ATF In the Gearbox

I know the use of ATF in the Gearbox is divided, some folk consider that it provides less internal drag and gives a lighter gear change, others that it gives better clutch action
And on the other side folk feel that the box was originally specked to use 75/90 gear oil or alike so this is what should be used ....
Well i recently purchased this product from Opie oils, and very interested to read that the specification of it match that of a GL4 gear oil

There may be short comings in the product you mention , why not just use the gear oil specified in our service manual , I never found a good reason to experiment with my GB oil , G box always worked exactly as it should ….

I have used 75 wt as was speced for Saab 99, 900, etc. in my Commando. It does have a lighter feeling shift, especially in cold weather. I note that for the AMC boxes from '57 on, the factory Matchless manual specifies 50 wt except for winter in Canada where the spec is 30wt .

Some Volvos with electric overdirve specified ATF, maybe the standard ones also. I think what ever you use not be prone to foaming. My Chevrolet truck 4-speed transmission shifted much better when I abandoned they EP90 Hypoid gear oil in favor of the specified 90 wt mineral oil. Of course AMC gearboxes have no syncros to be concerned about.

Thomasa said:

I note that for the AMC boxes from '57 on, the factory Matchless manual specifies 50 wt except for winter in Canada where the spec is 30wt .

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Yes, but they would be engine oil viscosity ratings as engine oil would also have been used in the gearbox at that time.

Craig said:

There may be short comings in the product you mention , why not just use the gear oil specified in our service manual , I never found a good reason to experiment with my GB oil , G box always worked exactly as it should ….

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Hi Craig (and others).
I hear and understand your point of view regarding using lubricants originally specified by the manufacturer.
However I respectfully suggest that perhaps a good case can be made for changing to other oils in som circumstances on the basis that there has been major advances in lubrication technology in the past half century. Nortons ( and British bikes in general) definitely had their feet stuck in the clay of the past even when new. I doubt they were embracing the latest oil technology even if available but rather tended to stick with what was known and expected by their customers.
Whether ATF is superior or even suitable, I cannot say and I’m not about to change to it until such time as it has resounding approval from this members of this forum but I will say this, ATF is often found in the most demanding environments and obviously performs well. Personally I find the gear change on my Commando rather slow, heavy and antique in feel in comparison to other bikes including my Triumphs. Anything that improves the change without adversely affecting reliability would be a good thing.
I should point out we mostly use ATF in our primary transmission although I don’t believe it was originally special.
Lastly, I must confess I don’t truly understand the differences between the properties of ATF and conventional hypoid gear oil and why some are specified in certain situations. superficially they appear so different it is hard for a non expert to understand how they can perform a similar function.
Obviously ATF is better suited to wet clutch operations. As an interesting aside I note the entire transmission, differential and hydraulic system in my antique Massey Ferguson 88 tractor uses ATF where nearly identical models use conventional lubricants, the only difference is the 88 has a wet PTO clutch. The point being the two lubricants are obviously far more interchangeable than we might think.
In humour, I note the oil filler cap on my Humber Imperial is clearly placarded ‘USE ONLY SHELL OIL’ but I don’t think anyone would suggest that Shell is the only suitable manufacturer of lubricants.
just a thought
Al

ATF was a ' reduce friction ' trick , to reduce losses . In TR 500s & 750s at Daytona , according to the Perry Chief Mechanic and Tuner .

In automobiles , the SYNTHETIC is way better in power steering & T 5 etc gearboxes . The ATF is specified .
Needle rollers & synchro oilways malfunction on gear oil there , as theyre NOT designed for it .

Unfortunately ! ? etc , theres been comments on Synthetic GEAR OIL that it disolves some bronze bushes .
Wonder if the synthetic ATF does the same ?

So , ATF is really a race trick . Hot Weather high load & the lack of ' high pressure ' aditives might see the somewhat marginal gears
cry enough . Like pukekohe Closing , Perry ' Retireing ' . etc , NORTON continually uprated the gear profile & material in their gearboxes .
Which is why a 60 Dommie 2nd cog & layshaft dropped straight in a Commando . Er . . .

