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ATF in a two-stroke gear box

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Posted by: Rich Rohrich---------------------

While I have every reason to believe that ATF is a good alternative to conventional gear lubes it has always left me with a lot of un-answered questions. I came across the following and I thought it was interesting. Even though it doesn't speak directly to the issue at hand, it does indirectly make a case for ATF in a high speed gear box, and addresses to a degree the trade off of viscosity. Just something to ponder when you are stuck in traffic.

From the book LUBRICATION FOR INDUSTRIAL FACILITIES by Heinz Bloch
This is from the section on Gear Lubrication:

The oil furnished to high speed gears has a dual purpose:
Lubrication of the teeth and bearings, and cooling. Usually only
10% to 30% of the oil is for lubrication and 70% to 90% is for
cooling.

For some reason, the high speed gear makes all the compromises
when oil viscosity for a combined lube oil system is determined.
Usually a viscosity preferred for compressor seals or bearings
is selected and gear life is probably reduced. The bearings in a
gear unit can use the lightest oils available, but gear teeth
would like a much heavier oil to increase film thickness between
the teeth.




------------------
Rich Rohrich

"Wisdom is not a product of schooling but of the life-long attempt to acquire it."
               - Albert Einstein


Posted by: techman---------------------

If I read it right, bearings are ok with thin oil but heavily loaded and abused meshing gear teeth (read clutchless shifting) prefer an uninterrupted oil film to prevent damage - and higher viscosity oil provides said uninterrupted oil film layer better than thin oil.  Sounds like using ATF could lead to pitted gear faces and chunked  gear edges.  Sounds right?

techman


Posted by: ToddHawaii---------------------

Interesting.  I wasn't able to aquire the usual Amsoil ATF used in my Husky last weekend and had to use friend's Belray stuff(85w).  The bike shifted fine, but the clutch complained bitterly.  Yesterday I went riding with the Amsoil ATF, and noticed immediately that shifting was rougher!  Had no problems with clutch fading, but could really feel the different in shifting.  I know that Huskys are known for not having the smoothest gearbox...interested in your two cents Rich.


Posted by: SUnruh---------------------

rich,
i understand what you are saying, but how does changing ATF every 2 weeks compare (still looks, feels and smells fresh as it drains) to say 10w40 from any other brand or bel-ray gearsaver that is NOT changed as often?

i'm sure there has to be some compromises along the way unless you are changing the oil as often no matter what type/viscosity it may be.

i've seen guys drain bel-ray gearsaver that was brown.  YUCK!!!  

exactly what viscosity is 85wt that has been burnt?


Posted by: dirt bike dave---------------------

I've always used the manufacturer's recomended 10w/40 in my Kawasakis, but was talking about ATF with a friend.  He commented that  ATF is an excellent detergent and would be good at suspending any particles, such as those from the wearing clutch plates.  Rich, do you know if that is accurate?


Posted by: Ando---------------------

IMHO ATF has a a couple of points in it's favor.  
It is originally engineered to work in a high temperature(~280degrees) wet clutch gear box.  That is what an automatic transmission is.  So its primary design goals are: to cool the transmission, serve as a hydralic fluid in the valve body, lubricate the gears and bearings, and keep particulate suspended to prevent damage.  I feel some compromises are made in the automatic transmission application.  

One is viscosity, ATF has a viscosity in the range on ~7wt so that it can be pumped easily, flow through the valve body, and actuate the clutches and bands.  A viscosity this low is, as has been stated, not that good for film strength.  Compared to a standard transmission, there are no hard shifts in an automatic transmission that necessate the thick strong films that a standard transmission requires.  ATF is definately lacking film strength compared to any gear lube.  Granted, in a motorcycle, on dirt there is nowhere near the shock in the gear box that you would see in an automobile shifting at low speed.  And of course the Borg-Warner series of transmissions(T-5, T-56) all use ATF as a lubricant.  So?  What's the answer?  Does ATF provide "enough" film strength?  For a dirt bike?  I'll answer with an unqualifed maybe, but, gear oil is stronger.

Another big difference is in high temperature stability.  ATF "burns" at a much lower temperature then a heavy weight gear oil.  ATF is designed to work in a cooled thermally stable environment, and it performs so many functions that its additives are a compromise.  You've all seen what happens when you tow on a hill in a truck, the fluid burns and needs replacement.  Standard gear boxes, including your motorcycle's are not externally cooled and can get quite hot with the addition of a clutch and fanning fingers.  The thicker oils resists break down at high temperatures.  This is easy to answer though, if you're draining a fluid that is "burnt" then it is not heavy enough, or changed often enough.  If your ATF is coming out clean and it smells good, then you're cool.

But to get back to Rich's paste, motorcycle gear boxes are quite hardy (YZFs exceptedhttp://208.56.125.175/forums/ubb/wink.gif) and the gears themselves tend not to fail, and in those rare sorry circumstances the failure tends to be a material or design problem as opposed to a lubricant failure.  Thus the final conclusion is to run the thin ATF to minimize pumping losses and maximize horse power to the dirt.  Of course this really doesn't matter to me as I am a four stroker and untill I get a Cannondale, I have to share my engine oil with my gear box. http://208.56.125.175/forums/ubb/frown.gif


Posted by: Kramer---------------------

some generalities to keep in mind:
[ramble mode]

Straight-cut gears, as opposed to helical or hypoid, impact tooth to tooth and shear. They would ideally like thicker oil to cushion and high film strength for the shear.  

