Driveline or tire vibration?
My nephew's car, Nova, 12 bolt, 'glide, stock rear suspension, CalTracs. Has a vibration in high gear, around 5500 rpm, or about 95 mph. The car will only do it for a split second, then quit. It will do it in the burn-out too, but only in high gear, around 5500. Even broke a trans case last year. He's been through the engine, trans after the case was broke, and replaced the gears, all for other reasons, not just for the vib. Even had a new driveshaft built.
He claims it won't do it after he puts new slicks on it, but it's only good for about five passes, then it comes back. He just had them rebalanced, and they were out less than 2oz each. He runs Hoosiers, small tire car. I've never seen a tire vib come and go at a small window. But, sounds like he's covered everything else. Motor/trans was out of his roadster, which went high 5's (1/8) and never had the vib... In this car it goes mid 6's and has had the vibration....any ideas?