M8 trans fluid leaking in primary

[JMHD]

Sorry that I'm getting in at the end of this but are all M8's having this issue?  I have a 2018 RG ultra... 8K on it.  Gonna def check my fluid when I get home tonight.  Going on a 4500 mile ride next week to PEI

Just about everyone I have worked on has had it to some degree, some worse than others. Just remember to check the trans on the side stand with the dipstick threaded in till the oring just touches the case (dipstick has markings)and the primary is checked with the bike straight up and level with the bottom of the pressure plate. Hope that helps and have a safe trip to the east coast. 👍👍

in Touring Models

Sorry I forgot to mention that part, just touring models.🍻

[JMHD]

  I believe you check both with the bike upright.

5 speeds were straight up ,6 speeds on the jiffy stand.🍻

[Jaycee1964]

Guess what?  50oz in my Primary and down to about 10oz in the trans.  Called my dealer and they are getting me in tomorrow to do the update!  Hope it works well!  Glad I read this thread!  Thanks

[cbumdumb]

My 19 RGU has and appointment on the 19th this month Trans was down a half quart in 3200 miles I hope the install the vent kit

[HogMike]

Guess what?  50oz in my Primary and down to about 10oz in the trans.  Called my dealer and they are getting me in tomorrow to do the update!  Hope it works well!  Glad I read this thread!  Thanks

It would be to your dealers benefit to educate them how to Change oils

Pull trans dipstick
Remove clutch cover (have a drain pan under)
Pull engine oil dipstick
THEN drain and measure each tank.
If they LOOK for any oil transfer the may see it BEFORE they just pull all 3 plugs and replace oils which is what most dealers do.
JMHO

[SluggoMagoo]

I know this thread is a few months old. I purchased a 2017 Road Glide with 5k back in January from out of state about 45 miles north of me. I didn't take delivery on it for a couple of month and took my first road trip on it in April. After 600 miles the transmission started to get clunky and hard to shift into neutral. After getting it home, upon inspection of the transmission dip stick, there was no fluid on it. It took 7oz to get it to show. Long story short there's a dealer 1 mile from me so I took it to them. The primary cover was pulled and when it came off they found the missing transmission fluid. They told me that they're going to order a vent kit like you all are talking about. I'm really concerned about the previous 5k miles. It must have had a fluid change at 1k and either nobody notice the issue or the issues wasn't occurring. The Harley Dealer I purchased it from won't even talk to me about this problem so I'm dealing with the guy around the corner.  So I guess my question is, does this problem crop up all of a sudden or maybe a different riding style make it happen?!?! There's no service record about this issue on the VIN when I had it pulled.

[bigcraig]

I know this thread is a few months old. I purchased a 2017 Road Glide with 5k back in January from out of state about 45 miles north of me. I didn't take delivery on it for a couple of month and took my first road trip on it in April. After 600 miles the transmission started to get clunky and hard to shift into neutral. After getting it home, upon inspection of the transmission dip stick, there was no fluid on it. It took 7oz to get it to show. Long story short there's a dealer 1 mile from me so I took it to them. The primary cover was pulled and when it came off they found the missing transmission fluid. They told me that they're going to order a vent kit like you all are talking about. I'm really concerned about the previous 5k miles. It must have had a fluid change at 1k and either nobody notice the issue or the issues wasn't occurring. The Harley Dealer I purchased it from won't even talk to me about this problem so I'm dealing with the guy around the corner.  So I guess my question is, does this problem crop up all of a sudden or maybe a different riding style make it happen?!?! There's no service record about this issue on the VIN when I had it pulled.

My CVO didn't start this migration problem for the first 6k miles, after that, I could correct fluid levels, ride 20 miles and 12-14oz would transfer then stop.

[road-dawgs1]

I'm guessing the 20's will come with the vent standard. I just got my 19 and have a trip for VT to KS and back the end of July. Once I get 1k miles on it I'm going to check it real good. I wish you could simply go purchase the vent and do it yourself as I would just do it right off.

[borrec]

I'm guessing the 20's will come with the vent standard. I just got my 19 and have a trip for VT to KS and back the end of July. Once I get 1k miles on it I'm going to check it real good. I wish you could simply go purchase the vent and do it yourself as I would just do it right off.

You can, Part # 26500027. I installed it yesterday. 

[road-dawgs1]

I'm guessing the 20's will come with the vent standard. I just got my 19 and have a trip for VT to KS and back the end of July. Once I get 1k miles on it I'm going to check it real good. I wish you could simply go purchase the vent and do it yourself as I would just do it right off.

You can, Part # 26500027. I installed it yesterday. 

Sweet, I thought you had to bring it in and go through the whole process.

[cbumdumb]

Well dealer installed vent kit ....I would like to know what else was done it never shifted this effortlessly, quite as well doesn't sound like a Harley any more .

[yobtaf103]

probably activated the auto tensioner, while in there?

[Rockout Rocker Products]

Well dealer installed vent kit ....I would like to know what else was done it never shifted this effortlessly, quite as well doesn't sound like a Harley any more .

Maybe changed your primary fluid to the new juice?

[road-dawgs1]

Dealer did mine this past week. Haven't checked the levels, but assume all is well.

[kd]

Without the excessive primary fluid level the clutch is now releasing properly.

[cbumdumb]

Even when I set fluids my self it was harsh noisy
They change the blown clutch slave it was worse .

[6speed96]

I was at my dealer last week to pick up some parts and the service manager called me over to show me a bike they had in for service. I had asked him awhile back about trans oil migrating to the primary after I had one for service with that problem and he said hadn't heard of it. But now he showed me a vent kit that the company is supplying and they were installing on the primary to stop the migration.

