Oil leak from gearbox final drive

[trevinoz]

Well said, Brian.
The EP 90 oil is about the same viscosity as straight 30.
Trev.

[LJ.]

Brian... Quite right what you say about "oil supply holes drilled radially to allow oil to the bearing surfaces" Thanks for correcting me on that one. Is it correct though that grease would have been used in the single cylinder gear boxes? I seem to recall this being mentioned on the WD M20 forum, and that it was common practice to do this. I cant think without looking, if the singles rigid gearboxes are similar constructed as the later A10s.

Edit: Just found where I've read up about this grease malarky...

http://pub37.bravenet.com/forum/static/show.php?usernum=3155626639&frmid=16&msgid=1149939&cmd=show

[Brian]

As far as I know LJ none of the BSA gearboxes are meant to have grease in them. I've attatched a scan out of the WDM20 manual and you will see it recommends the same oil as the engine.

It has been common practice to put grease in gearboxes to stop it leaking out. I've pulled many a box apart that has been filled with grease but I wouldnt use it. I recently dismantled a box out of a swingarm B33 that had grease in it and every single hole in the gears and shaft were blocked solid.

The early singles, and A twins didnt have a seal behind the sprocket and always leak but this can be cured by fitting a bearing with the seal left in the outside. I did this to my WDM20 and it doesnt leak. You always get a bit of weeping around the gearshaft and kickstart shaft but not enough to be a problem.

I have found that 80/90 gear oil is a good compromise between having good lubrication but not leaking out easily.

[orabanda]

The three speed gearbox on my 1927 557cc Ariel Model A is (factory) packed with grease.

However, excellent point from others re grease blocking oil holes.

Grease is a solidified petroleum product; in oil it can behave (have the effect of) as a contaminant, blocking filters, orifices, galleries, etc.

Richard

[DazSeaton]

Wow, seem to have started a good discussion here.
I have some EP90 in the garage, so think I will drain and refill the gearbox with that to see if it makes any difference.
Absolutely no grease.

Trev,
Am I right in saying the Castrol GP50 is thicker than EP90 (if the EP90 is equivalent to a straight 30)?
I don't really want to remove and strip down the gearbox just yet, so am trying different oils, then a new seal if that doesn't work, last resort remove & stripdown.
Can the sleeve gear bush be accessed from the sprocket end of the gearbox whilst I change the oil seal?
I presume there is just one, but see page 54/55, nos 16 & 17 on the link below. Why does it state drill holes after fitting?
What is the relevance of the needle roller bearings on the layshaft you mention.
Found this brilliant link on the Britbike forum, see page 54 onwards:
http://www.draganfly.co.uk/data/pdf/ListB3.pdf
chrz Darren

[chaterlea25]

Hi Darren,
To replace the sleeve gear bush, the gearbox must be dismantled completely, The shell can be left in the frame
The bush/s are pressed into the sleeve gear
There are oil holes in the inner bush half, which are drilled after fitting the bush, through the radial holes in the gear
I jut did this today on a plunger box,
If your gearbox has neele roller bearings on the layshaft (bottom shaft) you can see the one in the inner cover through the inspection plate

Another thought 
 A possible source of leakage is the "frost plug" (if fitted) on the end of the layshaft underneath the gearbox sprocket,
Sometimes a non closed end needle bearing can be found fitted, this will let oil out to the pressed in plug
I have cured this leak on Burman gearboxes by laying the bike on its right side and covering the area with sealer or epoxy (after thorough cleaning)

Cheers
John O R

[Hubie]

G'day mate, I had a similar problem with mine and a new seal did the job.  There is a large circlip that holds the seal in place but I would advise a bit of gasket gew or similar to aid with the seal.  I found out the hard way and that sorted mine.

Cheers
Hubie.

[bsa-bill]

Just a word here, when I did my last box up the large oil seal over the output shaft was slightly oversize meaning it would not fit into the end of the box without a bit of filing around it's perimeter.
Now with hindsight I should have sent it back and got a replacement because making it fit around the outside could mean it doesn't put even pressure on the shaft because it may not be central after filing.
I think I would have taken enough off so that the seal had some float - but memory's not my strong point

[DazSeaton]

Hi Darren,
To replace the sleeve gear bush, the gearbox must be dismantled completely, The shell can be left in the frame
The bush/s are pressed into the sleeve gear
There are oil holes in the inner bush half, which are drilled after fitting the bush, through the radial holes in the gear
I jut did this today on a plunger box,
If your gearbox has neele roller bearings on the layshaft (bottom shaft) you can see the one in the inner cover through the inspection plate

Another thought 
 A possible source of leakage is the "frost plug" (if fitted) on the end of the layshaft underneath the gearbox sprocket,
Sometimes a non closed end needle bearing can be found fitted, this will let oil out to the pressed in plug
I have cured this leak on Burman gearboxes by laying the bike on its right side and covering the area with sealer or epoxy (after thorough cleaning)

Cheers
John O R

You can dissemble the gearbox completely without removing it!!. Thats excellent news.
Yes, I saw the copper frost plug behind the sprocket.The oil though is leaking down the shaft onto the sprocket and not down the casing. good thought though. Will seal it when fitting new oil seal.
Cheers
Darren

[DazSeaton]

Right then!!!
Stripped off the primary chaincase and the chain sprocket. the final drive oil seal is rock hard and knackered so hopefully a new one (and a new crankshaft seal while were at it) will do the trick.

Can anyone tell me how much play there should be between the gearbox shaft and the sleeve gear bush. I can move it a little (with some force), click the link to see a little video.

http://youtu.be/HFsm_LwnWwA

I can now see why thicker oil will leak less and being on the side stand all the time with thinner oil in (the main stand bracket has snapped off, another mammoth job to do) will cause dripping between the shaft and bush.

[chaterlea25]

Hi Again Darren,
I would be of the opinion that theres too much play in the bushes, after looking at your video
A couple of thou at most is acceptable, oil will pee out there 

Going back to my other reply, its important to have free play in the belt drive especially when the engine and everything is at full working temp
Was the belt tight when you removed the primary side?? this could contribute to bush wear!!

HTH
John O R

[BSA500]

Pah you call that play mine is at least 3x that(I'm not proud I am just waiting for the bushes and then I will fix it). Still using the bike every day but the vibration is, shall we say ,interesting.

[DazSeaton]

Hi Again Darren,
I would be of the opinion that theres too much play in the bushes, after looking at your video
A couple of thou at most is acceptable, oil will pee out there 

Going back to my other reply, its important to have free play in the belt drive especially when the engine and everything is at full working temp
Was the belt tight when you removed the primary side?? this could contribute to bush wear!!

HTH
John O R

Yes John, it was very tight. Hence I was after some fitting instructions which apparently don't exist for torque settings/tensioning information.
It did leak out faster when the engine got up to temperature, so I am assuming the belt was too tight and causing the oil to leak more.
Darren

[DazSeaton]

Pah you call that play mine is at least 3x that(I'm not proud I am just waiting for the bushes and then I will fix it). Still using the bike every day but the vibration is, shall we say ,interesting.

Is it not pouring oil out if there is that much play?

[chaterlea25]

Darren,
the same basics will hold for Triumph and BSA
Read the pages I gave the link for 
http://www.britcycle.com/manuals/hayward_belt_drive_hints_and_tips.htm

John