Thread: No drive

Originally Posted by benji

Great work getting it back on the road so quick!

It's the viscous couplings job to effectively lock the diff. It will heat up and lock the speeds of the front and rear output shafts of the transfer case, I.e. it will stop the diffing action of the diff.
Even though it's at the front of the transfer case its still splined directly onto the rear output shaft on it's inner spline, and it's outer spline forms part of the front output shaft.

When locked it can send 100 percent (or close enough) of the torque to either axle. They mostly fail locked up, but occasionally they will fail open. They don't need any resistance from an axle to lock, only a difference in rotational speeds which will heat up the silicon and lock the plates.

It would be interesting to see if you can jack up a front wheel, and with a brick in front of each rear wheel, drive forwards.
I've replaced three in the last few years and have noticed that just before they fail they get very weak, pretty much won't lock up, then within a few months they will lock solid.

Benji

Not sure how I could (safely) jack up the front before trying to drive over blocks? I am thinking trolley jack with the tyre only just off the ground. You do have me concerned with the VC though!

Gary

Originally Posted by mtb_gary

Benji

Not sure how I could (safely) jack up the front before trying to drive over blocks? I am thinking trolley jack with the tyre only just off the ground. You do have me concerned with the VC though!

Gary

I've seen people do it with a trolley jack on the axle or diff and Jack both wheels up while on nice flat concrete so it can roll... Only internet videos mind you.

http://www.youtube.com/watch?v=9B0AN...cM&app=desktop

Sorry, didn't really expain that too well. In the past I've used a bottle jack under the axle and driven off it.

I had a scenario with my classic about six months before it locked whereby I was up a steep hill and the left front dropped into a hole and I just sat there spinning. Even after 15 or so seconds it wouldn't lock up - the back had plenty of grip on both wheels. After replacing the vc it locked up almost instantly.

I've also used the handbrake instead of the bricks in the past too. In lowrange it shouldn't have any problems driving past the handbrake.

Before trying the more exotic tests which can be somewhat problematic PeterH recently had questions re. his VC which are explained here: Sneaky pulley noise..grrrr! (posts on page 2). I'd suggest FWIW testing the VC by conventional means first.... as per the referenced posts.
cheers

Originally Posted by Hoges

Before trying the more exotic tests which can be somewhat problematic PeterH recently had questions re. his VC which are explained here: Sneaky pulley noise..grrrr! (posts on page 2). I'd suggest FWIW testing the VC by conventional means first.... as per the referenced posts.
cheers

Hoges

I've just tried the conventional means and the wheel & prop shaft turn freely, a little too freely as was the problem in the first place with no drive to the rear. I don't think the VC has seized, quite the opposite, it's just not locking up at all. Or something else has sheared along the driveline.

Gary

Originally Posted by benji

Sorry, didn't really expain that too well. In the past I've used a bottle jack under the axle and driven off it.

I had a scenario with my classic about six months before it locked whereby I was up a steep hill and the left front dropped into a hole and I just sat there spinning. Even after 15 or so seconds it wouldn't lock up - the back had plenty of grip on both wheels. After replacing the vc it locked up almost instantly.

I've also used the handbrake instead of the bricks in the past too. In lowrange it shouldn't have any problems driving past the handbrake.

Benji

I've just tried with a trolley jack, jacked up the front right wheel so that it cleared the ground, wheels lined up straight on the jack, blocks in front of both back wheels. The front wheel when I put the car in drive spun freely, I could not climb over a 45mm high block of wood with the 265/75's . It's time to start work on the transfer box/VC to see what else is broken.

Gary

When you jacked up thefront wheel and turned it by hand, was the here any resistance to it, it did it just free wheel. I assume the handbrake was on and it was in park when you turned it by hand?
If there was no resistance at all, then it's failed open or you've busted the rear output shaft forward of where it's splined onto the rear sun gear (personally I doubt that though).

If there was some uniform resistance it sounds like the vc.

Originally Posted by benji

When you jacked up thefront wheel and turned it by hand, was the here any resistance to it, it did it just free wheel. I assume the handbrake was on and it was in park when you turned it by hand?
If there was no resistance at all, then it's failed open or you've busted the rear output shaft forward of where it's splined onto the rear sun gear (personally I doubt that though).

If there was some uniform resistance it sounds like the vc.

Benji

When turning the wheel by hand it was in neutral, handbrake on, it turned smoothly with little resistance. If I put it in park the wheel will not turn.

Gary