2023 HD Road Glide Limited. HPL Primary Oil. Primary fluid analysis at 7400mi.

[Panda87]

This analysis was done at the same time as my engine oil analysis in my other post. The oil held up, but there was some form of dirt intrusion going on. I wanted to get HPL’s take on it and got a call from David. He discussed his concern over the amount of silicon in the analysis and recommended I change the fluid to get the contamination out and try to find out where the contamination was coming from. It was super neat getting to discuss this with him! The standard change interval for the Primary is 10k miles. Come to find out, in 2018, HD issued a service bulletin to install a “Primary Breather Tube” to Milwaukee 8 bikes from the factory after that point, and to retrofit that breather tube to all bikes prior to that as a recall. The reason for the breather is the primary chain case would siphon transmission fluid over from the trans case. The breather introduced a contamination path. I’m changing my Primary change interval to every 5k. Pics of the analysis and of the filthy breather.

 

[Highlander 1459]

not familiar with the newer HD stuff but if the trans, primary and engine still run separate oil supply's it would not seem likely trans oil would go into the primary.. generally if the trans leaks it just goes on the ground.

that said all I ever ran was 15w40 in the primary.
two bikes went over 200k on that stuff with nary an issue. original clutches and all..

it is a dirty environment, doe to clutch and chain wear but it wont hurt anything
so no real need for anything special.

FWIW I used to know guys who ran ATf, I tired it but found the clutch was grabby

 

[Propflux01]

I’ve always changed primary at 5k. Silicone definitely coming from the breather. Iron coming from the compensator ramps. Aluminum, not as sure.

 

[Propflux01]

not familiar with the newer HD stuff but if the trans, primary and engine still run separate oil supply's it would not seem likely trans oil would go into the primary.. generally if the trans leaks it just goes on the ground.

that said all I ever ran was 15w40 in the primary.
two bikes went over 200k on that stuff with nary an issue. original clutches and all..

it is a dirty environment, doe to clutch and chain wear but it wont hurt anything
so no real need for anything special.

FWIW I used to know guys who ran ATf, I tired it but found the clutch was grabby

Common with the M8. The primary vent was supposed to relieve the pressure causing the transfer. I think it’s because the trap door area doesn’t allow drainage, and what gets caught there just travels down the clutch rod. My 2020 transfers about 4 ounces every 3-4k. I use 10w-30 atv jaso oil in the primary, and gear oil in the tranny, and you can smell the gear oil in the primary when I change it.

 

[Panda87]

Common with the M8. The primary vent was supposed to relieve the pressure causing the transfer. I think it’s because the trap door area doesn’t allow drainage, and what gets caught there just travels down the clutch rod. My 2020 transfers about 4 ounces every 3-4k. I use 10w-30 atv jaso oil in the primary, and gear oil in the tranny, and you can smell the gear oil in the primary when I change it.

This is my first HD, so I’m not as intimately familiar with its inner workings as you are, so I very much appreciate your input!!! I’m not sure on the aluminum either. I do a lot of lock to lock low speed work riding the friction zone and rear brake, so some of the wear may be accelerated from that, or it’s simply just break in contamination as parts wear in.

 

[Panda87]

not familiar with the newer HD stuff but if the trans, primary and engine still run separate oil supply's it would not seem likely trans oil would go into the primary.. generally if the trans leaks it just goes on the ground.

that said all I ever ran was 15w40 in the primary.
two bikes went over 200k on that stuff with nary an issue. original clutches and all..

it is a dirty environment, doe to clutch and chain wear but it wont hurt anything
so no real need for anything special.

FWIW I used to know guys who ran ATf, I tired it but found the clutch was grabby

Any particular brand or just whatever 15w-40 JASO you could get for a reasonable price?

 

[thastinger]

Any particular brand or just whatever 15w-40 JASO you could get for a reasonable price?

He is probably talking about good ol T4. It is very popular in wet clutch applications.

 

[Panda87]

He is probably talking about good ol T4. It is very popular in wet clutch applications.

