I think I get it. So in the pic below, if my instance center were the red dot and my bars are pointed as drawn in blue, they will act like a lever arm pivoting around the red dot and will try to lift the front of the truck in up as indicated by the blue arrow. If the bars were angled up like the green line, they would still act as a lever arm pivoting around the red dot but would try to push the front of the truck down, as indicated by the green arrow. Correct?

If that's right, then even if I can't get the bars to point up enough to push the front of the truck down, then moving them up into the higher holes would shorten the lever arm that was pushing the front of the truck up, giving them less of an ability to do so, which would help.

Now you're gettin it lol. Accept your instant center is much farther forward than in that pic. It's going to be closer to the front door jam of your truck.

 

[thunder550]

That makes it even better. Less of an angle needed. I'm going to move my bars up as soon as I get a chance.