Oil leaks

[a101960]

Got a few oil leaks to sort out so I need some advice please. First a few words about the gearbox. I am pretty sure that the seal behind the sprocket requires replacing. Is it a straight forward job to do? And secondly is it actually worth doing? When I ride the bike it does not mark its territory when I park up, but after a few days of not being used there is oil in the drip tray. I use the side stand all the time, because I am no longer able to haul it up onto the main stand for medical reasons. The second problem I have is that there is a slight weep from the OPRV the fibre washers could probably do with replacing (both of them). Can anyone tell me what size and thickness they should be? I am not really a great fan of fibre washers sooner or later they all seem to leak. Would I be better off substituting copper washers in place of the fibre ones? Obviously any old washer can’t be used because with the wrong thickness washers the operating limits of the OPRV could possibly be changed I would think. I have always preferred dowty washers but they are rather on the thick side. Oil is not exactly pouring out, but I think it is fair to say that things will only get worse. What do you reckon folks? Oh, and one last thing would help to put some sealant on the OPRV washers or is that a no, no?
John

[Rocket Racer]

John,
 not answering any of your questions; the main gearbox seal locates around the o/d of the sleeve gear. Whereas if you are parking on the side stand the more likely cause is oil seeping down the main shaft past the sleeve gear bushes, which a gearbox seal change will not correct. Perhaps the new SRM magic seal nut might make a difference there
If its not marking its territory it seems a shame to be pulling it down. Perhaps you just need a paddock stand of some form to park it upright without doing yourself an injury.
I have a roll in stand which takes the bikes forwards or backwards and is very useful.

Can't help either with the OPV, perhaps some thread tape might stop it weeping

Tim

[tinu]

Hi John
I had the same trouble with oil leaking on the side stand after a while (5 min), just like Tim describes it. I could reduce the leaking with a lower oil level in the gearbox. But I do not use the side stand anymore... but this does not help you, i'm sorry. Maybe it is one possibility to lenghten the leverage of the main stand...
Martin

[ellis]

Hi a101960,

PRV valve fiber washer sizes are as follows. Inner 24.5 o/d 22.0 I/d 1.5 thick.  Outer  22.8 o/d 16.0 I/d  2.4 thick. I have never had these fiber washers leak and never had to use sealant. Hope this is helpful.

 ELLIS

[a101960]

O.K. an update on the gearbox oil leak. This afternoon I put the bike up on the bike lift so that it was not leaning over on the side stand.  I then removed the gearbox oil level plug ( item "K" in the drawing) and much to my amazement quite a lot of oil ran out. So, this might have caused the oil leak problem. It certainly would not have helped matters. So, looks like the gearbox was over filled. Now what puzzled me is that earlier this year I had changed the gearbox oil. I drained all the old oil out leaving the drain plug out all night to make sure that all the oil had completely drained from the gearbox. Next day I carefully measured out 1 pint of oil and re-filled the box. Thank you for the misinformation Mr Haynes. My own fault I suppose. If I had read the BSA instruction manual instead, I would have read that the gearbox capacity is 14 fl ozs. With the benefit of hind sight I now realise that I should have double checked with the BSA manual. Serves me right! I will report back and let you know if this what was causing the problem. I must say when I removed the inspection cover afterwards it was a bit worrying, the gearbox looked almost empty, but the bike was on the level, and I did it as per the book. Martin, Tim, and Ellis thank for your contributions.

John

[duTch]

 I remember suggesting a figure of ~400ml, and my level comes to about the top of the layshaft (on centre stand).
  My'73 Haynes book page 10 says "Gearbox- 1 pint (570cc)", and underneath "(actual capacity 398cc), and bottom of the 'gearbox specs' page 58 also says 398ml.

 It does look almost empty in the inspection cover.

[kiwi george]

Away from the oil leak problem I have fitted to both my swinging arm bikes a pillion footrest inverted on the triangular reinforcing plate just forward of the shock  top mount this replaces the bolt, when required you lift up the footrest now it becomes an extra lifting handle to assist placing on the main stand this makes a hard task so much easier.

[Greybeard]

I take out the side plug and squirt oil in the inspection hole until the oil flows out of the side plug hole.

[a101960]

  My'73 Haynes book page 10 says "Gearbox- 1 pint (570cc)", and underneath "(actual capacity 398cc), and bottom of the 'gearbox specs' page 58 also says 398ml.

Yes, that is exactly what the haynes book says, and obviously I did not read what it said properly, hence the confusion, but in mitigation that is a very obtuse description of what the actual capacity is. I just wonder why it is written like that. well, it all goes to prove that it still holds true, that if all else fails then read and follow the instructions! And that also applies to using the level plug to set the correct oil level, as greybeard pointed out.

[duTch]

 All that being said, I think mine still struggled to take the whole 400ml to the level plug, and still leaks as you described even with a new seal; I lean it against the wall the other side to compensate.
 
  The Plungers take the same even with slightly different cases

[mikeb]

PRV valve fiber washer sizes are as follows. Inner 24.5 o/d 22.0 I/d 1.5 thick.  Outer  22.8 o/d 16.0 I/d  2.4 thick.

I got some fibre ones off ebay in a pack for an a10 engine for a few $$, esp as a little hard come by individually. mine not leaking - can't see any need for copper etc. if you do take out the PRV check some (online) threads about potential leaking past the lower (prv) threads that can steal your oil pressure: some 60year old prvs are so loose in the thread the oil bypasses the valve. details elsewhere on this fabulous forum

[BSA500]

Mine leaks like a sieve with a huge hole in it . I have the SRM nut/seal thinking that was the issue. Wrong of course, it did leak badly, but after fixing it found out the main seal leaks as well-badly. Can't be arsed to sort it while the sun shines. I have found the quality of the main seal to be very variable. I even have had to grind the diameter down in the past just to get it to fit the case. I am not convinced that the circlip does a great job holding the seal particularly tight against the bearing either.

[Peter in Aus]

. I even have had to grind the diameter down in the past just to get it to fit the case. I am not convinced that the circlip does a great job holding the seal particularly tight against the bearing either.

Yes I had to grind my seal down to on my A7 to make it fit I used lots Loctite 518 flange Sealant when I put the seal in also some around the circlip and it dose not leak.
Peter

[chaterlea25]

Hi All,
I put up some photos of the seal fitting issues here

http://www.a7a10.net/forum/index.php?topic=8786.msg62713#msg62713

The last gearbox I was working on the seal and circlip fitted in without problems ??? 
I have fitted several of the SRM sprocket nuts with seal and they seem to work well
However oil can also leak out around or along the layshaft bush between it and the alloy casing
if there's a score in the alloy or the bush isn't a 100% fit   

John