Thread: After many years of faithful service...

My guess is the reverse gear, its shaft or bearings - or possibly the gearbox housing (does happen!). You may well be able to see what is wrong by removing the gearbox top and draining the oil (don't lose any little balls or springs). This can be done in situ, but it is bery likely the box will have to come out to fix it.

John

I dropped the oil and fortunately no gear teeth, bearing balls/rollers or lumps of alloy came out. The oil had the usual gear oil metallic sheen but dragging a magnet through it picked up only a tiny amount of steel 'dust'.

I'll try to get the top off the box on the weekend and see what things look like inside.

Ian

Thinking about it overnight, the lack of bits in the oil suggest that you may have managed ot get it in two gears at once. This suggests that the problem may be one or more selector forks loose on the selector shafts, or a problem with the interlocks that are supposed to prevent this. All these can be fixed when you take the top off. (try not to drop any small bits into the box - this will really spoil your day!).

Hope this helps,

John

most likely the detent and interlocs have bebome sticky allowing the box to select 2 gears at once.

if you're unlucky its slipping a selector fork on the rod and has dropped the locking bolt to the bottom of the box.

it could also be a binding syncro but this will also get bound up in any pair o 1/2, 3/4 and R combo depending on which syncro is sticking in place.

Many thanks to JDNSW & Blknight for their great help.

Looks like I might have struck it lucky. Got the top cover off and, after a bit of wrestling, removed the selector shafts and forks. (The 'man-well' said to put the 'box into 3rd before removing the selectors. Shame it didn't say to do this before removing the gear lever, 'cause mine had no intention of going into third with no leverage on the selector shaft...)

Could now see that everything inside appeared to be intact, including the reverse idler gear and shaft. Managed to get the 'box into and out of all gears by 'manual' (hand) changing and running it with the transfer case in neutral.

So then looked at the selectors and some signs of previous butchery started to appear. First, the manual says I should have a reverse gear stop bolt and locknut that limits the rearward travel of the reverse selector shaft. Mine has none, just a small bolt blocking the hole at the back of the 'box(?). Then looked at the position of the reverse fork on the shaft - and it appeared to be too far forward. Removing the clamp bolt revealed the shaft groove has at some time be 'modified' with a grinder. (Photos attached.)

So, if I'm reading all this correctly, it seems that without the stop bolt and the elongated groove, repeated putting it 'firmly' into reverse may have pushed the fork too far forward on the shaft. This then would prevent the reverse idler being pushed fully back into mesh? Also, perhaps the rev. shaft is then not sitting in the right place for the interlock 'eggs' to prevent first/second also being partially engaged? Sound feasible??

So, should I try to restore the reverse selector shaft groove with, say, Knead-It Steel or just lash out on a new one? And also buy a reverse gear stop bolt and locknut?

Any ideas on why my box may have been 'enhanced' in this way? The guys who rebuilt it in about 2002 were ex-Army mechanics who advertised as being specialists in Land Rover and Unimog transmissions. It has worked fine until this lock-up the other day.

All suggestions appreciated.
Ian

So, esteemed Gurus, any clues??

I would replace the selector shaft, and the stop bolt. While a new one should not cost much, they are not a usual replacement part as they rarely give trouble, but other parts of the Series 3 box do, so there ought to be quite a few people on this forum with an otherwise unserviceable box who could be easily persuaded to part with a selector shaft. Sorry, I don't have any for S3, not sure if S2a is the same. And you should be able to find one in SEQ - try HoHars.

John

Hi again Boys & Girls,

Leo's gearbox job went 'on hold' for some time, while we went away for a fortnight and I was waiting for new selector shaft seals to arrive. These duly arrived last week and I finally got around to putting everything back together again today.

I kept the 'enhanced' reverse selector shaft and experimented with the positioning of the fork and fudged together a suitable stop bolt. Everything seemed to work properly, both before re-fitting the top cover & gear lever, and afterwards.

BUT! When I started him up and tried the gearbox with the transfer case in neutral it worked in all forward gears OK and in reverse for a while and then, CLUNK! and the engine stalled. I tried this several times: once freed-up again, the 'box will engage all forward gears correctly. But once put into reverse, it will run for a few seconds and then jam up solid.

All the selectors seem be pushing the correct gears into the correct positions. All the detent balls and springs are in place and working correctly. The two 'steel eggs' that interlock the selector shafts, so that only one may move from the neutral position at a time, are in place and working correctly.

So, it seems that for 'reasons still unknown', one of the forward gears is falling into mesh while the 'box is in reverse. I suspect that it's either first or second. Is there some weak spring in the 1st/2nd cluster that should be keeping these gears/dogs in place until they are positively selected that's failed? Can't see anything in the manual that might be a likely cause.

All suggestions very welcome. I want to try everything possible before resorting to pulling the whole she-bang apart.

Thanks again,
Ian