Pinion angle
02-15-2006, 11:12 PM
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You need to distinguish pinion angle from torque arm
angle. With a fixed arm they are related, but for
traction you want to play with the torque arm angle
(as a component of instant center, affecting weight
transfer on launch) and then true up pinion angle
to get a null driveline angle under worst high load
suspension deflection. -That- is where 1-2 degrees
of "windage" comes from, a guesstimate of the angle
deflection in the various bungy bushings and flexing
members. More for stock, less for hard links. But the
pinion angle itself does nothing to traction. The nose
of the torque arm is where bite adjustments are made.
That is not the arm itself, but the mount point that
matters. Some crossmembers like Yank and BMR either
reposition it for a designed best bite or allow you to
pick your own angle. Shorter torque arms with variable
angle are there for drag racing.
The right torque arm angle has to do with the lower
control arms and body height. You are going to have
to try out your linkage and not depend on a cookbook
answer, tuning for traction. You have to get the pinion
angle back to smooth. But it's the finishing touch, not
the main event (traction-wise).
angle. With a fixed arm they are related, but for
traction you want to play with the torque arm angle
(as a component of instant center, affecting weight
transfer on launch) and then true up pinion angle
to get a null driveline angle under worst high load
suspension deflection. -That- is where 1-2 degrees
of "windage" comes from, a guesstimate of the angle
deflection in the various bungy bushings and flexing
members. More for stock, less for hard links. But the
pinion angle itself does nothing to traction. The nose
of the torque arm is where bite adjustments are made.
That is not the arm itself, but the mount point that
matters. Some crossmembers like Yank and BMR either
reposition it for a designed best bite or allow you to
pick your own angle. Shorter torque arms with variable
angle are there for drag racing.
The right torque arm angle has to do with the lower
control arms and body height. You are going to have
to try out your linkage and not depend on a cookbook
answer, tuning for traction. You have to get the pinion
angle back to smooth. But it's the finishing touch, not
the main event (traction-wise).
Last edited by jimmyblue; 02-15-2006 at 11:17 PM.