The Yamaha Road Star Warrior Forum

 This write up is about spinning both of the bearings that hold the middle drive shaft in my transfer case that spins the front pulley.  I will go over some history, what I found, how I am going to repair my baby.  So get comfortable because this is not a short story.

About a year ago I started to hear a gear “chirp” when I would unload the drivetrain in any gear while riding.  I never could find any damage anywhere I looked, so I literally had to wait till something broke.  Once I know what is broke I can pretty much fix it, but this dam “chirp” eluded me until last weekend.  Someone tried to convince me it was the drive belt unloading off the front pulley and rubbing against the white rollers that help to keep the belt from jumping a tooth.  There are two plastic or teflon rollers located behind the front pulley cover.  Since I could not prove what I thought was the problem I simply agreed with him.  Partly because I wanted to believe it was something simple and did not want to find what I thought was the problem because I knew it would be expensive.  Turns out I was correct, it was the gears/bearings somewhere in the transfer case.

Sunday the drivetrain started to make a whine and rubbing noise with every tire revolution at any speed I rode but only when the drive train was loaded.  If I pulled in the clutch, while moving the noise disappeared.  Fast forward this post,,,,, made it home safe and did not get stranded in 105F desert heat.

Here is a screenshot of the middle drive gear assembly so you can see what I am talking about.

When I removed the front pulley I found the splines on the middle drive shaft #8, were eaten up by a loose front pulley.  No surprise, I expected this because I could see the bottom of the drive belt jumping up and down as I drove home so I figured there was a problem with the pulley.  The torque spec is 72 ft/# for nut #79 on the blowup drawing, and it was still on there tighter than 72#’s.  I run a RS billet 1.5 inch wide front pulley and not the stock 1.125” steel pulley, maybe for this reason I never saw the dreaded red dust to warn me the splines on the middle drive shaft are being eaten up.  I did find black metallic dust, so if you guys run a RS billet pulley do not just look for the red dust.  The two brown rings on the smooth shaft end next to the splines are where the bearing and the front pulley rest on the shaft, looks like they have been rubbing and got hot.

I call around and find out the new replacement shaft is about $250.  One person I talk to says he also has a complete used transfer case with about 300 miles of usage and asks if I would need that instead, and offers me the sale price of $250 for the entire transfer case or just $100 for the shaft.  “Give me a day to get into the case and check things out to see if I might just do that” I tell him.

Once the nut #44 is removed you can pull the middle drive shaft, drive chain, and sprocket #7 out of the transfer case.  I notice the middle drive shaft comes out with no resistance at all, it practically falls out.  I figure not good because there are two different roller bearings that should be holding on to it.  

I take a dead blow hammer and dowel and remove bearings #2 & #5 and this is what I find.  I thought the bearings were good because they do not growl when spinning.  But the exterior surface shows there is a problem. Even the bearing on the right shows some smearing on the surface.

This is the explanation from SKF bearings, the black stain on the bearing surface you see is called smearing.  
SKF: Smearing may occur on the external surfaces of heavily loaded bearings.  Smearing is the result of movement of the bearing ring relative to its shaft or housing. Smearing of the inner ring bore, outer ring outside surface and ring faces can only be avoided if the fits are tight enough to prevent movement of the ring concerned in relation to its seating. Increasing the axial compression does not result in any improvement.
Appearance:  Scored and discoloured ring bore or outside surface or faces.
Cause:  Ring rotation relative to shaft or housing.
Action:  Select heavier interference fits.

So not only is the transfer case housing that holds the bearings too large but the shaft is too small because the bearings just drop onto the shaft with no resistance.  So the bearing was turning inside the transfer case housing and the shaft was also spinning or bouncing inside the bearing inner ring surface.

I am not going to even try to guess why, how, or what is the cause.  I can only say damage is greatest at the front pulley to the splines contact of the middle drive shaft, then bearing #5 with the heaviest smearing, followed with light smearing on bearing #2, and just trace scoring on the main drive shaft where sprocket #7 sits on.  One suggestion from a machinist was that as movement and damage worked its way up the drivetrain towards the engine.  Maybe the machinist theory has some merit, I dunno?

So in a week I will have my replacement transfer case.  I am EXTREMELY lucky the splines on the main shaft for sprocket #7 were not damaged.  If they were, the only fix is to pull the entire engine, remove, heads, cylinders, and split the case.  

If I did not have the offer of the complete transfer case I would have just replaced the middle drive shaft and not known there was smearing on the bearings, and would have to repeat the entire process in my near future.  My lesson learned is that if I think something is wrong you just got to dig until the answers are found.  I think I found everything or at least am practically replacing just about everything.  Only when I have it back together will I know if the main shaft and transmission are ok.  This truly is an easy bike to work on, all you need is the manual, tools

Makes me want to change the transfer case oil. WTH it has went 37k, might as well try for another 30k.

