The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Gearbox, Clutch, Primary => Topic started by: Drew Back on 22.04. 2017 21:54
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I was riding my 55 plunger all was going great then all of the sudden I could not shift to 3rd or 4th gear. What could cause this to just happen out of the blue??
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G'day DB.
Do you get any crunching or does the pedal go full movement and nothing happens?
Usually with wear things happen gradually, gets harder and harder to get the gears.
The selector fork for 3 & 4 can wear or bend or the lug that acts from the camplate. The selector arm claw can wear (or chip) it only grabs the camplate by a bees dick (hence the need to use a very thin gasket between the case and inner cover).
All of the above have happened to my 51.
Cheers
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...it only grabs the camplate by a bees dick...
That's an Ozzie measure. In the UK we prefer the ISO approved Gnats Cock. It's about a third the length of the aforementioned Bees Dick but you know, size isn't everything.
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A gnats cock, that's about the size of a poofteenth!
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I was riding my 55 plunger all was going great then all of the sudden I could not shift to 3rd or 4th gear. What could cause this to just happen out of the blue??
I can't envisage what's happening without more info, like what was happening with the shift lever?
What gear were you in when it went awry ?
If in 3rd or 4th at the time, could you find second or 1st thereafter, or did it remain in the 3rd/4th realm and jam, or move but not select?
Irrespective of any of this, it fairly much needs surgery....depending on the symptom, I'd suggest there's an issue with the lug on the selector fork that engages with the groove in the camplate, or the groove itself.
If there's too much gap (too-thick gasket behind camplate bearing/spindle) between the selector fork lug-face and camplate, it could jam, or maybe the selector fork shaft is a tad bent ('tad' is a different measure again- but much more refined *conf* )
*dunno* until more info
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From memory I think there are 1.6 Gnats Cocks to a Tad. *conf2*
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I had been riding the bike around for about 1 hour it was shifting great. I started off at a light got 1rst and second but it would not go down to third or fourth no click no movement would go back to 2nd and first as well as neutral quite easily will try to tear into it this weekend..
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G'day DB.
From that I'm still going fork and/or claw.
Ease off the detent spring a "tad" (1-2 turns).
Tad's can be big or small depending on the application *conf*
Cheers
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Tad's can be big or small depending on the application
You colonists and your ingenious ways! I imagine that genuine Tads were in short supply back in the penal colony days so you had to devise clever ways to measure your Gnats Cocks. ;)
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I got her going nice and smooth it ended up being worn/broken springs..Thank you for the imformation.
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Good stuff/ too easy- 'tis often too easy to over-tink tings....now we'll all say "why dinae oi tinka dat?" *conf*