Transmission main shaft

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Scorpion07 said:
Still haven't received a callback from F.A.G. (No matter how many times I write that - it just doesn't sound right!). I'll give them another call today.

I'm still leaning towards bore misalignment.
When I pulled my compensator it came straight out (with the clutch and chain) without having to grind any of the inner primary in that area. In fact there was about 1/8" - 1/4" of room. I've read in the forum that it seems quite a few have to grind.
Also - 2 of the 4 roll pins are very loose in the inner primary - fall out loose.
This is a critical alignment, and to have it just slightly out whack would stress something in the assy.
I first started noticing a difference in my drivetrain at 20K (22K miles ago). Took it in - no problems. I'm thinking that's when the bearing "self adjusted" to accommodate the misalignment. Once it aligned it was just a matter of wearing out completely after that point.
In my case the Main bearing was the weakest link. Others have the Primary bearing go. But for some reason the incidence of the two needle bearing failures (inside the Main Drive Gear seems pretty rare. And even rarer still, is the trap door bearing.
I think it's a mechanical advantage that put's all the stress on the center bearing, in this case the Main Drive Gear Bearing.
I sketched up a rough idea of what I'm talking about:


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I have looked all over the place for a sketch with it all together and I had made up my mind that the next time I tore it down I was going to check some dimensions on most of the pieces and do a 3d solid model of it in NX6.
Just like to add if you are doing your own work you can pull the rear wheel and move the drive belt forward out of the pulley and with the primary chain off verify the bearings and alignment are acceptable. If its free spinning out to the clutch hub in gear 4 th that will spin both shafts in the transmission and 5th will pick up just the main shaft. You can also trial fit your inner primary cover to the engine with the outer race of the inner primary bearing remover. Attach an indicator to the output shaft and sweep the bore and the face. I believe checking for free spinning shaft should be good enough. I think a whole lot of problems of the bearing on the primary side is caused by the shavings in the oil. Japan built 5 speeds I have been in have metal shield bearings to protect the bearings from trash. They are packed in grease yet run in 70-90 SYN and it washes in yet the large shavings stay out just like the Baker man told Scorpion07 about his bearing.
Click to expand...
 
Iclick,
I noticed one day riding home from work a howling coming from the primary/clutch area. I was riding between 50 - 70 mph. When I got home i wheeled her in the garage and could hear something going on around the drive pulley. When I backed her up I heard clicking. Immediately thought I tightened the belt too tight. So I loosened it and took it into the dealer. The dealer said nothing was wrong and charged me for tightening the belt! THE reason I do my own work now! Anyway - when I got it back the howling was gone, but there was still a worsening vibration I lived with over the last 22K miles! I attribute that howl now, to the bearing "adjusting" and the primary chain tensioner being ratcheting up. Perhaps they even adjusted the tensioner??

I misspoke earlier on the Main drive gear and called it the 5th gear. Seeing that it is helical cut, it has to be 6th gear output.

GRF000,
Yes using a dial indicator when lining things up, is a great idea! Problem is I'll need to remove the primary again to press in the bearing. Loosing all reference at that point.
Unless I can find a solid surface off the trans case to measure from, and see if there is any deflection on the end of the mainshaft, with the primary on and off?
 
My whining was audible at around 35-55mph, less noticeable above that probably because other noises were more evident, and inaudible below that. I never had any clicking that I notice while sitting on the bike, but in the end when the whine had grown into a more ominous growl I could hear some muffled clicking if I jacked the bike up, put my ear to the front belt pulley, and rotated the rear wheel. At that time I knew a bearing was shot but I didn't know which one 'til they pulled it apart.

For 16k miles I rode the bike with this bad bearing, even taking one long trip to the Smokies in the interim, all that time thinking it was either the belt or rear tire. I tried everything from silicone grease on the belt to different belt tensions, but nothing worked. The HD shop initially blamed the belt and this in fact was a credible diagnosis considering the sounds it was making early in the experience. The problem was that no changes to tension made any or much difference in the sound. It makes me cringe thinking that I took a 3k-mile trip with a shot bearing, but it actually seemed to quieten down a bit on the trip. What also led me away from thinking it was a bearing was that I was getting normal metal deposits on both primary and tranny drain-plug magnets. The tech told me one ball had fallen out of the 8967 bearing and there was evidence that another ball or two had created some shavings, but no other damage was seen. He also replaced the output-gear assembly as a precaution which includes two needle bearings that are in that vicinity.
 
