disco not working

91 4.0 aw4 d30 disco my axle shafts stopped locking. the vaccum is fine i tested it and the disco motor itself is fine putting out a strong amount of resistance. i also replaced the pass side u joint today. i can manually lock the two shafts if i take the motor housing off and lift the wheel hub shaft 1/8'' up and slide the collar over . the fork and collar are fine and have no damage. i know the shaft coming out of the diff has a stub on it and the wheel hub shaft has a indentation for that to slide in so they stay parallel. if either is worn to much can that cause the two shafts not to lock?

:dunno:

My guess would be screwed up assembly, :wave1: wither that or there is a strange irony that it stopped working the same day as you changed a u-joint.

it has not worked for about three weeks now . i replaced the joint thinking it might help solve the problem.

Are you sure the Fork is engaging the slip collar? Just a thought…

the fork attempts to engage the collar but since the hub side shaft is a little lower it cannot slide over.

mark91xjbeef said:

the fork attempts to engage the collar but since the hub side shaft is a little lower it cannot slide over.

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Hummm… That sounds strange. Is the hub side shaft lose where is engages the middle shaft? I don’t think there should be any way for them to not be aliened if everything is put together. How old are the shafts. Could it be that the hole in the shaft is worn out?L

Someone needs to correct me if I'm wrong, but isn't thier a plastic bushing in the end of the axle shaft where they join? Sounds like this is missing or worn. Maybe not but I'm sure I remember one in my '91 axle. This should solve any misalignment between the axle shafts.
Tony

tchase said:

Someone needs to correct me if I'm wrong, but isn't thier a plastic bushing in the end of the axle shaft where they join? Sounds like this is missing or worn. Maybe not but I'm sure I remember one in my '91 axle. This should solve any misalignment between the axle shafts.
Tony

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I’ll look at my spare axels tonight and see if either side has a bushing of any kind.

if there is suppose to be a plastic bushing there is not . the axle shafts have 220000 miles on them so the plastic bushing may have worn away. if there is does anyone know a part # or is it pick and pull time for some used shafts.
thanks for the replies. mark

I looked at mine and they fit together really close not tight but there is no room for any bushing. Is there play in yours that is letting to droop? I guess you did say you could lift it up to slide the color over. I think before I went a bought a new set of shafts I would pull the shift motor so I could get in there and try to figure out what was going on. If you pull the outer shaft a bit you could look at the hole and maybe even measure it. If they are worn you could find someone with a lathe to turn you a sleeve to make up the difference. I know of at least one machine shop that could do this kind of job fairly cheap. And most any place with a lathe could do it. They would be better than new.