Tight viscous coupling

[desert rat]

Hello all,
I have just tested my VC and it is a little tight as in it won't tick over as it just stalls the engine out!
Which is better - to fit a new VC or leave it tight and fit a Decoupler?
Also most of the mileage this year will be done on the road!!
Paul

[syncrosimon]

Take the strain out of the system and get a de coupler, last time I had mine in 4wd was for the snow. Mine is a tight VC and seems ideal for off roading. Do use it just occasionally for manoeuvrings on grass etc, climbing onto ramps.

In my opinion the front end when de-coupled will not wear.

Makes the handling better in 2wd.

Forget about tyre rotation and buying 5 tyres at once.

Peace of mind.

How the de coupler can cost so much is totally beyond me, all that is added is a shaft and a cog, plus a plunger. must be the worlds most expensive mechanical part. real rip off.

Simon.

[desert rat]

cheers for that simon!!

I had in my mind decided that a de coupler was probably the best option. Yes i know what you mean when you actually see what is in a de coupler. They are a rip off but i will have to get one now because i really dont want to drive the van with the vc as tight as it is!!

Where did you purchase your decoupler from? or can you recommend a seller!
Thanks Paul

[syncrosimon]

I got mine from busman.be when he was a the cheapest. Syncroservices was the cheapest but syncroswede got his last cheap one, mike ghia got one from canada when the pound was strong.

Both mine and mals arrived with broken diff lock actuators, and the pre refund price is 300 quid more. Ouch.

[peasant]

just to be contrary

The whole point of a Syncro IMO is the effortless safety of the automatic 4WD ...especially on the road. Yes, you can take it off road, but it's not an off-roading vehicle by design ...it was designed for poor roads and bad weather. I certainly get enough of both where I am and wouldn't want to miss the the 4WD.

Unless most of your road driving happens on motorways or very good roads, i'd buy a new VC (seenashow it costs roughly the same as a de-coupler anyway) and if 95% of your driving indeed happens on first class roads ...sell the Syncro, make a mint and buy yourself a superb 2WD

[syncrosimon]

Yes, but I dont need 4x4 for 95% of the time, and do for the other 5%, so the decoupler is the best. If you tried one you would never go back, I have as much fun in mine soft roading in 2wd with the reasurance that when she grinds to a halt I just pull the middle button out. Real test of driving skills.

The front end components are too expensive to wear out un necessarily on the motorway.

If it is raining hard etc I pull the lever. More driver input more fun.

[peasant]

On that note:

Makes the handling better in 2wd.

I would contest that a good VC actually makes the Syncro handle better than the 2WD ...even on dry roads (wet or slippery roads are no contest anyway)
I've had 2WD T3's for 15 years and the Syncro for two years now. The Syncro is a much sportier (if a diesel T3 can ever be sporty) drive than the 2WD.
You can push it through tight corners much more forcefully than a 2WD.

All this off-road thing with the Syncro is great fun and a big boon, as it can go where no other van went before ...but do not neglect the on-road advantages of 4WD over it. I mean, Audi builds quattros for a reason, don't they?...and they don't usually go off road

IMO, by driving the Syncro with a stiff VC and a de-coupler you're crippling it and taking away from, not adding to its original design.

[Russel]

You are actualy going back to its original desighn with a decoupler only it used a bowden cable instead of vacume and would automaticaly engage 4WD if crawler gear was selected.
Russel

[syncrosimon]

Peasant wrote

Yeah, but they are old buses now, and I dont thrash around in my camper like I did in my first syncro back in 1989, so unless you are pushing the envelope you are gonna see no difference. No doubt if you are on the max, foot to the floor, the syncro is just miles better, but the tight VC is better in those conditions, they are only that loose new anyway because it has to cope with good grip road surfaces. Not having to spin up the rear wheels when off roading is a real boon, and when on the roads between lanes, just switch it out. Still get all the advantages of a visco, just take it out when you dont need it. It is refining the design.

[peasant]

You are actualy going back to its original desighn with a decoupler only it used a bowden cable instead of vacume and would automaticaly engage 4WD if crawler gear was selected.
Russel

You sure?

I always thought that when they initially put in the decoupler, there was no VC ...just a straight through drive. Selectable 4WD like any other.

Because, technically speaking, a working (i.e not stiff) VC AND decoupler makes no sense

(They did however use up some of the housings with decouplers when they made the first Syncros with VC)

[syncrosimon]

It only makes no sense on paper, the reality works just fine.

I have to rely on the third middle green light to tell me i am in 2 or 4 wheel drive for normal driving. Works better off road, and better on road, perfect sense.

[desert rat]

still confused by what to do?
Do i fit a decoupler or a new viscous coupling?
I understand that having a decoupler would take the strain out of the front part of the drive train especially on road where you dont need 4wd!
If i fitted a decoupler would i get a slight saving on fuel consumption or is that just another subject?

[syncrosimon]

No saving in fuel as far as I can tell, I look at the decoupler as being kind to the front end, how much for cv joints and diffs on a 16?

The new VC method is also good, but I prefer the decoupler, just being able to jack up a rear wheel and spin it is a real boon.

On these now fragile machines anything that aids longevity has to be a good thing.

[Russel]

You will make no saving on fuel.
The first setups did use a billet shaft.I was not referring to that part of the drive train.
Using an old tight VC with a decoupler is not ideal as a stiff VC can slip under load. The two best options are a billet shaft or a sports VC.
Russel

[desert rat]

hi russell, in your expert opinion would i be better off replacing the VC with a new unit as a decoupler and a sports vc are slightly too expensive for me at the moment!