German transaxle rebuilt viscous coupling

[Pcforno]

I'm in the position of replacing my VC. I do run a decoupler and run the van decoupled most of the time except when I'm off pavement or on snow. Im interested in opinions from actual owners of rebuilt units from German transaxle (found on van cafe). Im looking at the sport VC. I don't wish this to become a VC vs solid shaft thread or an argument about how VC's work (as I think these topics have been beat to death). Looking for real world reviews of rebuilt VC's, especially sport VC. Thanks!

[insyncro]

I have a huge collection of VCs.
My experience is with rebuilt units from AA trans.
They have performed exactly as described.
Sorry, no experience with the VC / GTA units.

[Pcforno]

Thanks Insyncro. Seems like not many have had experience with the VC's from van cafe. In that case, any comments about rebuilt units from AA transaxle? Curious as to how quickly the 'sport' engages. My old VC would allow perhaps 1 full rear wheel revolution before climbing a 2x4. Is a "sport" unit about the same?
Thanks in advance
Phil

[Syncronoid]

I acquired a rebuilt VC from GTA when they rebuilt my front locker. So far, so good.
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'90 Syncro Westy w/GW2.5L

[vandoka]

Well folks, I just got thru a fun front end overhaul on my 87' Syncro Doka. This involved replacing ball joints, bushings and boots. As well I had a bad Viscous coupling, based on the VC test, so I replaced it with a rebuilt unit from Van Cafe.

Well, I got it aligned and now the front wheels are very bound up. Even going straight I can barely get into second gear. I followed all the steps in the bentley and took my time.

With the front end jacked up the front tires spin fine, but when driving it seems the VC is really binding up. Any ideas on why this might be happening other than a possible bad unit?

[Sodo]

That's some real nice looking nether regions ya got there......

[IdahoDoug]

Agree on the confusion with being unable to use 2nd gear. Are you saying the binding is so bad when you declutch to shift to 2nd the van slows so fast you nearly need 1st gear again? That's the way I'm reading it.

If so, you're subjecting the drivetrain to enormous force and indeed I would also wonder about extreme tire size differences or the F/R ratio question. Going straight that's about all I can see doing that.
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[crazyvwvanman]

For the shifting, if the shift linkage was undone from the tranny, it is pretty common to put it back slightly wrong which makes 2nd hard to get into or stay in. The rod bushing plate needs to be on the FRONT side of the 2 small tranny ears that the plate bolts to.

Mark

[vandoka]

The truck was working fine prior to changing out the viscous coupling. I did not do anything to the trans or linkage or ring and pinion. And the resistance is what keeps me in first gear, it's not a shifter issue. So I am gonna pull out the driveshaft today and see if I can isolate the problem.

Wondering though if anyone has seen similar issues when a viscous coupling was swapped?

Thanks for the help.

[DanHoug]

are your 4 tires EXACTLY the same size? if the previous VC was bad and slipping, your new VC could be binding due to different ratios as Sodo said. tires will do that.
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60% of what you find on the internet is wrong, including this post.

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[crazyvwvanman]

As mentioned, if the old VC was freewheeling it could have masked some underlying issue that is now exposed with a working VC.

Mark

[vandoka]

The tires are all the same size. Here is a thought, I added new schwenk springs to the front, this raised the truck a bit, and despite the driveshaft bolting back up just fine could the slight change in angle and or length affect how the driveline functions? I can easily add the new rear springs to level it out.

[vandoka]

Mark, that is also a consideration...the front differential could have had some terminal issue..

[crazyvwvanman]

Before pulling the drive shaft: If you jack up only one side of the Syncro so both tires on that side are off the ground, turning the rear tire should cause the front tire to rotate the exact same amount. Mark both tires with a piece of tape so you can see that their positions are always synchronized. Try 10 revolutions, watching the marks. Exactly synchronized the whole time?

Mark

[vandoka]

Ok mark, I will give that a try. I did have one side of the truck up in the air and the front and rear were rotating together, but I will measure the ratio more closely.

[tencentlife]

You can easily test your VC that it isn't overly stiff and isn't binding. Lift just one front wheel, all others on the ground (you can set the handbrake for the rears and lift one side, or lift under the front control arm). Trans in neutral or in gear, doesn't matter, the rear pinion will be locked by the rear wheels. Coupled if you have a decoupler.

Turn the lifted front wheel, you should be able to turn the tire slowly and smoothly by hand against constant resistance. One turn of the tire equals almost 5 turns of the VC, so you don't even need to go all the way around to feel the VC thru a full rev. Feel for any irregularities in the force required to turn.

If you have a beam-type torque wrench, put it on the wheel axle nut, or a lug nut, and you can measure the VC's static or breakaway torque. Build up torque as slowly as you can while watching the beam indicator. Note the torque when the wheel starts to move at all. I have what I consider a "normal" VC, it requires about 20ft.lb. applied to the axle before the wheel begins to turn.

With the beam wrench you can turn the wheel steadily, the faster you turn the higher constant torque it will require. Even better than turning the wheel with your hands, this would let you see a jump in required torque that would indicate binding inside the VC. As a comparison, when I apply a steady 80ft.lb. it takes about 8 seconds to make 1/4 turn of the wheel.

Anyway, measuring torque is extra, my main point is you can assess the VC for being overly stiff statically and for binding thru a full rev. very easily at one front wheel.
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[photogdave]

Is it possible you mistakenly received a "sport" VC?
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[davevickery]

As Sodo and Mark already pointed out, maybe your R&Ps don't match. You have only had the van for a year right, so maybe the front diff has had the wrong gear ratio the whole time and the VC was free wheeling the whole time.

[tencentlife]

[alaskadan]

Good reading. I had to fix a torn boot on a rear axle a couple days ago. I recalled that I should be able to slowly turn a wheel and have the vc slip. Just one rear wheel off the ground and grabbing the tire with two hands it took a lot of force to very very slowly turn the tire. ( doing this to access all the cv bolts easier). More than 20 ft lbs I'm sure. My vc has been feeling stiffer and scrubbing in tight turns seems worse. Could a stiffening vc cause a shudder or vibe in a 3rd gear deceleration or steep down hill coast? Sorry for the little hijack.