Last week I had some success in reducing prop shaft vibrations. If you read this blog you know I have been chasing this problem up one tree and down the other. One thing to finally clear up before I go on, is the question of the presence or not of a plastic spacer on the front mount of the front diff. I think I can conclude, for sure, that on my diff at least, there is no plastic spacer(s). The hole in the diff mounting ear is too small in diameter to allow the spacers found on the other mounts to fit.

Here is a pic of one rubber mount (they are installed in pairs), a stock plastic spacer, and a home made spacer when I was still thinking my van was missing them.

As is, this still leaves the front diff flange pointing down at 3.7 degrees which is not close to the transmission flange angle of 4.6 degrees. By the book, these angles should be within 0.5 degrees. When I say by the book, I am not referring to the Bentley manual which has no information on this subject. Instead, I get this fact from a drive shaft makers publication, here;

SpicerDriveline

I don’t like the fact that the transmission angles down that much, but I can’t really see how to raise front of trans. easily, and besides , it looks like there is little room above transmission to do this.

Out of frustration more than anything else, I decided to try adding weight to the drive shaft, thinking that perhaps the shaft was out of balance (I had replaced U joints, and who knows, it may have been out of balance before I got the van). I attached a gear clamp 3 ” from the front end of the shaft, right where there is a factory weight. test drive revealed no change. I rotated clamp 90 degrees and, by god, test drive showed a big reduction in vibrations, in fact the vibrations were almost gone.

Next step is to refine position and try additional weight. Local drive line repair shop does not have mandrels to do syncro shafts, but the tech. said he would be willing to make mandrels if supplied with measurements. I may be on to something.

Update: Well I got wrong info, there never was a spacer on front mount. In fact the tabs on the plastic spacer will not fit into mounting hole on the front mount.

I recently posted how I looked at the front diff. mounts and discovered that the foremost one had slightly distorted rubber mounts. What I did not realise was that some syncros have plastic spacers on those mounts too. Mine did not. A quick survey on the syncro and the vanagon mailing lists only returned one other owner (also an ’86 van) that did not have those spacers installed in the front mount. The parts catalogue shows none of the front diff. mounts having spacers, but do list them on the side, and 4 needed (4 would be enough for only the 2 rearmost mounts) You can see at least the rearmost ones with spacers in the Bentley manual. The part number is 251 199 399 , its the same plastic spacer that is found the transmission mount. I decided to try and make a spacer(s) and found a scrap of polyethylene cutting board that was big enough to make a reasonable copy. I just need to make another then install and see what difference it makes in the front diff. flange angle saga.

Here is a diagram of the transmission mount arrangement, the spacer, #9 is the one in question

And here is a diagram of the front diff. mount arrangement, note absence of spacer in all 3 mounts.

And here is the spacer with my cutting board copy (note flats on sides of my copy, the scrap bit was not quite large enough)

If there is anyone out there interested enough to have a look at their own syncro front diff front mount and report back presence or absence of spacer, I’d be very grateful.

Took my time with my revised laser thingy and measured front diff and transmission flange angles. The pictures show the process. Laser on flange, measuring jig on other flange. I added a plumb bob to measuring jig to be sure it was plumb so that any lateral misalignment would show up (you can see the string in the pics). As it turned out there is very little sideways error in flange orientation. I remeasured the flange centre to centre distance as 1820 mm, and the vertical measurements are as follows:
Laser on transmission – dot 103 mm below centre of front diff. flange. This works out to be a 4.6 degree angle on the trans. flange.
Laser on front diff. – dot 83 mm below trans. flange. This works out to be a 3.7 degree angle on the front diff. flange.

The numbers are close to what I measured before, but I feel confident in these measurements. In the pictures the laser dot size seems larger than real life, and in one shot you can see the laser beam itself. The CCD in the camera must be sensitive to the wavelength of the laser.

Note: picture showing measuring stick on front flange and dot around the #8 mark is actually showing an erroneous first try, I had a bit of “schmumf” stuck between laser and flange, second try had dot further down measuring stick, and that is shown in close up pic.

Not being happy with how the laser pointer was held in the jig, I finally did what I should have done all along and that is use the laser’s own mounting bracket. The bit of aluminium angle bolted to the round jig gets clamped by the red bracket’s captured screws (not visible in pic). Now I can adjust the beam so that it is pretty well aligned with centre of jig. Previously the best I could do was a 1 cm circle, over the 1.285 m between flanges, when jig rotated on flange. The thing on the left is the crude reference jig that sticks onto the the flange opposite and shows the laser dot.

My last posts showed how the transmission flange is pointing down at a steeper angle than the front diff flange. I could not see a way of easily changing the transmission angle so I decided to shift the front diff. I supported the diff with a bottle jack and took off the front carrier and the rubber mount. You can see where the mounts go in the diagram, (No. 6). Looking at the mounts, I could see the lower mount was squished a bit.

So I swapped the thicker, or less collapsed top mount with the lower mount, and I added a couple of washers for good measure to help lift the front of the diff. so that the rear, where the flange is, would point down more.

I did a quick measurement with the Beall Angle Box, and the flanges were within half a degree of each other. My laser thingy showed that the angle had indeed changed, calculated out at approx. 0.65 degree difference…but I am not confident in my measurements. The electronic angle finder is sensitive to how it is placed on the flange and the laser pointer is not perfectly fitted at 90 degrees to the base so that it scribes a 1 cm circle when rotated. I have to refine my methods, but its close enough for the time being.

So I put the drive shaft in and took the van for a drive…. still a slight vibration at 50 kph (mind you, it is less than before). I left the bolts on the 2 rear most rubber mounts of the front diff. loose, wondering if the diff will find its happy spot during driving. No such luck. Will try again but with yoke bolts loose. Next “major” step is to go over lateral alignment.

