The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Gearbox, Clutch, Primary => Topic started by: pedrochapala on 10.06. 2014 21:59
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i've been down for 11 weeks now and done everything i can think of. replaced inside cover bearing on mainshaft and layshaft bush. took apart clutch and repacked the 18 roller bearings[looks like it could use 19?]. dificullt to get into neutral. once i do and it runs for a bit it pops out and makes a gawdawfull racket and i can't get it back. tried shifting into third on a short run and racket. got it apart again but not the inner cover. ran it for a bit with primary cover off and clutch side seems ok but it popped out but not totally and made the racket. please tell me i just need to adjust the gear control plunger! i'm going nuts!
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Hi Pedro,
Could it be you lined up the dots on the selector lever and the inner casing to well?
I remember when taking my box together again after a rebuild, I hit about everything except the correct gear (or any gear at all). I had to take it apart again and put the lever a notch higher to make it work correctly.
Since then I'm still wondering why the dots are there. I think it's a trick from the Brits to confuse us foreigners! *smile*
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i didn't take the box apart so the blue dots wouldn't have been moved? i just removed the inner and outer case covers in order to change the bearing race and brass bush. the noise started before i did this and that's why i did that in the first place. i thought it was a con rod but definitely from the gear box. the noise is at low rpm and seems to go away at speed. but now did it when i shifted to 3rd.
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Heya Pedro, getting' all a bit excited hey…?? *conf*
Morris- it's a plunger, so there's no dots like on a S/A(I think they do work, except for foreigners-just need the right colour- who said anything about blue, try red they work better *smile*)- the shift mechanism is different, but the main box internals are the same.
Can't say for anything for sure, but seems most have a whine in third gear, almost like it has a surrogate part number..! What kind of noise is it..??
Is the flange on the new bush the same thick as the original?
End float on layshaft minimal no- more than a couple thou?
didn't take first gear off the shaft and lose the inboard shim ?
18 rollers is right- I think, S/A have 20...?
Mine sometimes slips out of third under load- note to self...!
I have a spazzo connection at the mo so'll have a think about it and get back later..maybe try the selector plunger, but can't see why that'd suddenly need a change...?
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G'day pedro.
Sounds like a bent selector fork or badly worn cam plate.
To remove the forks the shaft they run on must come out. It's held by a grub screw best got at with the bike lying on it's side. The two forks are the same so mark which one comes out first. Put them back on the shaft and see if one isn't quite square to the shaft and other fork. It only takes a poofteenth to cause problems. If they look OK put them back in but swap positions. If the problem moves from 1-2 to 3-4 you can be sure one is out.
Hard hurried changes can do this. While it's apart check the teeth on the selector arm claw, they can chip or wear causing problems too.
Best of luck.
Cheers
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the noise in third is a clacking like teeth aren't meshing. as soon as i go back to second,it's gone. the noise when starting and idling is like a slapping con rod but as soon as i ride at higher rpm it disappears. when i stop i discover it has slipped out of neutral and i suspect into 3rd or 4th or something that doesn't exist[?] because one can still kick start and the bike won't run away or stall. actually, what i just said is strange-eh!
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Hi Pedro and All,
In your first photo it can be seen that the outer gears have fallen out of mesh,
This would seem to indicate a lot of wear on the inner end bush of the layshaft (bottom shaft)
A full strip and inspection would be my recommendation
HTH
John
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or something that doesn't exist[?]
Maybe you've discovered that elusive 'Warp Drive' that they've been searching for years for....?
Remembered I had a noise when putting my box together- had put the shim behind layshaft first on the outside my mistake... *eek*
Usually they jump into neutral, rather than 'out of neutral...?
I agree with the other guys though, and you can pull the innards out for a look, with box in place, but if you need to do the other bush, it's engine out.
Kinda hard to check play on the inner bush though however you do it...?
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I will go for a worn fork / sliding gear or cam plate as well.
Had this happen a few times to me with old leaky boxes.
the fork ends wear around the spot that they contact the grove in the sliding gear.
When this happens it causes increased wear in the grove so some times the gear will "flick" into full contact but light pressure will cause the gears not to mesh properly
The whine in only 1 gear also leans towards this theory as a dud bearing will tend to wine in all gears.
A dud countershaft bearing will whine only in top gear.
Selector fork scuffing ( and thus wearing ) will cause a whine in that gear only and oft it will be different depending upon weather you have up shifted or down shifted ito that gear.
A bad detent cam causing a mal alignment will usually make no difference up or down both will be bad.
So yes it is out with the box time.
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there is no whine. read my description again please. i have it out now so what am i looking for?
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G'day Pedro. Your going to need w
hine and lots of it ;D.
Do you have a parts diagram?
First check the camplate for fit on the bearing (not too much wobble), the grooves and the indents for the plunger. No nicks or rounded edges. Next the forks as described, square, no perceivable wear and fit on the shaft, also the pins that slide in the camplate grooves. With the gears look for rounded dogs and the respective holes and fit on the shafts. Check the two locating rings are in place. Check the selector claw for wear and chips and it's spring and plunger work. Check the constant mesh gear bushes for wear. If all that is good it should work.
Best leaving the whine till after it's checked.
Cheers
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Ok Pedro, there's no whine, but in your first post all we had was a "gawdawfull racket', which could have been clunks, clatters, rattle and hum or a whine.... which I'll say more about later...
