Need driveline help

[Recombobulated]

I have a 78 fj 40 with stock engine and running gear. With hubs engaged and in 4hi or 4low, with the throttle on it feels like it is engaging and disengaging. Does not happen in 2hi. No problems or noises when i have the hubs out and shifted into 4hi or low. Have checked all fluids, no metal in the diffs or transfercase. Both hubs are good and splines and u-joints are good. I wasn't driving hard when it started either. Any help would be greatly appreciated.

 

[78tlc]

check your shift fork?

 

[dgangle]

Try this..it won't cost you anything.

Turn it off, park on a flat surface, set parking brake, put trans in neutral, lock hubs. Now crawl underneath and turn the front driveshaft with your hands - if it turns freely you have a locking hub that's not engaging. Fix this. If it turns 10-15 degrees then stops the hubs are functioning properly.

Now unlock hubs and put TC in 4HI. Crawl under and spin the front DS again. Turns feely? Then the TC is not engaging. Fix this**. Repeat with TC in 4LO.

** could be lever is binding, not moving far enough to engage, has come off the nose cone on the TC, internal actuating mechanism (for lack of correct technical term) is binding or possibly someone has had the TC apart and put the TC 4WD actuating mechanism in backwards.

 

[Recombobulated]

Thanks, I've tried both suggestions and no luck. A second flush of the T case shows a bit of metal. Still stumped though. I opened the inspection plate and front output shaft, all looks fine. WTF?

 

[Poser]

Where are you located?

 

[Recombobulated]

BC Canada

 

[dgangle]

Thanks, I've tried both suggestions and no luck. A second flush of the T case shows a bit of metal. Still stumped though. I opened the inspection plate and front output shaft, all looks fine. WTF?

I don't understand what you mean by 'no luck'. Does this mean with your hubs and/or TC in 4WD you could spin the driveshaft freely? Which one? Both?

 

[Recombobulated]

With the hubs locked and brake on it only moves the 10 degrees, so the hubs must be good. Then with the hubs in and in 4hi the Tcase is locked in. I took the driver side tcase inspection cover off, everything looks fine on that side. I took the front output shaft and shift fork, all looks fine there too. I can't get the top inspection cover off, I have an aqualu tub and everything is just too close.

 

[dgangle]

With the hubs locked and brake on it only moves the 10 degrees, so the hubs must be good. Then with the hubs in and in 4hi the Tcase is locked in. I took the driver side tcase inspection cover off, everything looks fine on that side. I took the front output shaft and shift fork, all looks fine there too. I can't get the top inspection cover off, I have an aqualu tub and everything is just too close.

...so the hubs appear to be engaging.

Did you do the second part of my suggestion to determine if the TC is actually engaging also? Results?

Maybe I'm just not understanding your explanation. If these two things check out (read hubs engaging and TC engaging) then I don't know what you mean by it 'with the throttle on it feels like it is engaging and disengaging.'

What do you mean by 'the hubs in'? Engaged or disengaged?

 

[Recombobulated]

I did both tests and both the Tcase and hubs check out fine. The problem is intermittent. When I am driving in 4x4 it feels like it jumps completely out of gear then back in by itself. It drives perfect in 4x2.

 

[dgangle]

I did both tests and both the Tcase and hubs check out fine. The problem is intermittent. When I am driving in 4x4 it feels like it jumps completely out of gear then back in by itself. It drives perfect in 4x2.

Ok, I understand better now. I guess you are going to have to isolate when/how/under what circumstances this happens to further diagnose.

What are the symptoms? What makes you think it is jumping in/out of 4WD? Could this be another problem? It is vibration, sound, jerking, binding? At what speed is this happening and on what type of surface (dirt, pavement, ??????????????????) ?

You are going to have to throw us a bone here.

 

[Recombobulated]

It happens only when trying to accelerate. It happens on dirt, pavement, and snow. I believe it is jumping out of 4wd because I can feel the power to the wheels lost then re-engaged quickly. It happens at all speeds. There is a shift fork to go from 4hi to 4low, could that be any issue? I can't get to that inspection cover.

 

[dgangle]

If it were going in/out of 4WD you would not feel anything unless the front/rear wheels were turning at different speeds such as spinning the rear tires. I think you got some other driveline problems. If it only acts up in 4WD that pretty much points to the front drivetrain (front diff, front DS or TC). I don't know what to tell you other than to either take it somewhere or ask someone (familiar with FJ40/55/60's) to take a ride with you to take advantage of their experience/understanding.

Good luck, I'm out.

 

[Recombobulated]

Thanks for the help

 

[dgangle]

Not a problem. I hope you figure it out. Please post back with what you find.