Pinion Cup & Drive Shaft Failure

[DDT (12)]

I've just returned from a road trip out west, by way of Mandeville, LA. The pinion cup and drive shaft went out again on ALI (third time in two years!), and I had to haul her from Carlsbad, NM, back to Mandeville so Troutdude could have a look and perform repairs. What follows is an excerpt from a story I wrote about the trip... the whole story is really, really long, and I figured it would be too long to post in its entirety... Anyway... once I arrived at Dennis' house...

It didn't take long before the rear wheel was off, and the shaft and pinion cup were exposed... Rust! And, the splines were bone dry and worn down considerably. Dennis checked the boot very carefully to see if water may have gotten in through there... Nope, the boot was perfectly positioned, so no source of water through there.

Next, the universal joint was removed and inspected. Good shape, practically new... t-man403 had replaced that too the winter before. The problem was that water was getting to the pinion cup somehow, and until the source of that problem was found, any repair or replacement of worn parts would only be a temporary fix... Something besides mechanic error or oversight and simple neglect had to be going on here...

Dennis is very insightful and most knowledgeable about wrenchifyin' and such... He'd impressed me on several occasions before, and this time I was confident things were going to work out... He is also patient, confident, and unperturbed... stress and frustration are seemingly unknown to this cool customer. I was sure answers were soon to be found. I was right.

Closer inspection revealed that the inside surface of the swing arm had a great deal of rust, gunk, grease, and metal filings all up and down it and all inside the part between the two 'arms', as well.

He figured the problem must be in the swing arm... We removed that, then covered one end with plastic and filled the arm with water... Water flowed out of a hole on one side of the swing arm about a third of the way down the side opposite the side that housed the drive shaft... Hmmm, that doesn't seem right!!!

We also learned that there were actually two holes, one on each 'arm' of the swing arm put there by the manufacturer. They are located at each end of the weld bead that runs from just below the 'horseshoe' up the arm, around the inside of the 'horseshoe' to the same distance down the other side. From the ends of the weld bead and holes to the ends of the arms there is a channel on each arm.

One of those holes on ALI had been clogged up (the one on the drive shaft arm side), who knows how long ago, and that had prevented water from being able to exit or dry out through ventilation... The trapped water then migrated down to the pinion cup where it collected and did its nasty work in corroding everything and severely shortening the life of the splines of the shaft.

We'd eliminated all other sources of water intrusion - the universal boot, swing arm bearings and entry points, and where the swing arm attaches to the 'pumpkin'. At least, that's our theory... We'll see how this theory holds up when we inspect the cup and shaft at the next rear tire change...

Warlock had the special tool necessary to remove the left side swing arm bearing lock nut, and he volunteered to meet us at Punisher's house Friday and let us have it... Yes, Punisher had a spare swing arm, and he had offered it to us already! Can you believe this?! 'Our bike' is becoming even more so every day, it appears!!!

Dennis and I rode up to Hattiesburg, MS, Friday morning... No, I didn't ride as a passenger. Shelia kindly consented to allow this humble rider to straddle 'Saphera', her '98 Valk Tourer.  We had a nice visit, too, at the 'manor'.

We returned to Mandeville and began assembly of parts. We were still at it the following day when Allan & Jackie arrived, so Allan jumped right in and helped Dennis... I was doing a very good job of staying out of their way... something all good mechanics insist I do...

At dusk, the work was finished, and it was time for a test ride... and I got the honor. WOW! She felt mighty good, and no noises or other signs of a problem were detected. Dennis also gave her a ride... All was good, it seemed!

I'm back at my place now, and the ride back here was uneventful... except for being the wonderful ride that it was. I now have greater confidence in ALI's delicate derriere, and I'm very much looking forward to riding her again and again...

Dennis especially, but also Allen, David, Gordon and others who participated either in person or via phone have my undying gratitude... Thanks folks.

DDT

[Gryphon Rider]

Another thing to inspect during regular rear-end maintenance: swing arm drain holes.  Put a note in your maintenance log, everyone.

[BobB]

I have the rear wheel and pumpkin off my '98 Tourer.  Just went down in the shop to locate these "drain holes".  After a very close inspection, there was none to be found on either side.  What year and model do you have?  A picture will help.  I had to replace the drive shaft and pinion cup right after Inzane 12 and have inspected the wear therein every winter since then. 

