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Discussion Starter · #1 ·
A few months back I had a 5th gear seal go on me. Since the scooter was still under its extended warrantee I took it to the shop and they gladly replaced this seal and all other seals/gaskets etc in the primary chaincase. Doing my last fluid change I noticed the distinct odor of gear oil when I drained the primary chaincase. What was in there was NOT the recomended lube. I guess my question is this. Is it possible for lubricant to move from the tranny into the primary chaincase (if some seals are left out or incorrectly installed) or is it most likely the guy doing the oil change just botched it and stuck the wrong lube in the wrong hole? I know for a fact that the HD mechanic that worked on the scoot was a brand new employee and fresh out of school. Excuse my ignorance here as I've never had an up close and personal look at the design of the internals between the tranny and chaincase. Thanks folks and Happy New Year
 

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With a bad seal or one improperly installed, I believe that it is indeed possible for tranny fluid to migrate to the primary. As you said, since this was a new guy, the wrong fluid or an improperly installed seal could be the issue.

Ragnar
 

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Dontdial911 said:
A few months back I had a 5th gear seal go on me. Since the scooter was still under its extended warrantee I took it to the shop and they gladly replaced this seal and all other seals/gaskets etc in the primary chaincase. Doing my last fluid change I noticed the distinct odor of gear oil when I drained the primary chaincase. What was in there was NOT the recomended lube. I guess my question is this. Is it possible for lubricant to move from the tranny into the primary chaincase (if some seals are left out or incorrectly installed) or is it most likely the guy doing the oil change just botched it and stuck the wrong lube in the wrong hole? I know for a fact that the HD mechanic that worked on the scoot was a brand new employee and fresh out of school. Excuse my ignorance here as I've never had an up close and personal look at the design of the internals between the tranny and chaincase. Thanks folks and Happy New Year
What makes you think it was the wrong fluid? Gear lube is fine - Redline MTL in mine works superbly....
 

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Well if a dealer did the work they did not put Red Line MTL in it. And last time I looked at the bulk in my dealer I did not see any Gear Lube. If he has a smell of gear lube, which we all know is distinct in its smell, then it has to be coming from the transmission somehow.

Maybe the seal took a moment to heat up and seat and you had blow by for a heart beat. For those seals to go in, the inner primary must come off so it should have been cleaned and fresh oil in it. I would not think they would capture the old oil and re-use it?

Me I would keep an eye on it, call or take it to them to document and see what happens. Check your trany fluid and make sure of levels and keep checking it, if it goes down, you are loosing it somewhere.
 

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There is no way for the trans fluid to contaminate the primary fluid or vice versa because they are not interconnected. If the tranny leaks at the mainshaft it will leak out behind the belt pulley and onto the ground. The other leak point would be the shifter shaft seal. Again, would leak to the ground.

On the other hand, primary fluid and engine oil could mix if the engines crank seal fails.
 

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The primary fluid and trans fluid that the dealer sells now is all one fluid. I asked the parts dude what wt. it was and he told me it is unrated. I bought 2 qts. to try it out and it seems to be a combination of trans fluid and something else (don't know) but it does have the smell of gear oil.
 

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Martin64 said:
The primary fluid and trans fluid that the dealer sells now is all one fluid. I asked the parts dude what wt. it was and he told me it is unrated. I bought 2 qts. to try it out and it seems to be a combination of trans fluid and something else (don't know) but it does have the smell of gear oil.
Martin64:Thanks for the info will look into it. I thought they were 20-50 synth in all three. And 20-50 in engine and trany, with then their primary fluid, or whatever it is, when using dino.

Timbo: I knew you would be along to straiten me out. I know of your recent experience (and suggestion to me) and you are versed first hand in this. I did pull the manual after reading what you said so I could understand. Still learning....

Seems to me there must be something out there in HD lineup that smells like gear lube. I don't know as I don't use HD brand oils but did not think other then the Screaming Chicken Synth there was anything new from them?
 

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Discussion Starter · #8 ·
Thanks for the replies. Usually when HD replaces any fluids doing warrantee work they use the cheaper dino oils. In this case their primary chaincase oil use to be just that.. primary chaincase oil in a black bottle. Gear lube was a semi-synthetic blend with the normal gear oil type smell. This could well have changed. I did ask the shop manager about it and it left him scratching his head as to how that oil with 'gear oil' smell ended up in my chaincase. Whatever the case i assume it hasnt hurt anything. I'm using Amsoil products everywhere but the primary. There I just use a quaility semi-synthetic 10w30 or 10w40. I'm not buying into using 20w50 in all 3 holes. Though I'm sure it works common sense tells that gear lube does the intended job better in the tranny, and gear lube in the primary could very well cause clutch to slip. On a side note I've often wondered what additive gives gear oil that nasty stink.
yall folks be safe... and thanks again
 

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just a note for those here the primary is vented though the clutch pushrod into the trans and the trans vent hose vents them both. it is possible for a small amount of trans oil to endup in the primary if the trans was filled on the sidestand, if you where pouring fast the level in the side cover could come up over the level of the mainshaft end and run down the pushrod inside the mainshft to the primary. as we all know it don't take much to stink either.
 

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pws said:
Ya think??

The point was that Gear Lube is fine for the primary.
Point taken. :duh?:

I just have never seen or have done it. On this Twin Cam any service that was done from the dealer, first two free, involved dino changes, and then me dumping it, and I never ran into that smell coming from my primary. Always 10W40 something for me in there. I have been curious as to the MTL as I hear others also run it. I am running amsoil in there now.
 
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