glockman

I have a problem I subframed my Z and I put 3 point UMI subframe and rear control arms along with relocation Brackets now at about 80 mph I have a major shimmey. The car has 12K miles on it upgraded trans and cold air induction. Still has the stock tires so right now really dont want to drive it on tires that old. But I never had a shimmey before I upgraded the suspension. Any Ideas whats going on?