The BSA A7-A10 Forum

Technical => Clutch, Primary, Gearbox => Topic started by: BSA500 on 04.10. 2012 13:39

Title: Sleeve gear bushes
Post by: BSA500 on 04.10. 2012 13:39
Can the sleeve gear bush from a A50/65 be used in an A7 swingarm box?. Curious minds(mine) need to know or are the shaft dimensions different.
Title: Re: Sleeve gear bushes
Post by: muskrat on 04.10. 2012 20:33
G'day, can't say for sure but looking at my parts books the A10 has two bushes 67-3073 and the A65 has a long one 68-3026. Would have to compare and measure.
Title: Re: Sleeve gear bushes
Post by: groily on 04.10. 2012 21:38
Dunno either, except to say that when I replaced the bushes on mine a few years ago I made a new full length single one. Though I sez it as shouldn't, it's been good and shows no appreciable wear after a good few miles.
The difficult part was getting the outer portion of the mainshaft down to the somewhat-reduced diameter of the wearing section (and truing that up too). Seems to me that absent a really excellent mainshaft it would be difficult to use any bush of standard id and expect a good fit?
Cheers, Bill
Title: Re: Sleeve gear bushes
Post by: BSA500 on 04.10. 2012 22:44
I am just considering different options as I have replaced them twice now. First time they moved in the gear and blocked the oil holes=rapid wear. When removed they did seem to be a sloppy fit-supplied by *****. After two months and alot of chasing. Next set supplied by c&d arrived quickly and until I get them out I can't say why they have worn out in approx 3 months. So I was looking around for alternatives like one long bush or oilites. Also pondering about the size of the oil holes in that when bsa made them they had very large holes,when we fit them we drill them afterwards giving relatively small holes. Now I must mention I am doing 150 miles a week on the A7 so the bushes are getting a good workout but I would expect them to last many thousands of miles. I don't remember reading anywhere about this being a particular problem of the A7/10's.
Title: Re: Sleeve gear bushes
Post by: muskrat on 05.10. 2012 08:48
 I'm almost sure the ones in the '51 are the originals and for that matter I don't recall replacing the ones in the '57 either. Probably just jinxed myself. *sad2*
I'm not gentle on'em either. I do use a teflon additive.
Title: Re: Sleeve gear bushes
Post by: BSA500 on 05.10. 2012 09:18
I only replaced them first time when the vibration became huge(I thought the mains and or big ends were fubared) and all the oil used to pour out when on the side stand. I had owned the bike over twenty years by this point so they should not wear out this quick. Has the quality of the bearing metal got that bad??
Title: Re: Sleeve gear bushes
Post by: muskrat on 05.10. 2012 10:19
 There is something amiss there. Bent mainshaft? Rear or primary chain too tight? A new pair of rear shocks a bit longer will alter your normal 1" play so chain will stress the bushes on compression. Front & rear sprockets not in line? Main & lay shafts not in line (dodgy lay shaft bush). "Like a box of chocolates."
But you know me, I often miss the simple things. Probably the way you pull mono's off the line. *eek*
Title: Re: Sleeve gear bushes
Post by: BSA500 on 05.10. 2012 10:56
Have checked the chains under compression etc and ok. Rear shocks correct lenght even if they are Koni's,checked the mainshft and layshaft when the box was down no bendyness. Spockets in line. Layshaft bush more than prob worn but no undue slackness/movement. So prob is the wheelies you got me ;). Other than the play up and down etc there is a little in and out play is that allowable?. I have the thurust washers etc in place?
Title: Re: Sleeve gear bushes
Post by: muskrat on 05.10. 2012 11:13
How much is a little? Once the sprocket nut is done up there should be no end float of the sleeve gear. Bearing loose?
Title: Re: Sleeve gear bushes
Post by: BSA500 on 05.10. 2012 15:54
Sorry I meant the main shaft has a little in/out play
Title: Re: Sleeve gear bushes
Post by: chaterlea25 on 05.10. 2012 16:15
I'm with all the possibilities suggested by Musky
Did you put the mainshaft between centres or on V blocks and check with a DTI ?
I recently changed the mainshaft in an A10 which had about 8 thou bend, mind you this had lasted for 10 years before there was much wear in the bushes
If theres in out play then I would look at the bearing at the kickstart ratchet end of the MS.
The only other thing I can think of is did you change any of the internal gears? If you fitted a gear with an extra tooth it would load the mainshaft/ layshaft bushes????
On each pair of gears the tooth count should add up to the same number
Or have the box end cases been changed?
I only had a one piece blank bush to fit to this box and had to bore and hone it to sizeafter fitting, I made a jig in the lathe that would hold the sleeve gear true, and then bored the bush centre to size, with a relief for oil in the centre
Trouble was that when I heaved up on the gearbox sprocket nut it tightened on the shaft  *sad2*
I honed it out a thou or so till I thought it was ok, but on the first run out it tightened again  *eek*
Strip and hone some more and all was OK
I have seen bushes that have turned so the oil holes were blocked and others where no holes were drilled
None of these seemed to give trouble in use  ???? ????

