ATF in primary...WOW!
Seasoned HDF Member
Joined: Mar 2010
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From: Honah Lee
Not negative
Not wanting to be negative here but you might want to go to the www.mobiloil.com site and hit the ask Mobil. Do a search for automatic transmission fluid in a Harley primary. It actually sounded like a good idea to me and I have been in my primary (check my album) and have rebuilt a GM Blazer transmission (took it out twice getting it right) Mobile says not to use it. They also say use their motor oil but I do not do that either. I am sure if you do not ride your Harley hard or in a lot of heat it would be fine but if you do it may not provide the protection the inner primary bearing behind the clutch pack (not the clutch drum bearing) needs.
Question: ATF Choices for a Harley-Davidson FLHT PrimaryI have been told that many Harley owners use Type F (Ford) ATF in their primaries, for one thing to make it easier to find neutral. I have some Mobil 1 Synthetic ATF Multi-Vehicle Formula that I was thinking about putting in my FLHT primary, but the back label states that it's not recommended for Type F applications. I don't want to put it in my primary if it has a lot of friction modifiers in it because I don't want to cause clutch slippage. What are your thoughts on using this ATF in a Harley primary? Thanks.-- Ken Carpenter, Buford, GA
Answer: Although an ATF may work, we suggest shying away from using it due to the low viscosity of ATFs and the possibility of premature chain wear and/or noise. We recommend Mobil 1 Racing 4T 10W-40 for Harley primary transfer cases. Alternatively, one could go with Mobil 1 V-Twin 20W-50.
Question: ATF Choices for a Harley-Davidson FLHT PrimaryI have been told that many Harley owners use Type F (Ford) ATF in their primaries, for one thing to make it easier to find neutral. I have some Mobil 1 Synthetic ATF Multi-Vehicle Formula that I was thinking about putting in my FLHT primary, but the back label states that it's not recommended for Type F applications. I don't want to put it in my primary if it has a lot of friction modifiers in it because I don't want to cause clutch slippage. What are your thoughts on using this ATF in a Harley primary? Thanks.-- Ken Carpenter, Buford, GA
Answer: Although an ATF may work, we suggest shying away from using it due to the low viscosity of ATFs and the possibility of premature chain wear and/or noise. We recommend Mobil 1 Racing 4T 10W-40 for Harley primary transfer cases. Alternatively, one could go with Mobil 1 V-Twin 20W-50.
Last edited by Jackie Paper; Sep 14, 2010 at 01:16 PM.
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I saw the answer where they pointed the asker to their Synthetic 10w40 or 20w50... but then here's another response from Mobile...
Automatic transmission fluid (ATF) would probably work fine in your primary but in the end you will have to decide if you are satisfied with its performance. Every biker feels his shifts and knows his sensitivity to clutch slippage. Every modern ATF is designed with specific frictional characteristics that complement transmission performance with very specific friction materials. Depending on which fluid you choose, you may or may not be satisfied. And even then your buddy may try the same fluid and have yet a different opinion.
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Ultimate HDF Member
Joined: Jun 2007
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From: Richmond, VA
I see you guys have answered the questions far batter than I could. I have no way to offer any imperial evidence of scientific proof that its better OR harmful to anything in my primary. What I can say is that the dreaded overnight clunk is gone, finding neutral is WAY easier and the bike shifts considerably better. As has been mentioned by others, it doesn't do anything for the tranny, it makes the clutch work better, so shifting the tranny is simply easier. At least on my bike that is the case. Anyone is free to do as I did, and do a search. I am by no means to inventor of this little trick and the people before me who started posts about ATF in primaries seemed to be as happy as I am. As a lawyer, I learned many years ago not to offer any advice or opinions in absolutes, but in this case, I absolutely am pleased with the switch from HD fluid to ATF. And again, I can only quote others here, but the clutches in our primary and the clutch pacs in and automatic transmission are essentially the same thing, so I don't suspect there is any potential harm that can occur from ATF in the primary. And the fact that the primary chain and adjuster shoe is in a 100% constant state of total submersion, I can only suspect its getting adequate lubrication. I would never argue that point to some one with proof to the opposite, but this video shows pretty clearly, that everything in that primary is in a state of constant drenching.
http://www.youtube.com/watch?v=m4dd6xxtWVc
http://www.youtube.com/watch?v=m4dd6xxtWVc
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