Atf

[ckattner]

How does everyone feel about useing ATF in the gearbox? This month's Motocross Action recommends using it for better clutch action. It also says to use GM-type ATF as opposed to Ford-type. It says that the Ford-type causes clutch slippage. From the input that I have read on this forum, it seems that the ATF users lean towards Type F, which I thought was the Ford type. Am I wrong? Any input would be greatly appreciated.
Collin ;)

 

[muscle]

Hey we just started using GM type ATF in our gearboxes (98 RM 125 and 02 YZ 250) and it is sweet!! Much better cluch feel and bike runs smoother. I highly recommend using it. I even spoke to a high ranking Yamaha wrench and he said that even though he recommends using what is listed in the owners manual, you should be safe with ATF as long as you change it regularly.

 

[muscle]

Me again,

Ford type ATF is the slippery type of fluid compared to the GM type which is the friction or "grabby" type fluid. Ford type F ATF SHOULD NOT BE USED. It should say on the bottle " Dextron-III/ Mercon and be approved for General Motors. Or one other way to be sure is to go up to the parts counter and ask for ATF for a Chevrolet 350 turbo automatic trans. such as the one in my '77 Blazer.

 

[BRush]

I have not read the MXA article, but it would not be the first time they got it wrong. The ATF question has been endlessly discussed here on DRN and here’s what I’ve learned: Type F ATF has a higher static friction coefficient the Dexron/Mercon types. Type F is more “grabby”. For a dirt bike clutch, slippery is bad, grabby is good. Type F ATF is the one you SHOULD be using in your bike.

 

[Bricks88]

Now Im totally confused. I also read the Motocross Action article and it said Dexron\Mercon not type F. Iam not calling anyone wrong but it would be nice to use cheaper fluid since I change it often in my 2 bikes.

 

[ckattner]

It is my understanding that Dextron, and its variants, specifically meet GM standards; and that Mercon, and its variants, meet Ford standards. The Dextron/Mercon meets both the GM and Ford standards. That doesn't necessarily mean that it meets characteristics, just quality standards. I am also assuming that that Type F is Ford specific. Am I right in all of my assumptions? Please help me to get all of this straight. Thanks for the replies.
Collin

 

[muscle]

OK I emailed Penzoil and Valvoline and Penziol said (haven't heard from Valvoline yet) that it was Ford type F. Like I said before, I'm running dextron/mercon and the clutch feels better than with 10W30 like what my manual recommends. I also emailed Motorcross Action and told them the same story and asked what the deal was. Still waiting to hear from them too. I think what I'm getting now is a clutch feel reflecting the lighter oil in the crankcase. So it sounds like BRush may be right and I need to drop some oil out of my bikes. We have only run this dextron for about a week though whigh may be a good thing.

We simply ran the dextron/mercon because, like alot of other folks, read the MXA article. I hope for them that they are right as there may be alot of prematurely worn-out clutches out there with their name on 'em!

I will keep all posted on what I hear back from MXA and Valvoline.

 

[BRush]

As I understand it (and I am not an automatic transmission expert) Mercon has a lower static coeff. or friction and allows the transmissions designed to use it to slip more and thus engage more smoothly (and slowly). Type F with a higher coeff. will allow that transmission to shift quicker with a faster lockup. This is exactly the type of characteristic desirable in a dirt bike clutch. Type F will ( in theory) allow the clutch plates to hold tigher with the same clamping pressure than if you a used Mercon/Dexron type.

I did a lot of oil experimentation last year and my own experience is this: shifting was generally better with motor oil (or gear oil - I could not detect a difference) with Mobil 1 15w-50 being the best ( and most expensive). Clutch engagement action and feel was by far the best using ATF (type F). Brand did not seem to matter, but ATF also made my shifting a bit notchier than I like. I finally arrived at 50% Castrol 20w-50 + 50% Type F ATF mix that I like a lot and using to this day.

There have been a number of good threads on DRN on this subject. This one delves into the "Why Type F ATF as opposed to MERCON or something else":

http://dirtrider.net/forums3/showthread.php?s=&threadid=5269

ATF in a two stroke gearbox

http://dirtrider.net/forums3/showthread.php?s=&threadid=5288

 

[ckattner]

Thanks for the info BRush. Very interesting posts.
Collin

 

[dhoward]

Good job, MXA. :|
What a bunch of twits....
Use type F.

 

[spanky250]

Type F works quite well in my tranny. I like the feel and grip that it gives the clutch.

 

[muscle]

Still havent heard back from MXA yet. You guys think thet got their tail between their legs? Sure would like to see how they reply. ( they probably dont give a crap)

 

[Lew]

I have been using the dexron III for some time now. No clutch slippage, and I do have smooth shifts. I use the entire quart, and change it every 100-150 miles. I figure it this way, type f by its design is different than dexronn III, as the previous posts state, but will it really matter in my tiny gear box as opossed to a large 1 ton truck?? I don't know, after all the manual does state you can use motor oil and I will bet it does not have friction inhancers as the type f??? The mechanic at my local kawi shop told me that in his 20 or so years the only oil related tranny failures he has seen has been due to lack of oil in the gear box. Again I am in no way an expert.
Lew

 

[muscle]

Thank you for your message. The Dexron III/Mercon ATF has more friction
modifier than the Type F fluid. For more information, please contact us at
1-800-354-8957, thank you very much.

OK get this, That was the email message from Valvoline. They say to use dextron. Penzoil says Ford type F. So who do we believe?

;) ??????????

 

[Kootenaycat]

From my experience as an Auto Technician for the last 14 years, I recall that Type F ATF will swell clutch plates, therefore making it more "grabby". The only problem I can see in using Type F would be a clutch that won't release because the plates have swollen. I doubt that it would ever happen, Ford used it in there C-4's and C-6's up to the mid '70's I believe. Like someone else posted, you are probably going to run into clutch/trans problems from low fluid level and/or lack of maintenance.

 

[muscle]

Hi Russ
Valvoline's comment is correct. What they mean is that ATF Dexron III has more slipperiness, that is more friction modifier than TYPE F. Therefore TYPE F would be more suitable.

Regards

Murray Reid
Pennz-Corp
Ph. 04-296-1089
Fax. 04-296-1090

Ok, cool were back to type F.

 

[BarryW]

I worked as an engineer in the ATF testing/qualification field for about three years and here's what I know: Dexron-III/Mercon fluids contain friction modifiers which give a lower static coefficient of friction than dynamic coefficient of friction. This has the effect of allowing a clutch pack to engage "softly". As the relative speed between the slipping elements approaches zero (clutch lockup), the friction drops and the clutch locks slowly rather than abruptly. This causes a smooth shift in an automatic tranny. Ford Type F does not contain the same friction modifiers and therefore has a higher static friction than dynamic friction, so the clutch locks abruptly resulting in a harsh shift. For a bike I assume either one will work as long as you don't encounter clutch slippage. I would expect the clutch to live longer with Type F but it might "feel" better with D-III/Mercon.