Primary fluids and YOU.

[Dave63]

I've been chatting on other forums, and researching alternatives to primary fluids in big twins. (Non-sportster models) One reason is, I hate grabby clutches and clutch drag on start up.

Another reason is, I'm always doing something..... This time, it's running ATF in the primary.

HD recommends a 20w50 oil, like their primary oil, or SYN3. I've also run Royal Purple, Mobile-1, and plain old 30wt oil. All of these basically feel about the same and provide the primary chain with good lubricant and keep the clutches cool.

3000 miles ago, (a tad more) I added 32 onces of F-Type Transmission fluid to the primary. The type-F has an additive for the clutches, but I've also run Mopar's ATF+4 fluid with good results as well. (In there now....)

First a little history: Dodge and GM both use ATF in their transfer cases of their 4x4 vehicles. In that transfer case are bearings, chain and shafts that spin constantly. (No lock-out hubs on my Dodge) Not sure about if Ford does or not. Robby might know for sure.

AFT is used (obviously) in automatic transmissions, where there are bearings, gears and multiple clutch packs and bands. Way more heat and friction by volume than you'll ever see in normal road use in your HD.

ATF is thin by nature, and remains thin, even in the cold. But so does synthetic oil, like Syn3. But it effects the clutch plates in a different way and causes them to grab, ans stick at times.

HOWEVER.....ATF causes little to no drag in your clutch pack like oil does and increases the engagement window by almost 50%, making the clutch smoother, with no chatter or grabbing, what so ever. It's like night and day..... especially on hills.

After 3000 miles, (yesterday) I dropped the drain plug and inspected the magnetic tip of the plug. There was no more metal slivers/debris then any other time, indicating no more wear than normal, with the ATF. For the record, I also have a new chain and an HD auto adjuster installed which was right at the time of this experiment. I expected to see a tad more metal on the plug with the new chain mating to the old gears. The clutch basket and plates are the originals with 34K on them.

HD primaries consist of the following: Primary chain, Adjuster shoe (Derlin or nylon) compensating sprocket, one inner primary bearing, (roller type) one double roller clutch hub bearing and a clutch basket with fiber and steel plates.

That's it.....

I'll run the ATF for yet another 3000 miles and report back again.

Barnett Clutches actually recommends it for some of their clutches and more and more people are running it in their bikes with good results.

Food for thought.

[Badassbrutus]

KOOL Info Dave I was just readibg about it on the horse guy had been usin it for 15 yrs and loves it.If i didnt have belt drive i would use it.
Used type F in my turbo 400, 4eva insted of dextron III.

[Rockerbox1]

thanks for the write up. I may just try this the next time I change primary fluid. Question is, since my bike is under a MoCo extended warantee, will using different fluids than they recomment adversely affect my warantee should there be any failure?

[Dave63]

If you're still under warranty, you have 4 choices:

1.) Run the fluid and drain it if it comes time to go to the dealer.

2.) Run the fluid and not care.

3.) Run the fluid and suck it up if they void your warranty in the event you have a primary failure due to something.

4.) Not run the fluid.

[SCHMIDTYS]

Yes , ATF works great in primarys . Quiets and smooths out the clutch action .
Remembering from my GM days the type F has a higher friction coherent than the GM atf so if you've got a slipping GM auto trans you could drain it out and put in the type F and get some more life out of it . The less than honest used car sales people used this trick .

[Rockerbox1]

pretty much sums it up

[Badassbrutus]

Originally Posted by SCHMIDTYS

Yes , ATF works great in primarys . Quiets and smooths out the clutch action .
Remembering from my GM days the type F has a higher friction coherent than the GM atf so if you've got a slipping GM auto trans you could drain it out and put in the type F and get some more life out of it . The less than honest used car sales people used this trick .

If you build a race tranny like the many I have you always run Type F the clutch packs grab better which means more traction/hp to the rear wheel.Oldest racer trick in the book.

Unfortunaty some chitbags used it like you said to rip people off

[GearheadDrew]

ATF is has alot if cleaners in it as well it is a very good debirs removing fluid. I have used it on some engine rebuilds that i didnt change piston rings. I simply squirted a couple drops in the spark plug holes and turned the engine over by hand it helps to free the rings and remove rust without scratching.

[Blackdog 15]

How do you think the trans fluid would compare to the 75W-90 Lucas synthetic I've been running in my 05 primary ?

[gruss]

have used ATF in "ALL" of my off road clutch packs to include:
yamaha yz 500
yamaha yz 250
suzuki dr 350 (with big bore kit)
kawasaki 250 ( with a heart condition)
"ALL" of these bikes run (ran) dexron 3 mercon, and have never needed a clutch service. the high detergent content of the ATF keeps the clutch packs spotless inside, and clutch cycle rate is faster, and smoother. (gear box lubed in these as well with no gear or bearing issues at all)
after all, the clutch is no different than the inside of an automatic gearbox.

i would have no hesitation using ATF in the primary drive of my harley. ( even a sportster ) IMHO those gears will have no trouble at all....g "and no clutch drag"