Oil for 1928 FS 3 Speed Gearbox

[olesuffolkbuoy]

Hi,
Have been searching the forum for the gear oil spec for my ’28 FS with 3 speed box.
Am I right in concluding that straight 140w gear oil is what I should be using?
Thanks all.

Tony

[PaulR]

The answer is yes, but if it leaks the answer is Thixotropic grease , obtainable from Enfield agents.Good luck.

[richard rawson]

you can get the thixotropic from land rover dealers it what they use in the cv joints it comes in a long sachet one sachet will be ample even better if there is any 4 wheel drive spares near to where you live its cheaper and its the same stuff
yours richard

[olesuffolkbuoy]

Thanks Gents.
By thixotropic, do you mean semi-fluid grease?
I use that in my ’21 Douglas gearbox.
Are there any dangers in trying it in the Scott?
Any need to clean out old lube first?

Tony

[Ted Robinson]

If the main drive bush is a good fit you will seize it up, if it is well worn you may be o.k. Why not use a straight S.A.E. 50 that was good enough when they were first made.

[Ted Robinson]

Just another thing do not use a hypoid gear oil it will destroy any bronze bushes.

[Bob Mather]

Hi Olesuffolkbuoy,
Stick with SAE 140 straight gear oil with no EP additives. I have been using it for years in my 1932 Flyer.
Regards,
Bob Mather.

[gammakeith]

My box had thixotropic grease in and the roller bearings were very badly worn when I stripped it for inspection and some pinions were showing rust damage. The box had clearly been worked on when the bike was restored as the clutch output side had been nicely re-bushed. The bike has clearly done very few miles since restoration so I’m inclined to suggest the grease may not be a good option for bikes that are not used regularly. I know its not a scientific test though! The box didn’t even leak when subsequentl filled with gear oil 😀

Keith

[BRIAN MARSHALL]

Morgan owners have reported similar problems with thixotropic oil/grease, notably Shell Tivela. Best just use a ‘straight’ gear oil. If it leaks out you are either overfilling it, have a worn high-gear bush, or are using a L/H side propstand instead of a centre-stand or rear stand.

[Stan Thomas]

The problem with grease or thick oil is the possibility of cavitation starving the gear-teeth whilst under load, so don’t use anything heavier than a straight SAE 90 grade (although modern oils nowadays don’t usually have the sulphorous addatives of yesteryear which divoured bronze – but best check with your supplier.

Using thicker lubricant is only attempting to mask the design fault of poor or non-existant oil sealing – which can be easily overcome by turning out the kick-starter boss and fitting a lip-seal, then using a modern synthetic gear oil.

[olesuffolkbuoy]

Thank you all for the comprehensive advice.
I had noted that EP oils were not to be used – thanks for the confirmation.
I also appreciate the channelling problems that too high a viscosity can cause.
Being a bit uncertain about the gearboxes internal condition, think I will start with 50w straight oil, observe for leaks and move towards 140w should it be necessary.

Ted: you said that straight S.A.E. 50 was good enough when they were first made ….. I cannot find any lubricant info in any of the books I have.
Is this listed somewhere or just that you happen top know this fact?

Tony

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