Bearings roll and tolerance is tight. They impact and shear on a microscopic level because of imperfections and geometry. Would this suggest that the oil's main function is heat transfer? (thermal expansion makes tight tolerance = no tolerance)


I would also think that a thinner oil would have greater cooling abilities because of a thinner boundary layer, but I don't know how the thermal properties change with viscosity.
[/ramble mode]


------------------
Kramer
member BRC, AMA
98 WR400 Dualsport!


Posted by: mean gene---------------------

A couple of questions: Doesn't 85wt gear oil roughly correspond to 30wt engine oil in viscosity? I know they use different rating systems. I know Mobil 1 ATF is the same viscosity as
7.5 wt fork fluid. Does fork fluid use the engine oil or gear lube rating system or something else entirely. Personally I think this is a overdone issue. Try ATF/F, Mobil 1 15W50, and 85wt-MTL and let your bike tell you the fluid and drain intervals it prefers.

------------------
Gene K
Decatur AL
00 GG300EC




Posted by: KDXIdaho---------------------

Kramer, you took the words outta my mouth.  However, the area that you briefly touched on that I think is critical is an oil's ability to resist shear.  Shear resistance and viscosity generally go hand in hand.  Motorcycle transmissions are generally shear friendly (for your above mentioned reasons), whereas hypoid gears (e.g. differentials) and, to a lesser extent, plain bearing surfaces, require higher viscosities to resist  shear. Resistance to shear is not temperature dependent; higher viscosities have been used in high temp applications due to the fact that viscosity changed excessively in common petroleum oils.  Synthetics are much more stable in that regard and do not require "high" viscosities to resist shear at elevated temps.

------------------
Peace,
KDXIdaho

Quote:
Ignorance is Strength

George Orwell, 1984



Posted by: Ivan Liechty---------------------

Although I can't contribute technically to this thread... let me just say that this is great info and I love that I am absorbing it all.  Not necessarily understanding it yet but each time a little more sinks in.

*sniff* *sniff* I love you guys...


Posted by: Rich Rohrich---------------------

I was hoping this thread would go this way http://208.56.125.175/forums/ubb/smile2.gif.
I'm pretty confident that ATF (especially the synthetics) are more than adequate, and potentially superior to gear lubes for the bearings and the clutch. I'm still unsure of the exact loads on the gearsets at the engagement dogs, and the loads at the gear face, and whether or not ATF is up to the task.**

So I called a friend of mine to see if he can get me these papers
ANSI/AGMA 6010-F97 Standard for Spur, Helical, Herringbone, and Bevel Enclosed Drives**
ANSI/AGMA 9005-D94 Industrial Gear Lubrication**

I'm pretty sure a lot of the remaining gear questions can be answered by these papers, but at $75 a pop I'll have to trade a favor to get them http://208.56.125.175/forums/ubb/smile2.gif
If I come up with anything useful I'll pass it along.

------------------
Rich Rohrich

"Wisdom is not a product of schooling but of the life-long attempt to acquire it."
************** - Albert Einstein <p align=right> 06-12-2000 :Edited
[ By Moderator ]


Posted by: MXSparx---------------------

mean gene,******SAE75W (gear rating) = 10W/40 (crankcase rating)**** thats all I know...

Rich so what your saying is I would be spending my $$$ more wisely if I use ATF instead of the high dollar gear oils?<p align=right>06-12-2000 :Edited


Posted by: Ando---------------------

Rich,
I would imagine that ATF would be up to the loads imposed on it just by its use in the Borg-Warner transmissions.&nbsp;&nbsp;Imagine the load placed upon first gear (2.95:1) in a T-56 launching away from a stoplight in a 3400lbs '00 Camaro with a slipped clutch, 345 ft-lbs of torque and 550mm of rubber to propel it on asphalt.&nbsp;&nbsp;Makes the 30 or so ft-lbs of torque and 120mm of rubber in the dirt kind of pale by comparison.&nbsp;&nbsp;


Posted by: Rich Rohrich---------------------

MotoSparx - I'm not saying you should use ATF, I was just interested in the potential benefits and liabilities associated with it's use, and I thought it might prove to be an interesting point of discussion.

Ando - I'm inclined to agree with you. I'm just not sure about the load distribution in the different applications. When you start digging into the factors that determine the allowable stresses in a spur gear set, I'm amazed that transmissions survive at all http://208.56.125.175/forums/ubb/smile2.gif



------------------
Rich Rohrich

"Wisdom is not a product of schooling but of the life-long attempt to acquire it."
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; - Albert Einstein


Posted by: kawman---------------------

Well, i cant say much on the technical side of things, but i have heard from several people who know a thing or two about gearboxes (tuner included) that type F atf will not hurt your gears at all. I have had no problems with mine running atf so i would reccommend it to anyone....just my 2 cents worth

------------------
88 kx 125
There is no such thing as too much power!




