Syncro Chat: VC's, solid shafts, decouplers, AWD/4WD, etc.

[insyncro]

Yup, reverse switches are for reverse gear on the transmission and decoupler switches are for decouplers.
I would send a note to the vendor selling them that they should offer the proper switch.

Also spacers must be used and if that distance is off a bit, the light becomes intermittent or always off...same as with the lockers.

I spring for the proper parts, the late parts with the plastic connectors so the factory wiring is plug and play.

[ryanoceros]

[insyncro]

It would totally depend upon the situation and need shown by the system.

Check out the way that those canisters are plumbed in other vehicles that use them as well.

[insyncro]

It would totally depend upon the situation and need shown by the system.

Check out the way that those canisters are plumbed in other vehicles that use them as well.[/youtube]

[Jon_slider]

look what I found in my signature link:
http://www.thesamba.com/vw/forum/viewtopic.php?p=7620682#7620682

[raoul mitgong]

[tarandusVDub]

[raoul mitgong]

Tdub,
You must not be watching the disagreements from Jon in Doug's crosswind coupling thread. My statement was aimed at Jon. He jumped over here as the conversation moved on without him in the other thread. He is claiming as fact things that many knowledgeable people are still debating and being unreasonable because some think he is wrong.
After Jon excused himself from the other conversations he must have missed lobbing turds at us and decided to do it over on this thread.
Agreed, Doug is very knowledgeable (but maybe just a little stubborn), I enjoy our debates as it makes me dig deeper.

-d
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84 Westy with a 2.1 (Groover)
86 Tintop Syncro (Crow)
86 Tintop Syncro to Westy project (Tom Servo)
91 Westy (Only the top 12 inches of this van (a burn victim))

[Sodo]

OK I read this whole thread ( I think).

I am currently servicing my FRONT axles. Clearly, they are worn more on the drive side than the coast side. So my Syncro (with a VC) has spent more of it's life PULLING with the front wheels (than pushing backwards ON the front wheels). Why (in 45 pages) has nobody else simply looked at the front CVs for evidence of pulling?
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'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

[Jon_slider]

Almost 3 years have passed, and the same people still think the front wheels pull the van, w a VC coupled on dry pavement ... because they cannot comprehend what iDoug has explained:


https://www.thesamba.com/vw/forum/viewtopic.php?p=7620740#7620740

[Sodo]

[raoul mitgong]

From reading all the data and papers available then doing some math- Even a 0.5% rear tire slip at 65mph will cause an 18 rpm difference at the vc. Because the vc starts to stiffen at 5 rpm, it will not allow the vc to hold steady at an 18 rpm difference.

I haven’t done the math, but I don’t think micro adjustments to the steering wheel to keep a van straight on an interstate are enough to create a curve where the front wheels travel farther and reverse the rpm difference. Even if it was, you would still be between a left and right correction the majority of the time. I certainly don’t feel a push/pull transition driving in a straight line.
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84 Westy with a 2.1 (Groover)
86 Tintop Syncro (Crow)
86 Tintop Syncro to Westy project (Tom Servo)
91 Westy (Only the top 12 inches of this van (a burn victim))

[WestyBob]

Slider --- it isn't because we "can't comprehend" what I-Doug is saying, it's that we believe there are other dynamics/variables/whatever going on that contradict his premise. You yourself changed your mind several times on this and other points in this mother of all syncro threads, then have carried on in your own new thread and now back to this one.

If you or anyone has newer information or data then let's see it. Let's not get into a sociopathic 'I'm right' game -- let's try to find out the truths of what we have been discussing for a while now. Some of Volkswagen of Germany's own scientific literature, presented way back in this thread, did not completely support your/Doug's claims.

That and my own extensive syncro driving experiences plus many discussions with syncro friends hold me to my conclusions although I'm always open to new information/data. I don't care if that new information proves me right or wrong. I'd hope you would behave similarly.

