Decouplers another con?

[jed the spread]

Lets let it go now fellas, everyone has said their bit and its all been logged. The final bit of last wordage has been gotten in now and of course the bits of jokes and stuff will obviously carry on for a while but no point in keep going on about it. If you want one get one if you dont then dont but now their is a guide of why to, or why not to get one.

jed

[syncropaddy]

Now....... how can Jed get all of this into a video on ....

....... http://www.campervanculture.com" onclick="window.open(this.href);return false; ............

[syncroand101]

Now....... how can Jed get all of this into a video on ....

....... http://www.campervanculture.com" onclick="window.open(this.href);return false; ............

I reckon a properly chaired debate. With an audience vote at the end...

[syncropaddy]

Now....... how can Jed get all of this into a video on ....

....... http://www.campervanculture.com" onclick="window.open(this.href);return false; ............

I reckon a properly chaired debate. With an audience vote at the end...

I feel a Kalashnikov moment coming on .......

[KarlT]

F'k me, Leyland! Can we have a real engineers view please?


I've had five syncros now, none with what I'd say is a tight VC, no scrubbing on tight turns. But all have got wind-up on fast long runs (although can't really tell with the Tristar as P/steering makes it harder to feel). Have I just been unlucky?








Anyone want to buy a decoupler? Hardly used.

No, honestly have I just been unlucky?
Does wind-up on long runs, really mean your VC is buggered or do they all do it?


If I can get mine working (honestly its not working only in 2wd ) but that's down some vacume system problem, none of my diff-locks are working but all are free.
To be honest steering doesn't feel any lighter, although it is the first time I've driven it in a long time & can't switch between the two to be definate.
I will probably run it in 4x4 90% of the time & just use it on runs & in event of problem, tyres/servicing etc etc.


One puzzle, why would VW feel it wanted to offer them as a option? Why three positions for diff-locks on dash? Doesn't make sense if their engineers thought it was a bad idea.

[jed the spread]

You could try setting up a "My VC isn't working propperly" thread. I can imagine lots of people are not following this thread due to the title alone so you might get more replies by a wider range of people.

Jed

[syncropaddy]

One puzzle, why would VW feel it wanted to offer them as a option? Why three positions for diff-locks on dash? Doesn't make sense if their engineers thought it was a bad idea.

We might never know that answer but probably SDP felt it might be good to have it in the option list. If it was deleted as an option, then the cost of remanufacturing the dash panel with the third hole and make it a two hole panel would cost too much so deemed uneccessary... which it would be.

[KarlT]

Hmmmmmm, again that doesn't make much sense.
I'd of thought, before a car, well a german car , goes into production a huge amount of time, effort & money is spent on highly trained & intelligent people figuring this sort of thing out. I think it was 8 years (maybe more) between VW toying with the 4x4 transporter idea before production finally started.
At that time someone or a team of highly-trained & qualified 4x4 specialists, with minds vastly superior to ours, thought fitting a decoupler was a good idea.
From how I understand it, the option was later dropped by VW, and as you say we don't as yet know why, but seeing as a decoupler apparantly cost a small fortune, it may of been seen as an expensive luxury option, with very little up take. (Bit like the Tristar really!! ) Who knows? But that's not the point really.


RE- Wind-up.........Surprised by lack of response, (or am I? ) But I thought every (99%) used VC did this. I'm sure that's what CJ or maybe S'nutz had said when it was mentioned years back.
Anyhow, suppose when I get my decoupler working I'll be able to test my VC performance more fully. Will report back my findings then.

[Mudlark]

At that time someone or a team of highly-trained & qualified 4x4 specialists, with minds vastly superior to ours, thought fitting a decoupler was a good idea.

and then the sales team moved in and told them what would sell and convinced the accountants it was pointless to add so much cost to the company for a feature that was of such little benefit to the majority of the target market (think volume here!). As the paper based memos flew around the departmental offices of VW, decisions no doubt had to be made about production models in order to meet scheduled deadlines; its what the Germans excel at.

Somewhere along the way the coupler, the third knob and its option were dropped, but by now the moulding for the gearbox casings and the 'knob dash trim' had very likely already been cast and they stayed as they were. No harm done.

The production vehicle would feature its unique selling point of permanently connected four wheel drive that required no driver intervention. This with the option of a rear and front diff-lock covered most users requirements, the addition of a 'third way' for the remainder was probably deemed unsell-able and indeed counter productive to the core selling feature. It would confuse the hell out of the customers and the salesmen; who are not engineers and dont understand the technology.

There is a pdf paper somewhere from 1985, think it is on syncro.org and from one of the VW technicians involved in the development and application of the new to them VC technology and he pretty much sets out the same sales based approach on page one. Four wheel drive without driver intervention; quite a new and revolutionary feature in 1985 for a mainstream vehicle and the foremost of the messages that VW marketed the vehicle on.

Call it plausible fantasy if you like

[syncropaddy]

Yes well said Mark. Syncro's came with no diff locks, the UK got rear locks as standard (I think), America got rears only because, as legend has it, VW thought a front locker would cause too many legal problems caused by misuse. Can you imagine the nightmare a de coupler would cause everyone - particularly in America - on many fronts. There are Syncro owners who joined this site not knowing what diff locks were for or when to use them and these people are enthusiasts. They know now! So can you imagine a harassed mother of 4 with a twin locker, decoupler spec'd Syncro in NYC in the winter trying to remember what the knobs are for while preventing Dirk, Brad, Brittney and Leroy from killing each other.... no I don't think so!

