5speed transmisson: 5th be slipping. I be tripping (1977 620 Kingcab)

[DatsunHiLife]

So I live on a very small island. Getting to use 5th gear isn't an everyday thing but I do like speed.

Are there any rebuild kits for the 5 speed? Mine falls out of 5th gear unless I hold it in.

Or should I look for a new transmission? I would consider a 4 speed as well.

I am curious.

Thank you for any advice

[datzenmike]

This is a common problem on the early FS5W71B 5transmissions. It's caused by the mainshaft lock nut backing off and being loose. Its the nut on the lower right with the collar or shoulder. This picture is of a newer 5 speed and revised nut where the collar is peened over with a hammer blow to prevent the nut moving. The nut holds the reverse and 5th gears in place on the rear of the mainshaft. If the nut is loose the gears move and 5th jumps out of gear. The mainshaft nut torque is 100- 120 ft lbs. Then stake the nut with a cold chisel and a few hard knocks. 

 

 

Here's a slightly better picture of my '79 zx 5 speed...

 

 

You can see where the nut has been staked to prevent turning

[john510]

My A series roadster 5 speed was jumping out of 5th.Like Mike said,it was a loose mainshaft nut.A simple fix if you arent scared to split the tranny cases apart.The nut was tightened and i have no more issues.

[flatcat19]

Problem solved; post tits.

[DatsunHiLife]

Datzenmike: You rule bro!!! Gonna handle this tomorrow on my day off!!!

John510: thanks for looking out!!

Flatcat19: Double D's Double D's