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Pcforno Samba Member
Joined: October 14, 2014 Posts: 575 Location: Santa Fe, nm
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Posted: Fri Feb 05, 2016 6:15 am Post subject: German transaxle rebuilt viscous coupling |
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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! |
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insyncro Banned
Joined: March 07, 2002 Posts: 15086 Location: New York
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Posted: Fri Feb 05, 2016 8:19 am Post subject: Re: German transaxle rebuilt viscous coupling |
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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. |
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Pcforno Samba Member
Joined: October 14, 2014 Posts: 575 Location: Santa Fe, nm
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Posted: Sat Feb 06, 2016 6:38 am Post subject: Re: German transaxle rebuilt viscous coupling |
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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 |
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Syncronoid Samba Member
Joined: January 21, 2012 Posts: 1111 Location: Stanford, CA and Bend, OR
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Posted: Sat Feb 06, 2016 10:47 am Post subject: Re: German transaxle rebuilt viscous coupling |
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I acquired a rebuilt VC from GTA when they rebuilt my front locker. So far, so good. _________________ '90 Syncro Westy w/GW2.5L |
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vandoka Samba Member
Joined: March 14, 2015 Posts: 92 Location: COLORADO
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Posted: Tue Oct 16, 2018 8:15 pm Post subject: Re: German transaxle rebuilt viscous coupling |
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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?
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Sodo Samba Member
Joined: July 06, 2007 Posts: 9618 Location: Western WA
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Posted: Tue Oct 16, 2018 9:15 pm Post subject: Re: German transaxle rebuilt viscous coupling |
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That's some real nice looking nether regions ya got there......
vandoka wrote: |
Well, I got it aligned and now the front wheels are very bound up. Even going straight I can barely get into second gear. |
Not sure what you're getting at here. The VC is gets its power off the mainshaft and cannot affect shifting.
If it seems all bound up driving straight that suggests that the front R&P ratio is not equal to the rear R&P ratio. Did you change the trans or the front diff? Or the Front & Rear tires are different sizes? I can see the high loads of four tires scrubbing making it hard to shift.
Two kinda crazy suggestions, I know. But your problem is a strange problem so I'm starting at square1. _________________
'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 |
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IdahoDoug Samba Member
Joined: June 12, 2010 Posts: 10251 Location: N. Idaho
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Posted: Tue Oct 16, 2018 11:16 pm Post subject: Re: German transaxle rebuilt viscous coupling |
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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. _________________ 1987 2WD Wolfsburg Vanagon Weekender "Mango", two fully locked 80 Series LandCruisers. 2017 Subaru Outback boxer. 1990 Audi 90 Quattro 20V with rear locking differential, 1990 burgundy parts Vanagon. 1984 Porsche 944, 1988 Toyota Supra 5 speed targa, 2002 BMW 325iX, 1982 Toyota Sunrader |
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crazyvwvanman Samba Member
Joined: January 28, 2008 Posts: 9937 Location: Orbiting San Diego
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Posted: Wed Oct 17, 2018 2:28 am Post subject: Re: German transaxle rebuilt viscous coupling |
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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 |
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vandoka Samba Member
Joined: March 14, 2015 Posts: 92 Location: COLORADO
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Posted: Wed Oct 17, 2018 4:15 am Post subject: Re: German transaxle rebuilt viscous coupling |
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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. |
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DanHoug Samba Member
Joined: December 05, 2016 Posts: 4800 Location: Bemidji, MN
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Posted: Wed Oct 17, 2018 4:40 am Post subject: Re: German transaxle rebuilt viscous coupling |
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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. _________________ -dan
60% of what you find on the internet is wrong, including this post.
'87 Westy & '89 Westy both 2.1 4spd
Past projects can be found at--
www.thefixitworkshop.com |
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crazyvwvanman Samba Member
Joined: January 28, 2008 Posts: 9937 Location: Orbiting San Diego
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Posted: Wed Oct 17, 2018 4:43 am Post subject: Re: German transaxle rebuilt viscous coupling |
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As mentioned, if the old VC was freewheeling it could have masked some underlying issue that is now exposed with a working VC.
Mark |
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vandoka Samba Member
Joined: March 14, 2015 Posts: 92 Location: COLORADO
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Posted: Wed Oct 17, 2018 4:45 am Post subject: Re: German transaxle rebuilt viscous coupling |
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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. |
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vandoka Samba Member
Joined: March 14, 2015 Posts: 92 Location: COLORADO
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Posted: Wed Oct 17, 2018 4:47 am Post subject: Re: German transaxle rebuilt viscous coupling |
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Mark, that is also a consideration...the front differential could have had some terminal issue.. |
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crazyvwvanman Samba Member
Joined: January 28, 2008 Posts: 9937 Location: Orbiting San Diego
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Posted: Wed Oct 17, 2018 4:56 am Post subject: Re: German transaxle rebuilt viscous coupling |
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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 |
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vandoka Samba Member
Joined: March 14, 2015 Posts: 92 Location: COLORADO
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Posted: Wed Oct 17, 2018 5:21 am Post subject: Re: German transaxle rebuilt viscous coupling |
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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. |
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tencentlife Samba Member
Joined: May 02, 2006 Posts: 10078 Location: Abiquiu, NM, USA
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Posted: Wed Oct 17, 2018 8:00 am Post subject: Re: German transaxle rebuilt viscous coupling |
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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. _________________ Shop for unique Vanagon accessories at the Vanistan shop:
https://intrepidoverland.com/vanistan/
Please don't PM here, I will not reply.
Experience is kryptonite to doctrine. |
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photogdave Samba Member
Joined: April 05, 2004 Posts: 3053 Location: Vancouver Island, B.C.
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davevickery Samba Member
Joined: July 16, 2005 Posts: 2887 Location: Fort Collins, CO
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Posted: Wed Oct 17, 2018 8:33 am Post subject: Re: German transaxle rebuilt viscous coupling |
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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. |
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tencentlife Samba Member
Joined: May 02, 2006 Posts: 10078 Location: Abiquiu, NM, USA
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Posted: Wed Oct 17, 2018 8:50 am Post subject: Re: German transaxle rebuilt viscous coupling |
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davevickery wrote: |
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. |
Yeah Mark's is a good easy test for mismatched R&P's. Do that and if it passes set the handbrake while it's up and do my test and you'll probably nail down the problem. _________________ Shop for unique Vanagon accessories at the Vanistan shop:
https://intrepidoverland.com/vanistan/
Please don't PM here, I will not reply.
Experience is kryptonite to doctrine. |
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alaskadan Samba Member
Joined: January 09, 2013 Posts: 1858 Location: anchor pt. alaska
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Posted: Wed Oct 17, 2018 9:14 am Post subject: Re: German transaxle rebuilt viscous coupling |
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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. |
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