Syncro decoupler

[jes*b]

So does anyone own a van with a factory fitted decoupler? If so what year were they introduced / discontinued?

[HarryMann]

One area you might notice from a missing or decoupled prop is engine/ transmission noise and vibration. Might be better might be worse - under heavy load my AAZ has a nasty crank shake around 1850 - 2000 rpm - with the prop off.

It might just be an open drive flange and output shaft rattling, but I don't like its 'nature'

If any decouplers at all were fitted at factory I doubt it was more than a small handful from my understanding.

[HarryMann]

Some more thoughts:

Pickups, panelvans and campers will probably change in handling differently prop/on/off.
My panelvan seemed to be quite atrocious prop off on tarmac on roundabouts, the Doka seems fine up to a point.

2mm or whatever is significant tyre tread difference on a factory 14" wheel is equiv. to a bit more than that on a 15 or 16" wheel.

And as my granny used to say when spotting something new and seemingly useful:-

Ooh! That'll be handy, even if I never use it

So on that basis I bought one years ago...

[silverbullet]

I bet Granny would have a thing to say about men and their "ways" too.

Penis envy aside and returning to the OP, bear in mind that all three (?) DeCo designs out there do not use the same internal parts. They are very similar, but use different splines for the coupling. Worth bearing in mind, long term, even if only considering the next owner down the line.

[Mudlark]

VW Quantum. (Passat) From Road and Tracks magazine writeup in September 86 provides some insight on the thinking behind knobs of the time:

"......... VW, through its Audi division, worked hard and came up with something that works well and no one else has: No muss, no fuss 4-wheel drive.

Before the decade is done, VW will offer 4wd everything. Golfs, Sciroccos, Jettas, vans, you name it; every wheel will get it's own driveshaft.

The beginning of all this is the Quantum Syncro wagon, VW's first 4wd for the American market. Syncro, incidentally, is VW's nametag for 4wd, much as Audis are called Quattros when they sprout rear differentials.

There is, of course, much commonality between VW and Audi, which is only fair because VW owns Audi. In the past this exchange program has meant that VW's biggest car was the same as Audi's smallest. But when the Dasher became the Quantum, it also grew a few inches so it's no longer identical to the Audi 4000.

The Audi 4000, you may remember, is available with 4wd. The Quantum shares the 4000's drivetrain and general layout, so adding 4wd to the Quantum was a piece of cake. Add a driveshaft behind the fwd transaxle, bolt-on the Audi's rear drive unit and suspension and, Bingo, a VW Syncro.

To provide some measure of exclusivity, the Audi 4000 Quattro is only available as a sedan and the VW Quantum Syncro is only available as a wagon. Nothing wrong with that. The Quantum, though a piece of cake, has a little less frosting and decoration than the more upscale Audi. This suits the more utilitarian wagon very nicely, thank you.

..........Of course, what the Syncro is made for is adverse conditions, and in those conditions it is superior in every way to any 2-wheel-drive car. In snow a slight loss of steering precision is an easy price to pay for the additional traction. And, if one of the Syncro's wheels does begin to slip, the knob on the center console can be pulled, locking the center differential and then the rear differential. In this arrangement only a snowplow is going to work better.

When the Audi Quattros were introduced, VW and Audi spokesmen emphasized that their permanent 4wd systems are suited for use in all weather conditions. Even when the roads aren't covered with snow, they said, the 4wd cars are superior. For the big Audi 5000 Quattro, because it has so much power to transmit, this appears to be true. With the non-turbo (Quantum) Syncro, however, dry-road handling hasn't benefitted. The improvements occur only when additional traction is needed, which obviously varies for customers in different parts of the country. Originally the Syncro was only offered in a few snow-country states, but it is now found at VW dealers around the country.

Depending on the options, a Quantum Syncro can cost between $15,645 and the $17,280 price of our test car, with its optional sunroof, electric window lifts and AM/FM stereo radio. This may sound steep for the Syncro until one tries to find a substitute. All the less expensive Japanese 4wd wagons are significantly smaller and have only part-time 4wd systems. Only Audi's 5000 Quattro wagon offers the convenience of this all-wheel drive system, and it costs nearly twice what the Quantum does.

The appeal of this car will no doubt vary with the weather. Dump enough snow on the roads and people will shovel a path to the VW dealer's doors."

[syncrosimon]

I did over 35k on my decoupled Syncro (whilst decoupled), and about 4k coupled. Some of the only original parts on the syncro were the front driveshafts, gearbox and wheel bearings, and VC. Do you see the pattern?

