Weird problem

[der Geist]

have your tires checked to see if they are "out of round" This will also cause the shaking even though they are perfectly balanced.

[ifmc100]

I had great luck just checking tire pressures...

I drive mine every three or four weeks and noticed the same problem after a while - also right at about 73-75 mph... It drove me nuts until I read about how import tire pressures are for club racers... Anyway, I got a digital pressure gauge and made sure both rear tires were at 32 psi and the fronts were at 28 psi and the shimmy at 75 is gone...