Transmission oil

[Hosk1956]

While researching for suitable transmission oil to run in my 250ED I have come across the use of ATF on many occasions.
Has anybody had an experience running ATF oil in their transmission?

Wayne from Oz

[olddogs]

There are many transmission/clutch and gearbox oils on the market today that in my personal opinion work better than ATF. I know a lot of guys use it, but I raced a grueling 16 event vintage motocross series in 2016 on a modified Super Combat and noticed accelerated wear on the clutch bushing after just a few races using type F automatic transmission fluid. When I switched to one of the top name gear oils, the bushing lasted much longer. This was the only place I noticed a difference. Shifting and clutch action behaved the same with either ATF or oil. The engine was highly modified and I was heavy for a 125, which could have put extra stress on the clutch, but I have since gone with conventional wisdoms and stuck with gear oil.

[socalhodaka]

KISS, keep it super simple. BelRay 80wt Gear oil from your local shop

[Joe Ormonde]

Honda calls for 10w40 Detergent Motor Oil for my CR500R. I use that in my Hodakas. Joe

[viclioce]

Danny Cooke turned me on to Klotz 30w Gear Oil. Been using it for 5 years now. I order it on eBay and have it mailed to the house! Victor

[Barndweller438]

Just offering information that I have collected over the years. Use at your own risk. I recall that one Hodaka manual I saw recommended SAE30. The minimum viscosity of SAE30 motor oil is 9.3 mm²/s at 100°C. The minimum viscosity of ATF is 5.6 mm²/s at 100°C. The minimum viscosity of Klotz Flex Drive 30 Gear Oil (a 75W/80 gear oil, not “30w”) is approximately 8.02 mm²/s at 100°C. If the manual was accurate and you trust the engineers at Hodaka, ATF falls way short of Hodaka’s recommended viscosity requirement. The Klotz Flex Drive 30 Gear Oil comes much closer than ATF to meeting Hodaka’s recommended viscosity requirement. The viscosity of a 10W40 motor oil is 12.5 mm²/s at 100°C which is considerably higher than Hodaka’s recommended viscosity requirement.

I believe it would be an interesting experiment to determine the highest temperature than the tranny oil is subject to under race conditions on a hot day and measure the viscosity of an SAE30 motor oil at that temperature. Then compare it to the viscosity of other types of oil heated to that temperature.

If SAE30 motor oil is used make sure it meets JASO MA / ILSAC GL-1 / API SH or earlier requirements. (API oils after SH, such as SL, SM, SN, etc., have less gear teeth protecting sulfur-zinc-phosphorus and more clutch slip causing molybdenum.)

[viclioce]

I had an interesting discussion with Lee Fabry about motor oils in Hodaka trannies.

Lee says, when these bikes were manufactured they recommended straight 30 weight motor oil. He says the closest thing to that today is store brand motor oils like you find at auto parts stores, on the shelf withe the store brand name on it. The “cheapest” oil in the store.

Now I don’t know what anyone else thinks about it. Just passing the discussion on. I’ll stick with the Klotz because it has proven itself to me, and, was recommended by a motor builder who’s opinion I trust. Victor

[Barndweller438]

I agree. Even if I found an API SH, SAE30 from Castrol, Mobil, etc., I don't think it would offer the protection of modern 75W/80 or straight weight 80 gear oils. If viscosity is a concern I am thinking the straight 80 might have a little higher viscosity than the 75W/80 since the tranny temp is below 100°C and the multi-grade 75W/80 may still be transitioning.

[viclioce]

The best thing I like about the newer synthetics is their cold pour-ability. They reach their working viscosity at running temps.

Oil discussions are always subject to opinion. So many people don’t bother to investigate what they use and whether or not it meets wrt clutch standards.

JASO/MA standards for wet clutches is a good place to start. Oils marked “For Older Engines” or “Energy Saving” usually have Teflon additives in it which are definitely not kind to wet clutch friction discs.

