LT77 Stuck in 4th

Quagmire · Post by **Quagmire** » Fri Nov 04, 2011 6:57 am

Two weeks ago I fitted an LT77 to my 90 that I rebuilt myself after the last box starting grabbing 4th and not wanting to come out easily. All was well with new box, and it has been bedding in nicely.

Tonight I did my 500 mile oil change, and that went fine. Found nothing untoward in the oil, just fine iron filings stuck to the magnetic drain plug.

Drove the 25miles home from my parents to my house, the shift was getting better all the time... I was actually beginning to enjoy driving it again.

Until I got to a roundabout and wanted to go from 4th to 3rd. Found I was totally stuck in 4th.

I was only a mile from home so have made it back and parked up, and no amount of jiggling can get it out of gear. Clutch in or out, engine on or off, transfer in low/neutral/high...

Seeing as my last box did this , and my rebuilt box has been fine with not a single crunch or bang could this be something to do with the selector mechanism? This is the only part that is common to both boxes.

Help!

Thanks

Jamie

Quagmire · Post by **Quagmire** » Sun Nov 06, 2011 6:20 pm

Update...

Its not the shifter mechanism. Took that off this morning and thats all fine. The box itself is totally jammed for some reason.

Will find out when I get the bloody thing back out the car I guess!

DaveEFI · Post by **DaveEFI** » Sun Nov 06, 2011 7:05 pm

Not had an LT77 apart, but had this on another box. The synchro sleeve had moved too far along the hub, and the spring loaded plunger had gone beyond the end of the sleeve stopping it returning. It happened after some 'enthusiastic' gear changing, and after popping it back in, never happened again. But that was on a low mileage box - I could see something similar happening with wear.

Quagmire · Post by **Quagmire** » Sun Nov 06, 2011 7:58 pm

Thanks for the tip Dave, I'll let you know what I find when its out and I've had a look.

ian.stewart · Post by **ian.stewart** » Sun Nov 06, 2011 10:12 pm

I would guess its the selector "rose Joint " has come loose, or broken selector fork

Quagmire · Post by **Quagmire** » Thu Nov 10, 2011 10:49 pm

Disassembled this evening and found this:

The little pawl thingy had dropped down/ popped out. This was preventing it moving back and out of 4th. I think maybe the synchro went too far?

Anyways, the upshot is that with the whole lot being wedged in this position it appears to have caused some wear on the selector fork:

D'oh!

I didn't change those little bits when I rebuilt, could they wear enough to allow this to happen? What should I do to stop it happening again?

Cheers

Jamie

DaveEFI · Post by **DaveEFI** » Thu Nov 10, 2011 11:10 pm

That's pretty well what happened on the box I mentioned. Different design - it had a series of spring loaded rods with a ball end. But I don't thing the actual hub assembly had a stop to prevent the sleeve moving beyond normal limits - it was down to the selector mechanism not to move it too far.