I know a lot of the old goldwingers loved the stuff. I always leaned toward motorcycle specific oils because it just makes me feel better

 

[thastinger]

I know a lot of the old goldwingers loved the stuff. I always leaned toward motorcycle specific oils because it just makes me feel better

Not sure if it still does but T4 used to have the JASO MA cert.

 

[Propflux01]

This is my first HD, so I’m not as intimately familiar with its inner workings as you are, so I very much appreciate your input!!! I’m not sure on the aluminum either. I do a lot of lock to lock low speed work riding the friction zone and rear brake, so some of the wear may be accelerated from that, or it’s simply just break in contamination as parts wear in.

How many miles on the bike?

 

[Panda87]

How many miles on the bike?

I’ve got 9500 on it now. Bought it December 21st of 23. Had 8000 total when I pulled the sample.

 

[Highlander 1459]

Any particular brand or just whatever 15w-40 JASO you could get for a reasonable price?

in my case it was mostly Rotella, as it carries an Allison C4 rating... aka it was designed for wet clutch applications..
realistically, the primary drive just isn't all that picky. I tired using ATF one time, but found the clutch grabbed to much, went back to 15w40 and never looked back..

got my curiosity up, how was the older stuff vented... never thought about it once in my life..
so I dug out an old inner primary I have laying around
and voila, the primary does not have a vent that I can see... which means any pressure must have bled out thru the trans shafts that go into the primary.

the trans used to have this for a vent

 

[Highlander 1459]

I’ve got 9500 on it now. Bought it December 21st of 23. Had 8000 total when I pulled the sample.

there isn't any reason to sample the primary... it is always going to be subject to wear materials.
what you do is ride it until the clutch slips and then fix it..
FWIW I never wore a clutch out... put more than 200,000 on 2 different Electra Glides..
I actually caught my 2001 FLHTC right when it flipped...
never got any pictures of my 95 Flhtc, it had the old 5 digit speedo
but I think it had 240k on it when it gave up the ghost.

 

[fantastic]

That is high Fe & Al numbers to say the least. Definitely follow HD's update & re-test.

 

[loneryder]

I always changed my primary fluid with an oil change...5k. Same oil...syn 20-50. It is always dirty @ 5k miles.

 

[Panda87]

in my case it was mostly Rotella, as it carries an Allison C4 rating... aka it was designed for wet clutch applications..
realistically, the primary drive just isn't all that picky. I tired using ATF one time, but found the clutch grabbed to much, went back to 15w40 and never looked back..

got my curiosity up, how was the older stuff vented... never thought about it once in my life..
so I dug out an old inner primary I have laying around
and voila, the primary does not have a vent that I can see... which means any pressure must have bled out thru the trans shafts that go into the primary.
View attachment 229676


the trans used to have this for a vent

View attachment 229677

So the trans case was vented, but the primary wasn’t. Thanks for the pics! I love seeing things apart and learning how they were put together.

 

[Panda87]

there isn't any reason to sample the primary... it is always going to be subject to wear materials.
what you do is ride it until the clutch slips and then fix it..
FWIW I never wore a clutch out... put more than 200,000 on 2 different Electra Glides..
I actually caught my 2001 FLHTC right when it flipped...
never got any pictures of my 95 Flhtc, it had the old 5 digit speedo
but I think it had 240k on it when it gave up the ghost.
View attachment 229678

THAT is cool. I always wish I could get my Odo pics at even intervals

 

[Panda87]

That is high Fe & Al numbers to say the least. Definitely follow HD's update & re-test.

HD says to run the primary to 10k. I’ll stick to 5k intervals because of the silicon loading.

 

[Panda87]

I always changed my primary fluid with an oil change...5k. Same oil...syn 20-50. It is always dirty @ 5k miles.

5k is my new interval for my primary. The HPL engine oil in my other thread can easily do 10k intervals.

 

[Highlander 1459]

So the trans case was vented, but the primary wasn’t. Thanks for the pics! I love seeing things apart and learning how they were put together.

yeah, I'm assuming due to the large volume in the primary and it being connected internally via the input shaft, any breathing is accomplished thru the main shaft...

I never thought about it in all my 30 years of playing with these machines... but for you, I would just say, dont worry about it. change the fluid when they say and dont do anything until it gives a problem... it probably never will.