Title: Re: Sleeve gear bushes
Post by: BSA500 on 12.10. 2012 13:32
I have done no major changes on this box for at least ten years and that was to change all the gear clusters(robbed a under used C12 box for the gears) the shafts have stayed the same. I do not have the equipment to check the shaft for true and there are no engineering shops anywhere local. The first time I had to replace these bushes was after 20 years of owning. That one ended with the bush turning and blocking the oil holes = new to worn out 1 month. I felt those bushes pressed in a little to easy. Next set(current ones) have been in 4 months so until I change them I cannot say what caused the premature wear yet. I will check what I can the bearings etc. I am going to drill out larger holes and see how we go
Title: Re: Sleeve gear bushes
Post by: chaterlea25 on 14.10. 2012 22:48
Hi BSA500,
Hopefully in the next week or two I will have a few sets of original steel backed bushes available
I will have to wait and see what exactly I bought on fleabay ???
I'm presuming you mean C11 heavyweight gears?? C12 has a lightweight box??
While those gears will fit they have a lesser number of engagement dogs and I believe a different material
A check for the mainshaft run out can be done by watching the primary chain tension while operating the kickstart with the clutch disengaged, tight and loose while turning indicates runout
Title: Re: Sleeve gear bushes
Post by: BSA500 on 15.10. 2012 13:17
Yes the c11 they are exactley the same bar the mainshaft. I had the gears pressed off the c11 shaft and pressed on to the a7 shaft. You may ask why I don't use this firm again,they took two weeks and wanted to charge me £100 for an hours labour when it truth it took them 20 mins. I managed to beat them down to £48.  :!. I will do as you suggest and check if there is any noticable run out. If there is I am buggered as new shafts seem to cost the earth and the poss of a good second hand one must be near impossible. Fingers crossed my theory of larger oil holes in the bush could be the answer. Oh new bushes have been ordered from Cake street.
Title: Re: Sleeve gear bushes
Post by: The pirate on 21.10. 2012 15:21
May sound stupid but; when you changed the gear cluster and put it back in did it spin freely - after the cases were tightened. It is possible to think tightness is the new bush, seal etc when in fact the cases are distorted or one of the shafts has no end float causing the cases to warp as they are tightened. Is the bush being pressed in to the case squarely. Also are the gears sitting square on the shafts. An out of line gear could cause an intermittent tight spot in only one gear that forces the shaft out of line and this only becomes apparent when you fitted a new bush allowing no movement. When I rebuild a gearbox I spin it by hand in every gear up and down the ranges, to check for tight spots and the change mechanism works correctly. Only thoughts to a strange problem.
Title: Re: Sleeve gear bushes
Post by: BSA500 on 21.10. 2012 18:14
No the box is nice and 'loose' and free spinning. Have the new bushes so I plan to strip the box later this week so I shall see how I go.
Title: Re: Sleeve gear bushes
Post by: BSA500 on 27.10. 2012 13:40
Box is stripped and the bushes do not look too bad but are worn enough to"rock" the pinion on, drilled bigger oil holes and pressed the bushes in. One was too long so had to trim the excess off. When measuring the id one bush was thicker than the other so reaming them has been tricky always fun *conf*.