Pull bar

[CHRISTINE]

if you move the pull bar up on the rear end should you soften or stiffen the pull bar spring to get the same movement?

[texas racer]

Stiffin up

[Dirtracer50]

Softer spring. The further from center of the axle the less spring required.

[racin6mod]

to me it's a leverage thing the higher you move the pulbar from center the more leverage the rearend housing has againest the pullbar.it'll take a stiffer spring to control the rotation of the housing.

[1Blacksheep]

I go softer. When you bore a hole with a drill and the bit binds up, how much easier is the drill to hold further out on the handle as opposed to being choked up on it by the trigger.

[smirk]

Softer further away from center...from experience...about 25yrs

[Dirtracer50]

The pullbar is not applying leverage the axle housing is. Its easier to contol the axle wrap further from center. Could you hold the axle housing with your hand to control torque? No but if you had a 20 ft. lever you may be able to. Not looking for a pissing match but it's easier to control the axle wrap the further from center.

[CHRISTINE]

Pull bar

So my car has the pull bar mount about 9-9-1/2 inches up from axle center line and i want to put more angle in it currently it has 15* but i cant move it down on the frame what effects will there be to making a bolt on bracket to move it up on the rear end? same spring ect.

[HEAVY DUTY]

If you move it up on the rear end you will have to soften the spring, because it travels farther at the same degree of pinion rotation. If you move it down on the frame you have only changed the angle and not the leverage against the spring. I know that 12" from the axle centerline moves the spring .208 inch per degree of pinion rotation. If it was 6" it would move .104 so it would take double the spring rate to control the wrap. That is how much they move on rotation only, when the chassis raises and the axle tube moves forward, the pinion can move farther because the pullbar can start unloading at that point which is why you see the pinion way above 0 degrees. The pinion will move up even with a solid pullbar on a 4 link or any car that has rear steer.

[smirk]

So my car has the pull bar mount about 9-9-1/2 inches up from axle center line and i want to put more angle in it currently it has 15* but i cant move it down on the frame what effects will there be to making a bolt on bracket to move it up on the rear end? same spring ect.

Just made this exact change w my car...think it helped my forward drive some. Ran one heat race in the slick w it and noticed it was breaking the tires easier looked at my pullbar travel..was way short of what i like softened the spring 200 travel is back seems to have more forward than what i started with...hope this helps good luck!