Wonder what advice the aftermarket RACE 5 & 6 speed trans manufactures would have on the OIL .

FWIW, I switched from the spec gear oil to ATF a couple of years ago. I found the shifting to be MAYBE slightly lighter though it could have been my expectation that made it feel lighter! I have always said the OEM Norton gearbox was maybe the best of all the motorcycles I have owned as far as shift feel is concerned so it wasn't that I thought it needed improvement.

I ran the ATF for a week and then drained it and installed the spec gear oil.

I just wasn't comfortable with ATF in there. That's the only reason. I realize that there are car manual gearboxes that specify ATF - I've owned a couple of them. But I just couldn't get into a "feel good" frame of mind re ATF in the Norton gearbox. TBF, if the gearbox with OEM gear oil had been notchy/troublesome and had the ATF made a noticeable improvement, I might have come to a different decision. But as it was, with nothing gained, I was more comfortable with gear oil than ATF in that application.

OTOH, I'm quite comfortable with ATF in the primary chain case instead of the spec oil. Go figure...

MexicoMike said:

FWIW, I switched from the spec gear oil to ATF a couple of years ago. I found the shifting to be MAYBE slightly lighter though it could have been my expectation that made it feel lighter! I have always said the OEM Norton gearbox was maybe the best of all the motorcycles I have owned as far as shift feel is concerned so it wasn't that I thought it needed improvement.

I ran the ATF for a week and then drained it and installed the spec gear oil.

I just wasn't comfortable with ATF in there. That's the only reason. I realize that there are car manual gearboxes that specify ATF - I've owned a couple of them. But I just couldn't get into a "feel good" frame of mind re ATF in the Norton gearbox. TBF, if the gearbox with OEM gear oil had been notchy/troublesome and had the ATF made a noticeable improvement, I might have come to a different decision. But as it was, with nothing gained, I was more comfortable with gear oil than ATF in that application.

OTOH, I'm quite comfortable with ATF in the primary chain case instead of the spec oil. Go figure...

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I've tried a 50/50 mix ,thinking I can only be half wrong,
But chickend out and went back to Castrol EP 90

Matt Spencer said:

Unfortunately ! ? etc , theres been comments on Synthetic GEAR OIL that it disolves some bronze bushes .

Wonder what advice the aftermarket RACE 5 & 6 speed trans manufactures would have on the OIL .

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As I've understood it, it is not the oil, mineral or synthetic that is harmful to bronze bushes, it is the additives in some GL-5 oils that hurts.

One of the most used 5 and 6 speed race boxes is TTI.
They specify MOTUL gear 300 75W90 GL-5 which is not harmful to yellow metal accoring to the data sheet.
Or CASTROL Syntrax 75W90 GL-5.

Craig said:

There may be short comings in the product you mention , why not just use the gear oil specified in our service manual , I never found a good reason to experiment with my GB oil , G box always worked exactly as it should ….

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Reading many posts on the subject, folk here have used ATF in its many variant for years (like myself) with no ill affects what's so ever
Personally i fine the change as slick as any modern machine.

The other point that needs to be considered is that oil specification have come on dramatically since the bike was designed, so why not take advantage of this?

Maybe I was jumping the gun , my GB always worked flawlessly , I do admit to using non-syn 80/90 gear oil , why fix when not broke …. Yes I too always used ATF type f in primary …. any oil thread usually becomes endless so I jumped in early , maybe to save us all ….. sorry , go for it as you wish !

On a recent trip to the BC interior one member had gearbox issues with his 750 Commando. After 400 miles or so the output side started squeaking. There were lots of bronze flecks in the oil.
Oil used was 20/50 motor oil of some type.
I'm not sure why the owner chose to use motor oil rather than gear oil in the gearbox, but it appears to be a bad idea.
ATF might be just fine. I seem to recall that JC uses it in his hotrod Commando.
I'll stay with gear oil.

Glen

I have tried ATF in my commando gearbox
I didn't notice any difference at all
A mate of mine uses it in all his old Brit bikes and swears by it

My concoction of choice is 75% 75w90 and 25% Lucas oil stabilizer - shifts like butter.