Posted by: bwalker---------------------

I do not think that atf will hurt your tranny. I however do not use it&nbsp;&nbsp;because mobil 1 works better for my application( cr 250).ATF does not seem to work as well in hondas as it does other bikes.It makes my bike shift rougher and causes it to pop out of gear at times.Mobil one seems to make the gearbox run with less noise also. bw


Posted by: WoodsRider---------------------

mene gene and MotoXsparx - According to some information I received from Mobil Oil Co., 85Wwt gear oil has an SAE gear viscosity number. 30wt engine oil has an SAE engine viscosity number. They have approximately the same SUS (Saybolt Universal Seconds) rating at both 40 and 100 degrees Celcius. As a reference, 10W-40wt engine oil is equivalent to 75W-90wt gear oil and 15W-50wt engine oil is equivalent to 80W-90wt gear oil.

Sorry Rich, the table I have does not list ATF, unless you happen to know it's AGMA lubricant number or ISO VG rating


Posted by: tileman---------------------

I would like to ask, we are running 80/90 gear oil in my wifes 00 yz 80
seems to work good so far. I asked on a post on mx tuners about running it
never got a direct answer back.
and also I asked about it being the same wieght as motor oil
one guy said no and the other said he had a friend break off a kick starter
gear....... using the 80/90 gear oil. When I pour out the 80/90 with 10/40
it looks the same, no thicker or different that I&nbsp;&nbsp;see but I am not a oil technician or a chemist. From what I see it seems the same.

We were running the Honda gear oil 80/90 and it seemed the same as the 80/90 gear box oil. The only difference is the cost. Is this right?

Any thoughts would be appreciated.


Posted by: Kramer---------------------

It's likely that the only difference is the label on the bottle.**My employer does a similar thing with paper.**They call it a "value added" product.**What, do you really think _____ (insert your favorite printer or photocopier mfg.) makes all that paper?... LOL<p align=right>06-14-2000 :Edited


Posted by: Rich Rohrich---------------------

It might not be faster, but if there is a maniac with a steel shoe riding it you better move the hell over in the turns.


Posted by: KX250Rider---------------------

Reading these posts has been quite interesting and informative.&nbsp;&nbsp;I have few questions and some comments.&nbsp;&nbsp;
&nbsp;&nbsp;If 10W-40 has the same viscosity as 80wt gear oil why buy the more expensive gear oil?&nbsp;&nbsp;The oil in the transmission has two perform three functions.&nbsp;&nbsp;Prevent metal to metal contact, remove heat, and suspend dirt.&nbsp;&nbsp;Now because a two stroke transmission does not have filter to remove the dirt the suspended dirt will become a problem.&nbsp;&nbsp;Prevention of metal to metal contact is a combination of the oil film strength and&nbsp;&nbsp;stability.&nbsp;&nbsp;Oil is basiscally a massive quantity of long polymer cha1ns.&nbsp;&nbsp;The structure of these chains are such that they do not interlock. This is lubrication,&nbsp;&nbsp;The strength of the chain film strength.&nbsp;&nbsp;The factors affecting this capability are heat and intermolecual shear.&nbsp;&nbsp;Heat causes the oil to expand.&nbsp;&nbsp;When a fluid expands the amount of molecules in a given volume decreases.&nbsp;&nbsp;Result: the viscosity decreases and the protection of an oil film cushion also decreases. Now if the heat becomes too high the oil becomes volital (spelling).&nbsp;&nbsp;The polymer chain breaks down then it gases off and you are left with the parafins and asphaultics in the oil.&nbsp;&nbsp;The wonderful black tacky stuff.&nbsp;&nbsp;
&nbsp;&nbsp;Shear is the second factor.&nbsp;&nbsp;The more the fluid is cut by a rotaing element the more force is applied the long polymer chain.&nbsp;&nbsp;Eventually the polymer chain fatigues and breaks.&nbsp;&nbsp;There goes the film strength.
&nbsp;&nbsp;Lastly the highest contributing factor to wear is dirt. Dirt (can we say clutch particles) does not decrease the film strength or lubrication capability of the oil what it does is displace the oil.&nbsp;&nbsp;Dirt suspended in the oil takes up volume. So again in a given quantity there is less oil.&nbsp;&nbsp;A dirt particle is also much greater in size than a oil molecule and it has sharp edges.&nbsp;&nbsp;So as the gears mesh the dirt gets smashed between the gear faces the sharp edge of the dirt displaces the oil.&nbsp;&nbsp;Now we are getting wear.&nbsp;&nbsp;
&nbsp;&nbsp;So what to do?&nbsp;&nbsp;Change the oil often!&nbsp;&nbsp;Give it a break! Get rid of the Dirt!&nbsp;&nbsp;If it is black or silver (aluminimum clutch plates) you are looking at dirt.&nbsp;&nbsp;Think about it. The engine oil that comes in with the gas is clean and every rotation of the crank expells some oil (there goes the dirt and the broken down oil molecule) and brings in fresh oil.&nbsp;&nbsp;Will ATF do work?&nbsp;&nbsp;Yep. Will the cheapest 10w-40 from Wal-Mart work? Yep.&nbsp;&nbsp;Will the high dollar synthetic do this? Yep.&nbsp;&nbsp;Which one is better?&nbsp;&nbsp;In my opinion if you never run it long enough to break down, get full of dirt and it has the correct viscocity and heat index for the task at hand all will work fine.&nbsp;&nbsp;Some maybe better but all will provide the needed protection.&nbsp;&nbsp;&nbsp;&nbsp;
&nbsp;&nbsp;
A final work of caution.&nbsp;&nbsp;Be careful of the marketing of Synthetic oils.&nbsp;&nbsp;What is a Synthetic oil?&nbsp;&nbsp;A man made lubricant?&nbsp;&nbsp;Well some times yes.&nbsp;&nbsp;But it can also be a full petroleum based oil with the parrafins removed, or an additive.&nbsp;&nbsp;Not all that much different from a regular oil. But if you put an regular oil in and change it before it becomes dirt loaded and broken down it will work fine.&nbsp;&nbsp;Be careful of extreme pressure additives.&nbsp;&nbsp;They are great for gears to prevent metal to metal contact, but in a clutch they prevent fiber plate to steel plate contact.&nbsp;&nbsp;

