Ive noticed that the A50 wasnt too wet in the sprocket area, whereas the B40 was and the T100 Triumph I have finished all leak out through the final drive bush.
The A50 uses two split bushes, the earlier A65 and the B40 used a single bush with a oil return groove. The B40 had its single bush 40-3178 replaced with two plain brass bushes, presumably the oil grove cant be replicated.
the question is, the A65 with the single oil grove bush , the A50 with the pair of split bushes or the B40 pair of plain bushes... which is the best/which is more likely to stop the oil weeping. My guess the groove was put in to stop the oil and letting it run back along the groove, does the idea of two bushes mean the oil can work its way back through the gap between the two and through the gears.
Hi Chaz,
I am not sure why the bush changed from two piece to one but I suspect the spilt could be the source of a leak. The bush usually extends through the seal in the clutch back plate so any oil escaping along the shaft stays in the primary cover. Over time the bush can wear a groove in the bush and ultimately wear through it giving rise to a leak. I think that originally there was a felt washer to help to keep dirt away from this area although I have never seen one.
Dave.
I've got the felt washer on the A50, all I can presume is the full length one let's the oil out of the gearbox, the gap between the two smaller ones maybe allows it to return.. as I said, new ones are big metal split, the old ones brass or phos bronze in the B40, I'm determined to try to make some to the original pattern.
The one piece bushes were superceded around March 1965 by 2 bushes made from Clevite 10, like Vandervell barings, a metal deposit on steel then rolled into shape. The originals were pre sized as vandervell. These bushes used through til end of production.
Same material but different sizes for A5/65 and C15/B40.
The steel outer also resists the wear grove caused by the seal.
Sorry, I'm just coming to this topic because I'm doing some refurbishment to my 1967 A65 that had its crankcases replaced in 1969.
I have a dry BNR clutch and I'm worried that gearbox oil is seeping into the (should be dry) primary drive case. There is seepage along the split in the final drive bush when I rotate the clutch shaft.
Please see the attached photo.
Should I be seeing this? It is the 1st time I've opened up the final drive and I'm in unfamiliar territory.
Hi,
You will get a minute amount of oil around the area, however as the bush wears the oil passing will unfortunately increase but shouldn't get into the primary drive.
Firstly I would replace the seal in the cover behind the clutch 68-0235, the felt washer between the sprocket nut and clutch cover 68-3194, check the gearbox vent is clear at the dipstick thread and check the oil specification before replacing the bushes.
Best wishes...
(Many) Thanks for the reply(ies). Much appreciated.
What I'm taking from your advice is that the combination of the felt washer and seal stop and then wick away any oil coming down the bush gap.
(the felt washer wasn't there when I took it all apart)
If so, I'll put it back together and plan for a gearbox service (by a reputable firm) next winter (21-22) I've a 1971 A65L I'd like to start on this winter - it needs a lot of work!
All the best
Hi,
Just to clarify something for my own benefit.
The bush protrudes in to the seal hence the seal can wear a groove in the bush. Does the bush not come through the seal and a tad through the plate behind the clutch?
One of my A65s the bush does come through and the other looks like the bush was shortened at the groove caused by the bush.
Dave.
Hi Dave,
Just checked with some spares. Seal (lip on the inside) is for the gearbox shaft, the bush will not go through.
Best wishes...
Hi Bess,
Is this seal to keep primary oil in the primary case? If so the open side of the seal should be to the inner side of the plate. so that pressure pushes the lip against the shaft rather than push past the lip. This way the shaft passes through the seal as the plate is pushed on and against the outer taper of the lip. If the bush is present then this too will push against the outer taper of the lip and through the seal and very slightly in to the primary case. How else would the seal be able to cause a wear groove in the bush? If the seal is fitted with the open side towards the sprocket then any pressure in the primary case will surely push oil past tapered lip of the seal.
Dave.
I've recently been working on my B40 which like most models has two oil seals, one either side of the gearbox sprocket. The lip side faces inwards to stop oil escaping, so in the photo of the seal from the sprocket cover plate behind the clutch, the top side would face the back of the clutch, to stop oil escaping from the primary case. You can make out the spring which presses the lip against the gearbox mainshaft.
Hi Dave,
Lip on the inside as I said previously, Greenfield stated and as BSA intended.
Best wishes...
Hi Bess,
I am a bit confused by your photos as it looks like the shafts are in through the wrong side. Isn't the ribbed side the inside so the shafts would come through from the plain side?
Dave.
Hi Dave,
As I said the parts are just from my spares box, not to be confused with an actual rebuild. I realised the seal was installed incorrectly (by another, not me) so wrote, "lip on the inside" for the eagle eyed person who may have mentioned it was wrong.
I picked the plate, shaft and gear out and tried to fit the gear with the bushes and the gear shaft to demonstrate which would fit for you. These are old parts and it was easier to push the parts into the seal the way it is shown rather than change the seal around (seal may have disintegrated), sorry you are confused and please don't build your bike as demonstrated.
If you need any more help with your bike let me know.
Best wishes...
Hi Bess,
Thanks for your concern. Both of my A65s are up and running with what I hope is the right fitment of the seal. I may have a rummage through what I have got to refresh my memory of how things go together.
Dave.