ATF in the primary?

[Scoop_Fraser]

I'm just wondering if anyone has any experience with using a synthetic ATF in the primary of a big twin HD. I am currently using Amsoil's 10W40 MC engine oil in my primary but have read that ATF would potentially be a more suitable choice.

Thanks,
Sean
----

 

[SKUNKY]

Keep using the Amsoil..the ATF is to thin..it will wear the clutch rod out faster.

 

[Titan]

MMMmmm...Not me. Not if it were my bike. Unless that's what the manufacturer recommends. And, they don't recommend ATF, do they?

 

[Master ACiD]

i run atf in the transmission of my 2 stroke atv. you could consider it to be similar to that of a primary in a hd except my atv has a wet clutch. my engine originally speced 10w30 or 10w40, but the atf works great. i know its alot thinner, but the reduced viscosity means i have less drag.

motorcycle transmissions are not all that dissimilar from an automatic trans in a car. both can have wet clutches. both have cross cut gears, bearings, shafts, differing metals bla bla.
only real difference is we dont have torque converters and oil pumps.

 

[Scoop_Fraser]

Hi guys,

Thanks for the input. I appreciate it...

Master,
My clutch is in the primary so it is a wet clutch as well. I recently read on a Harley forum that guys were liking the effects of running ATF in the primary, but thought I'd check it out here first.

Sean
----

 

[Fatboymoe]

I use Redline MTF with good results. A friend of mine has used Type F in his primary in his evo for over 70k with no problems at all.

 

[GMBoy]

ATF in a HArley Primary is new to me. Personally, I wouldn't do it. Let those other guys do it if they want and just check back with them in a few years and see what's up.

 

[wileyE]

If the power from a harley was electric motor smooth I might see it as a possibility, heck my 3/4 ton truck spec'd atf in the gearbox? But the power pulses and shock load from the HD motor might be happier with something with a little more substance to it. I'm just speculating though.

 

[Fatboymoe]

If ATF can be used in a transfer case(chain driven), I see no reason why it can't be used in a HD primary. The fluid in the primary only cools the clutch plates, and it's primary function is to keep the chain and compensator lubricated and not much else.

 

[wileyE]

moe, that makes more sense, I was thinking GEAR case

 

[cfromc]

Well, I'm trying it in mine next season so I guess check back in a few years. As FBM stated, "The fluid in the primary only cools the clutch plates, and it's primary function is to keep the chain and compensator lubricated and not much else." I've stated that same thing here and on V-Twin Forums. I really don't see the need for 10W-40 or thicker oil or gear lube. Redline MTL works fine - I'm on my second year with it.

 

[Jaybird]

ATF (specifically, type F) works quite well in racing 2cycle bikes...which are much harder on fluids than any Harley ever imagined being.

 

[wizzells]

I can't imagine there is any problem running ATF in the primary. Some clutch manufacturers require the use of ATF such as S&S and Rivera with their clutch setups. It would seem to me that the requirements of the primary are more clutch plate/material dependent than anything else.

Remember also that the primary fluid's partial responsibility is to keep the stator cool as well since it sits in that oil bath as well on H-D's.

At our shop the primary case fluid of choice is Redline MTL, and this works fine with S&S and Rivera setups.

 

[fuel tanker man]

One small advantage to using ATF in the primary is that if you get a leak, you can tell if it's motor oil or the red ATF.

I know a guy who runs it in his bike... he's not had any problems. The primary isn't real picky about oil...

The Harley Davidson----->

"Genuine!"

...stuff was once tested and determined to be nothing more than plain old vanilla 10W40 motor oil.

Dan

 

[Scoop_Fraser]

Hi all,

I just thought I'd give you an update. I switched over to the universal Amsoil ATF a few days ago and have noticed some improvements in terms of shifting. I would guess that the clutch pack is separating better because the shifts seem to take less effort and neutral is even easier to find than before. I also picked up a quart of the Amsoil racing transmission fluid (ART code) that is a type F equivalent. I will be trying this out at a later date.

Thanks for your comments.
Sean
----

 

[MULESKINNER]

I don't get it. HD engineers test and recommend a product for use in the primary case of their bikes. Why use something else than what the manufacturer recommends???????????

 

[Fatboymoe]

Muleskinner,
Why limit yourself to what the HD sells? I don't use any HD fluids. Usually, they market stuff that is manufactured with maximum profit in mind. Look at thier Syn 3. VOA's show a weak additive package at best at $8+ dollars a qt. There are much better alternatives than what HD markets and sells.
Without looking, I would bet that HD chaincase fluid has transmission fluid type properties. What was stated before is true, the chaincase is not very picky about it's fluid. Compatibility with the clutch being used is the most important factor in fluid choices.

 

[Bagger_Matt]

Fatboy, good point but $8 for syn3 would be on sale. Its more like $9.98.

 

[Fatboymoe]

I guess it shows how long it's been since I even looked at HD fluids.

 

[oldblueglide]

Guys on the Delphi forums have been running ATF in the primary for years and hundreds of thousands of miles with no lubrication related failures. Having said that, you could probably use sweet milk in the primary with no ill effects. Quantity of primary fluid is more important than weight of the oil.