------------------
1991 KX250
1998 1200 Bandit S
A bike, a sunny day and no agenda; Perfect




Posted by: Ando---------------------

KX rider- I’m with you.&nbsp;&nbsp;Change your oil before it is broken down for best service life.&nbsp;&nbsp;Just a couple of points though.

It is true that in the typical SAE classification tests (ASTM D 445, kinematic viscosity at 100 degrees C) that gear oils and engine oils exhibit similar viscosities, these conditions are not representative of a real world engine/gearbox environment.&nbsp;&nbsp;A much better test that simulates more closely a real engine/gear environment is a high temperature/high shear test (HT/HS such as ASTM D 4683 or 4741 at 150 degrees C in high shear).&nbsp;&nbsp;Standard multi-grade engine oil typically is composed primarily of a base stock that is the viscosity of the lower number, like the 10 in 10W-40, and polymers are added to increase the viscosity to the higher 40 weight at 100 degrees C.&nbsp;&nbsp;Under high shear conditions, such as in gears or in bearings the polymers behave in a non-Newtonian fashion and the oil exhibits a viscosity somewhere between the low and high numbers, the 10W-40 will act like a 20 weight.&nbsp;&nbsp;The higher the temperature and the higher the shear the low the exhibited viscosity.&nbsp;&nbsp;Gear oils use a heavier and higher viscosity base stock, and gear oils show much less viscosity drop in the HT/HS test and predictably perform better in field testing in gearboxes.&nbsp;&nbsp;However like I have stated before I don’t feel the loads experienced in a motorcycle gearbox necessarily warrant a heavy gear oil over a lighter fluid like engine oil or even ATF.&nbsp;&nbsp;Rich might be looking into the type of loads that our gears are seeing, and with that info we can determine how heavy an oil we need to run, but with most manufacturers recommending a multi-grade engine oil, most of the heavy thinking has already been done for us.&nbsp;&nbsp;

One other thing: Friction Modifiers are the additives that bond to the surface of flywheel and clutch disc.&nbsp;&nbsp;Friction modifiers are typically long chain organic acids that bond in a polar fashion to a metallic surface.&nbsp;&nbsp;The organic chain side of the molecule stands off of the surface and holds a layer of oil.&nbsp;&nbsp;These additives protect when the oil wedge is lost by keeping that bit of oil in place.&nbsp;&nbsp;Extreme pressure additives contain phosphorus, sulfur and chlorine.&nbsp;&nbsp;The way these work is that when the oil film is over loaded and there is actual metal to metal contact, the additives weld themselves to the high spots (asperities) that are hitting together.&nbsp;&nbsp;The additive welded to the metal is quite weak and breaks off easily.&nbsp;&nbsp;This causes wear, but it makes the surface more smooth and “broken in”.&nbsp;&nbsp;

This once again is a simplification of a pretty complex topic, but the more discussion and understanding the better.



Posted by: Vic---------------------

Do I sense that Eric is making sport of Rich's quest for TT-R 125 power? http://208.56.125.175/forums/ubb/smile2.gif


Posted by: Ando---------------------

I think Rich has the RM and Eric has the TT.<p align=right>06-15-2000 :Edited


Posted by: Rich Rohrich---------------------

Actually the TTR125L is mine as well. Eric is picking it up for me. The mighty 90 RM150 will get sold, and a super clean 96 RM125 with full MX-Tech suspension will take it's place.
Eric and I sort of share the RMs, but seeing as how he RARELY gets to come ride, I'm the one who gets the majority of the RM seat time while I'm finishing my YZ444.
I ordered the BBR springs for the TTR so I'll let you guys know how they work out. I'll be getting my steel show from Ken Maely next week so Okie, Pokie and Eric better just watch out in those flat hardpacked corners http://208.56.125.175/forums/ubb/smile2.gif

I'm a little behind in my fun projects but I'll get some TTR simulation info to you real soon Vic.
I see a little blue fire breather in my future. hehehehehehe

Have Blue baby!!!!<p align=right> 06-15-2000 :Edited
[ By Moderator ]


