<VV> Early Differential Yoke failure

[Dan & Synde]

Ever wonder what kind of damage occurs if your u-joint or yoke breaks on an
early model?  I found out!  I submit the following for your perusal. If you
are anything like me, I like to see mechanical carnage just not on my own
equipment.

We were returning from our annual trip to Lake Shasta when the driver side
axle stub yoke broke on our Greenbrier.  Lucky for us it occurred while
pulling away from a signal, 2 blocks from home.  It happened without
warning.

We are normally loaded for this trip with about 1,000 Lbs of camping gear
due to the length of the trip.  We have made the trip in recent years
numerous times without incident.  We also go camping many times during the
summer months but with less of a load and to a closer location.  What is
interesting is that we made it all the way there with more weight and almost
all the way home (over 350 miles) before it decided to give way.  I can't
think of any event during the trip that could have caused the failure other
than the weight exacerbating an existing problem.  I did the usual
inspection of the chassis, engine, drivetrain before the trip and didn't see
anything out of the ordinary.  I usually look for cracks, loose bolts, leaks
etc.

I have to say, that even though it broke, I have a new sense of respect for
the GM engineers.  The a-arm captured the axle and actually allowed us to
roll to the curb.  I'm not sure what would have happened at speed but at low
speed it held together and still supported the vehicle.  The u-joint itself
had less than 5,000 miles on it and looked fine.  Inspection of the stub
axle showed what appears to be the initial break on one side of one of the
loops and then a fresh break on the other side of the loop.  The first break
is dark in color, possibly indicating that it had been there for a while.  I
might have been able to catch this if the yoke had been magnafluxed while I
had it off less than 5,000 miles ago.  It's one of those failures where you
scratch your head trying to figure out what you could have done to detect it
or prevent it from happening.  I guess things just happen after 40 years.
We've driven the van 150,000 miles since we acquired it 20 years ago.  It's
the same yoke that was on it all that time so who knows?  Never had it
magnafluxed in all that time but how many people do?     

I've posted a few pictures at the following link for your enjoyment!

http://pg.photos.yahoo.com/ph/duchesskyra/album?.dir=b552scd&.src=ph&store=&
prodid=&.done=http%3a//pg.photos.yahoo.com/ph/duchesskyra/my_photos  

Looks like I may be able to get it back on the road with just a new u-joint,
new u-bolts, stub axle, seal and new speedometer cable.  The a-arm is a
little banged up around the inboard axle hole but I think it is serviceable.
Has anyone else experienced this failure that could elaborate on what else
usually gets damaged in the process?  I haven't torn it down completely yet
so some surprises many still await.  The differential was rebuilt about
40,000 miles ago with a new set of 3.89 gears, 4 spider carrier and new
bearings.  From the damage I can see so far, it looks like the stub axle
spun around and hit the end of the axle several times.  Some of the ears on
the carrier adjustment sleeve got banged up too.  I'm thinking of at least
pulling the cover on the diffential to see what the internals look like.
Will give me the opportunity to replace the bad heater blower motor while
I'm at it. 

I'm very thankful that it occurred on the way home, so close to home and no
one got hurt.  Made for an interesting end to an otherwise great trip.  


Dan Kling

1961 Greenbrier Deluxe, 4spd, 3.89  On the Road Again,  yeehaw :)
1963 Spyder, restored   4spd Saginaw
1967 Ultravan #299  Newest of the herd!! Almost killed me already!!


http://photos.yahoo.com/duchesskyra
A few pictures of the Greenbrier, UltraVan, engine and tranny tear down with
more to come!