Sleeve gear bushes replacement

[KiwiGF]

For what its worth looking at the pic I agree it seems to be lack of oil, leading to the bush melting onto the mainshaft? Either that or the shaft was too tight a fit in the bush but I guess you would have checked that....other possibility is the primary chain was too tight as I think was mentioned before. Good luck this time!

Just a thought did you clean off the traces of bush off the shaft?

[BSA500]

As much as I could  as I didnt want to damage the shaft(I had to have her back on the road today for work). I checked with my next door neighbour who was in engineering-sadly retired so no access to engineering stuff-and he agreed it was nice and smooth and no increase or decrease in shaft diameter. I checked the old sleeve gear and the bushes had slightly moved enough to block the oil way. If I remember right they were easier to press in than these last ones I did. Got to work ok most of the horrible vibration had gone just left with the standard shakes now

[duTch]

Good luck with it 500!
 Now if you'll excuse me regressing a bit to:-

(from KiwiGF)I'm still struggling with brians post that the mainshaft and sleeve gear do not turn together but

  Did you work that out Kiwi, as while I was figuring out my speedo drive a while back,(someone tell me if I'm wrong-quite likely) I noticed that if the sliding gear that engages with top(sleeve) gear is engaged at the same time that its mate on the layshaft, it'll lock up? It seems to me that the action is from clutch to mainshaft(obvious) to mainshaft-sliding-gear(disengaged from sleeve gear),to it's mate on layshaft engaged with layshaft fixed gear, to sleeve gear& sprocket-->   hence the mainshaft and sleeve gear don't spin at the same speed?? As I said I could be wrong, but I wanna know too??
  cheers duTch

[muskrat]

 I take it you didn't get much sleep last night  . You'll get a job on a race team, building boxes that quick  .
Best of luck.
Cheers

[BSA500]

Two hours to rebuild box/clutch etc. I reamed the bushes the day before. I was indoors early enough for the England team to dissappoint me 

[KiwiGF]

Hi Dutch, with the benefit of having all the gears on the bench.....in top the drive goes
1. clutch to mainshaft 1:1
2. Mainshaft to sliding gear nearest the primary drive as that gear is on the m/s spline so always rotates at m/s speed. 1:1
3. That Same sliding gear above (via dogs) to the sleeve gear as the selectors engaged those 2 gears in top 1:1
4. Sleeve gear to final drive sprocket 1:1

So the sleeve gear and m/s rotate together in top. 1:1

This pic has the shaft and gears side by side. Is Fosters counted as a beer in Oz then :-)

http://www.a7a10.net/forum/index.php?action=dlattach;topic=5742.0;attach=12802;image

[duTch]

Hi Kiwi,
         I've strange sleep pattern from working random nights(like last week), so tried to work gears out 2-4am, but Might be best to let the other guys explain their point of view, too much for me at the mo', the way the gears engage?
  Would be easier to see in the inspection cover of a S/A box, which I don't have.
 Dunno 'bout the fosters- staying away from that just now!!

Cheers duTch

[jjbsa]

Sorry not to have put in a pennyworth earlier - I had not had a look at this thread.
The rapid bush wear is almost certainly due to using oil with sulphur-based extreme pressure additives.  I once did this and only caught the problem because I happened to look into the gearbox for another reason after 300 miles.  By then the bush was completely dry, with dark brown dusty material in it, probably cupric sulphide.  The shaft was OK.  ALthough most modern gearbox oils no longer have sulphur EP additives it is best to make sure the oil in these boxes is either engine oil or one that the maker says is OK for bronze bushes.  The very good Opie oils website
http://www.opieoils.co.uk/ sells most oils and has data sheets on quite a few of its oils.  It's possible to identify oils that are definitely OK by these means.
Re Reaming, best to set the gear up on a bridgeport and run a good 13/16" reamer gently though the new bush, with lubrication.  This will give the right clearance for the shaft.  There should be a gap between the 2 plain bushes.  I always got old ones out with a hacksaw blade and I found the bore was not hardened as mush as the hacksaw blade!

[BSA500]

The high wear rate was down purely to the fact the bush had moved and blocked the oil holes. Hence the rapid new to knackered in under a month wear rate. As for the reaming my particular mainshaft had worn so the 13/16" reamer would give a sloppy fit. It has been running really well with no wandering clutch. The clutch still needs replacement its well notched innit

[duTch]

Must apologize, but just realized that my query with Kiwi, about ratios is more pertinent to the other thread that was running concurrently, re your mainshaft, and if you wish to respond, best do it there.
  I don't want to flog a dead horse but understand the main/layshaft bit, but my confusion is the fact that the ratios stated in specs give 'gearbox ratios' ranging from 1:11~ to 1:4.2~. is this overall ratios including crank-clutch/front/rear sproket?? or how is this otherwise calculated?
Cheers duTch

[KiwiGF]

Hi Dutch,  in top the gearbox is definitely 1:1 ratio.

The bottom gearbox ratio is calculated by multiplying the ratio of the 2 bottom gears (the layshaft/mainshaft pair nearest the kickstart) and the 2 constant mesh gears (the pair nearest the primary drive).

I've still got the advantage of having my gearbox apart whilst I wait for new layshaft bearings from Draganfly :-(

I've been able to study the   thing for weeks now.

[duTch]

Yeahbut,yehbut, I hear what you're saying there,and don't dissagree, but what I'm referring to is what is on page 57 of my 1973 Haynes book, same as I've seen in other factory pages??  -Example->

A10- top    4.42
     third     5.36
  second     7.77
  bottom   11.41
??
 
PS can't you just get bearings from a bearing supplier??

[KiwiGF]

Hi Dutch those are overall ratios made up of reductions in the gearbox, primary and final drive as per yr post above.

I doubt I could get the kickstart side plain bush layshaft bearing locally, I could get a one off made locally but decided to buy one instead along with other parts I need but thought I didn't.

[BSA500]

Well here we are again noticed the vibration again. When replacing the clutch(that really needed doing and is now a clutch to be proud of) the shaft shows signs of wear,and vibrates. Until I strip down again I have a theory. The reason BSA drilled quite large holes in the bushes was to hold more oil?. Bear with me on this. When supplied with new bushes you need to drill oil holes yes?. So we don't have to line up the oils when pressing in we do them after resulting in quite tiny holes. This, I guess, would not present a issue in a pressure fed oil system, but in a box with the gears flying around and an oil bath relying on luck to fed oil by splash into spinning shafts and gears through tiny holes is asking alot. Ah I hear you ask "I have tiny holes(fnarr)and my shafts do not move". Well I am doing at least 150 miles a week so the issue may show up earlier and I suspect parking on the main stand since the side stand broke does not help oil flow into the holes. So if you have large holes like BSA designed them perhaps thats why?. Or am I talking out of my bum?

[bsa-bill]

On the occasions I have replaced bushes (they came with holes in them) I line them up, press them in then check the oilway by trying a rod or spindle down through the case into the bush, said rod or spindle being as close to a tight fit as my shed content will allow, if I'm not happy I use a drill with a speed adjustment to slowly and carefully drill through the bush if it's not aligned correctly,  then you have to clean up the inside of the bush to remove any burr.

A hand drill would be the obvious choice for this job but that is one tool I have always wanted but never remember to buy when out and about - a hand drill and a memory and my life would be complete (not sure I like the sound of that)