Are all decouplers the same?

[kuchiman]

I have been checking into decouplers for my syncro and there are a few choices out there. If they are all the same then I'd just assume going with the chaepest one. What makes one one the best and who makes the best one?

[syncrodoka]

Buy one that has a bearing for the pinion shaft. Florian in the classifieds and Daryl at AA transaxle are the only ones that I am aware of that do this.

[whynotvw]

X2 AA Daryl, his reputation speaks for itself

[SyncroGhia]

No they're not!!

I've seen atleast 3 different designs on the market.

Most of the ones in europe have a bearing in the end of the shaft rather than just a bush like others.

The best one I've seen is offered by Syncroservices in Germany and is made by a chap called Stefan. He's not easy to get hold of though. I'd put the Busschmiede decoupler a close 2nd and they're similar in price and both come as a complete kit... but without solid shaft to remove the VC and both are exchange items.

MG
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T3 Syncro 16 S6 Westfalia Limey SOLD
T3 Syncro 6x6 SOLD
T3 RS6 Bluestar
T3 Tristar Syncro 16 SOLD
T3 Tristar Syncro RHD SOLD

[SyncroGhia]

Just a few photos of the decoupler from Busschmiede. There have been a few discussions on here about the differences between decouplers on the market and I have a few photos of other decouples including the one I use on Limey so I thought I'd post them up here.

First the Busschmiede decoupler:

Now the decoupler which I have on Limey which is a Stefan unit which Syncro Services supply.

The only difference I've seen between the Busschmiede and Stefan decouplers is the design of the teeth for the gear to engage. The Busschmiede unit teeth are just chamfered off where as the Stefan unit teeth are specifically designed in a similar fashion to those on synchroniser slider rings.

Here is a unit which I've seen advertised in the U.S. which doesn't have a bearing or bush in the end of the output shaft which would support the shaft. This part comes up against the end of the pinion shaft so damage here is very serious.

If I find anymore types, I'll add to the post.

MG
_________________
T3 Syncro 16 S6 Westfalia Limey SOLD
T3 Syncro 6x6 SOLD
T3 RS6 Bluestar
T3 Tristar Syncro 16 SOLD
T3 Tristar Syncro RHD SOLD

[Black'n'White]

I have another thread going here asking for help identifying the maker of the decoupler that was installed on my Syncro. I removed it because there was a leak around the actuator shaft where it emerged from the nose of the output housing.

Overall, it looks similar to the USA sourced decoupler mentioned by SyncroGhia, but seems to me more crudely made.

For example, the cause of the actuator shaft leak was a complete lack of either o-ring or lip seal anywhere along the shaft. There isn't even an o-ring groove on the shaft, or a counterbore on the nose of the output housing where a lip seal could have been fit.

Mine has no needle bearing on the pinion nose, and only a flimsy snap ring holds the selector jaw to the actuator arm.

There's a photo of the open end of a decoupler at GoWesty that looks very much like my decoupler, and I'm waiting on a response to the photos I sent them. If someone knows who is making it for them, I'd sure like to know who that is...
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'87 Syncro/Westy Homebrew
Whatever it takes...

[Sodo]

I'd think of some way to seal that shaft.

If looking for a new one, I'd go VanCafe. Top quality CNC machined parts, centerless ground actuator shaft; parts that are an honor to have in your transaxle. Very nice stuff.

I chose an AA unit 'cuz everyone said it was the best. Mostly because it has the "needle bearing" that I found later to be a sales gimmick. I admit "it is attractive" - it got me.
As is the "synchro-style engagement", another gimmick that has proved to be unnecessary. The elaborate engagement suits a gear-jamming mechanism for 1st/2nd/3rd/4th gear-change coupling, but is absolutely un-necessary for the once-a month (?) matched-RPM slide coupling by the little blue vacuum actuator. Even if once a day or once an hour there is no comparison to 1st-thru 4th gear-jamming under acceleration/deceleration, which is NOT rpm-matched, that the AA coupling suits. Anyway, it's way overkill. It's marketing that requires more important parts be cheaper elsewhere in the unit. As I found out.

But these features do sell decouplers because they're visible on the "open end" before install.

Construction is more important. Mine had a manufacturing defect where the slot for the e-clip was too 'tight' on the shift fork. The AA shift fork is a cheap laser-cut piece of steel sheet that wobbled a little on its hole. And being too tight on the e-clip, walked the (thin, weak) e-clip out of its slot. Stuff came apart, and rubbed on other stuff and filled my new $5,000 transaxle with metal filings. Was lucky that no parts went thru gear-meshes. All I have to change is all new bearings, (again), and get a better decoupler. But I bought it from AA in 2015 so they're saying 2019 is too far out of warranty. I'm trying to convince him, we'll see what happens.

