Anyone have driveline vibration?

[EtaSport]

So I got the m50 swap done in mike's [the fast one!] and it has a horrible driveline vibration. Its chewing up guibos. Apparantly it was like this before, all of a sudden it developed a vibration with the m20 still in it. I know that one of the motor mounts broke with the m20 in it, and that that could be a possible cause (trans mounts probably werent good, but unknown condition).

The guibo was trashed when we pulled the motor. Okay, bad guibo, replace it. (installed m50) I drive the car, dont notice anything. He drives it and says there is a bad vibration. I drive it and confirm. Center support bearing was questionable, so replace, why not... Some difference, but still there under acceleration. He gets under the car today and new guibo is trashed.

Im thinking its because of the transmisson mounting position. ie, the 10 degree shift and using the 320 mounts. I noticed that the trans was sitting a little higher than I thought it should be. I was able to tweak it back to a suitable position, but I dont know what else it could be.

Could a bad driveshaft (balanced or misaligned) make such a bad vibration. I've got the u-joints phased correctly, but they dont seem to line up perfectly, and they dont no matter if i go to the next spline. I also know the shaft has been split and probably not put back together in the same place. Should he consider another driveshaft? Why would it happen with the m20 still in all of a sudden, new mounts (motor and trans) put in, so I cant really blame them.

[Mike B.]

Is there any play in the u-joints? Did you preload the CSB? Have you tried rotating one half of the shaft 180 degrees to see if they may be out of phase? Bolts torqued properly?

If you have a good driveshaft, it couldn't hurt to throw it on there and see what happens.

[Jason89i]

The guibo was trashed when we pulled the motor. Okay, bad guibo, replace it. (installed m50) I drive the car, dont notice anything. He drives it and says there is a bad vibration. I drive it and confirm. Center support bearing was questionable, so replace, why not... Some difference, but still there under acceleration. He gets under the car today and new guibo is trashed.
......

Could a bad driveshaft (balanced or misaligned) make such a bad vibration. I've got the u-joints phased correctly, but they dont seem to line up perfectly, and they dont no matter if i go to the next spline. I also know the shaft has been split and probably not put back together in the same place. Should he consider another driveshaft? Why would it happen with the m20 still in all of a sudden, new mounts (motor and trans) put in, so I cant really blame them.

if you had a driveline problem before the swap, a new engine will not cure it. rarely do mounts cause driveline vibration. i bet its the driveshaft. there are white marks on each side of the driveshaft for alignment. double check. pull the driveshaft and feel the ujoint for any play or stiff/stickey spots while rotating the joint. if the driveshaft ujoint has a stickey spot, it will trash quibos quickly.

I noticed that the trans was sitting a little higher than I thought it should be. I was able to tweak it back to a suitable position, but I dont know what else it could be..

not sure how you can "reposition" the transmission without taking everything apart. something must be loose.


EDIT: good call mike. i have also seen center support bearings not bolted into position and guibo bolts missing......so double check all your work.
cheers, jason

[EtaSport]

I always preload center supports, and verified it. There is only one white mark on the driveshaft, so I dont know if it has ever been correct. The u-joint feel the same on both ends, and yes there is a stickey spot, but they feel exactly like mine and I have minimal is any driveline vibrations, so I dont know what to compare them too. I drove it today after fixing a bunch of bolts that vibrated their way out, and felt it coming slighty from the center but more from the rear. I am going to have to go with bad driveshaft, or misaligned, or broken balancing weight.

The trans mounts werent tight when i first was under the car, and the transmisson was resting up against the tunnel under the car. It came back down after tightening it, but still seemed high. Probably unrelated though since the problem was before the swap. I think I have to think of the way it was before with the m20 still in.