Some people will just not admit that for road driving you do not need 4wd, and in hindsight now that I have moved away from 4wd vehicles I can see that the de-coupler kind of disrespects the Syncro 4wd ethos and upsets people after a massive investment into the 4wd market. However it was my humble opinion that a decoupler adds to your Syncro experience, especially on the motorway where your VC is being slowly cooked however good it is. Look at touring cars, very limited advantage even in the wet in the 4x4 Audi versus 2wd everything else days.

My syncro had an honest and verified 107bhp, the rear tyres never had any problem transmitting 53hp each on a 2 tonne vehicle. The Bugatti Veyron needs 4wd with 290 bhp per tyre, a T3 doesn't.

On the limit of traction (enthusiastic driving) your handling suffers as you feel the front end being pushed, or as has been said earlier 'washes out'

Luckily it only takes a second to couple, and I was always happy to make that judgement call and realise when it might be rainy, snowy, icy or I just wanted to drive a little faster.

It is best to get a good working VC, but a decoupler can make a stiff one manageable and a stiffy is better for traction as you get 4wd lock up sooner rather than later. So after a punishing bit of rock climbing, decouple on the flat and let the VC cool down. Gauge better how much traction you have just in 2wd. Have a driving challenge and see how far you can get in 2wd. Its all good fun. If you have a VC that you like the characteristics of then a de-coupler will keep it that way for ever. VW did make stiffer VC's, and also weaker ones for people not into bind up.

I mainly did long trips in the syncro, and always felt better knowing that front drivetrain would not fail me, and if it worked at the beginning of the trip, then it would be working at the end.

The only draw back is the cost.

[jed the spread]

Hows the tent?

Jed

[syncrosimon]

The holiday cottage last week was exceptional. Not been camping since!

[axeman]

i fail to see any disadvantage to fitting a decoupler. based on my experience they engage almost instantly (far quicker than either the front or rear locker) , it will reduce where on the drive train (diff, cv joints,front bearings etc), no more tyre scrub on full lock ever, no more wind up after a long motorway run, less things worry about over all.

the camper will be getting one when funds allow based on my experience. rather than what people think they know with out having any actual experience of.

neil

[Mudlark]

Think thats the point Neil; based on any ones experience they can perceive the value it offers them. There is no right or wrong way on this; its simply down to individual choice.

Good to here from you Simon ! Where has your old camper got to ?

[footstuck]

I have covered 30k+ since fitting my decoupler, and i can say from experience that in 2wd it is a nicer drive.
No torque chatter or prop ringing at low engine revs (i have a solid prop), my VC gives excellent take-up

But, the times that i have needed my VC on or off-road are few.

In regard of Decoupler failure, you could say the same about fitting longer after market gears, which many of us also have.
The quality of engineering on the replacement parts is A1 and in my opinion will not fail or i would not have fitted it.
I comment from my experience in driving with one
having researched their design and fitted one
and from a mechanical design point of view, qualified experience building engines gearboxes and axles.

I got mine here http://www.aatransaxle.com" onclick="window.open(this.href);return false;
The reason that i chose this design was;
The inclusion of a needle roller bearing between the two replacement shafts (design not available in Europe at the time of purchase
A proven product and Solid commitment to quality
Great reviews and other supportive products giving confidence.
Great communication a reliable and genuinely nice fella
Great exchange rate at the time of purchase
No UK suppliers at the time of purchase.


As to the question 'Do I need one'? . . . . .Only till you've got one

[footstuck]

I will be at SP if anyone wants to try one out and make your own decision either way

[HarryMann]

Nice to hear from you again Simon... we are in Devon again, first weekend in August if you are able to drop by.

[syncrosimon]

Hi all, I went to see the old Syncro last week whilst on holiday. The owner was out, but she looked exactly as when she left my ownership. She now resides on the coast of West Sussex near Brighton and is used for family camping to festivals mainly.

Clive, I will see you in August.

[superbus]

Well, it looks like there's always 2 perspectives on this! I can see really valid points both ways. I guess if the VC was more affordable (the price bracket of a regular clutch) it wouldn't be such an issue.

In the end, I'm going to fit a decoupler and keep the tight VC. I figure in my case, as the van will spend a fair bit of time on tarmac, doing parallel parking etc, the decoupler will make that a lot easier with less tyre and trans wear. Anytime its off road, snowy or really wet, I can revert to 4x4 and if it fails, I'll figure out what to do at the time! It seems like there's plenty of other things on the syncro that may well fail first so I'm not going to worry too much!

Thanks for all the views and advice, I changed my mind at least 3 or 4 times over the last few days!