Decoupler = An expensive and unnecessary device fitted to a fundamentally flawed, but wonderful, intoxicating vehicle.

[KarlT]

Interesting stuff this.
So in summary..........

US Front Diff-lock..........A device designed & engineered by some of the best vehicle engineering minds & 4x4 specialists in the world intended for the 'wonderful' T3 Syncro. But reversed by accountants & salesmen worried about cost & distracted/incapable lady drivers?

Decoupler................A device designed & engineered by some of the best vehicle engineering minds & 4x4 specialists in the world intended for the 'wonderful' T3 Syncro. But reversed by accountants & salesmen worried about cost & distracted/incapable lady drivers?

I want both now!!!



But obviously, as salesmen said, not for everyone!

[KarlT]

As there seems to of been no disagreement................. .

I am going to save this post to pop up every time a decoupler thread crops up to save the same old same.
It could also stop the next generation of people who didnt understand how something worked before they bought it arguing about something just to justify there outlay on an unnecessary item and falling back on the already discussed and not acknowledged myths that have been busted all ready.

Pro's of fitting a decoupler

1,
Q. "reduce the wear and increace the life span of wearing components simples!"
A. True, by fitting a decoupler you are putting 5% more wear on your gearbox that was designed to work with a VC sending 5% up front (it is not a 2wd gear box), this also means 5% more on your rear CV joints that mysteriously failing and you not understanding why are getting 5% more wear..

2,
Q. Jed wouldnt have had to remove his prop with a failed UJ if he has a decoupler fitted.
A. When a decoupler is fitted the prop still turns even though the 4wd is disengaged meaning a failed very graunchy UJ is still turning on the prop and the same unbearable vibration would still be going through the prop. 5% of the the drive is going to the front wheels (it will be helped along with the free turning of the drivetrain too so more like 3% in real terms but I am no expert) it isnt enough to wear out the UJ's on a prop, no way. What about front engined cars with rear wheel drive they go for hundreds of thousands of miles with 100% of the power going down a prop..... and when I do get the full whammy through my prop that is when my 4wd is engaged and is needed when the back wheels spin, or when in your case you would be pulling the knob on your decoupler. Jeds van has done 339921KM more than likely and not unreasonably, general wear and tear caused a UJ to go and the prop having to be removed, if a Decoupler was fitted or not.

3,
Q. Can a decoupler fail and leave you stuck in the middle of nowhere without 4wd?
A. Yes it can, if one was fitted and it broke (because it is a mechanical part and aftermarket) and you are alone and remote you would be in trouble. No decoupler = No failure.

4,
Q. If you put new tires on your van you will cook the VC without a decoupler.
A. In the unlikely event you get a total blow out twice in one trip and you have to get a garage/tyre shop to fit two new tires you dont need a decoupler. If you dont want to take 10 minutes and take the prop off (remember you will be on a tar road more than likely) put them on opposite corners so the rolling radius would have stay the same. If you have to put only one spare tyre on with a deeper tread than the rest would not the diff on that axle take up any difference in rolling radius so they stay the same between the front and back axle.

5,
Q. Can a decoupler stop wind up on long drives?
A. Yes. You will have a stiff VC and it is not working like it should, I have personally seen a stiff VC fail open (will only work as a 2wd) much quicker than expected this year (infact it was quite early) due to its stiffness, it worked quicker but became hot quicker and failed quicker. I have video to prove this happens and actually the fact is your VC will be failing if your getting wind up and is getting stiff. A VC is an automatic clutch that sends drive to the front wheels when needed on its own, if you fit a decoupler to disengage the 4wd so you dont get wind up you have still got a VC that is failing and you run the risk of it letting you down big time. A Decoupler is about the same price as a reconditioned VC so I would think its better to fit a new VC and have a working van than to use one of my personal favorites, "put lipstick on a pig" or fit a decoupler to protect a broken VC . Think of your normal clutch on your van or car, when you feel it slipping and on its way out you get it changed so your vehicle works properly.

6,
Q. Does fitting a decoupler mean you will have a knob and a green light?
A. Yes, you will..... But like has been said already by defenders of the decoupler if you have a perfect VC their is no need for a decoupler. If its a willy waving compensation for anyone fitting a green light and a knob then you would be best sorting your Shlong out first.

7,
Q. Does fitting a decoupler make your steering lighter?
A, No, I took the prop off my van due to a failing UJ, is maintained as it should be and the steering is no different. I fitted a spare prop borrowed from my Doka just this minute and the steering is exactly the same.

8, US Front Diff-lock..........A device designed & engineered by some of the best vehicle engineering minds & 4x4 specialists in the world intended for the 'wonderful' T3 Syncro. But reversed by accountants & salesmen worried about cost & distracted/incapable drivers?

9, Decoupler................A device designed & engineered by some of the best vehicle engineering minds & 4x4 specialists in the world intended for the 'wonderful' T3 Syncro. But reversed by accountants & salesmen worried about cost & distracted/incapable drivers?




I hope this helps with any future discussions on the Decoupler as these are the points that have all ready been talked about time and time again and I hope this bit of time I have taken to type this lot out will act as some sort of confirmation of it being talked about and the answers have been given. An engineer with a long career and adequate actual qualifications has contributed to these discussions as well as keen amateurs such as myself and others.

Jed

[dave friday]

Just to add the disscusion! i fitted a decoupler because the front diff is noisy[but not on the over-run] and is the easiest and cheapest way to get rid of the whine!.
Replacing the diff is the best bet but im in Spain!.