Contrast this lasercut steel to SyncroShop's CNC shift fork, an item more worthy to go inside your transmission.

There is always debate on whether the no-load shaft nose needs any bushing at all. It seems like the composite bushing should be adequate. Honda uses composite bushings in power-transmission, and Hondas go the distance. Here we have a shaft in a no-load condition, that spins maybe a few lazy turns each day, if you park often. While the Hondas are putting FULL engine power across composite transmission bearings for 200,000 miles (or 300k?). And this little bushing spins 2.5 whole turns each day, under zero load. Don't worry, a composite bearing is more than adequate! And easier to clean too when you (if ever) flush your transaxle lubricant.

Here's a pic of the SyncroShop composite bearing (sold by Van Cafe)

If unsure about your decoupler WRT towing, its better to unbolt the driveshaft -if towing a Syncro with one axle down (2 wheels turning on-ground). Consider to tow ass-end up so the decoupler gets flooded with oil. But nobody does this, they use flatbeds.
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'90 Westy EJ25, NEW oil rings (!) 2Peloquins, 3knobs, SyncroShop pressure-oiled pinion-bearing & GT mainshaft, filtered, cooled gearbox.
'87 Tintop w 47k 53k, '12 SmallCar EJ25, cooled filtered original gearbox
....KTMs, GasGas, SPOT mtb

[Black'n'White]

Thanks for the detailed reply, and the warning. My transaxle was rebuilt by AA two years and about 500 miles ago (long story). That experience left me less than confident about the work and parts used. It seems that a lot of that may be due to Daryl's going to his ultimate reward. I did ask AA if the decoupler I have came from them, and was told it did not.

I'm not clear on the source of the decoupler with the CNC shift fork. I can't tell if the coupler rides on bearings or not from the photo. It sounds like the Van Cafe offering, but it's difficult to tell from the photos on their website. Could you clarify?

The setup I have now uses a steel shift fork kept on the actuator shaft with a flimsy snap ring, and the fit isn't exactly tight. The fork is sandwiched between a pair of brass/bronze washers that fit loosely over the cut down coupling, and that are also held on with a snap ring, albeit a thicker one. The bronze donuts are already showing wear marks where they rub on the coupler shoulder, shift fork, and circlip. So metal is already going into the transaxle, maybe the designers of that setup felt OK that at least it was brass instead of steel. Regardless, it seems it would be prone to the same failure you experienced. Which is why I think I'd be better off with a better quality decoupler, and why I'm shopping for one now.

BTW, I've been reading about your transaxle travails, and hope they've been resolved to your satisfaction!
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'87 Syncro/Westy Homebrew
Whatever it takes...

[Sodo]

The fit doesn’t have to be tight, floating is OK. It mainly needs to “never fall off”.

SyncroShop retails thru VanCafe because they are much better able to deal with credicards and the whole “core” process. So ya gotta call Van-Cafe. I doubt your decoupler will count as a core, cuz its already been modified to someone else’s design. Would be most efficient to fix yours, if you are confident about it not falling apart.

Maybe check if GoWestys mfr can put in a seal for you. Or DIY. Seal friction will add to the force the vacuum actuator must overcome, so it should be minimal.

Brass in your oil isn’t really a welcome addition, but you can almost call it a “lubricant” when compared to steel dust. It won't dent your bearing races like steel. As member PCForno says....simply put... "that stuff needs to get outta there".

edit: added a cutaway diagram for those who want to understand the "decoupler".

_________________


'90 Westy EJ25, NEW oil rings (!) 2Peloquins, 3knobs, SyncroShop pressure-oiled pinion-bearing & GT mainshaft, filtered, cooled gearbox.
'87 Tintop w 47k 53k, '12 SmallCar EJ25, cooled filtered original gearbox
....KTMs, GasGas, SPOT mtb

[Black'n'White]

That's a really good illustration. Thanks for sharing it.

Too bad AA was too cheap to thread the end of the actuator rod and put a nyloc nut on it. I believe I've seen that done on the German decouplers.

I have everything I need in my garage to fix the decoupler I have except a lip seal. There's a very good bearing house in town that can help size the seal and the counterbore it would need. Or I can cut a groove in the actuator shaft, using a carbide insert if need be.

But that won't fix the shift fork riding on the steel body of the coupler. The best way to keep metal out of the transaxle oil is to not cut it loose to begin with, and the SyncroShop design does that.