[Jobie]

Why hasn't the real problem been addressed?  When all the first so called fixes came in looking at the excessively large size hole in the main shaft thinking that was the cause of the oil transfer.  That was only one part of the problem. [ maybe ]  The main cause of the problem is....... ready for this......... Pressure building up in the tranny forcing oil through the main shaft into the primary.  When HD and others came up with the bushing or bigger pushrods that shoved into the main shaft to make the hole smaller [ fill the hole ] to stop or lessen oil transfer, all it did was make pressure build even more. [ think of a squirt gun ]   That's why the problem can get even worse, more pressure, faster transfer.  The second and current fix HD has is to vent the primary along with taking out the first fix.  Why would HD take out the first fix along with the venting the primary?  They take it out because that will "still" allow presser to build even more and "still" transfer oil into the primary.  With just venting the primary only, that will greatly slow down pressure building in the tranny and transfer will be greatly reduced.  When oil pressure is vented to the primary, it will "still" take some oil mist from the tranny along with it and "still" show some sign of oil transfer....... hence bandaid.
Why not put a bigger, more efficient vent in the tranny top cover?  Over the last few years HD went from a 3/16 [ gas line size ] vent down to 1/8 [ vacuum line size ] in the top cover.  The bigger hose the more the vent or less resistance.  With a bigger vent in the top cover along with HD's first fix....... Fill the hole because we all know what big holes do, they leak, would totally fix this issue by reliving pressure at the SOURCE.  Not sure if filling the hole would be necessary but it wouldn't hurt.   As we all know HD has to meet the E5 EPA police requirements.  One think EPA hates is venting to the atmosphere and allows a very limited amount of venting.

Pressure building up in the tranny is whats causing the so called migration.  FIX THE PROBLEM...... and forget the bandaids!  But is HD allowed to do it? 

[bigcraig]

Jobie, while I think your theory about the trans creating pressure has some merit. I am of the belief that the main problem is the design of the trans side cover and how much trans fluid is pushed against it. This causes the trans fluid to "pool up" high enough to the mainshaft hole where the push rod passes thru it.

Basically it is a combination of things.

Eliminate trans fluid from pooling up, add proper venting for the primary AND the transmission, problem solved.

Hell, I managed to completely stop the problem by modifying the trans cover, using the AIM s/c and the 'fat rod" with NO venting. (Note, that "fat rod" was tried first, it didn't work at all really, I left it in purely from sheer laziness and believe that I could put the stock clutch rod back in the bike and I would still not have a problem.)

[road-dawgs1]

Jobie, while I think your theory about the trans creating pressure has some merit. I am of the belief that the main problem is the design of the trans side cover and how much trans fluid is pushed against it. This causes the trans fluid to "pool up" high enough to the mainshaft hole where the push rod passes thru it.

Basically it is a combination of things.

Eliminate trans fluid from pooling up, add proper venting for the primary AND the transmission, problem solved.

Hell, I managed to completely stop the problem by modifying the trans cover, using the AIM s/c and the 'fat rod" with NO venting. (Note, that "fat rod" was tried first, it didn't work at all really, I left it in purely from sheer laziness and believe that I could put the stock clutch rod back in the bike and I would still not have a problem.)

So adding the Aim light force slave also aids in prevention aside from what it was designed to do?

[hd06]

 The trans has vent on it there isn't any pressure pushing fluid to the primary.   

[bigcraig]

Jobie, while I think your theory about the trans creating pressure has some merit. I am of the belief that the main problem is the design of the trans side cover and how much trans fluid is pushed against it. This causes the trans fluid to "pool up" high enough to the mainshaft hole where the push rod passes thru it.

Basically it is a combination of things.

Eliminate trans fluid from pooling up, add proper venting for the primary AND the transmission, problem solved.

Hell, I managed to completely stop the problem by modifying the trans cover, using the AIM s/c and the 'fat rod" with NO venting. (Note, that "fat rod" was tried first, it didn't work at all really, I left it in purely from sheer laziness and believe that I could put the stock clutch rod back in the bike and I would still not have a problem.)

So adding the Aim light force slave also aids in prevention aside from what it was designed to do?

Yep, although that was not AIMs intention.

If you look at the AIM s/c compared to the stock HD s/c you will see the differences. The AIM is cup shaped, much like a piston on a brake caliper, thus it increases the volume of the area where the trans fluid pools up. The stock HD s/c has a diaphram that sits almost flush with the dish of an un-modified trans side cover.

So, with the AIM installed creating more volume in that area and modifying the trans side cover so that trans fluid has an easier path to return to the transmission, you eliminate the trans fluid from ever getting pushed high enough to the main shaft. If trans fluid can't make it to the hole in the main shaft, then it can't transfer over to the primary.

[bigcraig]

The trans has vent on it there isn't any pressure pushing fluid to the primary.   

While the transmission is vented, the transmission to relieve pressure, in fact the trans vent is supposed to do double duty and be the vent for the primary as well.

The way it is supposed to work is primary vents thru main shaft hole where the clutch push rod lives to the transmission, transmission vent on top of the transmission vents for both.

Again, the real issue is the trans fluid that is pushed out around the main shaft bearing, it pools up in the convex area of the transmission side cover. Eliminate the pooling affect and transfer can't happen.

[Jobie]

Don't agree with the side cover theory.  If that was the case, why does the primary vent stop the oil migration to the primary using the same stock setup that believers are thinking is what's causing the problem.  If the problem wasn't pressure why does the vent work?  A vent will not change a thing if it wasn't pressure related.  Remember, some folks make and sell new style side covers with no "guarantee" in writing of stoping oil migration.  Strange, isn't that what the new cover is for?  Maybe not.  It's not rocket science, high pressure wins over low pressure.  It's like water or electricity, it takes the path of least resistance every time.

[hd06]

  The trans has a vent it can't build up pressure, let me give you another one .