The BSA A7-A10 Forum

Technical => Clutch, Primary, Gearbox => Topic started by: Topdad on 13.02. 2017 11:30

Title: Avery satisfying clunk and a question.
Post by: Topdad on 13.02. 2017 11:30
Been struggling with the g/box on the Beeza, namely to bloody cold to do much in the garage. So I had got to the point where the main drive bearing needed to be removed but couldn't get any where enough heat on the casing in the garage (freezer ?)  lots of head scratching , including asking the guy next door to use his out door oven , but that was a no no he'd disconnected his mains for the winter and was awaiting a new fuse box . A window of opportunity appeared in the shape of my wife and daughter having a spa day , so while the cats away cases in oven to 200c and 15 mins later the bearing fell out , even better after a quick warm up ,2-3 mins I dropped the new bearing (from Andrew Priory mags ) in and it bottomed with a really distinctive clonk , checked all was well ,put it outside  to cool and had the oil seal and circlip seated  went to push the sleeve gear through which went well but suddenly noticed just as ready to tighten the ring nut that the sleeve wasn't drilled for oilways . So theres the question , I've drilled the 3 holes through and smoothed out the inside so the mainshaft is ok on it but would it have seized had I not drilled the holes .I'd have said yes definitely until I looked at the sleeve gear from the box I'd taken out I had drilled that myself but on checking the bush had turned slightly and the holes were blocked ,however, it had been working perfectly up to taking the old box out so was that just lucky or are the oilways there no really needed, cheers for now Bob ps the wife didn't find out so unless one of you lot tell her my nuts are safe  *bash*
Title: Re: Avery satisfying clunk and a question.
Post by: bsa-bill on 13.02. 2017 11:48
not much of an answer to your question but am I right in thinking the same bush for RGS gearbox's never had oil holes
Title: Re: Avery satisfying clunk and a question.
Post by: chaterlea25 on 13.02. 2017 19:55
Hi Bill,
The RRT2 usually fitted to RGS models has a needle poller bearing in the inner end of the sleeve gear
Original needle bearings have one oil hole in the outer

John
Title: Re: Avery satisfying clunk and a question.
Post by: bsa-bill on 13.02. 2017 21:09
Ah of course, forgot the bearing bit which is what the RRT2 was about,
Title: Re: Avery satisfying clunk and a question.
Post by: coater87 on 13.02. 2017 23:55
 Im going to guess that the old sleeve bushes had enough slop, that you got enough oil, to not seize.

 Im also going to guess that new sleeve bushings properly fitted but with no oil hole, would not have made it 10 minutes.

 There is quite a bit of bearing area in the sleeve so it would not take long to overheat and lock tight without oil.

 The old ones may have been sloppy enough that it couldnt seize, but you would think the shaft would have been pretty rough. *conf*

 Either way I think it was a good catch to spot that.

 Lee

Title: Re: Avery satisfying clunk and a question.
Post by: Topdad on 14.02. 2017 10:30
Thanks every one , final bit , just where the hell did that bit of return spring get to  *dunno2* which was the original reason for the box change ?????????
Title: Re: Avery satisfying clunk and a question.
Post by: Topdad on 24.03. 2017 11:48
Just had a chance to rebuild this gearbox as I had an hour free in work, better light ,phones off and warm  so had some piece and started.
I refitted the cam plate and plunger at neutral and decided to check the movement of the gear dogs when fitted on there shaft and into the plate .With the plunger backed right off it was easy to turn the c/plate and watch the movement of the dogs . they moved nice and smoothly and the plunger held the gears as intended , a few mins of checking that helped clarify the refitting of layshaft and mainshaft plus dogs which followed and was done ,using the elastic band method someone mentioned before ,don't like tempting fate but it was easy ,better still I was rewarded with a really crisp click when I'd fitted the outer cover /gearchange arm . *wink2*

To our more competant engineers a question ,when BSA were machining the camplates back in the 40's/50's they didn't have computer controlled machines so what method did the use to produce such accurate tracks in the camplate , cheers Bob
Title: Re: Avery satisfying clunk and a question.
Post by: duTch on 24.03. 2017 12:41
 Hey Bob, I've been wondering how you're getting on/off with it. .. Other comments later but I've decided the camplate works on asymmetric concentricity *eek*.
 There's only actually three positions for the gears on each shaft (left/neutral/right) so three different radii on either side....I'll try and explain that better when I'm back at the very low chaparral in a while, and not at the pub


   ^^^^^^edited   *eek* *eek*^^^^^^^
Title: Re: Avery satisfying clunk and a question.
Post by: coater87 on 24.03. 2017 16:24
 Its hard to explain but easy to imagine.

 Take the maker Bridgeport for example. They have a duplicating mill that nobody wants anymore.

 Basically you make a pattern for the cut, use a complicated stylus attachment to copy the pattern- and the real milling head will cut that out in real time.

 Like one of those wooden things you can copy pictures with. One side you copy over the drawing, the other side has a pencil that duplicates the drawing to a new piece of paper. But in this case its cutting metal and using hydraulics for the tracer.

 Now with CNC, nobody wants that type of machinery. It takes a lot of space and has limited use and is not as accurate.

 It leaks oil all over the floor and there was a lot of cussing going on. Thats what I remember most about the one I saw working a long time ago.

 Lee
Title: Re: Avery satisfying clunk and a question.
Post by: coater87 on 26.03. 2017 00:24
https://youtu.be/Kisxs26wR4I (https://youtu.be/Kisxs26wR4I)
First time I've tried this. It's a you tube video showing how a very small (completely manual) duplicating mill works.

 The larger ones are not moved by hand like you see these guys do. Movement is much like a tracer attachment on a large lathe, lots of hydraulics involved.

 Also notice how clean this one is. The one I watched was literally covered in yuck. 10 feet surrounding the machine was a puddle of oil and chips, and the poor guy running it was just as filthy. It must have been almost completely worn out, it howled like you would not believe. Also the operators had a potty mouth almost as filthy as the machine and he was even louder. *smile*

 Lee
Title: Re: Avery satisfying clunk and a question.
Post by: kiwipom on 26.03. 2017 05:04
Hi, yes very interesting but very slow, cheers