Posted by: KX250Rider---------------------

Ando:
&nbsp;&nbsp;Good post. To further add to this.&nbsp;&nbsp;I have talked to three friends of mine. Two are certified motorcycle mechanics and another own a bike repair shop for the last 20 years.&nbsp;&nbsp;They all stated, run what the manufacture recommends and at the recommended change intervals.&nbsp;&nbsp;Stay way from full synthetic automotive oils and oils with anti-friction additives. These were not designed with a wet clutch in mind.&nbsp;&nbsp;If you want to run synthetic run a motorcyle oil specific one.&nbsp;&nbsp;The most damage they see in gear box's are from use of the wrong oils and not changing them. They all stated cases where the guy was complaining about shifting and clutch problems.&nbsp;&nbsp;They pulled the drain plugs and what came out was more like black goop then oil.&nbsp;&nbsp;They all stated do not run ATF.&nbsp;&nbsp;The viscosity is too low and that it is more similar to a hydraulic oil than a motor oil.&nbsp;&nbsp;They did state that a motorcycle oil is a little better because it contain detergents, these were removed from regual oils because of the quanity used, enviromental impact and processing costs, to help clean and they have an anti-foam additive.&nbsp;&nbsp;A regular motor oil will work fine but it is not designed to whipped up by the gears.&nbsp;&nbsp;&nbsp;&nbsp;
&nbsp;&nbsp;While I had them I asked a few other questions.

Oil drool out the exhaust.&nbsp;&nbsp;This is normal even it the engine is properly jetted.&nbsp;&nbsp;The unburnt oil leaves with the exhuast gasses.&nbsp;&nbsp;This means there is sufficient oil for lubrication.&nbsp;&nbsp;It is a two stroke it will leave oil residue.&nbsp;&nbsp;Even it the bike simulates a bug fogger (like the old yamahas that ran castrol at 20:1) as long as it is running correctly what is the problem.&nbsp;&nbsp;A little oil drool compared to the dirt, mud and muck on a dirt bike what is the difference.&nbsp;&nbsp;If you don't want it buy a four stroke.

Two stroke oils and ratios.&nbsp;&nbsp;Again run what the manufacture states the oil and ratio. If you go synthetic then run it at 50:1.&nbsp;&nbsp;Brand of synthetic?&nbsp;&nbsp;Any of them are good just don't cross caster and regular. The don't like each other.&nbsp;&nbsp;All of them stated that if you are running the engine like a 125 MX bike then richen up the mixture.&nbsp;&nbsp;24-32:1 petroleum grade, 40:1 synthetic.&nbsp;&nbsp;Oil is cheap compared to engine parts.&nbsp;&nbsp;Unless you have alot of money to change parts.&nbsp;&nbsp;

Soaking new clutch plates in oil.&nbsp;&nbsp;They never do it.&nbsp;&nbsp;They put the clutch in, start the bike in neutral and pull and hold the clutch lever to the bar until the bike warms up.&nbsp;&nbsp;This seperates the plates and allows the oil to flow to the plates. Never had a problem.&nbsp;&nbsp;The plates are not going to soak up any more oil soaking than by being ran in the bike.&nbsp;&nbsp;Plus they are a friction plate.&nbsp;&nbsp;

Lastly they all asked why I was asking these questions because I follow the manufacture recommendations.&nbsp;&nbsp;I told them why and they had two comments.&nbsp;&nbsp;Follow the manufacture recommendations because they designed built and tested the bike.&nbsp;&nbsp;Second (sarcasiticly) these are the things that keep them in business.&nbsp;&nbsp;

------------------
1991 KX250
1998 1200 Bandit S
A bike, a sunny day and no agenda; Perfect




Posted by: Rich Rohrich---------------------

http://dirtrider.net/ubb2/biggrin.gif http://dirtrider.net/ubb2/biggrin.gif http://dirtrider.net/ubb2/biggrin.gif


Posted by: Ando---------------------

There has been much discussion about the use of automotive oils in wet clutch applications.&nbsp;&nbsp;Please read this article written by the moderator.&nbsp;&nbsp;
http://www.ericgorr.com/mototech/mototech_june_1999.htm

I am of the opinion that it is the friction modifiers that are found in "energy conserving" labeled engine oils that cause clutch problems, and I am currently trying to determine just what constitutes an EC rating.




Posted by: Rich Rohrich---------------------

There are lots of new members and this is a subject that comes up fairly often, so I'm bumping this back to the top.


Posted by: Shaw520---------------------

There is alot of good technical info getting tossed around hear, so I doubt I can ad anything logical,(technical)
On a more basic observation, I have noticed that muti-viscosity oils arent what they claim. 20w-50w is supposed to be 20w at it coolest operating temp, and 50w at it highest temp. In reality I know that the viscosity of oil gets thinner as the temps go higher, pour some in the frying pan and watch it thin as it gets warmer. For this reason, I tend to run all of my vehicals at the highest recomended (and mostly beond) viscosity.
All of my Chevy P/U's spec 10w-30w, (stuff gets like water when its hot), I run 20w-50w in them all and never had any premature wear.
This post turned out longer than I expected, sorry.


Posted by: wrench---------------------

Quote:
Originally posted by KX250Rider:
Ando:
****They all stated do not run ATF.**The viscosity is too low and that it is more similar to a hydraulic oil than a motor oil.**They did state that a motorcycle oil is a little better because it contain detergents, these were removed from regual oils because of the quanity used, enviromental impact and processing costs, to help clean and they have an anti-foam additive.**


Hmmm ..... Last time I checked, ATF is high in detergent levels.
Also, if you ever take an automatic transmission apart you will see that it is full of shift drums and gears that have a series of "wet clutches" very simillar to what your bike clutch is. Instead of manually shifting the gearsv (via hand or foot), a hydraulic valve body is used to route the fluid under pressure to the proper clutch pack to be applied for the desired gear needed.