These things are difficult to troubleshoot but you did a good job, and now you have that experience in your 'tool kit' so don't be surprised if you get questions from other members over time!  BTW you've done a nice write-up too.   Its the kind of info that makes this site the best.  Its shty you were the trailblazer . . . but still I have to say thanks for the heads-up.

 wow - thanx for sharing and pls keep us updated on your progress.  I'm very interested....

I can't help but to wonder what factors caused this...just from a standpoint of learning what not to do and what to watch out for.  Do you suppose it was any particular riding habits like a series of hard drag launches over time taking it's toll or was it a particular mod like the front pulley or front pulley nut being loose, or was just just plain wear and tear from ordinary use...it's interesing  to see all the different cases of Warriors - some with high miles and no issues and others not so lucky...

I don't have any idea of the contributing factors.  I use my bike for whatever I feel like that day, it can be drag racing, bar hopping, 2-500+ mile drives, parade runs, rain roads, mountain roads etc .  I do all my mods and conduct  maintenance like engine oil changes every rear tire replacements.  Transfer gear oil every two years or whenever I am bored, since it only takes about ten minutes to do, and so on. 

Was it the 1.5" wide belt mod?  Drag racing?  Desert riding?  I have no idea on why the transfer case housing for the bearings are large and why there was no interference fit on the shaft.

Joe .... i'm very sorry to read about your recent middle shaft & transfer case problems brought about by running with a loose pulley. Without defending myself, i too supported Chris's prior diagnosis of a loose belt causing the 2-UHMW rollers to produce a noise (32T pulley) when backing off on the throttle in a coast situation. It was my understanding at the time that you tightened your belt and the chirping disappeared. I also assumed at that time that you were cognizant of the loose pulley syndrome and that the factory spec 72 ft~lbs torque was the root cause of the failure.

Regarding the metal fatague between the ferrous and nonferrous frt pulleys & red dust there have been warnings to the members by this writer.

• http://rswarrior.com/forums/p/26393/903168.aspx#903168
• http://rswarrior.com/forums/p/111958/918512.aspx#918512

I challange your diagnosis of the middle shaft markings adjacent to the splines to be from the hardened spacer behind the pulley and the inner race of the adjacent outer brg. These parts when properly torqued to 110-125 ft~lbs are under preload against the small stepped shoulder of the middle shaft. The geared end (opposite side) of the middle shaft is allowed to float in the inner bearing for growth and has a close running fit.

The black smudge/smear on the outer race of the inner middle shaft brg is caused by the aluminum oxide created when the hardened outer race started to spin in the aluminum middle shaft housing mixed w/ oil as a result of loosing the preload from the inner race, spacer, pulley and running loosie goosie IMHO.... just like loosing a frt wheel brg and hub when the brg spins out and enlargens the bored hole.

How about posting a photo of the Yamaha billet pulley!

Once again, i'm sorry to hear of your dilemma and if there is anything i can do pls let me know.

AlanH:

... It was my understanding at the time that you tightened your belt and the chirping disappeared.

****Alan - the noise disappeared when I took the pulley cover off and rode around the neighborhood, .  Because it stopped queaking, I said that must be it (the white rollers making the noise).  So of course when I put the cover back on and I again heard the squeak I thought the diagnosis was right.  I never adjusted the tension.  I am not trying to point any finger, it was just background.

......"I also assumed at that time that you were cognizant of the loose pulley syndrome and that the factory spec 72 ft~lbs torque was the root cause of the failure."

****Yes, I know the red is from two different materials.  But I have never seen red only black powder lately and I have never heard of anyone mention black dust before.

.....I challange your diagnosis of the middle shaft markings adjacent to the splines to be from the hardened spacer behind the pulley and the inner race of the adjacent outer brg. These parts when properly torqued to 110-125 ft~lbs are under preload against the small stepped shoulder of the middle shaft. The geared end (opposite side) of the middle shaft is allowed to float in the inner bearing for growth and has a close running fit.

 

****Ahhh ha (gotcha) - the bearing #5 rest on the shaft and the harden spacer is "on" the face of the bearing squeezed inside the greese seal #25.  So the brown ring furtheset away from the splines is caused by the bearing #5 becuase that is the only thing touching the shaft.

 

 

...How about posting a photo of the Yamaha billet pulley!

****I can do that when I get home, but it looks healthy, no marks, no stains, no scratches, no weird wearing, all the teeth are uniform, sharp and clean.

 

Once again, i'm sorry to hear of your dilemma and if there is anything i can do pls let me know.

