Modern Gearcase Oil Choice

I wish to use Castrol Axle, Limited Slip SAE 80W-90, API Rated GL-5 in my Gearcase. Is that a wise choice?

I would have thought a dedicated synthetic gear oil would be better than an axle oil for a limited slip differential as there isn't one in a Norton gearbox.

mooskie said:

I wish to use Castrol Axle, Limited Slip SAE 80W-90, API Rated GL-5 in my Gearcase. Is that a wise choice?

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Why do you wish to use that?

As Kommando said, a wise choice would seem to be an oil designed for the application IMHO...

I use Honda 80-90 in mine.
With a mainshaft clutch seal of course on the primary end to prevent that oil from drifting out into the clutch.
And believe me it does head straight for the clutch.

I've used synthetic and other heavy 80-90 gear oils, as long as I don't overfill and change bi-yearly..... It pretty much stays out of my clutch providing I keep it off the side stand. Twice per year keeps condensation to a minimum with no milk being visible. Heavy 80-90 does seem to shift smoother to me though.

Buy the seal . It's cheap.
I moved to Honda from Redline and it shifted smoother.

I would also recommend getting a magnetic drain plug.During usual maintenance,I found more shavings than I expected.In the process of taking the trans out now to see what is going on.

This Forum is GREAT! I had ordered a Gasket for between Outer/Inner Case because of a bit of a leak, but for the life of me I cannot get the Outer Case off. I did not undo the clutch cable, but pulling with Shift Lever and tapping with a Mallet is not getting job done! Now I am wondering if my Primary Case is full of Gear Oil! Always Learning.

Your clutch would be grabby and difficult to disengage from the gearbox when cold if the primary was full of Hypoid gear oil. You would also be able to smell it, if you are into that kind of thing.

Get the DynoDave clutch rod seal, and do any long term parking on the center stand as mentioned.

You can use that Castrol axle oil if it's all you have handy. It won't hurt anything.

Side note: Only time I've had shifting issues on my Norton is when the primary chain was tight. Gear oil never caused shifting issues in the gearbox. I've run Redline and Amsoil, meh. Gearbox is very happy with Pennzoil 80/90 GL-5 I got for nothing from a neighbor. I have Lucas 75-140 synth in the differential of my '65 Chevy. I have not tried that in the Norton, but it would work.

Put the gear lever back on but facing backwards, this will give you a pulling handle.

As Kommando says, the cover can stuck pretty bad on the two guiding studs for the outer case. It doesn´t help if a PO have used some old black Permatex gunk..... I used to do that almost everywhere back in the day, not anymore.

A heat gun on the cover works a treat.

With the clutch cable removed, I think that Bodger's idea is the best place to start while adding Kommando's suggestion. At that point you can also apply additional force with a finger through the inspection cover hole. A slight rocking motion may get the party started, but beware of what is behind you as the cover may yield without warning and send you backwards and/or tumbling. I start with both methods stated above, if this is not producing results I go around the cover applying light blows with a small hard rubber mallet with intermediate application of rocking force using the shifter and inspection port; I don't, at this point, recommend using bare hands, the cover will be hot.

All this is much easier with the G/B on the bench, but in the majority of cases (no pun intended) the outer cover comes off and saves you hours of time and a basket full of what-ifs if you do this while the G/B is still in the cradle. If the outer cover is still giving you the finger fueled by frustration; you can apply force to the G/B level plug, and also on the shift lever pointing forward using block of wood placed against the cradle; go back and forth on these two points.

When you win the day be sure to clean the alignment dowels and the corresponding holes. A Dremel driven wire brush for the males, but wear full face protection a hat and suitable gloves. For the holes a .22 or .25 caliber bronze firearm bore brush works well. Before you do the final assembly be sure that the outer cover can be fit and removed by hand. Try to overcome your urge to use a gasket sealing product; a thin uniform coating with axle grease works just fine.

The force(s) you exert should be GENTLY applied and very slowly escalated. Too much force applied too quickly will break parts; if you have gotten to that dreadful milestone then blast a way. Under no circumstances pry between the sealing surfaces. If you feel frustration building and, maybe, get an adrenaline leak then "Better call Saul".

Best.

I find a bit of WD or penetrating oil on case mating seams can help release suction between the halves. When tapping with rubber mallet, the fluid works its magic and casing separates.

Bodger said:

A heat gun on the cover works a treat.

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I will try that over stud area's, thanks