I have been using Amsoil 75w90 for years, along with ATF in the primary. Added benefit is colour coded leak identification:

Green - transmission
Red - Primary
Brown - engine

Food for thought - while AFT would likely work fine, there is a complete wet clutch additive package that is serving no purpose in the Norton transmission. Some manual transmissions make use of this package to prolong the life of synchronizer cone clutches, but no such animal exists in an AMC transmission...

FWIW

Derek Wilson said:

Food for thought - while AFT would likely work fine, there is a complete wet clutch additive package that is serving no purpose in the Norton transmission. Some manual transmissions make use of this package to prolong the life of synchronizer cone clutches, but no such animal exists in an AMC transmission...

FWIW

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And that is a good thing in the event that gearbox oil contaminates the clutches. The Bey Ray Gearsaver is recommended for use in some primary case applications.

Dan1950 said:

And that is a good thing in the event that gearbox oil contaminates the clutches. The Bey Ray Gearsaver is recommended for use in some primary case applications.

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Maybe - depending on what clutch you use. Barnett warns that their plates can get grabby if Mercon ATF is used, where as Dexron can moderate clutch friction. I have also heard stories of bent mainshafts from high HP engines running Barnett clutch's.

Can't comment on the Bel Ray oil - I have seen others try to run oils recommended for primary drives in their Nortons that did the clutch no favours... I really think it depends on the friction material compound that is used.

Like most things Norton, no easy "one-size fits all" answer. Experiment and figure out what works for you.

I have clutch push rod seals on my bikes to keep the trans oil where it belongs. I prefer to try to keep the clutch as dry as I can. I only run enough oil to keep the chain wet - about 150cc's. This has always worked well for me - FWIW

"
My concoction of choice is 75% 75w90 and 25% Lucas oil stabilizer - shifts like butter.

I have been using Amsoil 75w90 for years, along with ATF in the primary. Added benefit is colour coded leak identification: "

Indeed . The Moreys ( similar ) is very protective in boxes , diffs etc . too much in a L.S.D. however , and it dont .

maybe this or Lucas and Synthetic gear oil or synthetic A T F would be Wunderbar . Limited % may even be also , in the primary .

It gives protection on start up , ' opps the drain plug fell out ', and overheating also . Stops slapping with its surface retention .

I roadraced 883 H-D Sportsters for 6 seasons. We used ATF in the transmissions because it met all the criteria for gearbox, clutch, and primary chain. I never experienced nor heard of any wear or damage. Consider; a 50,000 pound garbage truck with 400 horsepower uses ATF.
However.
I don't run ATF in my manual transmissions because I'm not trying to gain 1/4 of a horsepower. That's not the 'rational' position, based on my own observation, but every transmission is different in design. Gear width matters, tooth pitch matters, tooth profile matters. 883s had modern, wide, round profile smooth ground gearteeth. I run Chevron Delo ESI 85-140 in my Moto Guzzi box; I'll do the same in the Norton. I would have no reservations about running ATF in the primary, though depending on the clutch feel I might move to H-D Primary lubricant. (or Sportster transmission lubricant for combined primary/gearbox)

pressureangle said:

I roadraced 883 H-D Sportsters for 6 seasons. We used ATF in the transmissions because it met all the criteria for gearbox, clutch, and primary chain. I never experienced nor heard of any wear or damage. Consider; a 50,000 pound garbage truck with 400 horsepower uses ATF.
However.
I don't run ATF in my manual transmissions because I'm not trying to gain 1/4 of a horsepower. That's not the 'rational' position, based on my own observation, but every transmission is different in design. Gear width matters, tooth pitch matters, tooth profile matters. 883s had modern, wide, round profile smooth ground gearteeth. I run Chevron Delo ESI 85-140 in my Moto Guzzi box; I'll do the same in the Norton. I would have no reservations about running ATF in the primary, though depending on the clutch feel I might move to H-D Primary lubricant. (or Sportster transmission lubricant for combined primary/gearbox)

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I tried Bel Ray Sport transmission fluid in my (since sold) 961 as it had shared gearbox / primary oil as per a Sportster.
I was so impressed with it I now use it as standard in all my classic bike gearboxes.