Forum

[Leon Novello]

JTL:
That will also work; downside is an outer cover with a lot of grease. Venting through the filler plug relieves pressure inside the box before any can be forced into the outer cover. A very small vent hole will not let in water unless the bike falls into the river, even then I doubt any would get in. Similar to vents on top of car or truck differentials when they are driven through flood waters.

[Dennis C]

Do you remove the inner seal?, Your choice of course, I never have done (sealed for life), says it all really. Do you need a vent?, Again you choice,these old boxes already have plenty of natural vents. Oil type, (O God why am I saying this) these boxes were designed to use straight 50 because that was the most available oil at the time, they are a heavy box and slow in operation the heaver the oil the more they drag and the worse the gear change becomes, I use 10/40 synthetic in my Super Meteor with good results.ducks and runs for cover

[JTL]

Dennis C, as you say "sealed for life", so why remove the inside seal for better lubing, when the bearing is pre-lubed for life. And the vent hole? Well, the old bearings were not pressure tight so no problem venting the gearbox, but sealed bearing are supposed to be tight for the sake of using oil instead of grease. Maybe this would demand some venting of the box?... Leon, I know no water will enter the box from a vent hole in the fille plug, but to be honest it's so much easier to drill a hole in the inner cover. Since everything behind the outer cover needs lubrication as well it could be the easy way out (if I go for a vent hole in the end)... Scalyback, have you considered to make a vent hole? And have you found out how to change the bearings when the box is still in the frame? Or have you removed the box? I'm also replacing the layshaft bushes with the bronze bushes from our host, and hope to be able to do all this with the box still in the frame... regards Jacob

[sofiaspin]

I struggle to see the benefit when, with the grease, there are not any leaks - on my classics anyway. I Top up with 90 to level mark.

[Dennis C]

Jacob, sealed bearings do help keep the oil in the box, but there are plenty of other available vents, unlike the engine they are not heavy breathers but another vent will do no harm,

Sofiaspin the lighter oil gives a smoother lighter to operate gearbox, perhaps reason enough?.

[Bullet Whisperer]

I use 20/50 oil in all my R.E. gearboxes, as it probably allows another 1-2 BHP through to the back wheel, without absorbing and losing them while the gears flounder around in thick, heavy grease. It is not like these machines have power to spare, after all. If I were to use sealed bearings in a gearbox, I would run their insides open to the gearbox and its' contents [oil]. I would also still run an oil seal outboard of a sealed bearing on the mainshaft sleeve [inboard of gearbox sprocket] for extra peace of mind.

[Scalyback]

Well it's all a bit psychedelic now, Tornado has gone off to the RE holiday centre, whilst I get ready to travel to France tomorrow. I guess the sealed bearings will still be sealed, and will look into a vent hole on my return. So It's looking good for SAE 50 then? As I can get that locally.

[sofiaspin]

Dennis C you have a point but I am not compelled to spend the ££ when, for once, I have a box that actually works within acceptable limits and does not leak. It is an 08 classic 4 speed. Previously for an 04 classic 500 I invested in plate upgrade, stiffener, pushrod upgrade etc etc. The 08 has nothing, and works fine, apart from the occasional crunch on down shifting from 4 - 3- 2.

[Scalyback]

Well, Tornado has a slight leak, so I might as well get it sorted the first time.

[Tim NZ]

Simply fitting 'sealed' bearing to the gear box and not having a vent somewhere (such as a sloppy gear change selector fork pin bushing?) will often result in oil being vented out of the mainshaft bearing cover, or out of the pin bushing. The former situation is often mistaken as a leaky kick-start shaft O ring. The latter as a dribble down the rear of the gear box case


Oil is quite able to pass though the bearing and its seals if the 'box is inadequately vented. The bearing seals are not a Garter seal and are quite able to flutter allowing oil in and out as relative pressure and temp differences between the gear box and atmosphere change.


A small vent hole is advised, as too is removal of the inner seal from the bearings; oil is a far superior lubricant than grease (grease = soap + oil). Engine oil is perfectly adequate lubricant, but change it when you do the engine. Otherwise use a #90 gear oil; you wont need a heavier oil.