[Grand73Am]

79 TA 403 auto, t-top. I've been fighting a shaking problem a long time, and decided to see if anyone else has had the problem and fixed it. It's fine up to 60 mph. Then I get a little shaking in the steering wheel. It feels mostly up front from what I can tell. It does this up to 70 mph. It smooths out above 70. I've already gone through the list from the Pontiac service manual below. I have new rebuilt front suspension and steering linkage parts. All new front and rear springs and shocks. New body mounts. I've used a couple of sets of different wheels and new tires, re-balanced a couple times. Balanced the drive shaft. It used to be worse, and some of these things I did made it better. I used to think the problem was only in the wheels and tires. I'm using 2 different sets of original Snowflakes and 2 sets of new BFG Radial TA's. The first tire store I used didn't seem capable of doing a good balance job. I switched to a local family owned tire store who does a better job of balancing and that's where I got a lot of improvement. Both sets of wheels/tires get the same shaking at the same speeds, so I'm now thinking there's a little something wrong with the car. It's tolerable, but it should be smooth riding at those speeds after all I've done, so that little shimmy is annoying. I'm out of ideas, so wondering if someone knows another reason that could cause this, that I haven't already thought of? Thanks!

Untitled by grand73am, on Flickr