This is a very basic overview, but it should be good enough to make the point.

I have been running the Mobil 1 ATF (synth.) for the last couple of Hare Scrambles (due to the cold weather), instead of the usual M1 15w50. I have not experienced any problems with clutch performance. Not to mention that the "notchy" shifting went away as MXTuner said it would.
When I changed the fluid it was still red!


wrench




Posted by: Reeko---------------------

Quote:
Originally posted by Shaw520:
On a more basic observation, I have noticed that muti-viscosity oils arent what they claim. 20w-50w is supposed to be 20w at it coolest operating temp, and 50w at it highest temp. In reality I know that the viscosity of oil gets thinner as the temps go higher, pour some in the frying pan and watch it thin as it gets warmer.

Shaw,
20w-50 does not mean that it is 20w at low and 50w at high temps, this is inpossible.
It means that at temp x (low temp), the 20w50 has the same viscocity as a straight 20w at that temp. At temp y (high temp) the 20w50 has the same viscocity as a straight 50w at that same temp, it is still thinner than at cold temp.



Posted by: Coop---------------------

Reeko, I have read in a motorcycle mechanic book that: Multi-viscosity oils contain additives that allow the oil to thicken at higher temperatures to improve the viscosity index. The viscosity index is the number used to indicate the consistency of the oil with changes of temperature. An oil labeled 10W30 is a 10 weight oil at 0 degrees and a 30 weight at 210 degrees.

Coop


Posted by: Shaw520---------------------

Reeko, whats the temp of x & y ?

If you take a quart of 10-40 dump it in your bike at room temp(70de), then ride the bike for any given amount of time, then dump the oil right away, obviously warmer temp (180-220 de) it will be thinner, than when you put it in.
I think "muli-viscosity" should read more like " minor viscosity change per temp variation" or something like that ??


Posted by: Reeko---------------------

Shaw,
I agree. A multi viscocity oil will not have as much change in viscocity over a temperature change as a straight weight oil.

Not sure what temps they measure the viscocity at.


Posted by: Coop---------------------

Reeko and Shaw520, Did either of you read my post? If that book isn't right, someone should notify them, because it is used in a motorcycle mechanic course. They measure multi viscosity at 0 and 210 degrees according to that book.

Coop


Posted by: Reeko---------------------

Coop,
Quick searches for motor oil FAQs I found this quote....
in this site...... http://www.atis.net/oil_faq.html
------------------------------------------
Viscosity is a measure of the "flowability" of an oil. More specifically, it is the property of an oil to develop and maintain a certain amount of shearing stress dependent on flow, and then to offer continued resistance to flow. Thicker oils generally have a higher viscosity, and thinner oils a lower viscosity. This is the most important property for an engine. An oil with too low a viscosity can shear and lose film strength at high temperatures. An oil with too high a viscosity may not pump to the proper parts at low temperatures and the film may tear at high rpm.

The weights given on oils are arbitrary numbers assigned by the S.A.E. (Society of Automotive Engineers). These numbers correspond to "real" viscosity, as measured by several accepted techniques. These measurements are taken at specific temperatures. Oils that fall into a certain range are designated 5, 10, 20, 30, 40, 50 by the S.A.E. The W means the oil meets specifications for viscosity at 0 F and is therefore suitable for Winter use.

Multi viscosity oils work like this: Polymers are added to a light base (5W, 10W, 20W), which prevent the oil from thinning as much as it warms up. At cold temperatures the polymers are coiled up and allow the oil to flow as their low numbers indicate. As the oil warms up the polymers begin to unwind into long chains that prevent the oil from thinning as much as it normally would. The result is that at 100 degrees C the oil has thinned only as much as the higher viscosity number indicates. Another way of looking at multi-vis oils is to think of a 20W-50 as a 20 weight oil that will not thin more than a 50 weight would when hot.
---------------------------------------

So, It seems that the info you have is not really wrong. I think the additives do thicken as temp goes up, but overall this reduces the overall thinning at high temp.

------------------
Reeko
(Now a Red Rider)
01CR250 (Me)
00XR100 (Wife)


Posted by: Coop---------------------

Thanks Reeko. I was worried I was wasting my time reading a book that was full of bs.

Coop


Posted by: MX Tuner---------------------

KX250rider,

I know way too many certified motorcycle mechanics and shop owners who are clueless. In fact most of the bike delaer mechanics recommend factory recommended lubricants because thats what they were taught in that particular manufacturers school. But look at the gear oil recommendations in your two stroke owners manual. They recommend a motor oil that meets an automotive spec.

I go into about one bottom end a month. All lubricated with everything from Wesson oil to axle grease. I've never seen a lubrication related failure of a gearbox (bearings or gears) when the oil was changed at a reasonable interval, regardless of the oil used. I've seen failures from bent parts and from contamination but not from the wrong oil. Your tech friends are full of it. If they believe what they told you, they're only fooling themselves.

------------------
MX Tuner
mxtuner@mindspring.com


Posted by: Rich Rohrich---------------------

This is a good thread and is worth bringing back up to the top.


