VC Advice

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Re: VC Advice

Postby ninja.turtle007 » 04 Aug 2018, 12:57

silverbullet wrote:Side note: "more aggressive tyres" ?

Lower temperatures require softer (winter) rubber compounds to maintain grip afaik.

Dare I say it but this is more like Expedition Portal forum territory, unless I am badly underestimating the syncronauts knowledge base?

Input from northern/central/eastern european members?

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Our current tyres are Cooper Discoverer AT3 and they performed really well in snow and ice in the Caucasus mountains last winter.

But......they are rubbish in mud. Looking at the 'roads' we have been driving recently, very hard mud but you can see how they will be when wet. There is no way would be able to deal with them.

I'm trying to source a set of BFG KM3's as I think these will be a better option. - Nowadays, this is a serious outlay for us. - More than a months budget in Kazakhstan.

With tyre choice, i don't think there is a right or wrong answer (within reason). But I'm all ears.
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Re: VC Advice

Postby silverbullet » 04 Aug 2018, 17:40

The state of the roads would have been my next question!

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Re: VC Advice

Postby HarryMann » 05 Aug 2018, 08:51

Not easy to do meaningful VC tests...
It doesn't take much to bog down in sand at 'high weights'.
Did you lower the tyre pressures?
Have you run those tyres at very reduced pressure over so so surfaces before? Carcass might be damaged I can see bulge too!
Fronts really ought to be turning IMHO.. certainly do on ice snow in mine.
Yes.. thus prob. best place for proper discussions

Hours/days of real world rough roads is always a severe test unlike playing in UK.. Any BFG ATs my choice unless someone proving otherwise. Barely any wear on mine and happy enough in snow earlier this year
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VC Advice

Postby clift_d » 05 Aug 2018, 20:48

Mud, and to a lesser extent sand, are about the only surfaces where ATs wouldn't necessarily be the best choice.

VDEG suggests:
- for mud BFG - MTs or Michelin O/R (XZL)
- for sand Michelin XS
Otherwise BFG ATs are the best all around compromise.

So unless you're travelling exclusively on mud or sand, if it was me I'd probably stick with ATs.

For snow you'd need to go to proper winter tyres to improve much on ATs.
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Re: VC Advice

Postby ninja.turtle007 » 06 Aug 2018, 10:40

clift_d wrote:Mud, and to a lesser extent sand, are about the only surfaces where ATs wouldn't necessarily be the best choice.

VDEG suggests:
- for mud BFG - MTs or Michelin O/R (XZL)
- for sand Michelin XS
Otherwise BFG ATs are the best all around compromise.

So unless you're travelling exclusively on mud or sand, if it was me I'd probably stick with ATs.

For snow you'd need to go to proper winter tyres to improve much on ATs.


In an ideal world we’d have a couple of different sets.

So far, it’s only mud that has completely stopped us.

The Discoverer AT3 have been decent all road tyres. But we are at a point where we need to replace them as they are 50% worn and we no longer have a spare.

Where we are are have 3 options for MT

BFG KM2 £145
Hankook MT £97
Nokian Rickproof £95

The Hankook look to be the winners at the moment.
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Re: VC Advice

Postby ninja.turtle007 » 06 Aug 2018, 10:42

After Mongolia, we will either going to Africa if South America with the set of tyres.
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Re: VC Advice

Postby ninja.turtle007 » 06 Aug 2018, 12:40

With regards to the VC Tanja @Visco Werkstatt Kern have been awesome and sent us one of their uprated VC’s that according to there data will transfer 50% more torque to the front wheels.
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Re: VC Advice

Postby silverbullet » 06 Aug 2018, 16:23

Higher viscosity fluid moves the VC performance J-curve up the graph as a whole, as I understand it.
Generally stiffer and heavier to drive across the board.
Sorry that I couldn't afford to throw you a freebie Tom, I have bills to pay.

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Re: VC Advice

Postby ninja.turtle007 » 06 Aug 2018, 17:09

silverbullet wrote:Higher viscosity fluid moves the VC performance J-curve up the graph as a whole, as I understand it.
Generally stiffer and heavier to drive across the board.
Sorry that I couldn't afford to throw you a freebie Tom, I have bills to pay.

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Same here, I totally understand. :ok

As part of the deal I'm sending this one to them to test.

I looking forward to trying out the new one. I should have in a few days.
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Re: VC Advice

Postby ELVIS » 06 Aug 2018, 19:09

ninja.turtle007 wrote:With regards to the VC Tanja @Visco Werkstatt Kern have been awesome and sent us one of their uprated VC’s that according to there data will transfer 50% more torque to the front wheels.


So have some members of this forum reading this thread.....

Credit where it’s due Chap :wink:
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Re: VC Advice

Postby orcecaveman » 06 Aug 2018, 19:27

Interesting advice. Thanks for sharing your knowledge with us Ian. :ok
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Re: VC Advice

Postby silverbullet » 07 Aug 2018, 08:22

orcecaveman wrote:Interesting advice. Thanks for sharing your knowledge with us Ian. :ok
There's only two parameters that can be changed:
1.The fill weight/volume, which determines the "hump" temperature. This is important as it decides when the VC pulls in i.e. not causing sudden engagement during long, slow turns when on tarmac (causing sudden understeer to oversteer behaviour)
2. The fluid viscosity, which determines the overall "stiffness" and torque transmission at a given tempetature.
Since the VC is within the front diff, its temperature-determined behaviour is directly related to, and influenced by, the diff oil temperature.
There's nothing else that can be changed.

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Re: VC Advice

Postby orcecaveman » 07 Aug 2018, 11:05

silverbullet wrote:
orcecaveman wrote:Interesting advice. Thanks for sharing your knowledge with us Ian. :ok
There's only two parameters that can be changed:
1.The fill weight/volume, which determines the "hump" temperature. This is important as it decides when the VC pulls in i.e. not causing sudden engagement during long, slow turns when on tarmac (causing sudden understeer to oversteer behaviour)
2. The fluid viscosity, which determines the overall "stiffness" and torque transmission at a given tempetature.
Since the VC is within the front diff, its temperature-determined behaviour is directly related to, and influenced by, the diff oil temperature.
There's nothing else that can be changed.

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Nice to have somebody who's willing to share their knowlefge and experiences these days rather than some who just seem to profiteer and build their empire from things they know or have learned from other owners.
Just for this reason alone i would choose to use your services over others. Thanks Ian

Right im off to make a video....
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Re: VC Advice

Postby silverbullet » 07 Aug 2018, 12:14

90% of what I "know" about VC's is all down to the efforts and trust of others anyway!
The rest is just observation.
I'm in it to do something good, as a way of returning the favours.
Cost-effective T3 VC's that work, that'll do for me. The parts will run out eventually...

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Re: VC Advice

Postby silverbullet » 07 Aug 2018, 22:05

PS by way of qualifying the bit about altering the viscosity of the fluid:
Its not widely known, but VW used to supply what was referred to as a "kunden visco" or "customer vc" for owners who complained that the original syncros were a little heavy to park (presumably non power steering models)
The VC was apparently filled with fluid around half the standard viscosity...
Early on in our collective efforts, I filled a VC with a similar viscosity sample that I had got from the suppliers and Neil tested it in his Moroccan Westy iirc
So how did it perform?
It was really nice to drive, performed without dramas when we tested it by pulling up on to a muddy verge (one side on tarmac, the other on saturated grass, no diff locks) but otherwise, not so different to the standard viscosity VC we had done and fitted to another syncro, just a little lighter on its wheels to drive.

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