Hi folks,
I have 2 questions about my S29 3 speed gearbox:
- what quantity of semi fluid grease should I put in following its rebuild ?
- what is the thread of the cover screws/studs p/no. 27-4406 ? Looks like 26 tpi BSF, rather than BCY, but I'm not sure. UPDATE: It's Bcy, but still interested in grease quantity.
Cheers,
Bevan
Hi Bevan
I've looked through what paperwork/service sheets and an instruction book ( 1930 models ) I have but I couldn't find anything relating to the quantity of oil . All I could find was reference to filling it till it reaches the level of the plug hole in the gearbox end plate . Though I also found a reference that says a moderately worn box for which possible spares are not available performs more quietly and efficiently if it is packed with a fairly heavy grade of HMP grease this in addition to the makers recommended grade and quantity of oil . Not sure about the packing of grease and the same amount of oil as this would raise the level of the oil in the box and can cause oil leaks , I found that out when I did it to my 1932 blue star hand change box and ended up with gear oil in my clutch and primary case . As it happens I finished rebuilding my sloper three speed box today so that's another step forward in getting a big box of bits to look more like a bike hopefully get to strip the Rocker box tomorrow and see what state thats in . Hopefully if there is a manufacturers recommended amount of oil someone will find/know it and get in touch regards Mark
Thanks Mark, I had incorrectly assumed it was a great box like the Burmans on my Panther and Ariel. I wonder if a mix of engine oil and gear oil would be best ?
Re your box: is there an end cap of any sort where the selector shaft penetrates the rear of the case ? Looks like there's a small machined step that may once have retained some sort of domed end cap perhaps ? Cheers, Bevan
Firgot to attach picture of what my selector shaft end looks like.
Cheers, Bevan
Hi Bevan
Your picture of the rear of the selector is the metal bush the end of the selector fits into but it looks as though the bush is broken round its edge though I don't think it would be detrimental in use . My instruction books says to use BSA heavy gear oil or if not available Castrol D mobiloil C or Shell gear oil . Also says another lubricant they recommend is Speedwell Crimsangere light which should be mixed with a little BSA engine oil to make it just thin enough to pour into the gearbox . I don't know if any of those are available but I was just going to use EP 90 and see how I get on but I won't be doing that many miles a year anyway . As I can't shrink down the photos very well to be able to post them I've PM you some pictures I've taken of my gearbox hope they help regards Mark
Hi Bevan
I couldn't send you a PM as I still couldn't reduce the size of a Photos hopefully this will work now as asked my daughter to help me I know nothing about computers or photo sizing . These pictures are from three separate gearboxes all have the same bush
Mark
Hi Mark,
Thanks for the photos. Odd than there's nothing to stop either oil getting out or dust & grit getting into the selector shaft bush. Since I've fitted a sealed main bearing, I may as well try to get it oil tight, so I think I will fit a domed cap over the exposed shaft end.
Perhaps a mix of engine and gear oil may be best. It had grease in it when I first opened it up. The level plug is about half way up when the box is in place, so thst amount of oil should splash around pretty well I'd have thought.
Cheers,
Bevan
Hi Bevan
Engine/gear oil mix should be fine if not to thin ( What do other readers think ? ) , the selector shaft fits tight up against the bush on the inside of the box but it hardly moves when selecting gears so would seem unlikely to leak much through the bush unless there's a lot of pressure in the box , having said all that my 1932 hand change four speed gear boxes have sealed bushes so maybe BSA thought it was a problem and updated the spec . A domed cap would certainly stop any leakage if it was to occur. A while back you posted a picture of your main shaft with a missing tooth did you every find out if the gears come off the main shaft am asking as I've got a good shaft with missing teeth on the gear and a damaged shaft with good gear so hope to make one good one out of the pair so I can make up a spare box just in case
Cheers Mark
Hi Mark,
I got a new tooth built up and profiled by a specialist gear making company. Luckily, there was no other gear damage and I managed to get a replacement selector shaft. I'll probably see if I can get someone to braise the broken piece back onto the fork collar so i have a spare.
A guy in Germany on the FB BSA Sloper page did say that he had the old damaged mainshaft gear machined off and a new one pressed on - see attached image.
Cheers,
Bevan
Hi Bevan
Thanks for the info about the gears , good luck with your rebuilt box hope all goes well and works as it should
Mark
Do NOT use EP90 in your gear box. chemicals in EP90 will gradually dissolve the phosphor bronze bushes in the gearbox.
I have several pre war BSA's including a 1929 sloper and since the mid 1970's have used Thixotropic grease "Eplith 00" in all the gearboxes. In case you don't know thixotropic grease breaks down into a heavy oil when under pressure as when between the gear teeth.This means you get good lubrication without oil coming out. BSA pre war gearboxes don't have any oil seals.
Hope this helps.
My S29 leaks gearbox oil terribly. So far my fix has been to put a drip tray under it. I'd love a proper solution and thixotropic grease/oil sounds possible, However does the Sloper gearbos have the small oil holes in the gears? If so even thixotropic grease could lead to oil starvation surely as the grease that gets into them never gets mashed by the gears.
I would love to be wrong in my fears, so, do Sloper gears have oil holes in them?
Hi Dean
Yes some of the sloper gears do have holes in them and some bushes have crossed slots on the outer edge for oil to get into them , the main shaft also as worm type groove along it for the oil to be able to get round and lubricate the gearbox pinion bush which is possibly where some of the oil may be coming out from your box . There is a felt washer that fits up against this bush behind your clutch centre which is supposed to stop the oil leaking I also have one on my 32 blue star doesn't exactly do what it says on the tin but does help a little . I've tried normal grease in gearboxs in the past with gear oil or engine oil I found that the grease just gets flung and sticks to the casings , had one box were it clogged up the drain plug hole so thinking I didn't have much oil in it took off the inspection plate and put more oil in only for it to come leaking out later ( didn't do my clutch much good either ) with hindsight I obviously should've filled it at the filler/level bung
Mark
Hi Mark
many thnks for that. I'd better give grease a swerve then and make time to check for the felt washer.
Hi Dean,
I fitted a sealed main bearing which should deal to any leakage out the clutch sleeve, so will probably try it with SAE 50 oil, which is the same viscosity as 90 weight gear oil apparently. Cheers, Bevan
Hi Bevan yes 50 engine is equivalent to 90 gear oil
Keep us posted on the effectivenes of the sealed bearing. I did this with the M20 and it now just drops s few drips after a run.
Hi Dean, I have been using Thixotropic grease on all my pre-war BSA gearboxes for over 45 years and particularly on my 1932 G32/12 & sidecar have ridden many thousands of miles with absolutely no gearbox lubrication problems. Hope this gives you confidence to locate some. Regards Alan