Posted by: cp380sx---------------------

Quote:
Originally posted by MX Tuner

I go into about one bottom end a month. All lubricated with everything from Wesson oil to axle grease. I've never seen a lubrication related failure of a gearbox (bearings or gears) when the oil was changed at a reasonable interval, regardless of the oil used. I've seen failures from bent parts and from contamination but not from the wrong oil. Your tech friends are full of it. If they believe what they told you, they're only fooling themselves.

------------------
MX Tuner
mxtuner@mindspring.com


I second this. I have had 30 bikes over the years and I have run all types of automotive gear oil in the trannys and have never had a gear or bearing failure. I usually use the cheapest 10w40 and it's never caused a problem. Keep in mind that I run my bikes very hard and I'm a notorious clutch abuser. Almost any oil will do an acceptable job as long as it is changed often.


Posted by: Jaybird---------------------

I have to also concur with MXTuner's thoughts on this topic. We could go on forever rehashing the viscosities of oils and the additives to eliviate oxidation as well as film strengths. Bottom line to me is, any oil should be fine in a dirtbike for protecting the gears, up to a certain point. As decribed before, contaminants and heat can change the effects of the film. IMO, to get away from the problems of thermal breakdown and contamination one simply needs to increase the frequency of replacement. I also beleive that ATF will also protect our gears sufficiently, but with one added plus....our clutches preffer a fluid like type F ATF.
My limited knowledge leaves me to believe that the best scenario would be to use Type F ATF and change out frequently and one will enjoy adequate gear protection as well as experiencing clutches that perform properly.


Posted by: fishhead---------------------

Borg Warner specs atf type "a" in the marine gear series 70,71, 72, and 73 with planetary gear reductions and these typically see a lot of hours between service and oil temps of 180F. I seem to recall the 73 series was good for up to 500 cu in diesels and the 70 series up to 300 cu in gas engines. In workboat applications these gears were extremly reliable and would last several engines or up to ten years. Service would conssit of clutch packs and a thrust bearing if needed. I never heard of a gear failure in 30 years.


Posted by: Flummo---------------------

I use ATF because it gives the clutch better grip, if i use a standard transmission oil it slips but now it works just fine. As someone wrote: a automatic transmission is full of clutches. So the ATF is made to give the clutch good grip, and I have never had any problems with wear on the bearings or gears. And this bike has much more power than Honda ever intended...


Posted by: TM-Frank---------------------

Ok, I read through this complete thread and didn't find any information abourt the above mentioned specs.

In another thread in the "Mods and Performance Forum" some people said that Type D and Dexron II or III (is this the same?) will harm the clutch and only Type F shall be used.

As far as I know Dexron II is a GM specification and Dexron III is just a newer version of this spec.

On the rear fender of my TM 250 Enduro was a sticker, that told me to use Agip Dexron II (for those who don't know, Agip is an Italian oil brand. I don't know if it's sold in the US).

I am using Dexron II and III from various oil brands in the TM's gear box without any problems since '96. Neither the clutch nor gears nor the shifting mechanism failed in these 5 years.

The friction plates of the TM 250 engine are absolutely identical to those in a Honda CR250. I was told they come from the same japanese supplier.

I never saw any other ATF Type than Dexron at the gas stations here in Germany and I don't even know where to get Type F.

Currently I believe, based on the above described experiences, that it doesn't matter which ATF (or gear oil) you use. I agree with the other people here who said that change intervals are much more important.

So can someone please shed some light onto this Type F - Type D thing?

Frank


Posted by: Jaybird---------------------

If someone knowlegable does weigh in to asnswer TM-frank, please add info on type FA ATF. I've been wondering about it.


Posted by: BRush---------------------

Quote:
Originally posted by Jaybird
If someone knowlegable does weigh in to asnswer TM-frank, please add info on type FA ATF. I've been wondering about it.


I'm not that person , but I remember an old thread that delved into this a bit. Look for Ando's post about halfway down the first page:


http://dirtrider.net/forums3/showth...=&threadid=5269


Posted by: yardpro---------------------

type f was ford trans. lube that could not be used in chevy's. dextron111 can be used in either.


Posted by: Jaybird---------------------

LOL....ok yardpro, now distiguish between type F and type FA.


Posted by: TM-Frank---------------------

FA is obviously For All gearboxes!


Posted by: the Eel---------------------

I lost my gearbox on ATF type F. Never again.


Posted by: Jaybird---------------------

Just what were the conditions surrounding this loss? What brand of ATF was it.
Inquiring minds want to know.

I'm betting lots that if you lost your gearbox it had nothing to do with ATF, unless it's been in that gearbox for a couple of years.


Posted by: the Eel---------------------

A generic brand and I changed the oil religiously.


Posted by: bwalker---------------------

What part failed?


Posted by: the Eel---------------------

A broken tooth (dog ?) which then took out 4 countershaft gears and 2 mainshaft gears.


Posted by: bwalker---------------------

What ,Makes you think that the ATF caused the failure? If the tooth actually sheared off it could be a metalurgy issue, not a lubrication problem.


Posted by: smokeyhaze---------------------

Eel - could you clarify? Was it a gear tooth or an engagement dog?


Posted by: the Eel---------------------

a dog


Posted by: spanky250---------------------

A broken dog is not lubrication related.