[Smokinjoe-VRCCDS#0005]

I have the rear wheel and pumpkin off my '98 Tourer.  Just went down in the shop to locate these "drain holes".  After a very close inspection, there was none to be found on either side.  What year and model do you have?  A picture will help.  I had to replace the drive shaft and pinion cup right after Inzane 12 and have inspected the wear therein every winter since then.  

They are there ... Look right where the tire would be in the middle of the " horseshoe " . With the tire on they ( 2 ) are hidden. You have to look close to see them but they are there. DDT's is a 1997 mine is a 1999 they are both the same.

[hubcapsc]

I, too, am confused by the holes. I guess these are them:



I don't see any way these, or any, holes have access to the driveshaft side of the
swingarm.





Except for the part about laying in the shed for about four years, this is a real clean
swingarm. I just don't see anything but a smooth closed surface down inside the
driveshaft side. DDTs swingarm has 400,000 miles on it, is possible that something like
water sitting inside the cavity the holes lead to finally rusted through, letting water
get inside where it normally couldn't? The driveshaft side of the swingarm seems to
be a closed tube, and the holes seem to lead inside of a gusset or strengthening shell
welded to the critical section of the swingarm. I closed off one end of the swingarm and
shined a bright light into the holes, no light made it into the swingarm tube...

Bruce? Dennis? Allan?

-Mike

[sandy]

There's no mention of what grease was used. I have 146K with no signs of wear on the shaft/pinion cup. I use Valvoline Durablend wheel bearing grease.It has 3% moly in it.

[trout dude]

Sandy it had nothing to do with the grease when the water got in it boiled the grease out then there was just water. Hope this helps clear things up.
  Dennis
Here are some pictures

This was on the bike





This is when I cut the swingarm open












This is what came out the swingarm

[Hook#3287]

I found this hole in the swing arm, I put a tooth pick in it.  Seems like it goes right into the interior of the swing arm and any moisture in the swing arm could transfer into the drive shaft tunnel then down into the pinion cup area.

So the holes in the swing arm by the tire area are supposed to allow moisture to exit?  And if they don't, this hole allows the moisture to enter the pinion area?

[Rio Wil]

Ya know,  I would almost have to think this swingarm was at one time submerged in water and the bike not ridden for extended time.  Even the grungiest ones on ebay do not show this amount of rust. Another clue as to something unusual is going on with this swing is the black stuff that came out of the tube. Can't decide if the stuff is rubbery like a drive shaft boot or not, in any case either a boot got sucked into the tube from a yoke disintegrating  or some such silly thing......fact is, there is no place in the tube that should ever have any thing like that stuff.  Anyone have any history on this arm.....Another thing, I seem to remember that beneath the plates that are riveted on the top and bottom sides of the swingarm, that there were fairly large holes cut into the sheet metal of the arm......don't see them in any of these pic's.....

[hubcapsc]

OK... this makes it easier to understand...



I guess it's the holes in the picture I posted are the ones that got clogged... the big
pile of rust came out of the void covered by the riveted-on plastic covers?

The hole in the toothpick picture leads to the void I think... once I saw the toothpick picture,
I easily found the hole in my swingarm...

-Mike

[BobB]

I again crawled under the bike to look for drain holes.  Nothing so far.  The toothpick holes cannot be seen with the swing arm in the bike.  I order for a drain hole to be effective, it must be at the lowest point in the cavity to be drained.  That is not the case for any of the holes located above.  I have seen some holes punched into the steel stampings that make up the swing arm.  These do not go through to the interior of the swing arms.  I believe these to be locating holes for the welding jigs that allow the swing arm to be aligned properly before welding.  That's more than a guess, I have education and experience in this.  

[Hook#3287]

I believe these are the holes that are being discussed above that may need to be clear.  I found the other (interior) while looking around a swing arm I got hanging around.

It's looks like there is room behind the plate with these holes for moisture to leak out.

[97BLKVALK]

Hole into Pinion Shaft.

Why is it there?

A breather for the shaft?

Michael

Whatever its for, this is a great find of information for rusted pinion cups and shafts.

[trout dude]

Good find Hook I did not see those but when i saw your post it made me look. There is another hole across in the void area going to the other arm. All I can think is all the rust flakes was holding the water in the swing arm. Thanks for you pictures
  Dennis

[trout dude]

Mike we drilled the rivet's out and came to the conclusion that the riveted-on plastic covers are there for a sound barrie when rocks and any thing else hit's it because the void is hollow. It would make a hell of a noise if they were not there. Just a theory we had don't know for sure.
  Dennis

[sandy]

Sandy it had nothing to do with the grease when the water got in it boiled the grease out then there was just water. Hope this helps clear things up.
  Dennis
Here are some pictures

This was on the bike

The point I was trying to make is if the grease is waterproof, the water wouldn't have had such a great affect on the cup.




