Transmission main shaft

U

unknownspiritx5

New member
Yeah, it's a mystery, and I'm told that the part number has not changed for subsequent year-models. I agree with you that since the part has apparently not changed and not all '07's are having the problem the fundamental bearing design may not be at fault. Looking at my parts book I notice this bearing is also used in the bearing housing assembly on the right side of the tranny, but I haven't heard of these failing. I have another theory:

My bike started whining during a trip to TX in May 2008. Before the trip I adjusted my belt according to the book only slightly looser, but once the trip was underway I noticed the belt was very tight once warmed up--way tighter than I was comfortable with. I didn't have the tools to adjust so I let it go 'til I returned home. Instead of the 1/4" spec for SG's I used 3/8" cold before the trip, the minimum for EG's since I was using a shock height midway between the two models (12
 
Can someone tell me what bearing that you are talking about. What I consider the bearing that actually supports the front pulley for the drive belt is the inner primary bearing. Held by a snap ring in the inner primary case. There is an inner race for this bearing pressed on the main drive gear that the drive pulley is splined to. This bearing is lubricated my the primary fluid. In one post someone is talking about transmission fluid. My Harley has the old manual primary adjuster and I have enough run out to go from max to minimum on the chain slop. Starting to wonder maybe the rear bearing is worn enough to cause this problem. I have a lot of noise coming from somewhere in the primary. Is there a way to check a run out for this bearing or is a teardown required?
 
Iclick, Yes I agree that the excess stress of over tightening the belt could effect the bearings - mainly the 5th gear output bearing and the inner primary. But thinking about this scenario, you'd think the smaller primary bearing would go first?
Here's another theory based on miss alignment of bores, and where your theory actually helps to prove.

The Mainshaft turns on 5 bearings (trap door, 5th gear bearing, 2 mainshaft bearings (inside 5th gear), primary inner bearing). Take the 2 mainshaft bearings out of the equation, since they effectively turn the mainshaft and 5th gear into a single unit (ideally).
Now envision, 3 bores on a centerline from the trap door through the trans case left and into the primary inner. If one of those are out of alignment by a small fraction, the stress would eventually wear one of them out (at the least). My guess is that the miss-alignment occurs when the inner primary is installed to the engine and trans. Since the only alignment features between the three bores are the rolled dowel pins, there could potentially be enough room for our miss alignment.
I've heard since I was a youngster, that you should always avoid 3 bearings on the same shaft, presumably for this reason.
While we're contemplating this stuff, I've contacted someone at F.A.G. and he's looking into it.
I'll relay his thoughts when I get them.
 
The primary bearing was checked and was in perfect shape according to the tech, so it wasn't replaced. In fact, everything in the primary was checked and found to be fine, so all I did was install the SE compensator since everything was apart anyway. Anyway, if that bearing fails I understand the symptoms are different, and makes noise only if the clutch is engaged. Pull the clutch lever in and the noise stops. With the tranny bearing the noise occurs regardless of the gear selected or clutch position, and is speed related (i.e. no noise when stationary). There has been a smattering of reports of primary-bearing failure, and this was a big problem on early-'06 Dynas, as they had no alignment dowels at the bearing location. Later bikes had the dowels added and all '07 and later FLH's had them.

FWIW they also replaced the "gear assembly, driven output" (#35122-06) on my bike as a precaution.



I didn't see the tranny and primary hardware apart when they did the job and the parts-manual schematic leaves me confused on some of what you describe, as it doesn't show everything sufficiently. It would seem that if there was a misalignment the bearings would fail earlier than what we're seeing. OTOH, that's as good an explanation as any. Another idea is that F.A.G. made a run of bad bearings and we were the lucky ones to get them. Most failures seem to be with '07's, right? It might also be interesting to compare build dates. Mine is Oct. '06.



I'll look forward to the report, and I wonder if they'll really tell you the whole story. Let's hope so and you don't get a bunch of bureaucratic spin. In the past I've had good luck calling independent manufacturers on matters like this, though.
 
My build date was May 07, that's a big batch of bad bearings!!!!
Knowing manufacturing tolerances and stack up extremes, I'm sure our bikes are the extreme variance case, and more then likely the reason for our failures.
 
I assume Harley designed there bearing for ease of assembly and disassembly of the inner primary cover by not locking the inner race to the bearing. Appears that by using the Baker bearing it no longer needs the primary lube. Is it a sealed bearing? Since its held in inner primary cover by a snap ring is it a tight fit on the main drive gear shaft?
 
IClick . . .

HD made an update to the inner primary (mainshaft) bearing. I believe the early bearings (06 dynas and 07 touring) had faulty (soft) inner bearing races. I also believe that HD knows this and is waiting out the failures without saying anything. Too many have failed at low mileage IMO.

I replaced my inner primary bearing at 20K. The race and bearing were both failing. Here are the threads started at that time.

http://www.hdforums.com/forum/touring-models/479940-primary-noise-in-neutral-only-help.html

This thread shows that there was an update to the mainshaft and bearing in late 07, early 08. My 07 had the updated bearing and when I ordered the bearing from the 07 parts book, it was the wrong bearing. I did some research and came up with the updated bearing.

http://www.hdforums.com/forum/primary-transmission-driveline-clutch/486341-inner-primary-bearing-race-i-need-help.html

Curious thing is that my bike had the updated bearing but it still failed early.

I actually kept my belt slightly looser that spec so I doubt that was a factor. I do ride 2up all the time and we are often loaded with gear. I wonder if the added weight causes the belt to run tighter.

What do you think??????? Anyone????
 
There has been a part number change for the bearing and race. I believe the part was updated in late 07. My 07 had the updated bearing and my bike had a late 07 build date. I beileve the updated bearing race is hardened more than the previous bearing. You can see the difference in size in my thread. Of course, you can't see if the race is harder. I'm assuming that from what I've read in other threads especially in the dyna section.

Steve
 
That's exactly my question to Baker. I would think it has to be a slip fit, otherwise the process of pressing it onto the mainshaft at the same tiime the primary is installed could potentially side load the bearing. My concern with the slip fit though, is having the bearing spin on the mainshaft under load. Once that happens the mainshaft would loose tolerance and be toast.
I tried calling earlier today but couldn't get a person. I'll try again tomorrow.
 
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