Tight viscous coupling

[syncrosimon]

Technical discussions should contain facts and documented evidence on the subject matter. Technical discussion will get nowhere when people cant tell the difference between unqualified opinion and facts. If I want to learn and discuss gardening I will talk to a qualified gardener, I wouldnt talk to a policeman. There is no harm in asking questions in a technical discussion as long as a qualified person gives the correct answer. There is far too much unqualified opinion floating about on forums like this one. Sometimes it can be scary!

Paddy, come on now. I am actually a traffic warden, and you just dont know how long I have been waiting for a technical discussion on double yellow lines to come up, so that I can post on something I am qualified to talk about.

As I am not an engineer Paddy, could you answer this question for me. I was wondering how the 4x4 system works in the Kangoo Trekka, I am only a traffic warden, so please explain.

Much love

Simon.

[silverbullet]

Just about every common AWD vehicle here, but no Kangoo Trekka :
http://www.awdwiki.com/awd.html

[syncrosimon]

Very interesting quote from that site.

The disadvantage of a viscous coupling is that it engages too slowly and allows for excessive wheelspin before transferring torque to another wheels. This is especially critical in automatic all wheel drive systems - when cornering under acceleration, the rear end is engaged with a slight delay, causing sudden change in the car's behaviour fron understeer to oversteer. Also, when taking-off in sand, front wheels can become bogged down before all wheel drive is engaged.

In an attempt to reduce the coupling's activation time, VW Golf MkII Syncro always transfers 5% of torque to rear wheels (this is achieved by rear driveshaft rotating slower than front driveshaft in normal conditions, causing viscous fluid warm-up and slight solidification).

At the same time, pre-tensioning the coupling too much leads to undesireable transmission wind-up and makes the system too sensitive to uneven tread wear on front and rear tires. This is why Volvo first reduced the pre-tensioning in 2000 and then replaced the viscous coupling with Haldex clutch on their all wheel drive vehicles in model year 2003 (Volvo s60 has Haldex since 2002). (Source: http://www.volvoxc.com)

Fortunately the low power of most T3 Syncros cant induce corner wheelspin at the best of times.

[silverbullet]

Re: First paragraph ^^^that's probably why a syncro is best driven in a "positive" manner on loose or slippery surfaces, with a scruff-of-the-neck style to get the most positive/predictable handling.
That's certainly my experience after this winter.
I have a mate with a ghastly Honda CR-V (Honda's own AWD system) which in the snow was a disaster. If you bogged down it would kangaroo from front to rear axle and back again, but not actually getting anywhere

[v-lux]

Jeeezus fecking christ are you lot still banging on about this?

Go outside and have fecking word with yourself will you, life's too short

[syncrosimon]

Someone needs a nap

[syncropaddy]

Paddy, come on now. I am actually a traffic warden, and you just dont know how long I have been waiting for a technical discussion on double yellow lines to come up, so that I can post on something I am qualified to talk about.

As I am not an engineer Paddy, could you answer this question for me. I was wondering how the 4x4 system works in the Kangoo Trekka, I am only a traffic warden, so please explain.

Much love

Simon.

If you Google 'Nissan sourced automatic torque coupling' you should get a good description from a few sites including http://www.difflock.com and some interesting papers written by Nissan Engineering staff on Science Links Japan. Also you can look HERE for a very good .pdf on the ATC. Pity its in French. Its a thing you should look for yourself as detail might be lost in translation.

On the double yellow line thing as its something you are qualified to talk about, Id be interested on finding out the most environmentally friendly method of removing double yellow lines from Tarmacadam without damaging the Tarmacadam or filling the atmosphere with chocking fumes.

Hugs and kisses

Andrew

[syncrosimon]

On the double yellow line thing as its something you are qualified to talk about, Id be interested on finding out the most environmentally friendly method of removing double yellow lines from Tarmacadam without damaging the Tarmacadam or filling the atmosphere with chocking fumes.

Hugs and kisses

Andrew

My recommendation would be to petition your local council to not have the things painted in the first place, unfortunately there are more people that petition for there placement, usually outside there own houses.

[silverbullet]

Time to ask for an OCD right-brain oriented technical discussion forum for us ASD marginal types
Call it "Special Engineering"

[HarryMann]

Oh yes, can't have 'glass half full' types interfering with a good 'technical discussion'

Will suggest a Tech Squared Forum, to avoid interrruptions from those lwithout a serious case of discussitis

[jebiga41]

Jeeezus fecking christ are you lot still banging on about this?

Go outside and have fecking word with yourself will you, life's too short

They are still going

[silverbullet]

Oh yes, can't have 'glass half full' types interfering with a good 'technical discussion'

The glass should be the correct volume for the contents to be contained IIRC

[syncropaddy]

Oh yes, can't have 'glass half full' types interfering with a good 'technical discussion'

The glass should be the correct volume for the contents to be contained IIRC

Correct. In engineering terms if a glass is half full them it twice the size it needs to be.

[silverbullet]

Very interesting quote from that site.

In an attempt to reduce the coupling's activation time, VW Golf MkII Syncro always transfers 5% of torque to rear wheels (this is achieved by rear driveshaft rotating slower than front driveshaft in normal conditions, causing viscous fluid warm-up and slight solidification).

At the same time, pre-tensioning the coupling too much leads to undesireable transmission wind-up and makes the system too sensitive to uneven tread wear on front and rear tires.[/i]

I find this interesting.
Freelander 1 (VC drive to rear axle) had a built-in front-torque bias for predictable car-like handling (it's target market)
This was achieved by having markedly different diff ratios front to rear. Unfortunately this resulted in a VC service life of around 60k, sometimes considerably less. Since the majority of these vehicles spent their days on tarmac, what can we draw from this?
As has been noted in another thread, the higher rear tyre pressures needed for the T3's rear engine give rise to an increase in rear tyre rolling radius, subtly altering the relative diff ratios when on tarmac.
So the drivetrain would behave like the Golf syncro ^^^, but the reversed. Front engine, higher front pressures, bigger radius, slight front drive bias.
Well I find it interesting.

[jebiga41]

Very interesting quote from that site.

In an attempt to reduce the coupling's activation time, VW Golf MkII Syncro always transfers 5% of torque to rear wheels (this is achieved by rear driveshaft rotating slower than front driveshaft in normal conditions, causing viscous fluid warm-up and slight solidification).

At the same time, pre-tensioning the coupling too much leads to undesireable transmission wind-up and makes the system too sensitive to uneven tread wear on front and rear tires.[/i]

As has been noted in another thread, the higher rear tyre pressures needed for the T3's rear engine give rise to an increase in rear tyre rolling radius, subtly altering the relative diff ratios when on tarmac.
So the drivetrain would behave like the Golf syncro ^^^, but the reversed. Front engine, higher front pressures, bigger radius, slight front drive bias.
Well I find it interesting.

Or does the golf behave like a Syncro ????