Two weeks ago, I replaced the engine in my son's '92 Integra. I also replaced the clutch, pressure plate, throw-out bearing, input shaft bearing, and had the flywheel turned. Now it has a vibration that is particularly noticeable while accelerating in 1st, 2nd, and 3rd gear. I think I felt it in 4th, but not as severe. There is no vibration in neutral with the clutch in or out. Any ideas? I hate FWD.

external balanced motor? sounds like the weight balance of the flywheel is off or not matched to the motor. Any weights come off when they turned it? Alignement pins on the crank?

No, it's internally balanced, but I think we found the problem. The drivers side lower control arm was loose, and the passenger side axle and outer control arm needed to be replaced. Still has a little noise that I think is the wheel bearing.

And by the way, thanks for your response.

Sounded like an axle/CV problem. You might also want to check out the ball joints as well. Bad CV units tend to stress the ball joints and accelerate wear. Had similar issues with my son's '93 LS.

Thanks for the heads up. He put Koni DA's on it with Ground Control springs. The drivers side axle is being replaced as I type, along with the drivers side outer tie rod. I hope he's having fun.

...yeah sounded like the CV problem I had with our old commuter car a while ago....sounds like you got a handle on it.