BSA Owners' Club Workshop Discussions

The BSA Workshop => Twins => Topic started by: Kevin1963 on 28 Sep, 2024, 15:18

Title: Gear change lever not returning
Post by: Kevin1963 on 28 Sep, 2024, 15:18
On my a10 changing gear the lever does not return when changing from 3rd to 4th and visa versa!
It returns in both 1st and 2nd. Have replaced the spring thinking it was that but no difference.
It was working perfectly until a couple of weeks ago?
Anyone any ideas before I take the box apart and have a look inside.
Kev
Title: Re: Gear change lever not returning
Post by: cornishbob on 28 Sep, 2024, 16:03
does it do 2nd to 3rd and 3rd to 2nd? does it happen when rear wheel is off the ground? is chain adjustment good (not too tight)?
Title: Re: Gear change lever not returning
Post by: Kevin1963 on 29 Sep, 2024, 11:26
Thanks for reply.
It happened with wheel off the ground and will riding.
No not between 2nd and 3rd. Have jus t slackened the chain by two flats on the back wheel and appears to have cured it on the ramp so now need a nice day to check on the road!
So thank you   I thought I had the chain right?
Kev
Title: Re: Gear change lever not returning
Post by: cornishbob on 29 Sep, 2024, 12:12
i have had experience of this (not with bsa)

if loosening the chain does cure it then maybe theres a bushing worn or even shims deteriorating. even a cam plate badly adjusted but if it has happened recently then thats unlikely

i should point out, as i always do, i know less than nothing about bsa gearbox innards and the workings there in.

i work on the premice they're all fundamentally the same. just fewer or more teeth and wearability can vary.

always remember... if all else fails theres always a bigger hammer
Title: Re: Gear change lever not returning
Post by: DAVE BRADY on 29 Sep, 2024, 13:06
Hi,

Check the primary chain as well.  If both are a bit tight then the friction on the sleeve gear will be quite high.

Dave.
Title: Re: Gear change lever not returning
Post by: cornishbob on 29 Sep, 2024, 13:53
good point but it was being used ok then suddenly started happening. unless cover came off and chain adjusted which would be difficult to forget
Title: Re: Gear change lever not returning
Post by: DAVE BRADY on 29 Sep, 2024, 14:08
Hi,

As you will know the tension of each chain can be affected by the other as they both depend on the gearbox adjuster and bolts being tight.
If the rear chain was too tight it can cause the gearbox to move backwards.  In practice I have found that the rear will dominate and cause the the primary to become too tight.  My routine was to do the primary first and really tighten the gearbox bolts, then do the rear and then check the primary again just in case.

Dave.
Title: Re: Gear change lever not returning
Post by: cornishbob on 29 Sep, 2024, 15:35
absolutely its a possability but both chains would have had to be 'tight'. i am assuming, as no primary adjustment was mentioned, that it was only the final drive that got a bit arthritic and only a teensy weensy ammount of slackening off improved it

if it were me i'd check the primary now that an inprovement has been attained and then go from there. if the primary isnt particularly tight leave well alone and see what happens over a few rides.

if its a bit tight have a dabble. oooh!! i like a good dabble now and again

my way though is to just change one thing at a time. my brain cant cope with more than one thing at a time
Title: Re: Gear change lever not returning
Post by: Kevin1963 on 01 Oct, 2024, 07:13
Thanks for replies waiting for some good weather or at least a dry day to try it out!