Transmission Leak

[RLJ]

5 speed transmission from a 280z. 
Tail-shaft is leaking. Put a new seal in and no change, still leaking. No excessive bushing play.
Anybody ever seen the driveshaft yoke leak?

[datzenmike]

Over filled? oil should be only up to the fill hole.

 

Yoke may be scored or was rusty. May be able to polish it out.

 

Using synthetic base oil?

 

[RLJ]

Only filled up to the fill hole.

 

Didn’t notice anything obvious on the yoke seal area. 

Did put synthetic oil in. Do you really think synthetic oil by itself could be causing the leak?

Going to pull the driveshaft again for closer inspection. 
 

When the driveshaft was removed before to replace the seal it looked like it was a new seal. Was leaking with non synthetic oil then. 

 

Thinking the oil is leaking down the splines in the yoke and a flaw in the yoke allowing the leak. Could this be?
 

[datzenmike]

Synthetic can leak past an otherwise good but worn seal. New ones usually fix the problem.

 

There may be wear right where the old seal was riding. The last seal I put in was thinner front to back than the one that was pried out. This would put the contact point farther into the transmission on fresh spline.

[Crashtd420]

13 hours ago, RLJ said:

5 speed transmission from a 280z. 
Tail-shaft is leaking. Put a new seal in and no change, still leaking. No excessive bushing play.
Anybody ever seen the driveshaft yoke leak?

What's the driveshaft from?

I'm not sure if it was only a 521 thing but my yoke actually was a through hole and not sealed ... I believe some yokes were bolted in.... mine never was but my driveshaft was the type that did.... So I had to install a core plug in the end to stop my leaking.....

[datzenmike]

 

This is a L16 powered PL510 transmission and the spline bolts in, you can see the nut. The drive shaft bolts to it.

 

If you swap to a '71B 5 speed there is no threaded mainshaft to bolt to so that hole must be plugged. I think it's a 40mm core plug with sealer..