And putting in a seal won't fix the circlip keeping the shift fork on the end of the actuator rod. Yeah, I could drill and tap the end of the rod for a bolt, then red Loctite the bolt in. A properly sized shim would keep it in position. Or just put a couple tack welds on it. That would be needed for the SyncroShop decoupler before I felt safe with it, too.

But again, the one I have is a bad design, and I don't trust it in a newly rebuilt transaxle. I suspect you're correct about this output housing not being suitable for a core for the Van Cafe/SyncroShop decoupler. So I'm hoping GoWesty or whoever made this thing will come through to make it right.

But you know what they say about hope, especially these days: Hope in one hand, spit in the other, and see which one gets filled first.
_________________
'87 Syncro/Westy Homebrew
Whatever it takes...

[Black'n'White]

With regard to the bearing on the pinion shaft nose, maybe I'm missing something, but if wear were an issue, wouldn't the factory VW setup, which uses no bearing, also be an issue? I haven't seen the factory coupler, so I assume it is a slip fit over the nose of the pinion shaft, similar to the SyncroShop setup, less the composite bearing. Is that correct?

If it is, the factory coupler is in constant engagement, and alignment won't be controlled all that well with the slip fit on the splines. I can envision enough radial play that there would be contact between the pilot on the end of the pinion shaft and the ID of the coupler. That would cause wear and the attendant release of metal particles into the transaxle lubricant.

By using a composite bearing, there would still be wear, but the composite would not harm the pilot on the pinion shaft, sacrificing itself in the process. That would still put stuff in the oil, but it wouldn't be as harmful as steel. If wear in the composite bearing (isn't it really a bushing?) became an issue, it would be fairly straightforward to replace, or even fabricate a replacement given the correct material composition.

But at this point, it's all armchair conjecture, and likely there's more hair splitting going on here than there needs to be.
_________________
'87 Syncro/Westy Homebrew
Whatever it takes...

[Black'n'White]

Funny thing about warranties. They're meant to inspire customer confidence, but they're really about demonstrating the reputability of the vendor. If you think about it, reputation is key in any small circle such as is found in the Vanagon community. One would think a vendor would bend over backwards to keep that reputation intact, especially after a failure due to poor manufacturing. Same goes even when there's been no failure, but it's obvious that a design is poor and can potentially lead to reliability problems, or damage to expensive parts found elsewhere in the assembly. My misadventure started with a small oil leak, and it's opened a whole can of worms, one that won't be fixed by just installing a seal or o-ring.
_________________
'87 Syncro/Westy Homebrew
Whatever it takes...

[Sodo]

[Black'n'White]

I'm not sure what the shift fork on my decoupler is made from, but it looks to me like a piece of hot rolled mild steel that didn't even have the mill scale removed. In other words, it's softer than the coupler it rides on, and that coupler will be turning against the stationary shift fork whenever the van is moving. I've seen the insides of a few motorcycle transmissions, and the shift forks and gears are made from quality steels that are hardened and tempered, then smoothed to resist wear. My shift fork is not. It's a small point, but the Syncro Shop design eliminates that wear point with bearings.

I also agree that e-clips and snap rings are used elsewhere in the transaxle. What I don't see in those applications, though, is loads applied across those e-clips along the axis of the shafts they're installed on as is the case with the decoupler actuator arm. Manufacturing defect or not, that kind of loading is hard on the e-clip. A threaded design or a weld eliminates that potential point of failure, and whatever decoupler ends up on my van will not have an e-clip or snap ring in it, even if I have to alter it myself.

I agree that when coupled, there would be no rotational motion between the pilot on the pinion and the coupler, and if I understand how the coupler works, those two parts are not in contact when decoupled. I was referring to a bending motion due to the clearance between the coupler ID and the OD of the two splined shafts, exacerbated by the unsupported nature of the rear end of the decoupler shaft. In other words, the decoupler shaft is only supported by the bearing on the front end, leaving the rear end to wobble on the pilot of the pinion shaft. That would cause a wallowing out of the hole, and a needle bearing would be better able to resist that and eliminate wear in that location. Again, it's probably picking nits because the van should be spending most of its life decoupled, and the majority of time spent coupled would be at lower speeds where marginal traction conditions prevail.

