Syncro – propshaft with intermediate bearing support

John B. sent along some pics of his new propshaft. He was having some difficulty in getting the stock set up running vibration free so he went this route.

Due to some errors on my side, I can’t find his emails where he described the set up. Until I get that info I’ll post the pics as is.

   
    
    
    
    
    
   
Addendum.

In reply to Hans’ comment about CV jointed prop shaft. A couple of pics. First is the flange of my spare propshaft. Approximate measurements make it a 74mm bolt hole circle, the recess is 47mm diameter and about 2.5mm deep.

   
Stock 100mm diameter cv joint has a 6 on 86mm bolt hole circle.

 
A 108mm diameter CV joint, has a 95mm bolt hole circle.

   
I have the half shaft for that 108mm diameter CV joint. One could imagine cutting the spline section off and mounting it to a flange that mimics the stick propshaft flange, then the slides connecting to the 108mm diameter CV joint bolted to the propshaft. I hope you understand this is all just free thinking, just for discussion.

 

  1. #1 by hans on December 1, 2015 - 9:57 pm

    I need to do this to mine! I’ve been thinking about an adapter though, between the syncro flange and the 100mm CV. They also made a later driveline with a CV in the center instead of the heavy U-joint. Also he might want to flip the bolts and use some button head bolts? I’m pretty sure I’d snag them on something!

    • #2 by albell on December 2, 2015 - 5:20 pm

      Hi Hans

      I’ve thought about cv joints replacing u joints too. You know it is done on some trucks, and you can buy the cv joint assembly designed for that purpose.

      But I’m thinking of how to make a standard cv joint fit. I haven’t come up with anything concrete yet but your comment had me looking at a pair of cv joints and my spare propshaft. I took some measurements and pics and I will post them at the end of this blog post later this evening.

      Alistair

  2. #3 by John B on December 6, 2015 - 9:55 pm

    I also initially thought to use a cv joint set up too. It’s quite a bit of planning and machining work as one discovers when taking a serious look, hence I did the UJ split shaft thing to get the van running satisfactorily.

    I will still attempt a cv joint prop too at some stage.

    If I redid the UJ split shaft again, I would also try it without a slip joint. They clearly transmit more sound than a guibo type joint. Perhaps no joint at all ? Not sure that we really need them on the Syncro set up. Very little movement. Westy make them without joints, love to know how noisy or rough it is?

    • #4 by albell on December 7, 2015 - 7:47 am

      John,

      Yeah the cv joint replacing the standard u joint does mean some machine work for adapters. Mind you I have seen, at the local driveline shop, factory cv joints for propshafts. But you’d still need an adapter to mate with vanagon transmission flanges.

      Last weekend I helped install a propshaft in an 86 syncro, and the haft had no guibo. I don’t know the full history if this van but the new owners removed the shaft when they experienced VC binding when turning into a car park after an hour of driving. They were concerned that the VC had gone south. But since then they had replaced the old worn tires and I suggested they try the propshaft again while they wait to finally decide on a decoupler. So far, driving around town, they say it’s working out ok. I should have noted the part number on the shaft, I think it was a VW part number and not an aftermarket unit. I believe that some vanagons, dokas and single cabs, had factory shaft like that. Why some with rubber, why some without? And why in the diesel syncros the shaft is installed with guibo at front?

      Cheers

      Ab

      >

      • #5 by JohnB on December 8, 2015 - 9:43 am

        Yes, I believe VW did do shafts with no joint. My understanding is that the guibo coupling is really to reduce noise further.
        Interestingly, my first foray into slip joint single shafts had quite a narrow diameter slip joint and worked very quietly but wore out really soon and so went to a larger diameter slip joint for strength purposes but the noise increase was really quite obvious.

        Maybe I should use my old guibo ( with new bushes of course) in place of a slip joint on a split shaft? Maybe best of all worlds? I wonder how much engine noise a CV joint transmits in comparison?

        If only I had my own workshop, endless time and money !!!!

      • #6 by albell on December 9, 2015 - 10:18 pm

        Hi,

        Just back home from a starter reinstall after rebuild today. What a hellish job. I’ll answer about propshaft when I settle down.

        Cheers

        Ab

  3. #7 by John B on December 10, 2015 - 10:37 pm

    Yes I remember when I had the wbx 2.1 that I had endless starter problems at one stage and its was a nightmare to get in and out. The Audi/VW 2.6 5 cylinder is a breeze in comparison. The starter lies beautifully exposed well away from drive shafts and the like. Not that I’ve taken it out at all, but just looks really open and exposed.

    The negative on the 2.6 is the exhaust system that runs forward from the motor just under the left drive shaft and then back out the vehicle, which is great until you need to do any work on the left drive shaft. Its either entire exhaust system off or left wheel hub (and brake system) off and drive shaft pulled out through the wheel hub. Have done it once when replacing rear wheel bearings and not sure which route is worst!

  4. #8 by John B on March 14, 2016 - 7:33 am

    Hi Alistair,

    Well, my 2 part prop-shaft with center carrier bearing is ultimately a no go! Although we got the shaft running really smoothly, you literally can’t tell when it’s on or off the vehicle, it had one quirk we couldn’t get rid of and that’s a drone at 120km/h!

    I tried different size slip joints, checked and reworked angles, checked for “touching”, you name it, just seems that shaft carries this 2.6 5 cyl engine noise through at that particular speed and it drones and drives you nuts.
    We even tried filling the shafts with different stuff, some from Nissan, some cardboard type products when we made it up to damp the noise.

    Well after about 6 new prop shafts of various sizes and shapes I have finally gone back to the original Syncro one piece, donut and all, but with very tightly rolled closed cell type of heavy duty cardboard placed inside while making it up as a sound damper. Very shallow working angles on the UJ’s, 1.6 and 1.8 degrees if I remember correctly. Its runs well and the drone at high speed is indeed just about completely muffled. Seems the rubber coupling that VW used was there for a really “sound” reason!

    I will do a bit more sound proofing in the vehicle, up the sides and mainly in the front of the cab. The noise does seem to be coming up from the front drive and diff. I have had the front diff completely redone as well and new cv joints in front to make sure it wasn’t them causing the drone.

    Anyway I have now done a longish trip and all is well, perhaps I am just too “sound and vibration” aware now to drive any Syncro!!

    Cheers
    John B

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: