A10 Gearbox

[duncan32bsa]

Hi there,
I'm (slowly) restoring my 1960 Golden Flash. My attention has now turned to the gearbox. I want to replace the mainshaft bearing and the layshaft bush fitted into the shell.
I assume that I can drop these out by heating the shell. However I can see that it is going to be a bit trickier to refit them as they go in from opposite sides and I can foresee that one will drop out as I turn the shell to fit the other. Also keeping the oilway aligned on the bush will probably be tricky with a very hot shell.
Does anyone have any advice on the best method for doing this efficiently - and in which order I should proceed - bush then bearing, or vise versa?
Thanks for any help
Gary

[bsa-bill]

Hi Gary - done this a couple of times.

Did bush first, you need to line the bush up carefully then press it in, went well both times and oil hole lined up with same in case, as a matter of interest Lyford Classics list an 0.004 undersize bush for worn layshafts.
My thinking is/was that the mianshaft bearing will require less heat due to it's greater size (expansion effect will be greater on larger diameter housing). plus it only has to be tapped down with out worrying about oil hole, tap down evenly or use an old bearing outer with cloth or something over it, dead blow hammers of the rubber type are good in these situations.
best of luck with it

[Retired Fireman]

Hi Duncan, my expearience with this job and a couple of precautions! Firstly the mainshaft bearing is a common bearing BUT it is available in a few clearence sizes from your local friendly bearing supplier more on that later, you have to heat the gearbox casing to expand it for the bearing to come loose and fall out (Aluminium expands quicker than steel) to do this I use what every red blooded Aussie has in his back yard a BBQ! Mine is a 6 burner (REAL MEN HAVE NO LESS THAN 6 BURNERS IN THEIR BBQ'S) My BB has a temp guage, light No 1 and 6 jets on yu BB and watch the guauge get to 200 deg F then put the gearbox shell in the MIDDLE of the BB in old baking tray to catch the gearbox oil which will leach out of the assembly when it gets hot. Don't put it where the flames will touch or you will have a fire. you can judge the required temp by spitting on the casing when the golly rolls around madly on the aluminium it's hot enough. Then with gloves on remove the casing from the BB and push out the bearing from the inside.  Now drift out the gearbox bush from the outside while the casing is still hot. Allow the casting to compleatly cool then clean the casting and pay attention to the bush hole and clean up with paint thinners or simular, put the new bush and bearing in a plastic bag in the freezer then heat up the casing in yu BBQ till hot enough as the above method and drift in the bush from the inside after coating the outside with Loctite hydraulic lock to stop oil leaks then drop in the cool bearing which should just fall into the bottom of the housing of give it a couple of taps AROUND IT"S OUTER RING!!! equally till it's home. Now that brings us to the ball bearings, these things are made to the same sizes BUT the internal clearences are made different for various applications. In the case of an A10 gearbox the bearing is held by interference that means when the casing has cooled down the bearing is crushed to hold it from turning, in this application you have to fit a "C3" clearence bearing as the same size bearing is made in various internal clearence sizes to fit a range of applications this is important to fit the correct bearing. If you wish to know more about the gear box setting up let me know as I have devised a method to assemble them so they dont leak oil at all. ( too tired now got to go to bed! Hope this helps.

[brackenfel]

Hi Gary,
Did mine a little while ago with the help of a real (ex Rolls-Royce) engineer friend...

Careful use of a blowlamp on the alloy was sufficient to heat the casing to remove bush and bearing.. said friend decided original bearing was fine so that went back in ! (I had bought a replacement but wasn't going to argue...!).
We did them one at a time - I suggest you do the same, especially if you are working alone - applying heat only to the immediate area around the item we were working on..

Replacement - the trick was to get the cases sufficiently warm and to have the right-sized drifts available to tap them gently into place. Make sure you have a means of holding the case firm and still while you do this..As already mentioned do be sure to line up the oil hole on the bush.  Repace the oil seal as a matter of course.
I replaced both layshaft bushes & despite the shaft looking somewhat worn / grooved we had to apply gentle use of a reamer to them to get the shaft back in!


Hope this helps,

Adrian

[bsa-bill]

should have mentioned I used a heat gun - no chance of melting anything but gets hot enough for purpose

[duncan32bsa]

Hi Everyone,
Thanks for all your help and suggestions
Job done. Used wife's domestic oven (I had thoroughly degreased the case beforehand...).
Heated to approx 200C. Found holding the bush in place a bit tricky - it didn't just drop in... Used 'surgeon's tweezers' and then drifted with a very worn layshaft. (Very worn, presumably, since the old bush oilway did not align with the hole... Slight panic when after having to 'drift' in the m/s bearing, it fell straight out again when I inverted the case to check it was all the way in.
Anyway, the bush seems like a good fit on the replacement layshaft and the bearing centre seems OK too. I bought them both from Draganfly, BTW.
Retired Fireman, I would be very interested to hear your assembly method for oil-leak free operation.
Again thanks for all your help.
Gary

[Retired Fireman]

