Hello,
I'm looking at a 1996 Caprice with 72K miles to use as my daily drive so I can keep the miles off my camaro. The caprice I'm looking at is from an elderly couple and is in mint cond, fully loaded with all options. Its got the LT1 with the heavy duty suspension, trailor package w/tranny cooler, etc... all the goodies. I took it for a drive and I noticed that under heavy acceleration there was a vibration at high rpm. There's no tach but I'm guessing its around 4,000 and up. How concerned should I be? I'm tying to think of what it could be... flexplate, front dampner, engine mounts, rear tranny mount... The guy said I can take the car and bring it to a garage and put it on a lift if I'd like. Any other suggestions on what to look for. It looks like it could use a tune up.. could that be it? What are the chances of it being something actually in the engine itself? I really like this car but I don't want to have to put in a new engine.
Thanks
Craig

 

My dad's caprice is the exact same way.....

could it be driveshaft itself? but just throw it on the lift, check all the things....but if it were mouts, i bet it would be more noticeable under faster acceleration and more torque.

 

Could it be the belt or an accessory like the water pump pulley? Has anyone had a problem like this before?
thanks

 

Look at the balancer hub. The factory drilled the balancer hub to balance it. If it is drilled with more than 2 holes, mark the balancer position then remove it and rotate it 90* from it's previous mark. You may have to try 90* before and then 90* after your mark.

Mine had 1 deep hole and 1 shallow hole. After my Opti / Water Pump replacement, I reinstalled the balacer hub with the white arrow (for balancer to hub alignment) set as close to the keyway in the crank as I could. The balancer hub is not keyed to the crank.