In my previous post, the noise I referred to was actually what sounded like your description
the noise in third is a clacking like teeth aren't meshing.
, but if this was your original noise, my remedy is n/a anyway, but worth keeping in mind on reassembly... *ex*
If you haven't already dismembered the box, check the shaft end-floats first, and if there's a gasket in the joint, take note of its thickness, as that affects the layshaft float (obvious).
I suggest taking photos at each stage for your own reference...
The obvious check for bent shaft is roll it on a flat surface..?
I can't think much else that hasn't been said until you update us.....enjoy the sangria...!
Maybe not related to your issue Pedro, but just a thought on Trevs' post;-
I expect any clutch drag, and mismatched revs will help the selector forks wear quicker ...?
Selector fork scuffing ( and thus wearing ) will cause a whine in that gear only and oft it will be different depending upon weather you have up shifted or down shifted into that gear.
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my parts manual calls for a gear locating[c-clip] ring on each shaft. these were never on mine as long as memory serves. someone told me that they're only there to keep the gear clusters from falling of when you are servicing/inspecting. can i do without? it will take 2 to 3 weeks and maybe longer to get them mailed to me.
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G'day Pedro. I really can't say what happens if their omitted. I haven't got a spare box to try it. If it were mine I'd stick'em in. How did everything else check out?
Cheers
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i really don't wanna wait fer a coupla dinky parts that may not be necessary. it's been 12 weeks now. i hafta get then from abq, new mexico and if i use ups it will cost about $35usd. the layshaft rear bush is toast and i'm checking with a machinist here if he can make me one. i now know why neutral is so hard to hit on the cam. have any of you slightly enlarged the notch?
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Sorry can't help (the deepest recess of the gearbox is a big mystery to me!). But if you can find the time to post some detailed pictures + description of the work, the story, solutions and (forcefully) acquired expertise will be useful to future readers (myself included).
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I think the circlips may be needed they keep the end gear in place, it's quite a push to get the end gears over the clip and located correctly, don't see BSA doing that just to make assemble easier but you never know
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Good that you found the bush problem Pedro. Go to your local car engine re-conditioner and go through his tin of old gudgeon/wrist/little end pin clips. I'm sure you'll find something to use.
Cheers
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I also reckon best to have them, as it may(or may not) just be that if the gears the clips retain are not in the correct spot, it could be the cause of the problem- maybe not the worn bush, but slightly ineffective gear meshing (hard to find neutral- ?).
I wouldn't bother with deepening the notch any, that could create a whole other bucket of crap...
Also if you have a bush made, don't forget the oil scroll inside.
A mate made mine, but didn't have the correct gearing to do the scroll on the lathe, and while I was doing that by hand, (as an aside) put some thought into the direction of the scroll and whether it draws oil in to the bush in conjunction with the feed hole above bush top, through the scroll to be pumped up the shaft, or just fed via the feed hole, to be squeezed out the scroll (and up the shaft by the centrifuge action exiting through the three holes in the shaft)...?... any thoughts...?
How do the rest of the bits look..? Not hard to do, is it...?
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are we talking circlip on the mainshaft just in front of the pressed on cog ? oh sorry realise plunger box so don't know if the same. if it is when did mine i sure someone said this was only as a guide to how far the cog should be pressed on ,mine was damaged by the fitter so I removed it with no probs , so far or have I gotten the wrong end of the stick?BobH.
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How you getting on Pedro...?
You got me motivated to go investigate my spare box and the cluster that I swapped out of it.
I discovered the layshaft thrust washer between gear 1&2 missing....dunno how it didn't rattle, still investigating....so,....
I'll concede that the lack of circlip may be ok under duress if the gear is located correctly, and doesn't move, less likely I think on the layshaft than the mainshaft, as tightening the nut could pull the shaft into the gear/bearing further..(?)....
I'd still recommend this as no more than temporary fixit, but am open to stone-throwing in my direction...(haven't heard from Richard L. for a while...where is he when I need him *smile*m)
Yo Bob- as far as I can tell, all 'A' boxes are same internals- except for some gear ratios, and the use of needle rollers in RRT2 (Close Ratio) box, but not sure if these are in SC/T/other? box- oh and the Layshaft pressed on constant mesh gear on C/R is wider as I discovered (more on that later/elsewhere).
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hey thanks for everyone's input. shift's like a dream now and neutral has never been so easy to find. circlips aren't necessary. had the rear bush made as the layshaft had a 5 thou taper[from wear?], so a standard part may not have fit. the sprocket was loose and i tightened that as well.repointed the tip on the spring loaded selector on the lathe.
now i gotta keep on re-strengthening my leg as most of the time i still need one of my amigos to kick it for me.
i don't wanna do anything with this box again!
gracias again!
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shift's like a dream now
Great, nice to read about good news.
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Nice one Pedro- On Da Road Again..!
now i gotta keep on re-strengthening my leg as most of the time i still need one of my amigos to kick it for me.
But with the down-time I'da thought there'd be some fair leg-swingin' practice happening....in between sangrias....?
If it's any consolation, you made me go and pull my spare box apart, and do a full forensic analysis *eek*, and lucky so, as the 1st gear thrust washer was missing, but as I'd grafted my close ratio gears in that I had left over from the old Road Rocket, it meant the .......ah no- another day....!
But it told me if the gear is nice and snug on the shaft without the circlip, it should be ~ok, but personally I'd still rather have one.