Series III Gearbox

[Spyderman]

I've got a 1981 Series III Diesel. It jumps out of 1st & 2nd gear when it is not under load. What is the easiest fix? Is it best just to find another box and put that in or is a repair fairly straightforward. Excuse me, but gearboxes to me are Witchcraft.

[Les Henson]

Drain the oil out of the gearbox and look for bits of metal. Depending on what comes out will determine the extent of your problem. If flat bits of sprung steel comes out (blue coloured), then one of your synchro hub springs has busted - this is quite common, but requires the gearbox to be removed from the vehicle. I vaguely remember someone posting in the distant past that you could do it with the gearbox in, but I've never tried. 1at though you need to check the gear lever for wear at the bottom where it engages in the selector rods, then the detent balls in the top cover, then the selector forks. These last three can be checked with the gearbox still in the vehicle.


Les.

[Lucy1978]

It's quite a common problem, the syncros on 1st and 2nd are a weak point, the tabs that engage in the syncroniser wear and push it out of gear.

It's a gearbox out job to replace the syncro rings but they're only a few quid each,  the bit they sit into is about 30 quid though.

Chris

[lotusandy]

Drain the oil out of the gearbox and look for bits of metal. Depending on what comes out will determine the extent of your problem. If flat bits of sprung steel comes out (blue coloured), then one of your synchro hub springs has busted - this is quite common, but requires the gearbox to be removed from the vehicle. I vaguely remember someone posting in the distant past that you could do it with the gearbox in, but I've never tried. 1at though you need to check the gear lever for wear at the bottom where it engages in the selector rods, then the detent balls in the top cover, then the selector forks. These last three can be checked with the gearbox still in the vehicle.


Les.

I have a series 3 that has done 91,000 miles, the gearbox & synchro is fine, but finding first gear is very hard, is it likely to be a matter of renewing the detent balls selector forks and gear lever? if so how easy is it to do this? I am pretty able mechanically, but just not experienced in Landy gearboxes!

Thanks Andy

[Lucy1978]

I have a series 3 that has done 91,000 miles, the gearbox & synchro is fine, but finding first gear is very hard, is it likely to be a matter of renewing the detent balls selector forks and gear lever? if so how easy is it to do this? I am pretty able mechanically, but just not experienced in Landy gearboxes!

take the floor, the seatbox and the transmission tunnel out and you can get to the top of the box. you ca then remove the detent springs for the 3rd/4th and reverse selectors, two L shaped brackets, one on each side of the gearbox. next you can remove the top of the box the detent ball and spring for 1st/2nd are beneath the brass plug in the top cover so be carefull when removing the top of the gearbox.

you should now be able to see the selector rods and the 3rd/4th selector fork, they look something like this;

the reverse selector is missing in the photo, 1st/2nd is the one closest to the camera.

Check the positions of the forks on the rods with the measurements given in the manual.  You can remove the selectors, it's a little bit fiddly but not too difficult.  If this looks ok, it's likely it's something to do with the 1st/2nd syncroniser unit.  to change this is a gearbox out job.

[lotusandy]

I have a series 3 that has done 91,000 miles, the gearbox & synchro is fine, but finding first gear is very hard, is it likely to be a matter of renewing the detent balls selector forks and gear lever? if so how easy is it to do this? I am pretty able mechanically, but just not experienced in Landy gearboxes!

take the floor, the seatbox and the transmission tunnel out and you can get to the top of the box. you ca then remove the detent springs for the 3rd/4th and reverse selectors, two L shaped brackets, one on each side of the gearbox. next you can remove the top of the box the detent ball and spring for 1st/2nd are beneath the brass plug in the top cover so be carefull when removing the top of the gearbox.

you should now be able to see the selector rods and the 3rd/4th selector fork, they look something like this;

the reverse selector is missing in the photo, 1st/2nd is the one closest to the camera.

Check the positions of the forks on the rods with the measurements given in the manual.  You can remove the selectors, it's a little bit fiddly but not too difficult.  If this looks ok, it's likely it's something to do with the 1st/2nd syncroniser unit.  to change this is a gearbox out job.

Many thanks for that, in particular the photo was very helpful, when I get a spare few hours I will have a go..
Thanks Andy

[Spyderman]

Having looked at the Green Bible. I think I will buy another box, strip and rebuild that, then fit it complete, rather than ponse about trying to fix what I've got in situ. At least then I can take my time and get it right.

[Lucy1978]

there's a load more photos here

[Spyderman]

Great pictures, thanks. Much easier than the line drawings in the manual.

[Lucy1978]

If you're planning on buying a box to strip and rebuild wait till the Sodbury Sortout, I picked up what looks like a good box down there for 35 quid, trouble is you never know what state they're in till you get it home and opened up.

As a guide I spent about £250 on parts rebuilding my box.  I probably didn't need to replace everything I did, but I only wanted to be doing it the once.  It's just coming up to 1000 miles since I fitted it and so far it's been great  :D

[the-green-landy]

Oh how I hate S3 gearboxes.... im now on my Forth in Parsley... in as many years of owning her!!

[Lucy1978]

I'm on my 4th box in a year with mine, that's why I took the plunge and rebuilt the reconditioned one that broke  :roll:   My record was 3 days between putting a box in and taking it back out again cause it was broken.  Still I can do a solo gearbox swap in about 6 hours now,

[Spyderman]

Have bought a military 'D' spec gearbox from a mate, he bought it unused from surplus 4 years ago, he's only done about 3000 miles with it since and has now upgraded the running gear to rangerover. Looks like I've had a result, basically a brand new gearbox for £90, with decent parts in it. Will fit it next weekend. :D