M8 trans fluid leaking in primary

[Mark P]

Had a guy on the HDforums run his with out a dipstick to test the venting theory and he still got transfer. So this is was my guess:

Has the piston for the hydraulic clutch changed in the M8's or the rod? Is the piston cutting off the ability to vent down the mainshaft when the clutch is disengaged? Creating a hydro lock if you will, then when the clutch is engaged the primary just sucks the fluid down the main shaft like a straw once the pressure is released. Like priming a pump.

[14GuineaPig]

Interesting.  From what I've read it seems to occur during 'spirited' riding.  I'm guessing that more shifting of gears is occurring during the 'spirited' riding.  I wonder if that's why it happens for some people and not others.  Just a guess but maybe it has to do more with how many shifts are made rather than just riding at higher rpms.
I do not own a M-8, nor do I have any experience with dyno tuning/testing a bike.  I don't know how many shifts would occur during a tuning session versus how many shifts would occur on say a ride down the Tail of the Dragon.  Just a wild guess.

[103eagle]

Here is the link to another forum, this same subject for those that are interested.

https://www.hdforums.com/forum/milwaukee-eight-m8/1175678-who-s-been-having-to-add-transmission-fluid-9.html

Eagle Out

[FSG]

I don't have an M8 to look at but,

that hefty o-ring seals the slave to the inner side cover




but is the inside of the inner side cover RED RING AREA sealing




against the bearing housing RED RING AREA




hhmmmmm

[HV]

Interesting...that tapered splash area may be causing a slight turbine effect at high RPMs too 

[FSG]

maybe a different gasket taking Durwoods idea to the extreme

[VDeuce]

So pressure differential in trans case lower than at slave cylinder causing pumping action? Wonder if anything can be felt at clutch lever when this occurs?

[HV]

I know on all M8s  you can feel a pulse in the clutch lever every shift

[Durwood]

I know on all M8s  you can feel a pulse in the clutch lever every shift

Yes you can, I have felt the pulse just riding down the road applying light pressure to the lever.

[rbabos]

I know on all M8s  you can feel a pulse in the clutch lever every shift

Yes you can, I have felt the pulse just riding down the road applying light pressure to the lever.

Not sure if they are using slip assist clutch but my vrod does that as well. It's the ramps in the clutch causing  some on/off locking feedback to the leaver via the slave cyl. Normal. Higher rpms in the Revoluton it will be more of a lever buzz then a pulse. In the slower revving M8 this pulsing can be some of the oil pumping effect in the pushrod area although a constant supply of oil would be needed so most likely there's a two part problem here. Shared oil in the v rod so it won't matter.
Ron

[103eagle]

Funny but last night I posted in the other forum (listed above) that I was curious if there was a connection between the shift pulse felt in the clutch lever and oil transfer.  Reason it came to mind is some guys feel the pulse or feedback, some dont.  I do and I have oil transfer.  Some guys have oil transfer, some dont, some early production, some later.   Would be interesting to know how many that have transfer also feel pulse.  Its a longshot but just thinkin out loud.  Now if that is a connection, what is the difference?  Also the MOCO put out a informational sheet to dealers that they could give to customers to explain the slip/assist clutch and this feedback which they call normal.  Sorry but I dont have that sheet here, its at work. 

Eagle Out

[Admiral Akbar]

I don't have an M8 to look at but,

that hefty o-ring seals the slave to the inner side cover




but is the inside of the inner side cover RED RING AREA sealing




against the bearing housing RED RING AREA




hhmmmmm

It's not a sealing area.. The cover gasket will separate the 2 flat surfaces..

[1FSTRK]

So you have seen the gasket and it does not cover that surface as well?

[FSG]

It's not a sealing area.. The cover gasket will separate the 2 flat surfaces..

The M8 uses the 35260-06B  BEARING HOUSING,  I wonder what the difference is from the -06A 

TC and M8 use the same gasket

[Bike31]

One of the questions I and others raised on the HD Forum was the difference (if any) between the A (2016) and B (2017) bearing housings enough to create a new P/N. It might be revealing to compare and note changes if any. We assume the gasket thickness has remained the same between years?

[FSG]

it's not a new P/N, it's just a revision of some sort and can even be just because of a change of manufacturer   

It might be revealing to compare and note changes if any.

[Bike31]

I find it hard to believe a change of vendor alone would create a new P/N. Over time HD bids parts and manufacturers go away to be replaced by new. But

I do believe a comparison of A and B suffix parts would be worthwhile...same for trans shafts and slave clutch assemblies. There's also an intermediate part (release rod 37000217) between the slave and clutch rod that should be examined.

[1FSTRK]

I find it hard to believe a change of vendor alone would create a new P/N. Over time HD bids parts and manufacturers go away to be replaced by new. But

I do believe a comparison of A and B suffix parts would be worthwhile...same for trans shafts and slave clutch assemblies. There's also an intermediate part (release rod 37000217) between the slave and clutch rod that should be examined.

Have you looked at the difference in the twin cam lifters from A to B to C ? Same part number and totally interchangable but not the same maunufacturer or country.

[FSG]

I find it hard to believe a change of vendor alone would create a new P/N.

like I said earlier it's not a new P/N it's a revision , most revisions are backward compatible, some aren't

release rod 37000217 was first used in the 2015 Hyd Clutches 

[1FSTRK]

It's not a sealing area.. The cover gasket will separate the 2 flat surfaces..

The M8 uses the 35260-06B  BEARING HOUSING,  I wonder what the difference is from the -06A 

TC and M8 use the same gasket

Thanks for the gasket pic. Do you have access to to a list of the parts and numbers that are different in these areas? I have looked on line with little success. The bearing housing comparision would be a good start. I wonder if it somehow traps more oil compared to the earlier version.

[FSG]

just so there's no confusion as to what is a release rod and what is a pushrod, the release rod could have been named better 

[FSG]

Do you have access to to a list of the parts and numbers that are different in these areas?

Yes, it's all there online.

While I'm sure there are venting issues as Durwood is exploring, I can't help but think of the gears on both shafts acting like impellers and thrusting the oil toward the side door bearings and in the case of the rear bearing the oil can find it's way into the primary.  I've mentioned this earlier in this thread.

If I had an M8 I'd sure be modifying that Inner Side Cover so that the oil had an escape route other than just the gasket thickness.

Maybe a few drain slots

[rbabos]

Do you have access to to a list of the parts and numbers that are different in these areas?

Yes, it's all there online.

While I'm sure there are venting issues as Durwood is exploring, I can't help but think of the gears on both shafts acting like impellers and thrusting the oil toward the side door bearings and in the case of the rear bearing the oil can find it's way into the primary.  I've mentioned this earlier in this thread.

If I had an M8 I'd sure be modifying that Inner Side Cover so that the oil had an escape route other than just the gasket thickness.

Maybe a few drain slots

Can't hurt.
Ron

[1FSTRK]

This may have been a design change to trap more oil and better lube the bearing, but as with most HD improvements come the unintended consquences.

Perhaps drilling a drain hole turning it from an oil sump into a splash system would help.

[harleytuner]

If I had an M8 is be letting HD figure out out.  Last thing I would want to do is modify something and Give them a reason to void the warranty.