Unorthodox Underdrive Pulleys

[Jon Davis]

They aren't bad for $200. Don't expect to feel anything huge SOTP.
Lightening the flywheel did a lot more for me. You should be aware that the
UR crank pulley removes the harmonic balancer. The harmonic balancer is
there for torsional vibration in the crank (unlike balance shafts). The
crankshaft actually twists back and forth as the engine runs and the
balancer damps it. This vibration can beat the hell out of your bearings and
if severe can cause crank failure. That being said, I've had my UR pulleys
(2) for 50k over miles and I haven't had any problems yet. I have not had
any charging or overheating problems. The a/c doesn't cool quite as well
when idling in 100 degree heat with direct sun and 4 people in the car, but
other than that extreme you don't notice and it doesn't seem to drag the
engine as much. YMMV. They seem to be well made. If you get the crank
pulley, replace the oil seal.

Jon Davis

> I've read the pros and cons about using these on my SER. I'm still
> confused...........As a daily driver anyone got history that has used
them,or
> opinions if this is a trouble free mod and worth doing for the gain in
> performance?