[87vanwes]

I am a long time lurker on this subject and am reluctant to get involved.
But o well

Having rebuilt two viscous couplings and owning three, I will say I don't buy the vw promotional video on the syncro VC heating the fluid causing the coupling to lock up. I'm on the fluid shearing band wagon.

My bench tests on these bizarre things have shown that if you rapidly apply torque to even an ice cold VC, it will lock up and take a second or two before it will allow you to rotate it again very slowly. When I say slow I mean slow.

The aggressive one I made you would almost be lucky to keep up with the second hand on the clock before it locks up.

My opinion on this is, if you air your tires up to manufactures specs on a westy or a loaded down tin top I would say the front wheels are at least bound in the pulling position because the rear wheels are rolling rpm wise much faster.I wouldn't say it's pulling the van, but I would say it's trying to.

If you air your tires to spec and measure from the center of your axle shafts to the ground the rear will be lower. IMO that difference even with a stock VC is enough to upset it and cause some lockup which I would say at a minimum causes the drive line to favor the torque to the front wheels.

I air my tires by axle shaft ends to the ground measurements. This changes on every trip we take. This practice keeps every thing rolling in harmony.

The only downside I have discovered to this practice is drive shaft vibration. The same thing some of us have run into with a decoupler. When we run in somewhat of a bind things tend to be smoother.

Well I guess I said it.

Cheers...
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Kevin


1987 westy syncro tdi conversion and restoration.
http://www.thesamba.com/vw/forum/viewtopic.php?t=6...highlight=

[candyman]

[Sodo]

It SEEMS like axle height would make a difference but in reality, it does NOT.

Tire pressure does NOT change the tire's rolling diameter.
Axle height does NOT change the tire's rolling diameter.
The rolling diameter of a tire is set by the circumferential length of the tire carcass, which is very very permanent, steel-belt-consistent.

I googled tire pressure effect on diameter and Google led me back to Raoul Mitgong's post on page 18 (of THIS same thread). He links to a YouTube video test showing that tire pressure and axle height does NOT affect the distance. The guy deflates the tire and the sidewall visibly drops an inch - but it makes NO difference in rolling distance. The circumferential length of the tire carcass is the same regardless of the inflation. The circumference is really, really fricken consistent. Think of it as "steel-belt-consistent". It does NOT stretch or contract by air pressure.

OK can we get get back to the driveline discussion that took 45 pages and 3 years of wobbling all over?

----> Syncro Front wheels PULL. We need to put this to bed.
_________________


'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

[87vanwes]

[candyman]

[Sodo]

haha OK maybe it WAS put to bed. It should be.

But don't spend a LOT of time adjusting axle heights. If all 4 tires are the same brand, same size they will have the same carcass circumference, and over a wide range of pressures, will have the same rolling distance. Even with varying axle heights they still roll the length of the steel-belted carcass.
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'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

[Jon_slider]

Lets see if we can agree on the following 6 statements of Fact, not opinion.

1. With a Solid shaft coupled, the front and rear wheels always spin at the same RPM.

2. In a curve the front wheels of a 2wd Van (or decoupled syncro) always spin at a higher RPM than the rear wheels, because the pavement distance of the front wheel arc is longer than the pavement distance the rear wheels travel.

3. When a VC is in the hard condition, the front wheels can not spin faster than the rear wheels, and in a curve the RPM of the front wheels is going to cover less distance than the arc over the ground. Therefore the front wheels are resisting the force of the road, that is trying to make the front wheels spin at a higher RPM than the rear wheels. This is the same with a solid shaft as with a VC that is not in slip mode.

4. When a VC is in slip condition, or decoupled, the front wheels can be spun by the road at a higher RPM than the rear wheels are spun by the motor. Therefore the front wheels can not be pulling the van forward, while the VC is slipping, or decoupled.

5. A syncro has no planetary differential with separate front and rear wheel outputs.

6. A planetary center differential is capable of powering the front wheels faster than the rear wheels in a curve.

So, how can syncro front wheels power the van in a curve on dry pavement?
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My Soapboxes: Inflation; Handling; Gearing; Decoupling; Swepco