M8 trans fluid leaking in primary

[jls 64]

did you do anything else other than the vent?

Not in the customer bike we dyno tested, just the vent.

My own bike was cured by milling a vent-valley between the inside of the S/C housing and the gearboxes' air void.

Both mods do the same thing though, they create an air path for the primary to suck air rather than oil and stop the S/C cavity from developing oil pressure. No suck, no blow = no transfer.

. I did add HD06s vent mod to my own bike for good measure.

Maddo snr do you have a picture.?

[Maddo Snr]

Maddo snr do you have a picture.?

No, we were pushed for time and I forgot. I have the HAAS milling software for the mod if anyone wants it.

Its a 10mm wide valley milled to the depth where the dome joins the edge and at 30 degrees off vertical, radial from centre.

[HogMike]

Latest update from "reply 1299" above:

Dealer drained and measured oil from trans and primary
Refilled to factory levels and sent me on my way,

Had a short club ride yesterday about 130 miles.
Got home let the bike cool down, pulled the trans dip stick and no oil showing.
Dropped my trusty pencil in the hole and had some oil on the eraser about 1/4"
Let the SM know this is not going to work for me and the bike will be there Tuesday AM.
He assured me the parts will be there that they will possibly need.
Stay tuned for further updates!
i am slowing loosing my confidence in Harley-Davidson and my patience is very thin at this point

[96349]

Countless other owners have experienced what you describe since the M8s were introduced in August of 2016 as 2017 models. The  migration primarily affects only touring bikes that have hydraulic clutches. The MOCO has made numerous attempts from time to time to fix the issue but none of them have worked so far. In short,  they refuse to spend the money to  actually come up with a fix. Threatening them does no good. The dealers are just as frustrated as you are but they have no recourse. In short, nobody actually can prove what is happening to cause the migration. My solution is to never by their half assed engineered products again. Everybody is different though. The people who drink the kool-aid everyday think it is heresy to suggest that you boycott the bastards. I might be old but I am not stupid.

[98fxstc]

Countless other owners have experienced what you describe since the M8s were introduced in August of 2016 as 2017 models. The  migration primarily affects only touring bikes that have hydraulic clutches. The MOCO has made numerous attempts from time to time to fix the issue but none of them have worked so far. In short,  they refuse to spend the money to  actually come up with a fix. Threatening them does no good. The dealers are just as frustrated as you are but they have no recourse. In short, nobody actually can prove what is happening to cause the migration. My solution is to never by their half assed engineered products again. Everybody is different though. The people who drink the kool-aid everyday think it is heresy to suggest that you boycott the bastards. I might be old but I am not stupid.

You need to do a bit more reading.
There appear to be at least two fixes that I have seen reported and tested, not by the MoCo but by others.
Fixes which have been based on understanding and analysis of the cause.
Certainly does not put the MoCo in a better light but speaks to the dedication and commitment of some who want to continue the journey with a HD motorcycle.
I'll stick with my Evo and TC for the time being though. 

[hd06]

 Go to page 50, 1242 that what fixed mine 2 years of transfer, check it out.

[HogMike]

Go to page 50, 1242 that what fixed mine 2 years of transfer, check it out.

We saw that and it seems to have worked for some but I'm getting conflicted info as to the CAUSE of the vacuum in the first place! Pumping action from the s/c through the pushrod does not seem logical to transfer 21 oz in about an hour or two with mostly freeway miles.
This is a brand new bike and I take it easy for the break in. 2000-3000 rpm, no lugging, etc etc. not my first rodeo.

I'll let the dealer do his "cure" before I try anything else.
Warranty is the issue with a bike one week old and only 300 miles!

[Bike31]

HD delivering MC to Dealer who delivers to Owner>>>Then the Owner has to walk it back via warranty. All a downhill operation and everyone uphill knows it's a potential problem but sales are part of their business plan, so on it goes. Why bother to solve their problem?

My '18 FLDE has been ok so far but the first time it takes a dump I'm done.

[hd06]

 This is warranty work a Harley Rep. done it himself at a bike rally. Where your going I've been. 

[vetteandharley]

  Just purchased a 2017 Road Glide Special which I believe after checking the transmission fluid may have the transfer issue.
I'll have to do a little more monitoring but if so I intend to try hd06's cure.  Thanks for posting!!

[CarlosGGodfrog]

If venting the primary does the trick (pg 50 #1242) why not just put a vent in the primary cover ? You could even plumb a line to the A/C to create a positive vent.

[Maddo Snr]

Go to page 50, 1242 that what fixed mine 2 years of transfer, check it out.

We saw that and it seems to have worked for some but I'm getting conflicted info as to the CAUSE of the vacuum in the first place...

Hi Mike. After many hours of testing lots of variables on both dyno and road, here's my summation. I believe the primary is sucking oil from the gearbox.

These things all make the issue worse:
A) RPMs over 3000
B) gearbox oil heights above the bottom of the 'X' on the dipstick (bike level on stand)
C) thick primary lubricants
D) high primary oil levels
E) OEM slave cylinder

I tested a known problem bike with 80W140 in the trans (bottom of 'X'), 15W40 full syn in the primary (1/2" under fill notch in derby) and keeping under 2500rpm. Problem gone!

The 'fix' is to somehow kill the fluid transfer by extra air-bleeds in the S/C housing, a primary vent or a AIM light-force S/C. All seem to work.

The MoCo seems fixated on achieving a fix by disrupting the capillary through constant mods to the S/C diaphragm/piston, they're up to their THIRD version of the same part now. 

As to the exact nature of what's happening?

