Hi FF,
been running my 2004 Climbing for a while now & it's been great but have recently seem to have lost four wheel drive, first there was a dull thump coming from the rear when on & off the throttle, now that's been replaced by a clicking from the NSR wheel that's road speed related. I got down in the mud today & the outer CV joint gaiter has failed on that side. There doesn't seem to be any drive to the rear axle based on front wheel scrabble and inability to climb slight gradients on dirt/grass. I don't think it's the viscous coupling because that was replaced along with the prop-shaft less than 8k miles ago. I would've thought that if drive to the rear had failed the vicious coupling wouldn't be strong enough to send 100% power to the front & drive would be lost entirely or have I miss-understood how the permanent 4x4 works? Any thoughts much appreciated, I'll get it up in the air & have more of a look later this week. Thanks

The clicking and a failed outer cv joint gaiter sounds to me like that CV joint has failed.


Power comes out of the gearbox to the front axle as any normal FWD car and not through the viscous coupling.

The Panda 4x4 has another output on the gearbox to the rear shaft.

The power comes out of this rear output as well and down the prop shaft to the viscous coupling, it powers the prop all the time, though it won't fully power the rear axle until the viscous coupling locks up.

The coupling is on the far end of the prop, next to the nose of the rear diff. When enough torque is transmitted down the prop, the oil in the coupling expands and the plates (similar to a motorcycle wet clutch) inside lock together to allowing more and more power through to the rear diff.

The coupling does have some drag on it, so it will always transmit a bit of power to the rear axle, but the more torque through it, the more power it transmits.
So by jacking up all four wheels and running it in gear, all four wheels should turn.

One of the weak spots on these is the centre support bearing in the middle of the prop shaft, which would account for the dull thud from underneath when on and off the power.

Fiat don't sell them, but I believe there's a company that do sell them.

You could really do with getting it up in the air and checking out the driveline from one end to the other.

Thanks for that, good explanation. I believe the centre support bearing, viscous coupling & prop-shaft were all replaced as one unit but I'd have to check the receipts to be sure, think it was the best part of £1k in parts. When I've got a bit of time in the light I'll get the car up in the air & have a dig through everything.

PandaClimbing said:

Thanks for that, good explanation. I believe the centre support bearing, viscous coupling & prop-shaft were all replaced as one unit but I'd have to check the receipts to be sure, think it was the best part of £1k in parts. When I've got a bit of time in the light I'll get the car up in the air & have a dig through everything.

Click to expand...

Thinking about it, if that rear CV joint or shaft has failed, the open diff will shunt all it's power the way of least resistance (which would be to the broken shaft), so you'd get no drive to the other wheel on that axle (so no rear drive).

Update. Correct diagnosis, thanks. Jacked up the NSR wheel can be turned without the drive shaft turning, CV joint also very loose so it clearly has blown. As you suggested, power spins through the open rear diff & the NSR drive shaft effectively removing all rear drive. A good outcome considering the expense of the other drive components!