Except in cases where there's drive shaft vibration, something that's not uncommon in Syncros. Vibration would be very hard on the bearings at each end of the drive shaft, and would accentuate motion of the unsupported rear end of the decoupler shaft. When I got this van back from the "mechanic", it had a really bad vibration at around 25 MPH. I found that whoever installed the drive shaft had not tightened the flange bolts enough to bring the flanges at each end into contact; you could see daylight between them. The lips on each end had been mangled as a result. I took it apart, dressed the lips so they would once again engage the mating counterbores, and when reassembled, the vibration was almost completely gone. The rubber donuts in the front differential mount were not replaced, and the upper ones that support the weight of the van are about half the thickness of the ones on the bottom. If the same level of care was taken when aligning the front differential as was shown to the drive shaft, very likely the alignment there is off as well. I have new urethane bushings on hand, and it's on my list to replace the old ones and get the transaxle output flange and front differential input flange as close to aligned as possible, left/right and, to a lesser extent, up/down, observing what wisdom I've been able to find about allowable angular misalignment.

I think we're on the same page with regard to warranties. It's a shame that there is so much business that certain transaxle builders feel it is unnecessary to stand behind their work regardless of time. Time doesn't wear out bearings and break parts, miles do. But when a failure is caused by a manufacturing or material defect, IMHO neither time nor mileage should play a role in determining who should be held accountable for the costs of repair.
_________________
'87 Syncro/Westy Homebrew
Whatever it takes...

[Sodo]

[Atadloco]

How does the GoWesty decoupler compare to the VanCafe decoupler, any real difference between the two?

[deepseeman]

Anyone ever use the weddle industries decoupler?
_________________
in the barn:

61' Double Cab-restored driver
91 SYNCRO

[Sodo]

FYI here's another decoupler thread called [https://www.thesamba.com/vw/forum/viewtopic.php?p=9145312#9145312] Decoupler options[/url]

I didn't respond here, right away because I was hoping for someone else to get a word in edgewise.
Anyway that window has closed and now y'all have another book to read. Sorry.
It should be at least clear (above) that my opinion is the Van-Cafe unit (made by SyncroShop) is the best-built.

I can't tell you if there will be any noticeable "performance" difference between any of the decouplers available.
I can tell you the Van-Cafe decoupler is built by a craftsman, sparing no expense, if that's what you prefer for your Syncro.

Syncroshop shafts are centerless ground. The ball bearing used is a higher grade (C2) than the VW OEM bearings, for example, with less 'slop'.

The nose bearing is a composite bushing (like a plastic), which has less "play" than a needle bearing. BOTH bearings were chosen to reduce the possible 'slop' of the decoupler shaft, improving alignment, to ease engagement and other reasons. Because all you have is that little blue vacuum actuator to slide the coupler, it's preferable to hold the shafts in perfect alignment to slide the coupler. The bearing clearance of the composite bearing is tighter than a needle bearing.

That's one of the reasons Honda uses composite bearings in their Automobile transmissions (in some locations). The tighter tolerance holds the gear tooth circle in closer alignment, resulting in "rolling tooth contact" as opposed to sliding contact. Better mileage, less heat, better transmission longevity. Thus the transmission can be a little smaller, lighter cheaper. It's one of those things that is surprising - a plastic bearing superior to a steel roller bearing? --->YES under some conditions. Composite bearings don't pollute the lubricant with steel, and have no break-in period. And they don't have a "cup" that holds dirty oil, they drain completely.

And they cost less than an $8 needle bearing, BUT they go the distance. But how many turns the composite bearing can withstand is irrelevant in this application, because you can practically count the turns (every day) on your balls. The only time this bearing rotates is when the Syncro Rear wheels are going a different speed than the front wheels - when the van is 'turning'.

A needle bearing looks "cool", but "seldom, slow, zero-load rotations" does not require a needle bearing. "Zero-slop" is better here. Wiggle one sometime, you'd be surprised at how much "slop" is in a "new" needle bearing. If the brass bushing was machined to the same clearance, it would offer the same benefit over the needle bearing.

The goal of higher grade bearings is tighter control of the short decoupler output shaft, is to reduce "contributors" to driveshaft vibration. This output shaft is really short, the bearings are only 4 inches apart. For the driver flange to spin true(r), the short shaft should be "held" tightly between its two bearings .... with zero slop! Thus the bearings can be chosen with regards to minimize "slop". Van Cafe decoupler uses the C2 higher grade bearing at the front and the tighter composite bearing at the rear. It cannot be done any better than this.

Another Samba member MackayManx, who is no mechanical slouch, wrote of exchanging to the higher grade bearing on his decoupler to chase down driveshaft vibrations. Driveline vibrations often require prayer, but its just another example of what would come out of SyncroShop..... everything towards the goal.

The coupler and shift fork on the Van-Cafe decoupler are precision machined from 4140 steel. Compare this to a "lasercut sheet steel shift fork"....there is no comparison. All the parts in the Van-Cafe unit are top-notch, and deserve to be in your unobtanium Syncro trans.