Duncan, the gear box leaks in a number of places (there's a revelation!) but with some fiddling around and a couple of cheap machining jobs it can be made oil tight. I should have mentioned when you buy your 6307 C3 main bearing get one with seals then pick out one seal, when fitted the open end of the bearing faces in toward the oil supply, next you have to find an old gearbox sprocket and grind or turn most of the sprocket off it but be careful not to damage the oil seal area. You use this to make a tool to align the oil seal central to the gearbox sprocket befor inserting the clip to hold it in position.  After fitting bearing and bush but before you fit the new seal degrease all around the outer bearing/seal face and the case around it's outer edge with a good solvent and allow to dry, the bearing's seal will stop stuff getting into it's track, then lightly coat the outer inner face of the seal with a good gasket making silicone sealant (I use Loctite red gasket silicon)  lightly push the seal into position then slide the old sprocket to align the seal then fix home the circlip and remove the sprock/tool then fit new sprocket. Before fitting tab washer and nut give the inner side of the tab washer a coating of the silicone around it's centre to stop oil leaking out of the gearbox spline then fit the nut tighten bend tab. The seal in the bearing just stops any silicon from entering the bearing but maybe it helps hold back the oil. Another place for a leak (yes there are plenty more) is the selector rod hole on the sprocket side of the gear box after the rod is fitted smooth some silicon all over the outside of the rod and case after degreasing and roughing up with emery to help the silicon bond to the case/rod. Then the leak all A10's have that are fitted with a side stand, the gear oil leaks out of the top gear bush when you park your bike. This leak is easy if you have a lathe or a machinest friend. You have to mount the top gear in a lathe and machine out 1/4" of the bush from the inside of the gear then fabricate a seal holder that you press into the end of the gear to hold a small lipped seal as in the pic, from memory the sealis 1" od X 3/16 wide 13/16 ID or metric that is close to the ID. Hope this helps the other leaks are in the selector/kickstart shafts don't have time this morning to get to thse but if you want will post their fixes.

[duncan32bsa]

Hi Retired Fireman,
Thanks for the suggestion. By the way, did you forget to upload the picture you refer to?
Thanks
Gary

[Retired Fireman]

Tried twice to upload the pic and it didn't work, while I am proficiant at fixing A10's I am no good at computers DON"T SAY NUTHIN TREVOUR A54!!!. if you want a pic of the seal holder in position email me.

[BSA_54A10]

Awe Stevie Weivie, don't get like that.
Send the image to me & I will downsize it & post it .
I do this because it was a good idea and deserves to be seen by all.

[lefty]

I'd love to see the photos of the leakproofing steps - just to make sure i'm on the same wavelength before plunging into my 'box

cheers

[Peter in Aus]

Thanks Retired Fireman some good info there
Cheers
Peter

[duTch]

 Saw this thread the other day, but little time to comment...then

 

Then the leak all A10's have that are fitted with a side stand, the gear oil leaks out of the top gear bush when you park your bike. This leak is easy if you have a lathe or a machinest friend. You have to mount the top gear in a lathe and machine out 1/4" of the bush from the inside of the gear then fabricate a seal holder that you press into the end of the gear to hold a small lipped seal as in the pic, from memory the sealis 1" od X 3/16 wide 13/16 ID or metric that is close to the ID. Hope this helps the other leaks are in the selector/kickstart shafts don't have time this morning to get to thse but if you want will post their fixes.

 Good and well but wouldn't that restrict oil to the bush..? a seal at the other end would be better if possible...??

 

Another place for a leak (yes there are plenty more) is the selector rod hole on the sprocket side of the gear box after the rod is fitted smooth some silicon all over the outside of the rod and case after degreasing and roughing up with emery to help the silicon bond to the case/rod.

 How about cutting another groove inside the grub screw groove, for an 'O' ring...?

One thing I thought of, is to to drain excess oil from the sleeve gear bearing housing by drilling a small hole or two in the bottom of the bearing recess...? (picture)
  With regard to the layshaft bush; while playing with my spare (Plunger) box into which I grafted close ratio gears and layshaft, which has needle rollers, I noticed that the bush oil feed hole above the shaft had been obscured by the needle roller, so it had no oil supply.

 I did some research (probably about other stuff as well), and came across that Goldie resto which I now can't find(I think it's a scrambler?), that in the RRT2 box, the oil feed hole has been moved forward to near the intersection of the sleeve and fixed gears, and I think it would provide better supply by almost 'force feed' than where the bush oil hole is.(see photo)
 I don't know if it's a standard RRT2 thing or this guys mod- anyone with a RRT2 know??

 Could be one of these links, handy anyway; probably already here somewhere...I got lost...
http://www.britbike.com/forums/ubbthreads.php?ubb=showflat&Number=496950&page=9

http://www.britbike.com/forums/ubbthreads.php?ubb=showflat&Number=341901

...and Beeza Bils A10 box
http://www.bsa-a10.hailwood.com/billsgearbox.html

whoops forgot to ad the piccie(s)- done