I use M/T ET streets at the track and usually run about 15-19psi in them. After the 1/8th mile point once my car starts hitting higher speeds, it starts swaying left to right in the lane. Why is that? Sometimes I actually let off the gas cause it gets pretty bad. Most of my suspension is done but I don't have a torque arm. Would that help? Thanks.

 

Retork all the rear supension parts. Something seems loose to me.

 

Do you run bias-ply FRONT tires when you put ET Streets on the back?? If not, that's why. When you run radial tires and bias-ply tires on the same car, they don't act/react the same, and you'll get that "tail wagging" sensation. We ran my Dad's '73 that way last fall, and it's not really great to drive (technically, it's actually illegal to drive on the streets that way!! ).

If you want your car to handle properly, either get Drag Radials (Mickey Thompson now makes those too) or get BF Goodrich or Nittos. Otherwise, get a set of bias-ply front tires, and it'll correct that problem .

 

Get used to it

 

Rubber suspension mounts can allow excessive movement. I've also had trouble with high speed stability with a posi unit, spool fixed that.