Did another quick check on the transmission and front diff. flange angles, this time with my little “Beall Tilt Box” electronic angle finder.

Accounting for the the angle the van was sitting at (approx. 0.25 degrees) I measure a downward angle at the transmission flange of 4.90 degrees and at the front diff. flange I measured a downward angle of 2.50 degrees.

This is pretty close to the quick laser measurement (and subsequent trig calc. ) of 2.45 degrees and 4.45 degrees I did yesterday.

Time now to measure it with more care, using both methods, and then to see if I can adjust either the transmission or the front diff. angles so that they are the same.

God this blog must seem like the most boring place on earth… what an anorak I am turning into.

Mark II of my laser alignment tool for driveshaft, more to come if I get off my duff and make a registering strip to show where laser dot lands. Inspired by Herman’s work (see blog role, Herman’s Syncro Project).

My ’86 syncro has a Webasto BBW 46 coolant heater, but unfortunately it has been disconnected from the coolant system and does not work. Why was it disconnected? I don’t know, so here starts another syncro adventure.

The heater is quite cool, has a control unit that will start the heater up at pre-set times, it burns gasoline to heat and circulate the coolant, and also turns on the cabin heater fan, thus warming the engine and the cabin. But it seems a fairly complicated affair to troubleshoot…

One thing I did discover is that the small, lipped, sealing ring between the heat exchanger and the recirculation pump has failed, maybe that is why it was disconnected? Local marine repair shop is hung down a replacement for me.

But I have heard that the unit really needs to be used regularly, this one obviously has not been used in a while, so even if I get the seal installed there is no guarantee the heater will work.

I’ll take some pics tomorrow.

Resources:
Gary Lee has one installed in his van, and link to repair manual (but its not a vanagon specific manual, and the vanagon install does have its own “qualities”)

webasto in vanagon, in German, again…

parts manual:70966B

Dec 9, evening, slapping unlabelled pics up:

Over the last week or so I started hearing a slight knocking/clicking intermittent noise from front right of van. I had a look under van yesterday and found I could produce the noise if i bounced the front of the van. I narrowed it down to the upper ball joint by levering upper A-arm with pry bar (see pic), the joint would move and make the noise.
So today I set about replacing the joint. I looked at the manual and at Tom Forhan’s excellent description, bought a nice German ball joint, looked forward to one of those satisfying and straightforward repairs.

Oh, I did spray penetrating oil on the joint the night before, and also I heeded the warning on the ball joint box not to do this naked but rather wear overalls, a hat, and carry a huge wrench.

All went according to Tom’s instructions until I tried to “pop” the joint out. No way would it budge. Ideally what happens is that you drive the pickle fork in then strike the side of the assembly the joint goes into. On the syncro there is a suitable flat on the aft edge of the steering knuckle. I was using a 4 lb hand sledge. I ended up destroying the socket part of the joint leaving the ball part firmly in the steering knuckle. Believe me, I whacked that bugger a lot.

This was the time in these kind of jobs where the calm demeanour turns into hatred of mechanical things. Time to get the torch. I didn’t really want to heat up the knuckle, I thought that heating the ball then pouring water on it would break whatever unholy bond had been formed. Nope, still no luck. Finally broke down and “gently’ heated the upper portion of the knuckle, not red hot mind you, and then the pickle fork would drive the bugger off.

Installation of the new joint was simple (and slathered in anti-seize), apart from the fact that you have to hold the end of the threaded shaft (12 mm wrench) from turning as you tighten up the nylocked nut. Only closed ended 15/16” wrench (my 24 mm substitute) would fit and even then only allowed a few degrees of turning, grrr.

All this took 4 hours, including a few calming down breaks.

I’ve included a pic of my “Jack-All” high lift type jack with my home made adapter that fits in the vanagon jacking points.

to recap… purchased ’86 syncro this last summer, prop shaft out because of vibrations, vc was assured to be ok. U joints on prop shaft looked suspect, but i installed and yes, vibrations at 50-60 kph. Also vc was weak, not passing the 2×4 test.

I replaced u joints on shaft (precision brand, #813, see earlier post), checked the fit of the shaft and bushings on guibo end (nice and tight), and popped shaft back in. Still vibrated at same speeds. Loosened front diff mounting bolts, drove around, no difference.

Removed shaft, examined u joints, one was loose so I replaced circlip with thicker one (u joints came with 2 sets of circlips). Checked bushings and shaft fit again.

Two days ago I put it back in, but before it was installed I did a quick check on vc by using the volvo method outlined on testing vc post. I got a value of 17 ft/lbs. Not much eh? Confirms vc is weak.

It would would be interesting if others would do this simple and quick test and post results, I bet there is a range of values.

Oh, and as well as putting prop shaft back in today, I replaced the dodgy Uniroyal Laredo tires the van came with with some Nokian Hakkapeliitta CS tires.

Road test: tires louder and firmer. Vibrations almost gone, A very slight vibe at 50-60 kph, but its very slight and not bothersome (that said, I will work to eliminate it).

Mud test: on the farm here there are ample spots to get stuck, and it has been raining pretty hard the last 2 weeks. Last week with prop shaft out and the Laredo tires on, I tried going up a curving, maybe 20% hill, grass and clay/mud. I never made it, even with rear diff lock on. Today, with much wetter conditions, I made it up no bother, and no diff lock.
i toodled around lumpy, uneven, sloping ground, grass over North Saanich clay. Didn’t get stuck, but the front wheels didn’t “feel” like they are doing much.

Conclusion: prop shaft vibes mainly due to “loose” u joints, either when they were old worn out units, or new ones, not installed with correct circlips. The “off road” performance I attribute mainly to the great tires. Perhaps the vc is allowing a little torque to get to the front, probably wishful thinking.