I need some help with my 5 speed

[ksechler]

I have an early 5 speed transmission.  I'm guessing it is from a '79.  I had the transmission rebuilt recently.  After the rebuild I didn't have 2nd and 5th gear.  So I yanked it out and took it back to the mechanic.  I put it back in Saturday and I still don't have 5th gear.  It shifts flawlessly 1-4 and reverse seems ok, but when I put it in 5th it pops out when I let out the clutch.  Before anyone goes there, the mechanic is used by many hear and considered to be reputable.  I'm frankly pissed but I'm not going to call him out.  My questions are:  Does anyone have any ideas why 5th keeps popping out and if I leave it in for know and just use gears 1-4 am I going to mess something up?  I'm loath to pull it out again right away because it's a lot of work, and I'm also loath to take it back to the mechanic because I have lost confidence (and it entails 3 hours of driving).  Any advice is appreciated.  Thanks.

[siteunseen]

Take the shift rod out and look for the tell all signs of nicks above the snout.  Mine did it, drove me crazy.  Did a little grinding and now all is fine.

Dave WM had the same issue.

 

Edited April 16, 2018 by siteunseen

[Zed Head]

3 hours ago, ksechler said:

After the rebuild I didn't have 2nd and 5th gear.  So I yanked it out and took it back to the mechanic.  I put it back in Saturday and I still don't have 5th gear.  It shifts flawlessly 1-4 and reverse seems ok, but when I put it in 5th it pops out when I let out the clutch. 

So, the mechanic did something to fix the problem with 2nd gear?  Did he say what he found?  Might be a clue about quality of work.  I seem to recall reading about problems with 5th if the countershaft nut works loose.

Did you replace all of the shifter bushings?  It's a 240Z, right? 

Of course, more details needed.

[SoCalJim]

Zed Head’s comment is an excellent one.  I’ve seen a lot of discussion about the nut on the countershaft working loose and causing the transmission to pop out of 5th gear.  Google Datsun 280z popping out of 5th gear and you’ll get a lot of hits.

[Dave WM]

check to make sure its fully getting into 5th per the previous post. engine off shift into each gear, feel how the shifter is, should be some for aft looseness once in gear, now shift into 5th does it feel the same or does it feel solid with no play? You want the shift rods to be fully locked into the ball detents, if the shift throw is hindered to the point where the shift rod does not go into the detent, then the gear will  not be locked in. The solid feel is from the shift rod hitting a stopping point while the shift detent is still trying to pull the rod to its endpoint. The ideal setup would be to have the correct shifter as well. I think they are different pivot points and lengths. Is the shift lever the one that came with the transmission?

Edited April 16, 2018 by Dave WM

[ksechler]

1 hour ago, Zed Head said:

So, the mechanic did something to fix the problem with 2nd gear?  Did he say what he found?  Might be a clue about quality of work.  I seem to recall reading about problems with 5th if the countershaft nut works loose.

Did you replace all of the shifter bushings?  It's a 240Z, right? 

Of course, more details needed.

The countershaft nut is tight.  I don't think quality of work is an issue.  I'm pursuing the shift lever issue mentioned by siteunseen.  

details.....

The car is a '76 280z.  The transmission was a purchased from the shysters at Datsun LLC or California Datsun or whatever they are now.  It is an early 5 speed and I am using the original shift lever from my 4 speed transmission.  Before I had it rebuilt it held all 5 gears but the synchros weren't synchronizing very well.  For that reason I'm a little skeptical about the problem being the shifter, but it's the easiest thing to try so I'm going to try it.    

[Zed Head]

26 minutes ago, ksechler said:

The countershaft nut is tight.  I don't think quality of work is an issue. 

You asked the question.  What did he do to fix second gear?  Obviously it wasn't right the first time.

You can't blame California Datsun after the fact.

[ksechler]

8 minutes ago, Zed Head said:

You can't blame California Datsun after the fact.

Why not?  They sent me a "rebuilt" transmission that had never been rebuilt.  

[Zed Head]

I meant the non-shifting aspect.  It shifted before, it doesn't shift now.

Setting aside the CD issue, the logic is a bit off here.  CD sent you a supposedly rebuilt transmission that, apparently, shifted in to and held all of the gears.  Now you've had it rebuilt for sure, and it doesn't shift and hold the gears.  The guy you like did worse than the guy you don't like.

Sometimes my objectivity makes me wonder if I'm not a robot.  I don't like Al and what he does but the details here suggest the new guy didn't do it right.  And you're not saying what he fixed to fix second gear.  

[ksechler]

I believe he tightened and recrimped the nut on the countershaft which greatly improved shifting in gears 1-4.  What it didn't do was allow my transmission to hold 5th.  I'm still trying to ascertain whether or not it was done right.  The only viable theories I have so far is that I have the wrong shift lever or the nut on the countershaft is loose.  If it's the shift level I don't know why it used to work, but I doubt it is the nut because it was just tightened.  

[Zed Head]

Good luck.  The shifter gets people often.  Nissan changed something about the mechanism inside the transmission and the early shift levers have problems, especially if the bushings are worn.  Worse on the "close ratio" 5 speeds.  Nissan used the wide ratio on the 79 and 80 1/2 models.  How many exhaust hanger ears do you have?

[Dave WM]

Not rocket science, if the hubs were not chewed up then it should lock in nice a tight as long as you are getting the full engagement. If it was going into and out of 5th with no pop out issue before the rebuild to fix the synchro, with the existing shifter, and now it jumps out of gear, with the same shifter, then it pretty much has to be something in the rebuild. Please describe the exact nature of the orig prob, I presume it would grind or crunch when shifting up or down?

another test, with the engine off can you easily shift from 5th to Reverse? (I think yours does NOT have the lockout mech). Where I am going is another user had issues with 5th that were traced to incorrectly installed shift dogs (or whatever we ended up calling them) on the gear hub. An easy mistake due to a poor illustration in the FSM.

Edited April 16, 2018 by Dave WM