Aren't VCs great ...solid shafters, eat yer eart out!

[syncropaddy]

Mine has been great through both lots of snow until the decoupler failed on me last Tuesday.

[HarryMann]

So, back to the topic, any comparisons between VCs and solid shafts for driveability and controllability on/in snow?

[PetenAli]

So, back to the topic, any comparisons between VCs and solid shafts for driveability and controllability on/in snow?

Ooops! Can't make the comparison - but can say that it would have to be a very good system that would better our Syncro in the snow and particularly on ice.

[syncropaddy]

So, back to the topic, any comparisons between VCs and solid shafts for driveability and controllability on/in snow?

A lot of the cheaper Jap 4x4's dont have a centre diff so a solid shaft instead of a VC would be like driving one of those. My neighbour has an old Nissan Terano which is great in a straight line but when it tackles a bend it gets transmission wind up and therefore on snow and ice one or two of the wheels start to slip thereby loosing traction.

[syncrosimon]

PetenAli wrote:
does anyone have any particular ideas as to what may have heppened to a nearly new decoupler that was working well?


My decoupler became sluggish to engage at the same time that the pinion bearing in the gearbox ate itself. Since then the first pull takes about 15 seconds to engage, if I immediately dis-engage then it is the 'how it used to be' 2 second or so engagement. If I leave it either engaged or disengaged for more than about 15 seconds it resumes it's sluggish operation. It has always engaged, just slower than it used to be. Aidan checked it over and modified it's operating shaft seals when he fixed the bearing failure in June, and this did not improve it's operation. I am hoping that it is a fault with the non VW center knob, which is of an unknown origin from Busschmeide. Aidan is supplying me with a new VW vacuum switch as I am hoping that an internal pressure leak is weakening the vacuum pressure when left for more than 15 seconds. I will let you know what the outcome is.

Simon.

My decoupler is 4 years old and has covered 40,000ish miles.

[axeman]

PetenAli wrote:
does anyone have any particular ideas as to what may have heppened to a nearly new decoupler that was working well?


My decoupler became sluggish to engage at the same time that the pinion bearing in the gearbox ate itself. Since then the first pull takes about 15 seconds to engage, if I immediately dis-engage then it is the 'how it used to be' 2 second or so engagement. If I leave it either engaged or disengaged for more than about 15 seconds it resumes it's sluggish operation. It has always engaged, just slower than it used to be. Aidan checked it over and modified it's operating shaft seals when he fixed the bearing failure in June, and this did not improve it's operation. I am hoping that it is a fault with the non VW center knob, which is of an unknown origin from Busschmeide. Aidan is supplying me with a new VW vacuum switch as I am hoping that an internal pressure leak is weakening the vacuum pressure when left for more than 15 seconds. I will let you know what the outcome is.

Simon.

My decoupler is 4 years old and has covered 40,000ish miles.

so far with mine, fitted in october this year and with 4500miles on it, it will engage once the vacuum switch has been pulled , and the wheels have rotated the smallest amount, i only engage from a stand still (have stoped), as per the the instructions from aidan, it disengage as soon as i press the switch and back of the throttle. so only good things to report from me,

neil

[peasant]

So, back to the topic, any comparisons between VCs and solid shafts for driveability and controllability on/in snow?

Before the Syncro I used to have a Suzuki Jimny ...solid shaft, no centre diff .... so I'll do a quick comparison between the two.

First off ...general advantages of the Jimny over the Syncro ... better approach and departure angles, better axle articulation, about half the weight ...none of which matters (except maybe the weight when going down an icy hill) in on-road driving in snowy/icy conditions.

On the road, in ice&snow the solid shaft has only disadvantages:

- if the road is mostly clear and dry you have to have the 4WD off ...any surprises and you won't engage it quick enough
- if the road conditions alternate a lot you'll have to switch on/off all the time, using up valuable concentration (+taking one hand off the wheel)
- when the road is bad enough to warrant full time 4WD but still offers good grip, you'll still have to switch it off every now and then on a straight bit to allow the transmission to unwind after a lot of bends
- going through bends at speed, directional stability isn't the best. Due to the missing center diff you will get understeer or oversteer or in extreme cases both as individual wheels lose traction for a fraction of a second as the transmission wind up is equalised
- powering up a hill through bends you will also get some degree of wind up. This will usually just release itself in some wheelspin, but if that wheelspin happens in the wrong place you could get stuck
- creeping down an icy hill through bends, the transmission will wind up eventually and release the tension in a lurch. If you're lucky that lurch will just give you a fright. If you're unlucky it's enough to lose traction and induce a slide (now you're sliding with 4 locked wheels)


In comparison driving the Syncro in the same conditions is just boring ...it simply does what it is supposed to with a minimum of drama and fuss.


