Transmission / clutch fluid..beat to death

[sjmaster]

Ok...I know this has been beat to death, and I did look over past postings and could not find an answer to this: I drained the gear oil out (that was probably causing the clutch drag when cold) and was going to try automatic transmission fluid. I got Mobile 1 synthetic ATF fluid. I hear alot of guys are buying type F, which is apparently for older vehicles....do you have to use type F for some reason??. Are there any gears in an automatic?? I did not think so...well maybe the pump. Will ATF provide enough film strength to protect transmission gears.? I never thought when I purchased this bike my biggest issue would be tranny fluid :yikes:

 

[david01]

iam a gm tech and let me tell you there are plenty of gears in a automatic also GM is useing dextron3 in its manual transmissions as well i would think this fluid would be ideal for dirtbikes since you have both gears and clutchs

 

[SpeedyManiac]

ATF is just fine for a dirtbike transmission. Automatic transmissions have LOTS of gears in them (planetary gear systems) so it's no worry. I use ATF because it is cheap so I can change it often. Any engine/gear/transmission oil will work just fine, provided it has an appropriate viscosity for the application (engine oil should be ~0W-40 or so, gear oil between 75W and 90W, then any ATF is good). Right now I have type F in my bike but I've tried the other ATFs and can't really feel a difference. Just make sure you change the oil often as gears like clean oil and the clutch contaminates oil pretty fast.

 

[Lew]

I have been using Dex III for years.

 

[DLHamblin]

Ok...I know this has been beat to death, and I did look over past postings and could not find an answer to this: I drained the gear oil out (that was probably causing the clutch drag when cold) and was going to try automatic transmission fluid. I got Mobile 1 synthetic ATF fluid. I hear alot of guys are buying type F, which is apparently for older vehicles....do you have to use type F for some reason??. Are there any gears in an automatic?? I did not think so...well maybe the pump. Will ATF provide enough film strength to protect transmission gears.? I never thought when I purchased this bike my biggest issue would be tranny fluid :yikes:

ATF is (in SAE motor viscosity) equivalent to a 10W20 oil. 80W gear oil (AGMA scale, confusing isn't it...) translates into a 40W (10W-40 or 20W-40) SAE motor oil.

ATF is used by many; but true 80W gear oil will provide more "cush" to the gears than the thinner ATF.

Either if changed often will work for the average life span of a dirt bike engine.

Make your choice and be happy (I use the gear oil...)

 

[WhiskythrottleKeit]

Good point Hamblin ATF is way thin iv noticed you posted this in thumper talk too. for a good read on this subject go to this link. http://www.thumpertalk.com/forum/showthread.php?t=366279 Gets good on the last few pages

 

[motometal]

the thin vs thick explanation seems logical, but I think in reality there's a lot more to lubricants than that. It's sort of like saying "race gas can make your bike have less power becuase it burns slower".

 

[Jaybird]

The thicker the fluid, the more energy it takes to force it into tight clearances. Which increases heat and helps to shear the fluid down.
ATF fights degredation from heat as well as any engine oil does, as it has a higher flash point than most any engine oil.

Many engine oils will shear down very soon after being placed in the engine anyway.

 

[shadow171]

Stay away from anything with friction modifiers because of the clutch. :cool:

 

[WhiskythrottleKeit]

95% of the time the tight clearances are not where you will find the wear down to the point of failure. The wear in a bikes gear box will mostly be found in the areas that call for thicker oil to soften the impact ie (Dogs,Shift forks and drum).
I have fixed many gear boxes and i would think that thicker oil is a better choice. A bikes tranny does not have any real hot spots that cause seizures or bad scaring past the point of normal wear.
Any oil that is made for 2 stroke racing gear boxes is always pretty heavy oil and is never no wheres near as thin as ATF.

 

[Jaybird]

Stay away from anything with friction modifiers because of the clutch. :cool:

Just what friction modifiers would those be?
And just what do they have to do with the clutch?

 

[motometal]

what's your take on that, Jaybird? The corners/edges of the shift dogs are no doubt a critical area of any non-synchronized trans...

 

[Jaybird]

The thickness of an oil is not always idicative of how well it can protect.
You could have a 60wt motor oil that makes a fine fluid film, but the instant that fluid film is compromised there must be a quality mixture of barrier additives to take over. If that 60wt oil dos not have a robust additive package, the wear will occur no matter how thick the fluid remained.
No matter how hard an "impact" is, the fluid film has always been comprinised if damage occured from that impact. If the fluid film could stop it, there would be no damage, but it can't...no matter how "thick".

Film strength is the key. And film strength must take into account the total package and not simply one aspect, such as viscosity.

Now you could have a 60wt that was chock full of additives, and may well be a good protector, but there are also things like corrosion protection, foaming, heat/oxidation resistance, etc..that also must be considered. Not to mention that it is a fact that the thicker the fluid, the less energy your dyno will see. If you are racing at the top level this could well be of great importance.