I believe that at (US) freeway RPMs the primary oil cavitates/aerates and expands, which decreases the air volume in the primary, which vents to the box. As revs fall the vacuum in the primary acts on the uninterrupted oil path to the box and sucks oil.

This would explain why the MCC fat-rod works...its machined flat is of a big enough volume to open the capillary...

My main issue now is testing, none of the owners whose bikes we've cured will let's us put them back to OEM so we can test. 

[oldbag]

Maddo Snr was the vent groove you machined in your side cover at the top or bottom?

[Maddo Snr]

Maddo Snr was the vent groove you machined in your side cover at the top or bottom?

Top. In the pic below you can see the reason. The milled passage connects the cross-shaft end to the vent hole between and above the gear shafts.

I'll pull it off and take a pic next service OB.
The mod is a 10mm wide routed passage, radially from the centre, 30 degrees off vertical toward the front of the bike. I milled it down until its depth was where the dome met the side casting.

It's no great science, it just connects the cross shaft void to the gearbox void. Pressure can no longer build in the S/C void as its now vented to the box void, similarly, it that point goes into vac it sucks air from the box void, not oil.

[Maddo Snr]

Here's a better pic OB.

You can see the dome on the outer cover and how it seals the S/C cavity. Where the dome meets the edge is my machined depth.

With OEM slaves I also drill a 1/8"" hole through to the other side to relieve the pressure from box oil which has seeped into the cavity on the other side. (This is where the OEM seals split BTW)

With AIM slaves there's no need as the area around the cross-shaft end is open, not sealed as per OEM.

[FSG]

https://harleytechtalk.com/htt/index.php?topic=96613.msg1159741#msg1159741

[HogMike]

Thanks all for the detailed explanations WHY all this is happening in the first place.
The thing that gets me is the factory is aware of it and as yet has no cure and expecting us to just "ride it" for another "5000 miles" and "check oil levels" again!
When the cost (to the factory) gets too much having to replace damaged transmissions they will then have a fix. I would have to believe they are past that!

My bike goes in today, my healer promised to do all the checks, parts, etc to get this issue fixed today. If not, and the next 100 miles shows no change I'll have to take to next step. Not a good option as I really like the bike and the color.
I'll be updating as time progresses.

[Dmerch]

Isn't the surface where you're milling the slot already unsealed due to the gasket thickness?

[rbabos]

Isn't the surface where you're milling the slot already unsealed due to the gasket thickness?

That's too clever an observation for your first post.
Ron

[PoorUB]

Isn't the surface where you're milling the slot already unsealed due to the gasket thickness?

That's too clever an observation for your first post.
Ron

Keep an eye on him. This new guy is gonna be trouble with posts like that!

[Maddo Snr]

Isn't the surface where you're milling the slot already unsealed due to the gasket thickness?

Not when you do the calc based on the gasket compressed clearance and the viscosity of Formula+, it's virtually a seal. Evidenced by the fact that the MoCo fitted a white nylon oil deflector as a revision to the out-bye side of the mainshaft support bearing for oil control. The MoCo know they have issue with excess oil flow/pressure in that area

The step around the slave housing is approx 5mm wide with a gap of about <0.40mm, effectively a seal to 50W-80W oil flow at the pressure/vac levels were working with.

Even though the top of that surface is BELOW box oil fill height, I'm of the opinion that air doesn't bleed from the box-void past that surface in OEM spec, if it did the primary wouldn't suck oil...well spotted Dmerch, after 30+ years of building suspension one can spot what is, and isn't, a hydraulic bleed I guess.

p.s. Don't we all wish the MoCo would just own-up? The ONLY reason they don't is surely that they can't figure it out...

[Dmerch]

Uh oh, I'm causing trouble already...

Back on topic, perhaps the MoCo thought the gap was enough. I'm sure more space there can't hurt since they weren't trying to seal it anyway.

[Maddo Snr]

Uh oh, I'm causing trouble already...

Back on topic, perhaps the MoCo thought the gap was enough. I'm sure more space there can't hurt since they weren't trying to seal it anyway.

Exactly! And the logic behind milling a bleed path...

[Dmerch]

Just trying to understand the issues. My dealer called this morning to say that my own RG/M8 is being built this week. I have an AIM Light Force sitting here waiting for me to install once the bike is home.

[HogMike]

Isn't the surface where you're milling the slot already unsealed due to the gasket thickness?

Not when you do the calc based on the gasket compressed clearance and the viscosity of Formula+, it's virtually a seal. Evidenced by the fact that the MoCo fitted a white nylon oil deflector as a revision to the out-bye side of the mainshaft support bearing for oil control. The MoCo know they have issue with excess oil flow/pressure in that area

The step around the slave housing is approx 5mm wide with a gap of about <0.40mm, effectively a seal to 50W-80W oil flow at the pressure/vac levels were working with.

Even though the top of that surface is BELOW box oil fill height, I'm of the opinion that air doesn't bleed from the box-void past that surface in OEM spec, if it did the primary wouldn't suck oil...well spotted Dmerch, after 30+ years of building suspension one can spot what is, and isn't, a hydraulic bleed I guess.

p.s. Don't we all wish the MoCo would just own-up? The ONLY reason they don't is surely that they can't figure it out...

It's a shame we have to go through all the steps one by one then the dealership calls MOCO to get a RO # for the NEXT step.
Seems to me to do "one and done."
Does it make sense they don't have a good fix yet, after 2+ years?

The little white plastic "sleeve" that fits over the clutch release rod is a very loose fit on the rod will have some play. Mine had that from the factory but still has the issue. The new  sleeve is also a sloppy fit on the shaft, probably to avert any resistance along the clutch system.