No front drive in 4x4. Fg639:(

[canter tourer]

1996 fg639, help please.... With 4wd engaged, in either hi or Lo range, their is no drive to the front wheels. Hubs are locked in, 4wd selector on transfer case is in correct position and when watching the front drive shaft it does not spin when the rear tail shaft is spinning as it should.
Have I broken something in the transfer case for this to not be working? No loud or quiet bangs have ever been heard and I can,t put my finger on the problem. Any ideas appreciated.
Thanks Dave.

 

[Aussie Iron]

Okay cable or vacuum shift to the transfer case? Disengage hubs - engine off - if cable shift - climb under and have someone to move shifter in the vehicle while you are rotating front shaft by hand. You won't see anything move as it is all enclosed but you may be able to feel if something is trying to engage or even hear it moving inside. If it is vacuum shifter you will need it to have been running so as there is some vacuum in the tank. Engine off - ignition on - climb under and while you are rotating front shaft by hand have person inside select 4WD or low range you should see the linkages on the box moving and feel it engage or trying to engage. There is a chance that the grub screw has come out on the selector in the box but a very slim chance as they have all been very hard to undo when I fitted the new gearing in our boxes. Other than that it will be elimination by numbers - let us know what you find and we will try to help.

Dan.

 

[unkamonkey]

From your description it sounds like you have 2 problems. If your hubs are locked in and I assume you are driving the front drive shaft should be turning, bad hub? If a 1996 is like my 1994 there are 2 cables that run from the transfer case shifter down. Are the cables intact and adjusted, hooked up?

 

[gait]

something not quite right .... possibly two problems.

is the vehicle moving when you see the rear drive shaft rotate?

if yes, and if hubs engaged, then front drive shaft will be driven by front wheels moving.

extension of Dan's test is with hubs engaged / disengaged to rotate front drive shaft by hand.

 

[canter tourer]

Thanks for the replies, it is vacuum operated, I can see the selector on transfer case engage when 4wd is selected. It is currently stuck in the paddock due to wet ground, I had the wife jump in and try to drive it out and I see the rear shaft spinning and the rear wheels flinging mud everywhere but front shaft does not spin unless the front wheels roll forward a little before going nowhere, it's as if it's in 2wd.

Will try the suggestions with drive shaft engagement and trying to feel if something is attempting to engage in a couple of days when I'm next off work in daylight....
Dave.

 

[canter tourer]

Convinced the wife to brave the night. So hubs unlocked, front shaft spins freely, hubs locked front shaft no spin, all normal so far eliminating hubs as the problem.

Engage 4wd with hubs unlocked, front shaft spins freely, cannot feel any mechanical attempt to engage etc when engaging disengaging 4wd selector whilst hand spinning the shaft, it's as if something has sheared off and the shaft is not connected internally to the box....so I think it is the transfer case that's the issue, but not sure what has gone wrong or why. Gotta love a mystery...
Dave

 

[SkiFreak]

Gotta love a mystery...

Only in a novel, not in life...

As Dan suggested, can you see if the low range linkage is being engaged? If not, are you able to activate the low range linkage manually?

 

[canter tourer]

Only in a novel, not in life...

As Dan suggested, can you see if the low range linkage is being engaged? If not, are you able to activate the low range linkage manually?

Linkage engages as it always has, that's the strange part, appears to work completely normally, might have to unbolt it and see if that shows anything odd, or obviously busted..
Agreed, would rather this mystery was not the reality it appears to be

 

[pugslyyy]

Much more likely to be linkage/actuator then something actually gone bang inside the transfer case.

Sent from my SM-G935V using Tapatalk

 

[Aussie Iron]

Okay 2 vacuum chambers - one is to engage 4WD the other is low range. Try to engage 4WD and give a little assistance on the lever that is attempting to move with a block of wood (NOT BELT the S--- out of it). Could be sticky lever, where it runs through the seals, could be faulty vacuum chamber (hole in diaphragm) which would allow it to move some but won't move the load of selecting the gear. I can't tell you how much movement you should have till I have a look at my spare transfer case tomorrow. If you start to dismantle it . 4WD selection is in the front output shaft area (where the front tailshaft comes out of). Myself I wouldn't be pulling it apart yet till everything else is checked and a positive diagnosis is made.
Keep checking and let us know what you find we will get there.

Dan.

 

[unkamonkey]

Just wondering why they decided to go to a vacuum system. It is just asking for failure.

 

[SkiFreak]

Just wondering why they decided to go to a vacuum system. It is just asking for failure.

Only on some older models, not the most recent ones.

 

[unkamonkey]

It's OK. Among the many things I have done in my life I have been a mechanic and have seen many poorly thought out designs come from the factory.

 

[canter tourer]

As crap as the vacuum system is, it is still working and does not appear to be the problem here, although it does have other issues, just not impacting on this problem.

After checking again, Both the Lo range selector linkage and 4wd linkage on the transfer case are working and moving as they always have, and appear externally in the correct positions when engaged that they've always been when selected, there is no more travel available in either linkage.

Might have to take the side cover off and see if there's anything obvious visible doing that, but will have to wait til I can tow it out of the paddock to work on it....oh the embarrassment of being towed out by an 80 series!

 

[canter tourer]

Problem partially solved. Removed the selector linkage and eliminated the vacuum system and manually pushed the 4wd selector in and managed to engage it and drove out under its own steam, happy with that. Now to work out why everything appears to be working normally, but there is obviously a few mm of travel that is not occurring causing it not to engage, might pull all the external linkages apart and give everything a good lube and see if that fixes further issues.

Many thanks for the advice offered, was almost going to be the excuse needed to get Dan's transfer case gears, still something I'd love to do one day.
Dave