I'm sure HD didn't even know it was a thing back then. It's not like it was ever really reported here and you know people like to bitch about everything.

 

Enough of a problem that they found a fix and replacement parts. They don't RD replacement anything unless they have a issue.

 

Well they are quick to fix stuff when they find it. lol.. Sorry little joke.

Seriously though, I can't find more than one thread of people complaining about that problem from 2014-2016.

 

Hell I always put a quart in each and rode. Never thought to really check until Webb posted on this forum . Look at the **** he stirred up.lol . Mine isn't bad but it's happening and I'm more worried about my clutch.

 

I think you could be right about it being pushed or “pumped”. Basically the helical cut gears are picking up oil and when the mainshaft and counter shaft come together they push it in the direction the gears are slanted. It wouldn’t be to big a deal unless the cases have been machined so close that they actually make the transmission into a pump, pushing the oil through the bearing, filling the cavity and pumping oil through the mainshaft. Oil is blocked from going through the countershaft bearing by first gear. So depending on how your transmission case was machined it determines how efficient a pump you have. This is why some bikes transfer and some don’t. It is also why some transfer a lot and some just a little. In the TwinCams that did it vacuum might have been the cause, but I don’t believe that’s true with the M8’s.

 

Stonecold.. good theory. Does the hydraulic clutch compound the issue? Seems the clutch by itself wouldn't be the culprit, or else every bike since 2014 would be exhibiting transfer.
Seems a thin shield over the mainshaft would wall off the flow path.

 

So since this TA has come out, and I notice there is a "fix" listed in the doc for pre-M8 TC models, I'm trying to understand how different the components would be and why its seemingly so hard for them to find a fix for the M8's.

If two different models are having the same exact issue, there has to be a commonality somewhere, right?

 

I believe your logic is on spot, but I believe I read the gears are now helical cut to reduce noise, and the location height for the shaft is different on the newer tranny. These would be differing factors for sure if so.

 

I have given a couple of updates here but not for a while. Against my better judgement, last Saturday I went for a couple hour ride and kept the RPM's at around 4K as much as I could. I had alway thought maybe I didn't see the issue because of my riding pattern. This included a stretch of time over 5 minutes as well. Several hours after I put it away I checked the fluid and all good. I guess I am one of the lucky ones as well perhaps.

 

Yes the hydraulic system has a machined surface that mates to the bearing carrier. the only drainage is provided by the gasket that is .004" thick pre-compression. So it is basically trapping oil and that is then pushed down the mainshaft.


Maybe not. It wasn't prevalent in the pre-M8 models. There were only a few documented cases that I am aware of.

There is also a new case and a different bearing on the mainshaft. It could just be a perfect storm scenario. Everything just right, they transfer, otherwise they don't.