Rear Axle Epic Fail

[blyhigh]

Can anybody explain this? Bought an '89 Syncro Westy 4 years ago. Drove it from the west coast to the east coast. By the time I arrived the left rear axle was clanking. Outside CV joint was dry as a bone. Had the axle replaced. Drove it from the east coast to the west coast. In Idaho the left rear axle began to clank. Same thing: outside CV joint was dry as a bone. Over the last four years the left rear axle via the inside or outside CV joint has failed six (6) times. Yes, six. I've replaced with Empi. I've replaced with Lobro. I've replaced with rebuilds. I've had four different garages replace the axle (twice by gowesty) or boots and it always fails - once with only 2000 miles on it. I do not go off road. These are highway miles with a 2.4 gowesty engine and a solid shaft with decoupler. At this late date I've come to the conclusion that there's gotta be something with the van that's causing the problem. But what? Any of yous got any ideas? Thanks.

Max
'89 Syncro Westy (with a bad axletude)

[otiswesty]

Is your van lifted?
Lifting springs or spacers will change the angle at the CV and increase wear and failure frequency.
If your van is lifted, you can go back to stock springs or replace the CV joints with the 930 Porsche style that have a greater tolerance for the increased angles.
_________________
1978 Sage Green P22 Westfalia
1988 T3 Syncro Single cab

Just a regular guy

[syncrodoka]

I've had that happen many times with the boots they are just junk.
Put more grease than they provide in the kit and use a rockford 339-22 boot.
http://www.thesamba.com/vw/forum/viewtopic.php?t=243777&highlight=rockford

[Alaric.H]

I have seen worse.

[syncrodoka]

Yeah, he is horrid

[Classicvibe]

So just to clarify, are you saying that every fail has had a completely dry boot on either the inside our outside, but only on one side of the van?

You could just take some initial measurements on the height of the van at each wheel. You could go these easy route and look for a larger high quality boot. I think the 930 upgrade is such a no-brainer though. It would be nice to know that would for sure be the fix before jumping in.

Hmm, thinking...
_________________
On a mission, the destination is just an excuse.

Syncro Solstice 2022...see you there!

1986.5 Wolfsburg Syncro Westfalia Poptop Weekender Transporter

[euromog]

I bet if you installed a new viscous coupler and drove in all wheel drive all the time your problem would go away. You have added more HP and cut the distribution of that HP by half. I am seeing rear CV failures more and more on Syncro's with a decoupler. The 930 CV's will hold up better but you will still have to repack them every 10k OR 15k miles. If Peloquin ever gets his VC replacement diff it will make things even better.

[Alaric.H]

[blyhigh]

yes. van is lifted. didn't think of that. and, yes, it's always on the left rear, either inside or outside boot is dried out or torn as in the picture. when you say 930 upgrade are you talking about the whole deal: axle, stub axle, boots, etc? or just the upgraded boot?

[IdahoDoug]

If it's lifted, not only to you have a steeper running angle in terms of CV wear and boot wear, but when I look at my rear suspension (stock) it appears that a lift would also lengthen the axle. That means the boot is also stretched more than usual in the installation - again adding to the stress of the boot. These two changes taken together could make a difference in boot life.

Then, another thought occurred that may explain why the left one. When driving on the road, the crown (slope for water runoff) leans vehicles to the right. On the Van, that would extend the left suspension, making the boot stretch even more while doing the opposite on the right boot - helping that side last longer.

So, I'd be interested in a precise measurement. Perhaps you could find a way to have the small end of the boot mount on the axle closer to the joint to reduce the stretching effect. May require machining off the lip on the axle shaft for this purpose, or epoxying on a lip in closer.

Anyhow just an observation due to the suspension geometry. I'm assuming your lift is a normal suspension lift. Perhaps this issue is why the Syncro lift is a body lift, leaving the engine/trans down at the normal level to avoid changing the axle running angles.

DougM
_________________
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, 1993 Toyota LandCruiser, 2002 BMW 325iX, 1982 Toyota Sunrader

[Jon_slider]

youre seriously jinxed

> Same thing: outside CV joint was dry as a bone.

dry as a bone explains it.. as to why its going dry.. bad boot like syncrodoka said?

> I do not go off road. These are highway miles with a 2.4 gowesty engine and a solid shaft with decoupler.

so are you saying you Never engage the solid shaft on pavement, or do you?

and are you saying your axles break with rear wheel drive only?

Or do you drive like other (unnamed) people who break stuff in their drivetrain?

