[Hugh R]

I know this isn't the forum, but the Aston Martin board isn't any help. Don't know why I'm posting here, other than I don't know where else to go with knowledgeable motor heads.

My DB4 trannie was making a lot of rumbling noise at 4000 rpm in any gear so I pulled it, and replaced the front and rear cages ball bearings. Everything else looked fine. Now, I can't get it to go into fourth gear on the bench. I might have switched a sycro, but I didn't mean to. So I tried changing syncro rings around no luck. Its driving me nuts.

Best of all, on reflection, if I'm getting a vibration at 4000 rpm (engine) I now realize its probably not the trannie, but an imbalance on the front damper or the flywheel/pressure plate.

I think it won't go into fourth because the syncro under rotation seems to be about 1/2 tooth off on being able to push the cluster over the synchro and onto the gear. Other gears work fine, including reverse.

Wayne, sorry for wasting bandwidth on this non-Porsche problem. But the Aston Martin forum is not very helpful.