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Re: WM20 Gear selection thoughts?

And yet Bruce, this article by Rymax explains that there are different levels of EP additives, which is why it's safer to follow the manufacturers recommendations. EP oils where developed for use in spiral/bevel gears such as axles. Likewise I've covered thousands of miles over 35 years of ownership of my main WM20. One rebuild about 12 years ago where just the bearings were replaced (sealed drive side bearing) I'll stick with standard SAE 50 engine oil in my M20 boxes.

https://www.rymax-lubricants.com/updates/the-differences-between-gl-4-and-gl-5/

There are several other Q&A on the internet regarding the subject. Ron

email (option): ronpier@talk21.com

Re: WM20 Gear selection thoughts?

I used to run Royal Purple in the box because it was in fact purple
Primary was dextron
Thus purple spots = leaky box
Red spots = leaky primary
black spots = engine leak
For this ride I geard up the bike as I was riding with Shane on his speed triple & I did not want hin to wear out his 2nd gear going slow enough not to leave me behind as we went down via Goulburn & Crookwell then Borrawra because the servo at Crookwell was closed and most of those roads are fairly strait fas roads , not really where a WM20 shines .
However I ran out and it was going to be a big 3 day weekend ride in & ride out so I used some VolTrans that got ages ago at a auction.
This was on the assumption that it was going to be fine as it normally goes in Volvo auto boxes & diffs and the syncro cones in auto boxes are a bronze powder pressing
Well it wasn't
What really floored me was the layshaft bush worn oval

Re: WM20 Gear selection thoughts?

Just remember, engine oils and gear oils are not measured the same way for viscosity. As a side note, the older Mercedes truck gearboxes were easily ruined by using hypoy type gear oils. They recommended ATF.

email (option): pes.sales@btconnect.com

Re: WM20 Gear selection thoughts?

I'd say the question over gearbox oil selection is a similar debate to the one on ignition timing...

I've heard people propose that a change to the ignition timing is necessary due to the changes in fuel characteristics...That may or may not be true. To date nobody has provided the proof to support that argument based on dyno testing, which is the only accurate way to determine what effect any change would actually make to engine performance....

Likewise with oils...Unless the original grade is unobtainable an arbitrary change of oil type/grade without any supporting evidence to suggest an improvement is being made seems illogical. Especially so when the original specification has enabled gearboxes to function and survive way beyond their designed lifespan...The fact a replacement oil seems to work OK isn't a reasoned argument for its use...Doesn't the original grade do that?...

I'm broadly in agreement with Ron in that I can see no reason to change the oil grade that was originally recommended for the gearbox unless there are compelling reasons to do so...I retain an open mind on the subject but why change what isn't broken?...Ian

email (option): ian@wright52.plus.com

Re: WM20 Gear selection thoughts?

I am not looking to start a debate on the merits of one type of oil over the other. If you want a good laugh, go to a BMW motorcycle forum where they will debate endlessly how BMW oil (costs twice as much) is better than regular motor oil.

The point I was trying to make is that most gear oils will not corrode the bronze bearings in the gearbox. The gear oil I use says it is safe for bronze on the label.

I also have gear oil for modern bikes and cars where it states it is not safe for bronze.

As for using motor oil in the gearbox, I do on bikes I will be taking long trips on as I don't want to have to carry three different types of oil (motor, gearbox and primary) and use the 50W in everything.

In conclusion, if you want to use gear oil, read the label on the bottle. It will tell you if it is OK for bronze.

Re: WM20 Gear selection thoughts?

Yes Bruce, it was no ones fault but mine
I SHOULD gave checked the specification of the oil before I used it rather than making an assumption that being a modern oil it would be syncro safe ( usually way to note a non sulphur oil )
Sulphur oils will attack the grain boundry region of most copper based & some zinc based alloys which causes them to crumble .
I know that I was in a previous life a non-ferrous foundry metallurgist and prior to that an alalytical chemist for a foundry that made secondary foundry ingots.
And while it happens faster at higher temperatures, it still happens a lower temperatures.
Also the local temperature can get a lot higher than 250 C
The oil is also electrolytic apparently to do wit the electronic sensors in the gear box which makes things worse, but I would have expected the Cu-Al circuit to be a lot stronger than the Fe-Cu cell but circumstances were to prove that wrong.

Usually you only find sulphur in truck & tractor oils so I was surprised to find it in this stuff.
So I stuck the remaining 23 litres on evilpay and was floored when it got $ 18 / l .
The box needed a good rebuild having been through "best of the bad" rebuilds / repairs over the past 30 years

As stated I choose to use the oils I use for the reasons I mentioned .
As for using the original specification oil that would be impossible as that has not been made for near 50 years

And I was not trying to start an oil debate, just to highlight just how robust the horseshoe boxes really are.
In fact nearly all BSA boxes are full of gears cut from forged blanks , way over engineered for the relatively low output of BSA's in general and definately over engineered for our M series bikes .

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