****Not a problem, and thanks for your input, I always like to read them.  I am not really bothered by this down time, I kinda like to wrench on her.  And it keeps the Busa from getting jealous having to share the garage.

I'd be real interested in seeing an extreme closeup of that bearing. I don't think you can call that a spun bearing. More of a heat signature and signs of a dynamic that ball bearings do when... They are overloaded or under lubed, or both. You might want to think about using a higher capacity bearing (roller instead of balls). Also check the lube system, I remember an oil pump being part of that case. I bet the case is just fine, and bearing mount compound would fix any problems with that bore.

Hope all your luck is,   good!

Can you describe the chirping sound in more detail? Sometimes, (often) when I wack the gas hard or when I completely let off the throttle with the engine wound up I get a chirping sound. Only in the first three gears. But I have associated it with the back tire fighting for traction. But to be honest it sometimes sounds like it is coming from the right side of my engine.

Does that relate to what you heard?

Yamaha still needs to help us with this issue!!  Not to steal the thread, but does everyone still agree that the pulley nut should be torqued to 125ft lbs.  We keep hearing about this ussue and a definitive answer from people who have not had probs for many miles would be useful for everyone involved.  I replaced my lockwasher this past summer, torqued to 72, no loctite, it has held for 5k, but as we all know it could come loose at any time.  Too many posts like this.  Good luck getting it fixed, let us know how difficult it really was.

Bladerunr:

.... Also check the lube system, I remember an oil pump being part of that case. I bet the case is just fine, and bearing mount compound would fix any problems with that bore.

Hope all your luck is,   good!

The transfer case is just a case that holds gear oil.  The gears just sit in a bath of oil, there is no oil pump associated with the transfer case.  There is no dipstick to use, only a large screwed in cover about 2" wide that you remove to visually inspect oil level.

The bearing should sit in the housing (look next to #29 in diagram) and the outer race of the bearing should not move.  I have the smear marks on the transfer case housing walls that hold the bearing, this indicates the bearing was spinning inside the housing which it should never do.  As for the bearing being under lubed.... the level is constant, there is no blowby possible like with engine oil.  There is no only a fill hole and a small drain screw, it never was under lubed and when I opened it two days ago it was good.

Jabo -  I only heard the noise when unloading the drivetrain (chop off throttle).  It was a very quick duration sound, similar to a squeaky rusty spring being compressed.

Thanks megawatt, I guess it is the tire fighting for traction, it sounds nothing like a rusted spring.

Now, yer gonna make me go look stuff up

I know, it's the most over engineered jackshaft in the history of mankind... but it does have it's own pressurized oiling system complete with a pump and a strainer   Have a look at page 2-34 in your service manual.

As for the "Smearing", I can't really tell from that photo, but I've spun a few bearings. That one don't look spun.  Walking ("Fretting") a little maybe, but spun looks different.

All I'm saying is, that it's not so bad as you might think.  Ease off on the belt tension and replace that bearing, add some mounting compound and yer good to go. ( We'll assume that the oiling system works)

megawatt:

Bladerunr:

.... Also check the lube system, I remember an oil pump being part of that case. I bet the case is just fine, and bearing mount compound would fix any problems with that bore.

Hope all your luck is,   good!

The transfer case is just a case that holds gear oil.  The gears just sit in a bath of oil, there is no oil pump associated with the transfer case.  There is no dipstick to use, only a large screwed in cover about 2" wide that you remove to visually inspect oil level.

The bearing should sit in the housing (look next to #29 in diagram) and the outer race of the bearing should not move.  I have the smear marks on the transfer case housing walls that hold the bearing, this indicates the bearing was spinning inside the housing which it should never do.  As for the bearing being under lubed.... the level is constant, there is no blowby possible like with engine oil.  There is no only a fill hole and a small drain screw, it never was under lubed and when I opened it two days ago it was good.

Jabo -  I only heard the noise when unloading the drivetrain (chop off throttle).  It was a very quick duration sound, similar to a squeaky rusty spring being compressed.

Suggest you inspect and clean the mesh strainer for this pump that is located at the bottom left side when viewed from the frt and do your due dilligence when inspecting all the rotating parts that are worn because of spinning on the middle shaft. IMO, it's very critical that the perpendicularity of the parts are retained when torqued. So check the pulley nut, drive pulley, small o-ring & hardened spacer and observe the proper installation of the spacer.

I don't agree with Bladerunr's observation regarding the outer brg. The outer race is very shinny & polished in the photo which is indicative that the brg was spinning in the transfer case aluminum housing so your transfer case could be worn. Else, the brg O.D. would display the fine grinding marks from the centerless grinding

Here's the gallery cross-drilled feed hole visible in your photo, RIGHT SIDE