Axle Shift Motor (vacuum)

[ExpandingMan]

Instead of tracking down various vacuum leaks, I hooked up a vacuum pump directly to the shift motor which is supposed to lock the front axle of my 83 Cherokee (with swapped 208, btw). With the vehicle on 4 jackstands I tried applying up to 20 units of vacuum (and rotating wheels) with no lock of the axles. My understanding is:

-After removing the harness from the shift motor, there are 3 vacuum connections.
-Vacuum to the top connection keeps the axle unlocked (2wd)
-Vacuum to the second locks the axle for 4wd
-Vacuum FROM the third connection signals the T-Case to engage (but that NP229 has been removed and replaced with a 208 which does not require vacuum control, only the lever) after hubs/axle lock.

Correct me if I'm wrong about the above.

I can't seem to engage the front axle no matter what I do. My next step would be to open the peephole (fill hole) of the axle and see if I can spy the action of the shift motor, to see if it moves at all. I'm thinking I should be able to remove this fill-hole nut (with 1" square tool?) and stick my finger in there and feel around to see if that rod is moving down from the shift motor trying to engage the clip.

I've never messed with the axle before, but there's no way of removing/testing the shift motor without accessing the innards of the front axle.

Thanks for your input.

[joe]

I can send two diagrams if you want of what port/line gets vac in 2WD and 4WD. To get the axle motor out you just need to pull the diff cover. There's a retaining nut on the inside of the diff cover.

[ExpandingMan]

Thanks. I think I have these diagrams as well.

I'm just hesitant to pull said cover, and I'm hoping that if I remove the fill plug and look/feel around, I can determine what's happening inside.

How hard is it to get another shift motor?

[scotty]

i doubt that you will be able to feel anything. the collar and fork are over towards the edge of the cover.

why are you afraid to pull the cover? theres nothing complex about it,and some new oil will be good preventative maintenance

i wouldnt think it to be to hard to find one. most people are afraid of this axle,and either replace the whole assembly,or do someting goofy to "permantly lock it",so there are plenty of them not in use [img]smile.gif[/img]

they seldom actually go bad,so if you find one i a yard or on one of the boards you should be in good shape.

[ December 02, 2004, 07:13 AM: Message edited by: scotty ]

[sheffield]

I have a D44 from a wagoneer that worked when I bought it. I also got my hands on a set of locking hubs so if the motor doesnt work it doesnt bother me, so if you want to swap covers/motors it would work out. I'll be back home (Oxford Georgia, which is east of ATL about 45min) in about a week and can check to see if it still works for ya. Just let me know.

[Chevelleguy]

I pulled the cover and shifted the the fork to 4wd, then locked it in place with two small hose clamps on the vacuum motor shaft. Now the dash switch only opperates the t-case.