This is when I cut the swingarm open












This is what came out the swingarm

[Hook#3287]

I've always believed, until yesterday, that I didn't need to worry about rusty pinion cup & drive shaft failure.  If it happened to SmokingJoe, it can happen to anyone.

Obviously, even if your anal in your rear end maintenance, (that's just weird sounding)  as I believe Joe is, pinion cup failure is lurking.

The question (s) is, why does it happen?  Is it because someone rides in rain or standing water often?  Maybe because the owner washes (or power washes) their bike frequently?

Or maybe the owner does neither often and it's caused by the newly discovered swing arm holes being plugged and moisture is forced into the drive shaft tunnel through the newly discovered tunnel holes, then migrating to the pinion cup?

Moisture, in vapor form, will travel through those small holes and collect in the lower section of the drive tunnel.  But excessive vapor moisture usually has a heat source and I don't see that here.

Lots of ??? and not many answers.  Yet.

My opinion is that pinion cup drive shaft failure is the biggest concern we have on our bikes, with hydrolock right up there and carb jet plugging being third.  We know what causes hydrolock and jet plugging, if we can collectively solve this issue, that would be awesome.

[Hook#3287]

My first suggestion  -  How about drilling drain holes in the bottom of the swing arm?

[Smokinjoe-VRCCDS#0005]

My first suggestion  -  How about drilling drain holes in the bottom of the swing arm?

I'm no engineer however I think adding more holes would only add to the problem. Just make sure the next time you do maintence and pull the stump take a flashlight and look up in the drive-shaft tube. Mine wasn't wet as in water running out of it I would call it moisture / condensation. I did have a slightly boogered drive-shaft seal as well so I'm sure that help with getting moisture / condensation into the cup .... DAMNIFIKNOW 
As stated on the other thread in the sandbox this was the first time in 16 years of owning a Valkyrie that I noticed moisture / condensation in the tube  ???

[KY,Dave (AKA Misunderstood)]

I have 2 pictures from my spare rear setup and you can see, not only the channel holes that mike highlighted in his pictures that are probably where the water is getting slung in, but also 2 holes below them that would act as drains. I see it as Joe says to inspect the inside and insure the holes aren't clogged and thus preventing drainage. Keep in mind these pictures are of the swingarm upside down, so the drain holes are on the bottom.
one side



And the other side

[Firefighter]

That is a lot of rust, I think your lucky the swing arm didn't break and cause a crash! Has to have a lot of forces working on it.
Mine has always been clean, and I try not to expose it to rain or excessive water. I will look closer next time it is apart.  Thanks for all the info.  Firefighter

[BonS]

A quick Google search turns up many an issue with swing arms getting wet. KTM's apparently don't have drains and they end up full of water. I found some early Goldwing owners with serious internal rotting from moisture. Owners that have discovered their swing arms full of water drill drain holes and spray WD40 to dry the innards. You'd think that simply sealing up the holes would be a plan but water has its way of getting into voids when there are holes for bearings and drive shafts and it definitely needs a way to get out. I think mother Honda's plan of drain holes is a good one and going forward I'll be cleaning mine every time I have the rear tire off. Great find!

[Ricky-D]

As in most drive line coupling areas, the biggest

culprit regarding moisture is the rubber boot.

Failure or incorrect installation can account

for most all instances of rust.  Power washing

being the heavy hitter in my opinion.

***

[Chrisj CMA]

As stated.  Make sure the boot is on right and in good shape.  Also the condition of the oil seal at the pinion cup end of the drive shaft is critical.  The other thing is to use a good high pressure water resistant grease.

Don't rely on the final drive lube to lube the pinion cup.  This is how mine looks each time I service it
 

lastly, make sure the walls of the pinion cup are clean and the oil seal is clean and there is a good seal when you install the drive shaft into the pinion cup.  If you try putting the drive shaft into the swing arm by itself and then popping the final drive on the end, you have no idea how that oil seal faired the installation, that's why you do it this way

[KY,Dave (AKA Misunderstood)]

Chris I respect your procedures and know you know how to do the service as many of us do. It still remains that some have done all this correctly and still have had issues, so obviously more seems to be involved with these holes getting moisture in and needing to be cleared so it can get back out. 