Regular Motorcycle oils are usually sold only in quart bottles in MC shops, and currently run around $12-15 a quart or more. There are 5w 40 to 15w 40 diesel motor oils out there which meet JASO/MA standards for wet clutches for around $12-14 a gallon in traditional Dino oil, an $20-25 a gallon for full synthetic.

The Shell Rotella and Chevron Delo 400 products are examples which meet or exceed the JASO/MA standards for wet clutches. I’ve been using the Rotella products in my Suzuki VL1500 for over 10 years now. Victor

[Barndweller438]

It appears that you and I traveled the same online learning path to educate ourselves on gear oil. It's funny, how many of the same subjects, such as tranny oil, are discussed on other bike forums too. Rotella T has been my choice of oil for my 4-strokes. An 80 or 80W90 gear oil is my preference to meet the viscosity requirement of my 2-stroke's 20W50 recommendation.

[JPark]

There are three components that are being lubricated - gears, ball bearings, and bushings. The ball bearings don't need anything special, but being steel on steel a good dose of ZDDP [zinc diallyl dithiophosphate, or something like that] helps. That's the magic anti wear stuff that they had to reduce, like lead in gas, in motor oils to keep your catalytic converter from getting galvanized. So motor oils destined for bikes and diesels still have a more reasonable amount in there - for the moment, maybe - but I wouldn't make any long term plans.

Oils destined for gearboxes don't have to worry about that, so will have whatever type and amount of additives appropriate for gears and bearings. 80w gear oil is hard to improve on for the application. ATF would probably work well for the gears and bearings, but the weak spot in the plot is the pinion bushing and, as has been pointed out, it just isn't so good there. That said, Type F is probably the worst ATF version to use, being formulated to keep old '50s Fordomatics from slipping their bands. I don't know if the F stood for Ford or friction, but you have to wonder when you see it on the shelf how many Fordomatics are still needing a top up. ATFs are made for pressurized flow applications so the splash lube situation in a gearbox is pretty different, as is the additive package.

The pinion bushing, if you take a long look at what it is required to do, isn't what should ideally be there. If you're in gear, clutch pulled, revving to the moon, and let her rip, you're going to have maybe 8000 rpm spin on the bushing and a pretty massive gear load on it. This is after you have been centrifuging off any oil that might have found its way in there when the mainshaft gear was last turning and splashing oil its way. Quite how oil is supposed to defy all that centrifugal force [okay, lateral acceleration for the physics guys] is a mystery.

I think the bushing is some sort of sintered iron and is slightly porous, so you have a slight bit of oil that might still be around for what is called boundary lubrication. This is what the additives that they took out to save your catalytic converter were for. It's sort of an if all fails lube situation. To be fair, the bushing was all that was necessary for general puttering on a stock 90 but out of place on a race bike. To compound the problem, when the bushing wears it upsets the mesh on the primary gears and leads to a domino wear chain. I have a completely toothless big gear hanging on the wall, having been stripped clean by the pinion which had been wobbling about on the remaining half of the bushing.

What's worse is that the bushing will wear exponentially; the more it gets loose the more rapidly it wears. The same applies to the other case bushings. Once you exceed the wear limit on pretty much any part, the wear rate climbs and you're headed for disaster, especially if the bike is being used hard.

It would be very nice if the pinion bushing could be a roller like on the later motors. It would be possible to make a hardened sleeve of the same dimensions as the bushing and machine out the pinion to accept either a caged roller or loose rollers. However, the pinion is pretty hard and machining it out accurately would be an interesting challenge. Read tedious and expensive.

The other option is to pull the clutch cover and inspect the bushing regularly. The modification that puts an oil feed groove on the face of the pinion is assuming that oil will want to enter something spinning things off itself, but it's not a bad idea and probably worth doing.

So 80w gear is the logical choice.

[matt glascock]

Great report. One of my racing buddies custom blends his racing oils. Top secret stuff he'll take to his grave to hear him tell it. I'm going to hip him to this report and watch his facial expressions. Nice work. Thank you.