I have been battling today to change the transfer box on my defender in the hope that that will cure a vibration below about 45 mph in 4th and 5th, though there is vibration in 3rd at slow speed, which led me to think maybe it was the transfer box at fault. Edit: tried the usual tricks to cure vibrations like removing 1 prop shaft at a time ect to check they are not bent or anything and its definately transmission related.

Now having removed the transfer box who's input shaft bearings appeared in excellent condtion with no swarf in the oil upon removal I turned my attention to the gearbox.

with it in gear I turned the ouput shaft, and in first second and 3rd got solid clunks, as the gears locked. In 4th and 5th it felt more like it had to be wound up and was not giving the decisive clunk as the first 3 gears were. As it wound in 5th the output shaft also moved outwards ever so slightly. 4th being direct drive will not clunk obviously.

To me these symptoms scream worn bearing, but as I am no expert in landrover faults thought I would see if someone could give a more decisive answer.

The output shaft is like new and the transfer box has a cross drilled input gear so I assume this has had some serious work at some point, as my vehicle was manufactured in feb 1995, before the problems with 300's trashing output shafts came to light.

Just in case It is buggered have a spare gearbox and transfer box, but its a lot more work to change the gearbox so thought I'd check to see if my diagnosis seems correct.

Thoughts are appreciated on the subject.

Thanks

James

they should have known about the spline wear as lt77s suffered bad with it ,and miliary had oil throwers fitted to theres,shaft shouldnt have end float ,but not necessary mean bearings are knackered,what was oil like in gear box, since you gone this far pull of gear box and remove front bearing cover ,if you wobble input shaft outer races will push out ,rear races wera through bearing plate as are a loose fit ,i allways loctite them in to stop them rotating

Infact, there is a slight noisy bering noise from the gearbox when cold in neutral. , and and a sound like a few marbles have been let loose on top of the gearbox when driving along, which could lean towards input bearings then.


I think if I go as far as removing the gearbox I will just fit the replacement one - a 38k disco one that I have modified to accept the defender linkage.

Oh yes, at low speed in 4th and 5th its a loud drumming vibration not a general vibration.

not necessarily ,but would be worth checking as they can be without stripping box ,theres a small bearing between input shaft and front of mainshaft would fit some of your symptoms ,but usually 4th gear change gets worse ,gear box can be run without t/box if supported underneath

Thanks for the tip I'll investigate that bearing, assuming I do still have an original box (doubtful) Its still in pretty good shape at 146k.

While its apart I shall change the flywheel sprigot bush, clutch arm for a heavy duty one and crankshaft oil seal. I did the clutch 8k miles ago so assume that'll just need a clean up. Can anyone think of anything else to do while its all apart as I don't intend to do this again soon.

I think 5th gear is slightly worn!

all sorts of bearing material and the other half of this tooth came out in the oil. Bit of a mess really. Just as well I have nice low milage disco box to fit.

I think what has happened is as the clearances have increased as the bearings have worn the gears have started pushing apart when loaded up, fretting and eventually causing this damage. Looks like I got to it just in time.

or knackered ,dont throw old box away though

Unfortunately I never throw anything away!

I think that will be a good box with new 5th gear again and complete rebuild. It wasn't crunchy before.

5th gear baulk ring looks okay on dog teeth which is unusally on used box,id have a good 5th gear ,whever you get round to it

I thought I would update this. I finally got round to stripping the box to decide whether to keep or bin it and it was in excellent condition bar the damaged 5th gear. The vibration turned out to be a knackered propshaft.

As far as the damaged 5th gear goes, a strange sort of bent piece of wire/circlip looking thing on the 5th/4th/reverse syncro hub bad broken apart and a fragment landed square between the gears and chipped the tooth off, It then got progressively chewed up. The laygear shows no sign of damage nor do the rest of them, well normal for 140k so a new 5th gear and a rebuild kit and she'll be ready to go, though Hopefully the new box still has 100k left in it.

One other observation congratulations to land rover for designing a box where the drain plug is not the lowest point on the box, plenty of schrapnel in the bottom of the main casting.

thats why plug has a magnet ,and you only get a lot of debris when it needs rebuilding