[trout dude]

We are talking about ALI. Not any power washing going on there and the bike has 458,000 miles on it . I do think the drains was plugged up and made a rusting chamber in the void of the swing arm.
 Also when i pulled the shaft where the seal is on the shaft it was blue that means heat and a lot of it.
 I do believe we have the problem solved on ALI. I will be keeping a close eye on my drain holes and everyone else who's bike i work on.
  Dennis

[Rio Wil]

At the last time the final drive was service (10-15K miles ago I presume) what did the interior of the drive shaft tube look like. Hard to believe this all happened in the last comparatively short time. If the tube had even half this amount of rust it would be noticed, don't know where this bike has spent most of its life but it looks like it was rode hard and put up wet lots of times....maybe stored outside in high humidity? Or, does someone enjoy riding the streambeds?

Still no comment on what the black stuff might be?

[Ricky-D]

Again.  ALI

Using an acronym without defining what the acronym stands for, IMDOS.

***

[DDT (12)]

'ALI' - Absolutely Loving It... Never been stored, never 'submerged' or power washed... not even washed very much. Yes, ridden hard most of her life (we'll celebrate 16 years together on January 7th since I bought her new - '99 Tourer), parked outside for three and a half years when I lived on the road and traveled almost daily.

She's been down some pretty nasty roads, forded a stream or two (never a deep one, though), and she's no stranger to mud and highway construction stuff... A couple of dust storms, high humidity, rain storms, desert sand, salt/de-icer on roadways, coastal roads (salt spray)... Just about anything you can think of that can be encountered on more or less paved roads throughout North America, she's been on it and in it... 458,000 miles and still going strong...

DDT

[Firefighter]

Then she's doing good !

[ithitwhat]

Just thought I would weigh-in with my 2 cents. I pulled my shaft off to check pinion cup and shaft, and found the teeth on the shaft and in the pinion cup were half gone. The shaft looked like it had been lubed with moly and the moly had clogged the two holes at base of pinion cup, this will block oil fron the rear drive and cause the shaft and pinion to run dry. Bike only had 13,000 miles and this is way too soon for this kind of wear. There are lots of opinions about lubing the pinion cup and shaft, but I belive the pinion and shaft are supposed to be lubed by the oil in the final drive through the two holes in the base of the cup. I just coat it with wheel bearing grease (because it will mix well with the final drive oil) and check the cup and shaft when I do annual service. Again just my 2 cents.

[uturn]

458,000 miles on her!!! how do you keep track of that? a new speedo notch each time it turn over?

[trout dude]

Here's what blows your mind. We were in Canada and DDT is telling the locals more about roads and great scenic rides than they knew. There is not many places that I know of he has not been and some three or two times. If you ever get a chance to ride with Bruce do so and enjoy. I've enjoyed every ride i have been on with him and ALI and looking for many more.
  Dennis

[8Track]

I just checked those drain holes on my swingarm. They are present in the U shaped cross member and are clear. However they don't go through into the shaft. That part is not drilled through - solid steel lies under those drain holes.

[hubcapsc]

I just checked those drain holes on my swingarm. They are present in the U shaped cross member and are clear. However they don't go through into the shaft. That part is not drilled through - solid steel lies under those drain holes.

You need to read the whole thread and look at all the pictures. I have a clean off-the-bike swingarm
here to inspect, and at first I missed the hole into the driveshaft part of the swingarm too.

The holes you found lead into the void with the riveted on plastic covers. There's a lot of
air-access to the void through the holes and channels in the welded-on gusset.

The very-much-on-purpose hole in the driveshaft part of the swingarm also leads to the void.

Why those holes are there could be debated, but they form a clear vent path to the outside.

-Mike

[Hook#3287]

As too the exterior swing arms holes, mother Honda does everything with purpose and those lower holes are for some reason, she just keeps info like that to herself, leaving us to wonder and speculation.

I'm going with the theory they are drain holes for interior moisture to weep out.  They are indirect so road splash would have difficulty getting in.  Checking and keeping them clear just became part of my rear maintenance schedule.

The interior drive shaft tunnel hole must be for vapor as it is located half way up and the tunnel would have to be half full before it would do anything.

If any one has a junk but unmolisted swing arm, maybe some surgery might answer some questions.

This is exactly the reason this board rocks