Primary Oil for early Twin Cam
#11
04-23-2022, 12:02 PM
Whatever you use, just make sure it's rated for wet clutches
80w gear oil is not the same as an 80w motor oil
80w gear oil is about equal to a 30w motor oil
use either, or a good ATF. Avoid any friction modifiers. Do not use a hypoid rated gear oil in a primarily case unless you want your clutch to slip
80w gear oil is not the same as an 80w motor oil
80w gear oil is about equal to a 30w motor oil
use either, or a good ATF. Avoid any friction modifiers. Do not use a hypoid rated gear oil in a primarily case unless you want your clutch to slip
#12
04-23-2022, 12:30 PM
#13
04-23-2022, 12:50 PM
No, Thanks for asking. It was only an expression of speech, dont read too much into it. But since you asked it's from real world experience. When I was switching to Amsoil I put 90W in my transmission and was missing shifts on a fairly new bike. My dealer told me to use 140w and I never missed another shift. Amsoil even came out later and now recommends the heavier gear oil. 
Synthetic V-Twin Transmission Fluid MVT - AMSOIL
Synthetic V-Twin Transmission Fluid MVT - AMSOIL
Last edited by SirHarley; 04-23-2022 at 12:58 PM.
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Wrechar (04-24-2022)
#14
04-23-2022, 01:12 PM
Seasoned HDF Member
#15
04-23-2022, 01:20 PM
Road Captain
Been running Syn 3 for 124997 trouble free miles in my 04 FXST. Same for the Tranny. I pulled it apart less than 10k ago due to a 5th gear race trying to see what was inside. Replaced every bearing and seal while in there but nothing else. All looked good. I have bike pulled apart now for the 107 rebuild a few post down and am replacing the chain tensioner while I have it apart. Compensater looks good as does chain. Still have to do one inspection of clutch teeth and jack shaft.
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Wrechar (04-24-2022)
#16
04-23-2022, 02:18 PM
Seasoned HDF Member
The 80W factor raises my eyebrow a bit. But since the Dealer is recommending it, then I say U can go with it. 20-50w primary oil is what I think Evos were using in the 90's. Gear Oil is for manual transmissions with actual gears inside. I am told that Harleys Transmissions need higher than 80W. More in the 140W range actually. There is a stickiness factor to it that makes rotating gears not fling off so much lubricant. There's another thread on that one...
https://syntheticwarehouse.net/uncat...iring-a-75w-90
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Wrechar (04-24-2022)
#17
04-23-2022, 02:20 PM
Seasoned HDF Member
Trumph's, BSAs most other brit bikes back in the 60s specified ATF type F in the primary..
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#18
04-23-2022, 02:56 PM
Most aftermarket clutch manufacturers recomend type F ATF. NO synthetics.
There's nothing special in the primary that would need more lube than ATF provides for automatic transmissions and their bearings, clutch packs, etc.
All this thick synthetic gear lube people use then whine cuz they can't find neutral.
Use what gives you the best clutch feel. The thinner the better if that's motor oil. And no synthetic. 30 - 40wt. 50wt is fine if it doesn't cause stiction for you in colder weather.
While I dont have ALOT of miles on it yet, my new chain that came with my 30 tooth sprocket 3 years ago still looks brand new. No wear at all. Not the slightest hint of shavings on the magnetic drain plug ever.
There's nothing special in the primary that would need more lube than ATF provides for automatic transmissions and their bearings, clutch packs, etc.
All this thick synthetic gear lube people use then whine cuz they can't find neutral.
Use what gives you the best clutch feel. The thinner the better if that's motor oil. And no synthetic. 30 - 40wt. 50wt is fine if it doesn't cause stiction for you in colder weather.
While I dont have ALOT of miles on it yet, my new chain that came with my 30 tooth sprocket 3 years ago still looks brand new. No wear at all. Not the slightest hint of shavings on the magnetic drain plug ever.
Last edited by 60Gunner; 04-23-2022 at 03:06 PM.
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Wrechar (04-24-2022)
#19
04-23-2022, 03:19 PM
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