The BSA A7-A10 Forum

Technical (Descriptive Topic Titles - Stay on Topic) => Gearbox, Clutch, Primary => Topic started by: roadrocket on 05.11. 2012 22:01

Title: Clonk shifting 3rd to 2nd
Post by: roadrocket on 05.11. 2012 22:01

Hello

I have now had a few good runs on the Rocket since engine and gearbox overhaul, and it goes as sweet as never before in my ownership. But the box is not as it used to be, with some clunking and crunching shifting down, especially going from 3rd to 2nd, which gives a loud clunk when rushed. If I shift slowly it goes smoothly, but I used to be able to hurry through the box either way. Upshifting is much smoother. I can find neutral from first and second with ease. Is this indicative of some obvious fault? Maybe the indexing is not spot on?

Otto in Denmark

Title: Re: Clonk shifting 3rd to 2nd
Post by: wilko on 05.11. 2012 22:15

A clunk, or a crunch? There's a difference.Syncro ring worn out! *whistle*

Title: Re: Clonk shifting 3rd to 2nd
Post by: duTch on 06.11. 2012 09:44

some clunking and crunching
a loud clunk
 A clunk, or a crunch? Where's the boxing gloves for that whistly *whistle* basket *fight* ?

 we've covered most 'cl-cr' range except for the Cu..-basket ??, Maybe the clutch needs a little tweek??

Title: Re: Clonk shifting 3rd to 2nd
Post by: roadrocket on 06.11. 2012 16:43

Well, I searched the gearbox section quite thoroughly, and much was covered, but no clonks! The difficulty from 3rd to 2nd can be more accurately described as initially an unwillingness lifting out of 3rd, followed by a CLUNK when it finally shifts into 2nd, and this can be felt as a light smack on the boot upper when it CLUNKS into 2nd. A similar but lighter clunk can be felt shifting into 1st.

I have assembled my gearbox many times, but never noticed any syncro rings. The dogs on the individual gears of the constant mesh box are  fine though.

Cheers,

Otto in Denmark

Title: Re: Clonk shifting 3rd to 2nd
Post by: muskrat on 06.11. 2012 18:58

 Good one Wilco that'll get'em shaking their heads. *smile*
 Otto, you may have swapped the gear shift forks around. They are the same part but may have worn into a spot and now reversed giving problems.
Cheers

Title: Re: Clonk shifting 3rd to 2nd
Post by: wilko on 06.11. 2012 20:39

 *evil*

Title: Re: Clonk shifting 3rd to 2nd
Post by: Topdad on 07.11. 2012 12:54

Otto, take no notice of Wilco however do take notice of Musky ,he knows these boxes inside out, regards BobH.

Title: Re: Clonk shifting 3rd to 2nd
Post by: muskrat on 07.11. 2012 18:33

 Thanks Bob but there are much more knowledgeable folk here than I.
That's how I found a slightly bent one in the '51 box. Hard to go up from 3rd to 4th, I swapped them around and it was hard to go from 1st to 2nd.
Cheers