Vibrations from replacement transmission.

[Milenko2121]

This is a 1980 280zx Close Ratio 5 Speed transmission.

 

I just put in a replacement transmission. Everything felt smooth before install.

It shifts into gear easily, 1-5 don't grind and even reverse doesn't grind ever.

 

 

The problem shows up only when I apply any amount of throttle, mostly in 3rd and 5th. 1st and 2nd it's not as bad, and it's completely gone in 4th. 5th gear is the worst.

It does not vibrate as long as there is 0% throttle.

I could decel in gear and it won't do it. It's only when I open the throttle any amount while in gear.

 

I did not have any of these problems with the last transmission I had in here.

 

I've been trying to research this, but answers are all over the place mostly blaming driveshaft/half-shaft alignment/balance or even flywheel bolts hitting clutch, but this is not my case because wouldn't it have shown up with my previous transmission?

 

I'd appreciate the help with figuring out this issue.

Edited May 3, 2014 by Milenko2121

[randy 77zt]

Its the countershaft bearings-4th gear is 1to1 and does not load them.Are you rolling the dice and buying used trannys from pick&pull?I damaged a trans by letting the speedo gear drive leak-it took out the countershaft bearings.Unless you do your own trans work or have it rebuilt at a good shop you really dont know what you are getting.I consider any used trans a core trans until I open it to check it out.could possably be a chipped tooth on 5th.These trans are easy to rebuild/repair.

[Milenko2121]

The thing grenaded on me a few days ago(big surprise).

 

I've decided to do the 240sx transmission conversion instead. Should be swapped in Sunday.