Syncro Video, thoughts on Viscous Coupling and Solid Shaft

[Waldi]

The solid shaft just limits the usage of the Syncro.
It puts lot unnecessery load on the gearbox and drivetrain.
Having 2 or even 1 chain with you, gives you in 5 min a advantage with the VC over the solid shaft. Having all the possble best usage.

[gears]

There's a place for either choice. I knew a guy who had to drive on sand at low tide to get to his house. A solid shaft with decoupler would certainly be best for him (or for the surf-casters driving on sand a few times a week). I winter drive all the time, so a VC is a better choice for me. (I think all Syncros should have a decoupler.)
_________________
aka Pablo, Geary
9.36 @ 146 in '86 Hot & Sticky
'90 Syncro Westy SVX
'87 Syncro GL 2.5
https://guardtransaxle.com

[davevickery]

This short video is interesting and seems to suggest that without a solid shaft you could bury the rear end, but I've just never seen it. The couple times I've gotten stuck all my wheels were pretty well buried.


Link

[gears]

I know Jon Slider has tested this himself. A VC doesn't engage immediately, so the rear tires tend to burrow in until it does.
_________________
aka Pablo, Geary
9.36 @ 146 in '86 Hot & Sticky
'90 Syncro Westy SVX
'87 Syncro GL 2.5
https://guardtransaxle.com

[Sodo]

Sand conditions are like snow, in a way. Flawless techniques only need one of the various conditions to change and you need a NEW technique.

I noticed standing water at the end of the video. He was very near the "water table" so it's possible that disturbing the sand changed the water content of the mix, allowing it to pack, and when he "rolled" rather than dislodged the sand, it packed. Maybe all he needed was "time" (and surface tension).

When I first got my Syncro, I got stuck on a gravel bar, and was able to reverse much better than go forward, which I attributed to VC slippage. A major benefit of a solid shaft, that there's no initial slippage of the VC, thus Front + rear "start their push equally". With a VC, the rear spins a little before the VC locks, rear tire digs, then it has to climb out of that sand hole, plus the sand is loosened.

Another time in Mexico (driving a '72 loaf) we were on a beach and noticed the tide coming in. Decided to move the van but it was stuck !! Water got closer and we shitted more bricks. But then the sand firmed and we drove out. Looking back we could have used buckets of water to firm the sand. (I suppose).
_________________


'90 Westy EJ25, 2Peloquins, 3knobs, pressure-oiled GT mainshaft, filtered, cooled gearbox
'87 Tintop w 47k 53k, '12 SmallCar EJ25, cooled filtered gearbox
....KTMs, GasGas, SPOT mtb

[Syncro Jael]

[Jon_slider]

SyncroJael, thanks for the awesome video and photo.

I do agree with Daryl, as SyncroJael points out, that an Aggressive VC can protect against shock loads better than a solid shaft. The Aggressive VC is fine by me, I respect the choice. It will run tail low in sand, and it will require rear wheel spin Offroad to engage. And on dry pavement an Aggro VC will drag through turns. But, if a driver forgets to decouple an aggressive VC in a dry parking lot, the VC might slip a little and let the van finish parking. With a solid shaft, there is a point at which the van will simply stop moving forward. This will require decoupling to move forward again.

[davevickery]

Link

I'm not seeing the same thing as you in this video. In the beginning when he is stuck, what I see are all 4 tires fairly evenly buried.

And when he is driving out of there, it looks pretty level to me except when he is going up a slight incline, the rear is down, and when he is going down, the rear is up.

[Jon_slider]

[davevickery]

Haha, looks like you are cherry picking the data to fit your conclusion. That doka pic is an example. I see where that image comes from in the video, but if you watch the video, there are times where the front wheels are the only ones throwing sand, then the rears, then the fronts again. If that is the best video you can come up of a syncro rear end digging in, then I think your helping to make the opposite case.

And the picture of the rear end buried is from a website selling solid shafts. Haha. Maybe that happens to him all the time, but if I was selling solid shafts, I could figure out a way to bury the rear end of my van for the picture. Lots of gas, stop, lots of gas, stop. I actually did that once to level my van on a beach for camping, but I had to use my decoupler to make it happen. That could be a real life photo and all the people that drive beaches all the time know about the huge problem the VC is on sand, but I have not encountered it. And there are really no videos online showing it happening.

Obviously the solid shaft eliminates any response time. No one is arguing that. I'm just saying, I have not encountered rear well spin that buries the rear end only. And I have probably gotten stuck more often than most syncro owners, which isn't a lot.

Anyway I don't have a dog in this race. It just seems that if this were a real problem, there would be a lot of videos of syncro stuck in the sand with the rear axle buried. I can't find any. That' all.

[Sodo]

The rear could be buried because the sand is softer there, but it makes sense that the rear wheels are digging more turns because they are direct drive, and the front, having VC slippage, have simply made less turns in the sand. This is a valid VC.vs.solid shaft issue. It's the crux of the matter.

[Jon_slider]

[tjet]

Here's an interesting video that compares a stock VC to modified one with inert gas, or something like that. Behaves like a solid shaft now.


Link


https://vw-kern.at/visco-kupplung#anc-issues

[Klister]

[tjet]

Yeah it's an old thread. You may need to dig a little on the GW site. BTW, Van Cafe no longer has a description of their various options for coupler rebuilding

[the_benjamin_effect]

[Klister]

[Sodo]

I have a "sport VC" now.
My tires leave black lines on dry pavement, skidding, when I turn tight.
So now..... I have to decouple in the city.... where previously my van was "gentle AWD".

I'm quite curious how well the ‘Sport VC’ maintains adherance in snow/ice.... as it's obviously more 'locked up' now.
I wish I could do another "sand test" like in the video,,,,, to see if sand performance is better. But I'd need to find the same soft conditions. Not easy to re-test.
Plus I'd need more friends around. Bricks were shat that last time, being solo, and below the high-tide mark.

I really liked my VC before..... ——>except when I cursed it in the sand.
And in some off-road conditions where rear tires spun initially at that moment when I needed the fronts to pull immediately.
A tame example is the rear wheels spinning when I need the fronts to pull “immediately” to climb up onto leveling rocks....(campsite setup ).
OK.... there's a list of times that the VC slip bugged me. But I liked how it gripped the snow.
But where I live, Seattle, it snows for 2 days once every 3 years. Hmmmmm

Anyway this VC thing is a bit of a dilemma.
I want a 4th knob (that locks the VC).
_________________


'90 Westy EJ25, 2Peloquins, 3knobs, pressure-oiled GT mainshaft, filtered, cooled gearbox
'87 Tintop w 47k 53k, '12 SmallCar EJ25, cooled filtered gearbox
....KTMs, GasGas, SPOT mtb