Saturday, January 22, 2011

Every Ural rider needs an Oscar

Today, after a week of research, weighing and comparing options available to me in terms of either fixing or replacing Natasha's final drive, I finally decided to at least look at the innards of the final drive and judge for myself the extent of the damage.

As you might have read from my previous postings, I'd been unable to remove the axle from the rear or "pusher tire" and therefore couldn't remove the wheel in order to get at the final drive assembly.  It was well and truly stuck in there, and repeated hammerings accomplished nothing but damaging the threaded end of the axle.

Today, Oscar, a friend from work and my now best wrenching friend, came over with his tools.  The first order of business was to cut the outboard end of the axle, as close to the wheel hub as possible. Once the loose section of the axle was removed, we could then slide the wheel with final drive still attached to the left.

This would thereby free the mounting bolts which secure the FD to the right side swing arm mounting holes.  Once free of the mounting holes, the only thing holding the final drive to the motorcycle would be the prop shaft which mates it to the rubber donut which mates it in turn to the transmission.

Oscar wasted no time and before I knew it was sawing away at the axle:


Oscar and his sawsall

Using what Oscar described as a blade that was "toast", it took him
only a few minutes of steady cutting to cut the axle

The stub in the left swing arm's pinch bolt was being difficult in its own right, but Oscar's slide hammer made quick work of that.

Now came the fun part and the inspiration for the title of this posting.  Using a breaker bar, I managed to push the final drive to the left and off the mounting holes of the swing arm.  Now, the wheel and final drive assembly were only connected to the motorcycle via the prop shaft to the transmission.

I loosened the prop shaft from the donut and while Oscar basically dead-lifted the entire rear end of the motorcycle, I wrestled the final drive free of the portion of the donut which connects it to the transmission.  Oscar continued to hold the motorcycle's rear end in the air and I slid the wheel and final drive out from under it.

I then took the wheel off and we rolled it outside to examine it.  The axle remained stuck in the wheel hub and since it was toast anyways, Oscar then hammered it out.  We noted a groove had been "cut" into the axle so it was toast regardless.  So, what cut that groove you ask?  I'll tell you.

The Ural wheel design is like so:



Part number 20 in the picture above depicts the two roller bearings into which the axle, p/n 11 above, is inserted.  They ride on both ends of p/n 27 which is a bushing.

The inner roller bearing had apparently seized and basically shredded itself to pieces inside the wheel hub.  In the process of doing so, it seized the axle (probably where the slight groove was cut) and prevented me from pulling the axle as normal.

Here's the two roller bearings in question, the whole one is the outer bearing.  
The one in pieces, used to look like the one in the upper left corner.  Nice huh?

Here's the final drive, cracked open for your viewing pleasure and for my eventual disassembly to inspect for damage and replacement of parts as required.



As a portent of hope, all the gears spun smoothly within their respective housings.  
I could move them with easy with my fingers, and by using the prop shaft.  
So hopefully, no major damage to the final drive components themselves!

The wheel hub splines on the pusher wheel were of course toast as well.  I'll be needing a new wheel, again.  I am also thinking that I will need a new driven gear spline assembly:

The driven gear spline, looks pretty bad to me, and probably the cause of the stripped wheel hub splines.

I continued on for a bit more but stopped to take a break.  Pictures were sent to the Ural dealer for price quotes, we'll see what the totals entail.  It might be cheaper to replace the whole final drive with one of the newer ones which are better and more reliable.  Though a new one won't be full time 2WD, it will come with engageable 2WD.  We'll see.

The above start of repair efforts does not mean I've discarded the notion of perhaps replacing the motorcycle with a different tug.  Or finding a new rig to take Natasha's place.  All options remain on the table, to include as I mentioned, getting a new Ural Final Drive.

That is one thing about Urals, the design has changed so little in over 40 years, that a 2010 Final Drive bolts right onto a 1996 frame and transmission!

12 comments:

Murfs Spot said...

Ahhhh Grasshopper,do not falter on the path toward enlightment on the road to a BMW outfit.
The path of the rightous biker is beset on all sides by imposters and fornicators,and the false promises of the Urinal...

Stay the course brother..........

motoroz said...

Will Oscar come to Texas? I need an Oscar. What a great friend.

Charlie6 said...

Murph,

a bit harsh on the Ural don't you think? : )

Jay Barry said...

You'll enjoy having an final drive with the option of 2wd rather than full time 2wd.

RichardM said...

I was wondering if you were going to take the FD apart. It looks like most of it is still in pretty good shape as most of the damage seems to be in the hub and the FD output spline. Were the bearings dry?

Thank you for posting the pictures. Following your efforts with great interest. At one time I thought about looking for a Ural or the Chinese version but they may need way too much maintenance for me.

Richard

Jack Riepe said...

Dear Charlie6 (Dom):

"How is #236 today?" the young doctor asked the desk attendant.

"Same as usual," replied the attendant. "He sits in the center of the padded cell, draws mechanical diagrams in his feces, and screams one word at anyone who looks in at him."

The doctor peered in the cell's window to find the occupant exactly as described. Yet before he could step away, #236 looked up and screamed, "Ural."

Most people let women drive them crazy.

Fondest regards,
Jack • reep • Toad
Twisted Roads

Chris Luhman said...

I'm glad you took the time to survey the actual damage. The selectable 2WD is nice. I still only rarely use 2WD. Maybe if very loose stuff or more than three inches of snow.

-Chris @ everydayriding.org - year round riding in Minnnesota

Charlie6 said...

Motoroz, sorry, I'm keeping Oscar here as long as possible....I'll ask him if he's got a cousin in TX. : )

Jay: fulltime 2wd makes things smoother in terms of yaw. Then again, it's way more complicated too.

Richard, the outer roller bearing was not dry, there was lots of grease inside the wheel hub. Re your thoughts about Urals being too maintenance-intensive, can't argue that point at all right now.

Jack, fortunately I married a girl who understands my "quirks" and motorcycling addiction. As to my continuing to pick at the "ural scab", it's in the interest of further learning and perhaps being able to fix it. Patient #236 says hi.

Chris, yes, it's interesting stuff but then again, on a Beemer I probably wouldn't be doing this. We shall see how far I go on this "repair".

Chris Luhman said...

I'm not trying to defend Ural, but google "BMW final drive" or "BMW final drive failure".

I'm excited to see what you end up with :)

Charlie6 said...

Chris

yes, there's much ado about the FD failures in the newer Beemers.

Jack Riepe said...

Dear Charlie6 (Dom):

As Richared pointed out, the damage to the final drive unit doesn't sound as bad as it could be. If I am not mistaken, the damage was confined to a bearing and the drive shaft, no?

How much can the bearing be? $100? How much can the drive shaft be? $250? If you could fix this for $500, that would be an easy option. The question would be, how often would it reoccur?

Now if you like the concept of this rig maybe the trick would be getting a new one, like Chris Luhman's. Where there's a will...

Fondest regrads,
Jack • reep • Toad
Twisted Roads

Circle Blue said...

I want an Oscar.

~Keith