All that said, I can't fault the GoWesty unit for function. They work fine, and I don't know any more about it than the pics on their site. I noticed they use a brass bushing now for the pinion shaft nose, I "heard" in the past it was just a steel bore, and I have never heard of or seen pics of problems from the old steel bore design. The brass bushing is an improvement, in case someone tows the van with rear wheels on the road while the front wheels are stopped (an old-school tow truck). Which is 'less than ideal' but it gets you out of the woods and I can't see a problem with that. If you had to tow hundreds of miles at high speed, consider "nose-down" so the decoupler is below oil-level. If your decoupler has a steel-bore (or if you don't ....KNOW....) I'd remove the driveshaft.

Millions of electric motors have brass bushings and spin at 3450RPM for years and years ......under load. Your clothes washing machine, for example. But this decoupler brass bushing is under "zero-load", and in oil, it will last even longer. Look at the (nearby) shift-fork. It's steel-on-steel, and at the larger diameter has perhaps 6X the velocity and nobody worries about that 'bearing' causing problems. The bearing "type" is a non-issue WRT longevity. If you're looking for benefits; 'reduced slop' is it.

The diagram above could be the original Steyr-Puch decoupler. They used an external-tooth coupler and a needle bearing. They were marketing towards military and industrial uses, and did not have the luxury of 20 years of spline-type-coupler testing that we now have for Syncro Vanagon usage.
Real-world usage that has proven the spline-type coupling works.

It's worthwhile to understand the situation where a decoupler "shifts" between coupled and decoupled.
There are two shafts, aligned. The coupler slides across the gap; connects and disconnects the shafts. The ONLY way this can be done with that tiny vacuum actuator is when the shafts are under "no-load" --- consequently they are turning at the same speed. Perfectly alignment due to accurate bearings is also beneficial.

Nobody shifts a decoupler while they front and rear wheels are turning at different speeds. An example of this would be, you are STUCK, and spinning the rear tires in 2wd. With the REAR tires >SPINNING< and >FRONT STOPPED<, you try to "couple". Well that's just stupid, and the splines would buzz together, and fail to engage, only engaging after the nimrod realizes its not working, and the rear wheels have stopped spinning.
.....Don't try to couple during a "burnout".
Agreed, this is a silly example, because nobody is that dumb.
Of course if they are that dumb they ain't getting unstuck either.

The right way (while stopped) is to pull the knob, and rock the van back and forth gently until the decoupler light turns on (the light cannot turn on until 100% engagement). The preferred method is to "couple" while moving; before 4WD is needed, with front and rear wheels are generally turning the same speed. Weave a little.

Point of this, is there has turned out to be zero need for the "external-engagement dogs coupler" that is used in other decouplers. In 20 years no wear has appeared on the spline-type couplers; validated long ago. The external-spline coupler has turned out to be unnecessary bling that consumes $$, requiring shortcuts elsewhere.

==================

One could say there is a lot of interest in decouplers.
How can Sodo know "this much?" you might ask.
It's because I called Syncroshop on the phone and talked for 45 minutes (at least).

So "why doesn't Syncroshop post this stuff" you might then ask.
Well I have asked him that, and he says "I have better things to do than spend 45 minutes typing on the internet."

There ya have it.

I've never seen a Weddle decoupler, and had forgotten they offerred one, and haven't asked Syncroshop either.

You might also ask "why doesn't Van Cafe offer porn shots of their SyncroShop decoupler on their website, so customers can see the quality?"
That's another REALLY good question.
When I build my trans this winter (with a Van-Cafe decoupler) I'll get some pics and send them to van Cafe.
_________________


'90 Westy EJ25, NEW oil rings (!) 2Peloquins, 3knobs, SyncroShop pressure-oiled pinion-bearing & GT mainshaft, filtered, cooled gearbox.
'87 Tintop w 47k 53k, '12 SmallCar EJ25, cooled filtered original gearbox
....KTMs, GasGas, SPOT mtb

[tjet]

Thanks for explaining that, Sodo. I've been trying to learn about decoupler types, and I dismissed the Van Café one because of the last statement in their description (thinking the needle bearing version is the preferred model):

..."Both the end housing and the metal sleeve must be returned for credit. This is the bushing style decoupler"

https://www.vancafe.com/Decoupler-p/decoupler.htm

Also, if you're adding a decoupler, Campervan Culture makes repo knobs (not exact).

https://campervanculture.com/shop/vw-t25-t3-vanagon-syncro-diff-lock-knob-3d-printed/

[Atadloco]

Thanks Sodo, another great explanation.