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LT77 Problem

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I'll start by stating this problem is totally self inflicted, and the box was fine up until this point.

I removed my engine to replace the leaking rear crank seal. Which wasn't the problem, the gearbox seal was. So I removed the nose plate off the gearbox to replace the seal. At this point, no problem.

Then a very helpful person noted I was working on a vehicle without the handbrake on, jumped in and pulled the brake on for me. Very thoughtful. He also pushed it into gear to be sure.


This has shoved the input shaft out of the box by a couple of inches, and no matter which way I wiggle the shaft, I can't get it to sit back in place correctly, the outer bearing race doesn't fit back into the casing as snugly as it came out. I've now removed the box.

I'm confident nothing has been damaged, just dislodged. I can get the nose plate back on the box and it to sit flat, but it won't select gears and the selector is very tight, and extremely notchy.

Does this sound like an easy fix, or is it off to Ashcrofts with it, along with this month's rent?

Although I've rebuilt boxes before, I've no experience of stripping these boxes, so I'm not over the moon with the idea of opening it up.

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I can't quite see what the problem is but it sounds like you may have to split the box. The box has a primary shaft and a layshaft. So I guess that something has happened to the selector mechanism which sits on the mainshaft.

So long as you are not doing complete rebuild looking inside the box is not too bad a job.

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Now the box is out, I would do a partial stripdown to correct the problem and assure yourself it has been fixed properly. LT77/R380 boxes are easy enough to work on if you take your time and pay attention to detail, so this should not be a reason avoid investigating. Detailed manuals can be downloaded from the net.

Most of the gears are in the forward half of the box, the casing of which can be removed by undoing the bolts through the centre plate and also removing the guides for the gear selectors. Stand the box with the input shaft end up and lift the casing off. You will have a good, clear view how everything sits. The aft end (5th & reverse) is a bit more awkward to get to as you need to pull off a collar before you can remove the housing.

Reassemble with RTV silicon sealant on the joints.


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That is very helpful, thanks, a very comprehensive thread.

Hopefully I will be able to see the problem with just the front half casing off.

Is this all I need to do to achieve this:

Invert casing and remove front cover, selective washers and gasket.



Remove selector shaft spool retainer.


Lift off casing.



Or is it necessary to remove the rear half casing first?

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