> I am seeing rear CV failures more and more on Syncro's with a decoupler.

interesting observation John, nice to see you posting here

any chance the CV failures are associated with folks who have solid shafts?

or, do the people who break stuff have motors with more torque than a subaru 2.2?

for example, the OP has a 160 ft lb motor, similar to a subie 2.5...

or is the breakage associated with lifted vans, regardless of what kind of motor or whether they have a solid shaft, or whether they have a decoupler..?

curiouser and curiouser

most of the people I know who break axles, do it by engaging a solid shaft after getting stuck offroad (I know a couple people engage solid shafts on pavement for wind stability, and get away with it... risky business),

I also hear of broken axles/CV's/ring and pinions from folks running a motor with more than 200ft lbs of torque, like the SVX, 1.8T or some chipped TDi's..

Some of those SVX vans are not lifted, and do not have solid shafts nor decouplers.. I think the drivers just like to punch the gas.. (hard to resist when youve got it)

fwiw, my syncro westy is lifted with syncro.org springs, to 18.5" fender to axle height, 27" tires, and has never broken an axle.. it has a 2.2 subie, a viscous coupling, and no decoupler

[Alaric.H]

You could try takeing the little clamp off the end of the boot.

[euromog]

[IdahoDoug]

Any time you're replacing a 'soft' connection (VC, open diff) with a 'hard' one (solid shaft/decoupler, locker) you're adding a lot of stress to the axles/CVs. I don't think I'm telling anyone anything new with this statement, but I suspect not many understand how MUCH stress.

Here's something few will know that communicates this well. When you do a burnout with a vehicle or are stuck offroad and a spinning tire suddenly hooks up on a rock, the axle shaft is literally twisted - sometimes as much as a full revolution. It rebounds because it's made to do that. Now I realize Vanagons aren't doing burnouts but it serves to make the point that there are a lot of stresses going on some may underestimate. And these axles twist and rebound under duress all the time. So, lots of force even with an anemic stock engine and the axles were matched to the expected forces.

Back to the solid connections. The engineers that built the Syncro undoubtedly tested the system in numerous destructive testing scenarios and measured the force spikes, choosing the metallurgy and other things to ensure reliability. The VC allows some shock forces to be absorbed gently and indeed the heat generated to activate the VC is literally energy absorbed and turned into heat. Remove this and you can generate force spikes in the axles and driveshafts far higher than VW envisioned. Do that enough times and the CV joints have pitted surfaces and metal dust in the grease around the balls. Change the angle of the CV so it's experiencing radial forces (trying to straighten itself each time a ball scrapes across the cage surface) and the joint is wearing itself perhaps at 3 times the normal rate. Add a more powerful engine. Now you've got a paste of metallic grease in the wear areas, much more heat (which shortens boot life, too), more power and higher force spikes. Under these circumstances, the only way to have acceptable component life would be very aggressive grease repacking and using premium synthetic greases. In the absence of this aggressive servicing, the expected outcome would be shortened component life - perhaps dramatically.

So, some random thoughts on drivetrain modifications.
_________________
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, 1993 Toyota LandCruiser, 2002 BMW 325iX, 1982 Toyota Sunrader

[Classicvibe]

That is all nice analysis Doug. I am thinking on your random thoughts now, mainly deconstructing your 'run-off' scenario for the left rears...interesting! Could the height difference be just enough to allow for that fail? Hmmmm...
_________________
On a mission, the destination is just an excuse.

Syncro Solstice 2022...see you there!

1986.5 Wolfsburg Syncro Westfalia Poptop Weekender Transporter

[blyhigh]

I haven't actually broken an axle - or anything for that matter. I rarely engage the solid shaft, just check to make sure that it's working now and again. What seems to fail are the boots which in turn kill the joints themselves. Lot of interesting info here, but I'm wondering if I can get away with the larger 100mm boots or is this a question of installing the whole 930 axle set up left and right. Will that do the trick? Thanks for the help, btw. Can always count on The Samba.

[otiswesty]

I had the impression in your initial post that you were having CV joint failure, with a dry boot noted. It would seem that a higher quality boot with annual service of the CV with grease repacking would be the key for you. That assumes that your boot is losing all the grease and as such is the cause of premature CV joint failure.

Hard to say exactly what is going on. Maybe the lift is contributing, but I would start with the better boots and grease, recheck in 12 months, and go from there.
_________________
1978 Sage Green P22 Westfalia
1988 T3 Syncro Single cab

Just a regular guy

[IdahoDoug]

By complete coincidence, I was repacking an axle this evening and noticed that the inner CV has a startling amount of designed in play so the shaft can essentially elongate with suspension movement. So, it could certainly be rough on boots if you're lifted and the shaft's elongated and stretching them in everyday operation. I put the Lo.. something boots on and they were pretty inelastic but everyone seems to rate them OK for durability. I could easily see where if you have a similar boot or this stiff material is typical Vanagon fare that they would not take that long.

DougM
_________________
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, 1993 Toyota LandCruiser, 2002 BMW 325iX, 1982 Toyota Sunrader

[Bassyaks]

This is a little off topic but, if an rear axle fails, will the fronts still function with a straight shaft?
Can the van limp home?

[mrshrimp]