Classic diff lock problems

[discodee]

Im not sure whats happening but when im driving offroad and I engage diff lock I drive maybe a couple of metres and check the lever and it  seems to have meved back to the original position the light is still on but  I dont think the difflocks still engaged any ideas what could cause this and  does anyone have any ideas how to fix it,cheers the noo,Don oh and its an 88 v8 by the way

[crazymac]

There is a tendency for them to do this, but what makes you think its disengaged?

You can either hold it over (or get a passenger to do it) or get a piece of bungy to do the job.

I assume that there is some kind of a spring under the console? which may have gone weak, try to take a look?

[clbarclay]

It may just be something simple like mud or debris etc. built up on top of the transphere box thats pushing the leaver back or just a worn linkage allowing movement back without dissengaging. In case you haven't seen the top of a gearbox (might take a few pics if needs be) the transphere box leaver mounts on top of the gearbox and has a linkage going across, down and then across again to a rod into the transphere box.

The easy(ish) way to check if the difflock is working (other than getting it stuck cross axled and counting the spinning wheels) is to apply the hand brake with diff lock and in gear, jack up on front wheel and see if you can turn it. If the diff is lock then it should only turn a few degrees at most due to slack in the transmission.

[discodee]

thanks for that  :D  ill try it tomorrow is there any chance of the photos if its not too much of a hastle cheers,don

[Skibum346]

It may be a co-incidence, but I had this problem on my 1990 Disco. One weekend I had to change my rear diff (blew the B****r up!) and now it's gone.

Don't know how or why this happens but it ight be helpful.

Skibum

[clbarclay]

This is the the transphere box linkages. The gearbox is the ZF 4 speed auto fitted with LT230 transphere box. The picture was taken with the cammera positioned about where the drivers knees would be.



The short gear stick enters the box shaped casting above the gearbox from above. I side this is a linkage that seperates convers fore/aft and side/side movement into 2 outputs. The long vertical link is pinned to a shaft that moves left to right out of the side of the box. the verticle link is also pivots on a pin about a 3rd of the way down. the bottom of the verticle link has a short horivontal link to a cam fixed to a shaft that goes down into the transphere box above the differential. This works the diff lock. When you engadge the difflock the shaft on the side of the box on top moves out, the verticle link pivots around the middle pin and the bottom of the link moves towards the gearbox. Dirt and debris can build up round here as its relativerly flat so too much beteen the verticle link and the gearbox could act as a spring, pushing the link back and forcing the lock to disengage.

The second output from the box on top is a rotating cam with a diagona link going back and down to another cam (not very clear in the picture) which goes horizonatally into the side of the tansphere box. The rotaion of this selects between hight, neutral and low ranges.


<EDIT>
Slight error on my part :doh: the side to side output is the other way round, so the vertical leaver actually moves out away from the gearbox at the bottom when you engadge the diff lock

[discodee]

its fixed now it was full of crud and half a tree so it went in enough to let the light come on but wasnt properly engaged so thanks for your help no doubt ill break something else soon and need some help cheers,don