Technical Panda 4x4 system test

[Bonefish Blues]

Sedici, the Fiat's called. I had one for a while, and an excellent little car it was (and is still running for the guy I sold it to) Mechanically identical to the 4x4 SX4s. (and identical to the 2wd SX4s when Fiat switched from 4x4 to FWD for the last run-out model IIRC)

Here's Suzuki's blurb about their clever traction systems:

ALLGRIP Four Wheel Drive | Suzuki Cars UK

Our ALLGRIP 4WD technology provides you with excitement, confidence and peace of mind on any surface or under any driving conditions.

cars.suzuki.co.uk

 

[JayAre]

Yup, when there’s zero grip, especially for both front wheels, going anywhere is tricky. True for all 4x4s. But on many surfaces, the likelihood is that there will be different grip levels at different wheels. Otherwise, that’s when a winch is needed
The same is true of ABS: if all four wheels lock at the same time — such as a sheet of black ice — the car thinks it’s standing still (because none of the wheels are rotating) so the ABS does nothing.
I don’t know if there’s any common stuff between tbe Ignis and the Panda? At one point Fiat and Suzuki sold an identical car except for the badge… (SX4 and Sceicenti?)

The slip test could only test ‘zero grip’ (replicating ice)
5 ‘zero grip’ scenarios were tested, covering all possibilities:

1. Front - both
Auto Pass
ELD Pass
2. O/S - both
Auto Pass
ELD Pass
3. Offset - F O/S R N/S
Auto Pass
ELD Pass
4. All except F N/S
Auto Fail
ELD Pass
5. All except R N/S
Auto Fail
ELD Pass

I was surprised by the two failures for the normal (‘auto’) setting. I had understood that the system would still be able to transfer torque with one wheel still having good traction and on level ground (especially at the front, being essentially set up as a front wheel drive car) but it does vindicate the value of having the ELD select option (which previous Panda 4x4 iterations didn’t have apart from the final years 169 - where it may have used a different setup?).

Note: The “all four wheel lock up” ABS analogy doesn’t work here because in none of the scenarios are all four wheels on ice (for obvious reasons)

 

[Zardo]

Looks like the software needs an update. The ASR system could be much more aggressive with such big differences in wheel speeds (one wheel stationary, three others spinning like hell). I wonder if it's possible to officially or inofficially "tune" the system by reprogramming the ECU. Not that I need it now, but in case my next car is a Panda 4x4 it would be nice to have an offroad mode which allows to mimick a differential lock.

Panda 4x4 system “slip tests” - auto v ELD/Off Road

 

[Herts Hillhopper]

The only time I’ve ever got the Panda stuck was just like that - 3 wheels spinning and the back left not being driven. It was on an exceptionally muddy patch at the time though, and would have been ok with more aggressive tyres, I suspect. But all other times, it’s been brilliant.

 

[JayAre]

The only time I’ve ever got the Panda stuck was just like that - 3 wheels spinning and the back left not being driven. It was on an exceptionally muddy patch at the time though, and would have been ok with more aggressive tyres, I suspect. But all other times, it’s been brilliant.

was the 4th wheel on firm ground?
and knowing what you now know about “How the Panda 4x4 system works" (your thread) do you understand why the 4x4 system doesn’t transfer torque to the 4th wheel in ‘auto’ mode?

 

[Herts Hillhopper]

was the 4th wheel on firm ground?
and knowing what you now know about “How the Panda 4x4 system works" (your thread) do you understand why the 4x4 system doesn’t transfer torque to the 4th wheel in ‘auto’ mode?

Second part first: the 4th wheel gets no power because if one wheel spins freely, then the differential won’t let power reach the other on the same ‘axle’ —that happens with all ‘open’ (meaning not locked or limited) differential systems. But if the brake is applied to just that spinning wheel (the ELD effect which is able to detect spinning and then brake just that single wheel), then power will go to the other side. ELD isn’t available in auto mode…

First part: yes one wheel was on the grass. Were all four to have been in the slippery mud it is possible all four wheels would have spun without me moving forward. For the electronics to do their thing, there needs to be some difference in the individual wheel speeds.

All-terrain and mud tyres tend to have deep tread lugs on the sidewall as well as the ‘normal’ tread area. This reduces the ability of the wheels to spin freely in sticky situations and means there's likely to be some speed differences between them.

 

[JayAre]

the 4th wheel gets no power because if one wheel spins freely, then the differential won’t let power reach the other on the same ‘axle’

the ‘offset’ test also tests this scenario - it passed