The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Gearbox, Clutch, Primary => Topic started by: bakerlonglegs on 15.05. 2016 22:01
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The only part of my A10 project in one piece when I got was the gearbox (everything else was in bits). It's time to strip it down and see what I've got.
Now I've never taken a gearbox apart. Ever. Please take anything that follows as potentially rubbish, as I'm learning as I go along. Do feel free to chip in with corrections and observations.... *smile*
What I started with:
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First, off with the outer cover. Four, rather chewed, nuts and three screws later, all to be replaced, and it comes away thankfully easy. Underneath there is the speedo drive, the clutch actuating arm, the kickstart spindle and quadrant, and the gear change selector lever, all OK. The selector lever is bit loose on the spindle, I may peal the tab washer back and see if it can be tightened.
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Looking at the kickstart ratchet mechanism on the end of the main shaft, to my untrained/inexperienced eyes the teeth look rather worn. The tab washer looks like it's been off a few times, time for a new one of those too.
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The inner cover comes away with some gentle taps. (I have replacement gaskets already!)
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Now loosen the grub screw on the drive end and remove the selector shaft. Then lift out the cluster after taking out the main shaft.
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After taking out the grub screw holding the gear shifter shaft, I could take out the main and lay shaft gear clusters. As this is my first gearbox strip down I don't quite know what I'm looking for but, with one exception, they look OK to me.
Edit: thanks Trev! More to come....
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The exception is this gear on the end of the layshaft. The inside slots are rounded off. I think it's because the layshaft thrust washer had been assembled on the wrong side of the gear during a rebuild by a former owner, meaning the gear caught on the lugs (right word?) of the adjacent gear when the 'box was in neutral. Might look at replacing this if I can.
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Now to the clutch end of things. I followed the Haynes advice and clamped an old chain round the gearbox sprocket to hold it still while I took the nut off. The teeth on the sprocket have looked better and one has cracked, so that's another part to replace.
That's all for now, more tomorrow....
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The inner cover comes away with some gentle taps. (I have replacement gaskets already!)
Looking at the picture that ends in 580, there appears to be cracks around one of the holes. I believe it's the hole for the gear shifter fork shaft.
Richard L.
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RichardL - you're right, there are cracks around that hole *sad2* . I'll need to think about repair, if there's any way of doing that, or replacement.
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RichardL - you're right, there are cracks around that hole *sad2*
Strange place for stress cracks *dunno*...
BLL;- As you've no doubt discovered these boxes are fairly user friendly. To my inexperienced eye it all looks better than some of mine except for some 'chattering' on the teeth and the 'H' (1st l/s)gear.
The bottom rear mounts look a bit flogged, I got around this by tidying them up (filing them square), and fitting the box to frame with the top mount bolt in and adding some S/S washers under them to take up the slop. This can be also achieved by building up with weld and fettling.
Obviously you'll check for any wear /slop in the layshaft bushes? A bit hard to determine easily due to lack of access.
good luck, help is at hand
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If you need any parts send me a PM as I've got a box of gearbox bits which include a lot of plunger stuff ,no interest to me as mines a s/wing arm . Bob
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duTch - thanks for the advice!
Topdad - cheers! PM on the way, I just need to check the part number.
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The exception is this gear on the end of the layshaft. The inside slots are rounded off. I think it's because the layshaft thrust washer had been assembled on the wrong side of the gear during a rebuild by a former owner, meaning the gear caught on the lugs (right word?) of the adjacent gear when the 'box was in neutral. Might look at replacing this if I can.
Long time since I've had my 'box apart but I think those 'slots' are meant to be like that, to make it easier for the matching 'pegs' to engage.
Someone with a better memory please confirm or otherwise.
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Time for some more pics....
Circlip and oil removed. The bearing seems OK, but is that one of those parts that you should always replace when rebuilding an old gearbox?
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Sleeve pinion....
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Selector cam plate and associated parts....
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Now on to the clutch. First problem is snapped or flattened threads on some of the little bolts that connect to the clutch cover.
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Others may disagree, but I believe you could forego the cover. If so, I'd say remove all the nuts, shave off the stud that's broken in the photo plus the one that's 180 deg. opposite (for balance).
Richard L.
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You can run it without the cover. I prefer to run with the cover (a few missing nuts won't hurt) as I think it adds rigidity to the basket. I've seen the odd one spread a little causing the plates to rattle.
If you go without the cover make sure the oil you use is NOT friction modified.
Cheers