The only tranny failure I have ever had in a dirt bike tranny was while using Spectro 85 W gear oil. The third gear drive-gear sheared in half, certainly not because of lubication failure.


Posted by: the Eel---------------------

That's good to know. I'm still gonna stay from auto type oils anyway.

Thanks for all the info.

Also, here is a quote from another board which relates directly to my problem. It talks about the different trannies in the Husky WR's and Husky CR's -

"I recently talked with a dealer who's rep just got back from Italy. He said the WR got a new gearbox similar to the CR's cause of complaints about them. There should be relatively little difference between the two this year, except gear ratios of course."

Sounds like maybe the gearbox was an issue on these WR models. Just my luck I guess ...


Posted by: Tantrum---------------------

Quote:
Originally posted by Rich Rohrich
There are lots of new members and this is a subject that comes up fairly often, so I'm bumping this back to the top.


Again, this is getting moved back into view. Amazing info gentlemen.

B.


Posted by: Lew---------------------

I have read all the post and am a little unclear. is there a significant difference between type f and dexron 2 or 3. My local auto parts store only has the dexrons.
Thanks
Lew


Posted by: spanky250---------------------

I believe that the Dexron fluids are more "slippery" than type F, probably not a good thing for the clutch materials used in a bike clutch.


Posted by: Kramer---------------------

I can't tell you the difference between type F & FA.

Type F was an old Ford spec used at least through the 1970's.

Dexron is GM.

Mercon is a later Ford spec, similar to Dexron spec.

The design of the auto transmission is what dictates which oil it needs.

The type F does allow more friction for a quicker shift (clutch engagement).

Using Mercon/Dexron in a trans that calls for F will cause more slip than normal. The reverse is also true, F in a newer trans will give you quicker/firmer shifts.

The more a clutch slips, the more it wears.

Now, which would you like in your gearbox?


Posted by: BRush---------------------

I thought this (long) message thread had a pretty good discussion about the differences between type F and Dexron/Mercon


http://dirtrider.net/forums3/showth...=&threadid=5269


Posted by: spanky250---------------------

Quote:
Originally posted by BRush
I thought this (long) message thread had a pretty good discussion about the differences between type F and Dexron/Mercon


http://dirtrider.net/forums3/showth...=&threadid=5269
The link doesn't work...


Posted by: marcusgunby---------------------

Spanky just fill in the missing bits from the address line. Whats surprising is how many members dont post anymore-what happened to MX Tuner i liked debating with him.


Posted by: BRush---------------------

Quote:
Originally posted by spanky250
The link doesn't work...


Try it now:

http://dirtrider.net/forums3/showth...=&threadid=5269


Posted by: TM-Frank---------------------

I found this aticle, where the differences between Dexron and TypeF are explained. CLICK HERE!
The article was written for a website of Citroen D/S enthusiasts and it describes the various fluids that can be used in the hydraulic suspension system of that car.
I asked a guy who works at VOLKSWAGEN's Automatic Transmission R&D what he thinks about the TypeF/Dexron story.
He says that it's very unprobable that Dexron causes slippage in a dirt bike clutch. He said the friction plates in motorcycle clutches are of a much higher quality than those in a car AT anyway and therefor a modern motorcycle clutch doesn't need those friction enhancers, that TypeF contains.
He remarked that fourstroke dirtbikes (which use basically the same clutches as the twostrokes) have their gearboxes lubed with engine oil, which doesn't contain any friction enhancers and their clutches don't slip. Sounds logical to me.
As I said before: I'm using Dexron for nearly six years in my bike and I never had slippage problems. I toasted one set of clutch plates last year in a mud bog, but that wasn't oil related


Posted by: motometal---------------------

I'm not sure that I agree that a quicker shift wears less material off of the clutch. Less friction=less wear and less heat. Heat and friction are what wear the clutch fiber material.

Note that many newer car transmissions "slide" into gear, especially second gear.

It would seem to me that half the friction for twice the time would equal twice the friction for half the time, etc. (negating the effects of heat buildup).

What do you think, guys?


Posted by: Kramer---------------------

I'm not sure you can neglect heat though. Speaking in terms of auto trans.

Heat is usually named as the major factor in faliures.

In terms of a bike it makes me think. I would have to say that since you are modulating the clutch by hand, the fricion in any circumstance is the same. Same as saying you make it slip when you want it to.

The difference comes that last little bit when you have full traction, power, and clamping force, all while there's still relative motion between steels (Al) and fibers.

It's the same difference as the slip you'd get with weaker springs.

So, I'll agree that friction x time is where the wear is done. I'm just not sure about the linear relationship between force and friction. And exactly what is bearing the shear in what proportions. (We're not talking about dry friction). That's where I run out of resources. :think


Posted by: Kramer---------------------

Oh, moto, I almost forgot. In the case of a car w/o a lockup converter a firmer shift in the clutch will make a difference. More of the slip will be transferred to the converter and absorbed there.


Posted by: motometal---------------------

good points. hmmmmmm....


Posted by: Fark---------------------

t


Posted by: Fark---------------------

I was once told that you cannot use type F on an auto trans that has been already been subjected to Dextron/Mercon. Was told this by a GM tech though I have found inacuracies in some of the things he's shared.

By the way, TTT. Outstanding thread.



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