I find that TypeF ATF provides me with all that is really needed for the 2T box. It has additives to take care of the harsh meetings, it remains constant throughout the heat range unlike most most engine oils that can have big swings in viscosity(no need to change grades for Summer and Winter), very compatible with seals, and it fights degredation from heat and oxidation probably better than most all engine oils including the full synthetics. Not to mention its price.

Clutch baskets and shifter forks take lots of abuse. They are pretty much considered consumables.
And yes, perhaps a thicker fluid with a good additive package would allow them to remain alive a bit longer, but how much longer? And at what expense?
If we saw lots of gear failures from such a fluid, I would be the first to say stay away, but we don't.

Sure there is probably a better fluid to use other than ATF, but so often folks who do chose to buy the high-dollar boutique oils for $10-12 a qt. fail to change it out as often as they should. And no matter what fluid is used in a 2t wetclutch, the contamination that collects needs to be changed out fast.
I would be willing to bet good money that if I change out 10 times using $1 ATF, and another guy buys $12 Motorex and changes out 5 times, all other things being equal, my parts wiill mic out better. And I have money for a new rear tire as well. Or at least half of a ring chain. :)

 

[DLHamblin]

The thickness of an oil is not always idicative of how well it can protect.
You could have a 60wt motor oil that makes a fine fluid film, but the instant that fluid film is compromised there must be a quality mixture of barrier additives to take over. If that 60wt oil dos not have a robust additive package, the wear will occur no matter how thick the fluid remained.
No matter how hard an "impact" is, the fluid film has always been comprinised if damage occured from that impact. If the fluid film could stop it, there would be no damage, but it can't...no matter how "thick".

Film strength is the key. And film strength must take into account the total package and not simply one aspect, such as viscosity.

Now you could have a 60wt that was chock full of additives, and may well be a good protector, but there are also things like corrosion protection, foaming, heat/oxidation resistance, etc..that also must be considered. Not to mention that it is a fact that the thicker the fluid, the less energy your dyno will see. If you are racing at the top level this could well be of great importance.

I find that TypeF ATF provides me with all that is really needed for the 2T box. It has additives to take care of the harsh meetings, it remains constant throughout the heat range unlike most most engine oils that can have big swings in viscosity(no need to change grades for Summer and Winter), very compatible with seals, and it fights degredation from heat and oxidation probably better than most all engine oils including the full synthetics. Not to mention its price.

Clutch baskets and shifter forks take lots of abuse. They are pretty much considered consumables.
And yes, perhaps a thicker fluid with a good additive package would allow them to remain alive a bit longer, but how much longer? And at what expense?
If we saw lots of gear failures from such a fluid, I would be the first to say stay away, but we don't.

Sure there is probably a better fluid to use other than ATF, but so often folks who do chose to buy the high-dollar boutique oils for $10-12 a qt. fail to change it out as often as they should. And no matter what fluid is used in a 2t wetclutch, the contamination that collects needs to be changed out fast.
I would be willing to bet good money that if I change out 10 times using $1 ATF, and another guy buys $12 Motorex and changes out 5 times, all other things being equal, my parts wiill mic out better. And I have money for a new rear tire as well. Or at least half of a ring chain. :)

Remember though when talking about "gear oil" they use different standards so a 80W gear oil ins not like a 80W motor oil ("ATF is (in SAE motor viscosity) equivalent to a 10W20 oil. 80W gear oil (AGMA scale, confusing isn't it...) translates into a 40W (10W-40 or 20W-40) SAE motor oil.")

The Bel-Ray isn't much thicker than ATF.

 

[Satch0922]

No theory...just real world testimony. 2005 YZ250 Approx 70hrs on the bike.


I changed my oil last night (back to motor oil from Mobil1 ATF). I only ran ATF in there for two sessions (maybe 2hrs total). When I pulled the magnetic drain plug it was COVERED with metal shavings. Usually when I change the oil (previously ran Mobil 1 Motorcycle oil) there were very few small shavings....pretty normal.

Between the excessive shavings and metal particles on the magnetic drain plug, and the "popping out of gear" issue I had...I would say ATF is not the best choice in protection or performance.

I will let you know how the bike shifts today ....if the popping out of gear issue is gone...then I am 100% confident that ATF is no bueno.

 

[Jaybird]

I just changed the ATF in my 125sx that had about 6 total hours run time on it. Very few particles on the magnet, and the fluid was still red with a slight bit of metalic glisten.

I'm still 100% certain that TypeF ATF is good to go. Been using it for years.

Satch, are there also 70 hours on your clutch???

 

[robwbright]

I've been having clutch issues (notches, one missing fiber plate - both of which were unknown to me until 2 nights ago). These are being resolved as we speak - hopefully before the race this evening.

Anyway, in an attempt to placate the clutch problems (mostly "clunking" when going in gear, a bit of slipping), I tried ATF (not Type F). Seemed to work slightly better than 15w50 Mobil 1.

Then I decided to try the ATF Type F. The clutch began slipping 5 times as bad as before.

