Is the Panda a fulltime 4x4 or do the rear wheel come into action when the front wheels loose traction. ???

The Pretender said:

Is the Panda a fulltime 4x4 or do the rear wheel come into action when the front wheels loose traction. ???

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My panda is 4x4 and it is front wheel drive until the front wheels lose traction ! But I can engage full time 4x4 by turning the dial

OK, so most of the time it's a front wheel drive car.

The Pretender said:

OK, so most of the time it's a front wheel drive car.

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Yes!

No it's permanent 4 wheel drive system with torque on demand.

But I believe it will normally send 95% to the front and 5% to the back, that is until the centre "diff" locks up, then power is split anywhere up to 50/50.

http://www.fiat.co.uk/news/panda-4x4-paris

It's actually 98% front drive, 2% rear as the prop shaft to the rear is always spinning

The connection to the rear axle is via a Haldex coupling. I think this will be a fairly simple unit which locks up when there is a difference in rotational speed between the front and rear axles. I guess there may be some pre-load to reduce the time it takes for the coupling to lock up and transfer drive to the rear. However, in normal driving i do think (as per the above post) the overwhelming majority of drive is to the front wheels. I'm not sure what the electronic lock comprises or how it works, but I suspect it will be a fairly simple on/off system (imho), not the kind of fancy units with progressive hydraulic lock-up that some cars feature. This is not a dig at the FIAT 4x4 - after all they are built to a price. Full 'proper' 4x4 systems such as fitted by Subaru which can operate on tarmac with no wheel slip, typically include a centre diff are very expensive indeed and would push the FIAT into a much higher price bracket.

I'm no engineer, but i have some rudimentary understanding of how transmissions work, so take these comments with a pinch of salt!!

ATB

Agree with above, (98% front wheel drive normally). If ABS sensors detect front wheel slip, computer operates a solenoid to engage the rear drive. This is automatic. (And an improvement over the old viscous coupling system used on the old model) You can manually force engagement of 4x4 at speeds below 50km/hr (31 mph) by (on the 4x4) pressing the ELD button, or (on the Cross), turning the dial to the off road setting. This also allows the ABS sensors to act to provide 'electronic diff lock' if a rear wheel spins -- note that in this sense 4x4 and Cross are identical in the way they operate - the 'auto setting' on the Cross dial is what the 'normal' 4x4 defaults to anyway (But the Cross can also then bring in hill descent control with a second turn of the dial)

OK THX for the reply's