In you case 6th gear would just spin thru the primary shaft showing you are were in alignment and 4 would pick up both shafts. Since you have dowels if you went to the trouble of indicating and it was correct I believe the bearing to be a very light drive fit in the Al primary case and should go back the same. I do all my own work also. When I got this bike it had a few years left of the extended warranty plan and my experience with dealer left a lot to be desired. I have always done my own work and never though about paying for more warranty. The original owner also had a maintenance plan but that did not extend over. After servicing the bike all I can say is owners better watch and verify what is getting done. I bet the primary or fork oil had never been change and I believe the shark plugs were original and it had just had its 30K work done by dealer.
 
Seems when the main drive gear bearing fails it presents itself differently on different bikes.I noticed mine when we were on a ride and I pushed the bike backwards not running out of a parking space I got a loud clicking. I then pushed it forward and still had the loud click. The next morning when the bike was cold the noise was gone. I took a short warm up ride and sure enough the noise was back. I threw it on the trailer and took it to the dealer. They also had to warm the bike to duplicate the noise on the lift. They tore into the transmission kind of on the blind not really knowing what the noise was and found the #8967 bearing bad. Of course this was a few months after the warranty was out
 
One thing I have to say for the bearings used, besides a cage or ball/roller grenading, it seems there is a whole lot of time before things go catastrophic! Good to know if your on a trip. I do notice the engineering and design of these things is very basic. Which in my opinion is the essence of good engineering - K.I.S.S. (keep it stupid simple).
Just got off the phone with the F.A.G. rep. He's still researching. I'll keep bugging him until I get answers.
 
I had this same noise when pushing it backwards (only after it was hot) at 20K and had the 8967 and needle bearings replaced. Now at 65K same noise has appeared again.
 
Now that you mention it I don't recall anyone having a catastrophic failure, like running one minute and dead on the side of the road the next. If there is a good side to this story this must be it, but I'm still wondering if this is going to happen to me again in a few K miles. At least if I start hearing a speed-related whine I won't jump to blame the belt or rear tire.
 
Ok guy's - some info I'd like to pass along regarding the Main drive gear bearing, and doing my own research (F.A.G. is dragging their feet).

After removing the bearing in question, I've found that the bearings did not fall apart, contrary to what I suspected, partly because of all the slop on the Main gear, and partly because after the last few trans oil changes I found significant shiny powder and flakes on the drain plug, and in the trans and gears themselves. What I did find with the bearings though, was that the outer row of the bearing seams to have failed first - far worse wear then the inner. The race and balls were pitted on both however. Therefore I have come up with two, simpler, comon and more probable conclusions then bore miss alignment:

A) Fretting or false Brinelling - which is generally caused by small vibrations while the bearing is not in motion. The lubricant is displaced and surfaces no longer ride on a layer of oil. A slow but inevitable deterioration of the surfaces begins. Exponetially. I think this is the most likely cause, and is plausible because of the regular incidence of the Main drive gear being stationary, such as at a stop light, while the bike is not in motion and the engine is running. It's also plausible that the reason the outer row failed first, is that it's further away from the lubricating oil source, and runs dry for a longer period.

B) Brinelling - which is a single over load of the bearings capabilities - causing deformation of the balls and/or races. Also displacing lubrication, and an inevitable deterioration of the surfaces. This hypothysys generally leaves a uniform indent of the balls in the races. Which doesn't seem to be the case here, and the lack of, would eliminate bore missalignment in my thinking.

I can't determine exactly why - outside of bore offset and better production tolerances, that the problems seem to be limited to 07's. Other then a bearing revision which possibly addressed the above problems.
Also it stands to reason that with 07 being the first year for the 6 speed - these problems were new and where dealt with in succesive years.
I'll get some pics tonight for those interested.
 
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