Because of my other clutch issues, this story is not a fair statement on Type F ATF. Further, I have no doubt that Type F will protect the tranny sufficiently. However, my clutch worked well enough to get by before the Type F and basically didn't work at all after.

I'll be using either 80 wt gear oil or 15w50 this afternoon.

 

[chillrich]

I used ATF(F) in my YZ250 for a year or two, It shifted really nice and clutch wear seemed minimal. When I started landing jumps with the gas on I took out 3rd and 4th gears. Now the $9 a litre for Motul gear oil seems minor compared to the $800 repair bill. It doesn't shift as nice as the ATF though. I have considered trying a mix of the two but don't want to risk a repair bill again.

 

[Chili]

I used ATF(F) in my YZ250 for a year or two, It shifted really nice and clutch wear seemed minimal. When I started landing jumps with the gas on I took out 3rd and 4th gears. Now the $9 a litre for Motul gear oil seems minor compared to the $800 repair bill. It doesn't shift as nice as the ATF though. I have considered trying a mix of the two but don't want to risk a repair bill again.

Plenty of 98-06 YZ250 with grenaded 3rd gears out there, I'd be reluctant to lay the blame for this common YZ failure on your ATF usage.

 

[Jaybird]

Rob,
Are you getting an aftermarket basket and new springs?

 

[Masterphil]

I just changed the ATF in my 125sx that had about 6 total hours run time on it. Very few particles on the magnet, and the fluid was still red with a slight bit of metalic glisten.

Same here.

 

[Jaybird]

Just as an adder, I do not like to go as long as I did on the last fluid change. I will normally change out the fluid after about two or three tanks of fuel.
ATF is just too darn cheap not to change it out often.

 

[Satch0922]

Jaybird....I have about 15hrs on the clutch. I switced back to motor oil last night. I will change the oil tonight (ran it today and no popping out of gear issue like I had with ATF! YIPPEE!) Maybe ATF works better in some bikes than others. If I change the oil and the metal shavings are back to what I normally experience...then I think I have my answer.

I just wanted to try it after reading people swear by it....but...it no workie for me.

 

[ComradeMikhail]

Just what friction modifiers would those be?
And just what do they have to do with the clutch?

On the back of a bottle of oil should be a circular SAE stamp. On this stamp will be the stats of the oil. Most car motor oil has fricton modifiers, which people are generally told by bike manufacturers to not use in their gearboxes. The way to tell if the oil doesn't have friction modifiers would be to look on the circular SAE stamp, and there should be no writing above or below the SAE in the middle, if I remember correctly. I just buy my Yamalube that says right on the bottle "No friction modifiers". I guess the only reason I could see manufacturers say to not use oil with friction modifiers is because there's something in there that's rough on the clutch, but it's probably not too bad.

It has everything to do with the clutch. You don't want friction on your clutch. Friction=heat. Heat on a clutch=broken disks and other damages. I don't imagine using oil with friction modifiers would hurt much at all, nor would using ATF I'd think. Really, just use what you prefer or works best for you. I use Yamalube in all my bikes.

 

[teknition]

On the back of a bottle of oil should be a circular SAE stamp. On this stamp will be the stats of the oil. Most car motor oil has fricton modifiers, which people are generally told by bike manufacturers to not use in their gearboxes. The way to tell if the oil doesn't have friction modifiers would be to look on the circular SAE stamp, and there should be no writing above or below the SAE in the middle, if I remember correctly. I just buy my Yamalube that says right on the bottle "No friction modifiers". I guess the only reason I could see manufacturers say to not use oil with friction modifiers is because there's something in there that's rough on the clutch, but it's probably not too bad.

It has everything to do with the clutch. You don't want friction on your clutch. Friction=heat. Heat on a clutch=broken disks and other damages. I don't imagine using oil with friction modifiers would hurt much at all, nor would using ATF I'd think. Really, just use what you prefer or works best for you. I use Yamalube in all my bikes.

Actually your last paragraph is totally false.
You DO want friction on your clutch....static friction.....if you didnt have static friction on your clutch it would slip and create heat.

The reason you dont want to use oil with friction modifiers added is because your clutch is soaked in the oil and the friction modifiers do exactly what they were designed to do, make things extremely slippery, which is great for automotive applications on engine bearing surfaces where there is no wet clutch in the picture.

If you'd like an example of a very good friction modifier, slick50 is one, STP engine honey is another....and if you add that to your gear box on your bike i guarantee you will be replacing your clutch due to slippage.

Friction modifiers are the reason you shouldnt use automotive engine oils in a wet clutch environment, bike oils are specifically designed without the friction modifiers and with automotive oils its hit an miss but theres a very good chance that the one you chose will contain them.

Yes ,i know there will be someone here that has used automotive oil in there bike an had no problems whatsoever...and thats fine an dandy...you got lucky...continue using different auto oils an let me know when your clutch starts slipping....which it will....all in due time.

Tek