Having said that, even with the Syncro you can get yourself into a situation where you lose traction on an icy downhill stretch and find yourself sliding over all fours. In that case I'd rather be sitting in a 1 tonne Jimny than a 2 tonne Syncro ...especially since the Jimny has more of a crumple zone

[ericos_bob]

Yeah solidshafts will outperform the vc in every situation except tarmac
The way I see it
tarmac+cold climate = vc
reason: keeping solidshaft engaged would cause drivetrain wind up

tarmac and warm climate + all other surfaces. mud,sand,dirt,gravel etc = solidshaft
reason: 50/50 power distribution all the time means 0 delay in power transfer to front wheels

Australia is solidshaft land, UK is vc land

[PetenAli]

My decoupler became sluggish to engage at the same time that the pinion bearing in the gearbox ate itself. Since then the first pull takes about 15 seconds to engage, if I immediately dis-engage then it is the 'how it used to be' 2 second or so engagement. If I leave it either engaged or disengaged for more than about 15 seconds it resumes it's sluggish operation. It has always engaged, just slower than it used to be. Aidan checked it over and modified it's operating shaft seals when he fixed the bearing failure in June, and this did not improve it's operation. I am hoping that it is a fault with the non VW center knob, which is of an unknown origin from Busschmeide. Aidan is supplying me with a new VW vacuum switch as I am hoping that an internal pressure leak is weakening the vacuum pressure when left for more than 15 seconds. I will let you know what the outcome is.

Simon.

My decoupler is 4 years old and has covered 40,000ish miles.

Thanks Simon. The malfunctioning switch is something that I'd not thought of. When I push my centre switch back in I hear a slight "hiss". Do you know if this is normal? Presumably it is as the vacuum has to release somewhere?

Like Axeman I only engage / disengage decoupler or difflocks when stationary and then use forward and reverse gently to let them drop in.

[axeman]

the shhhhh sound is normal both when you pull and push the knob (diff locks included), what you can hear is air being diverted to the actuator.

neil

[peasant]

the shhhhh sound is normal both when you pull and push the knob (diff locks included)...

Is it?
Never heard anything when engaging difflocks on my yoke

[HarryMann]

Like Axeman I only engage / disengage decoupler or difflocks when stationary and then use forward and reverse gently to let them drop in.

Definitely not a practical approach to using difflocks... they were designed to be used on the fly, and so far have never heard of a problem caused by engaging them as and when required (although I'm sure someone could do some damage if they tried hard enough). Would have been stuck or failed ascent countless times adopting the above approach. It's often right at the top of a climb or after a sharp corner one needs the front, even in middle of sometime (climbing out of a gully). It's when they don't come on and off instantly in such conditions that compromises.

[HarryMann]

Ok ericos_bob, You say solid is better in all conditions except dry tarmac, but how do you answer peasants comments below then?

PS. I agree solid shafts don't fail (usually )
Although the decoupler might

On the road, in ice&snow the solid shaft has only disadvantages:

- if the road is mostly clear and dry you have to have the 4WD off ...any surprises and you won't engage it quick enough
- if the road conditions alternate a lot you'll have to switch on/off all the time, using up valuable concentration (+taking one hand off the wheel)
- when the road is bad enough to warrant full time 4WD but still offers good grip, you'll still have to switch it off every now and then on a straight bit to allow the transmission to unwind after a lot of bends
- going through bends at speed, directional stability isn't the best. Due to the missing center diff you will get understeer or oversteer or in extreme cases both as individual wheels lose traction for a fraction of a second as the transmission wind up is equalised
- powering up a hill through bends you will also get some degree of wind up. This will usually just release itself in some wheelspin, but if that wheelspin happens in the wrong place you could get stuck
- creeping down an icy hill through bends, the transmission will wind up eventually and release the tension in a lurch. If you're lucky that lurch will just give you a fright. If you're unlucky it's enough to lose traction and induce a slide (now you're sliding with 4 locked wheels)


In comparison driving the Syncro in the same conditions is just boring ...it simply does what it is supposed to with a minimum of drama and fuss.

[syncropaddy]

tarmac and warm climate + all other surfaces. mud,sand,dirt,gravel etc = solidshaft
reason: 50/50 power distribution all the time means 0 delay in power transfer to front wheels

Tarmac = transmission wind up in any part of the world with a solid shaft instead of a VC

[axeman]

it is only the decupler that i engage from a stand still as per advice and the advice form aidan, and once you look inside on and view the way in which it engages there is no way in which it will not damage the splined shaft in which it engages too if this is done on the move. ie metal fillings ending up in the gear box/oil. as clive said the diff locks get engaged as and when the are needed, most of the time on the move before i get stuck

next time that your in your van and it has built up enough vacuum (20sec after start up), place your head near the radio and pull any of the diff lock knobs and there should be a light shhhhhhh sound for second or two. well there is on my van, i hope that i am not alone on this? as every thing engages and disengages quickly.

the only time that i think that a solid shaft may be required, would be if the engine produced some much power/touque that it exceeded the vc's working range. there has to be a limit of how much power the vc can handle. have any of the turbo nutter tdi convershions ever over powered the vc? just a thought.

neil