A10 Kickstart shaft outer casing bush

[44T]

Hi all.  Worn A10 k/start bush. I have to bore out my outer casing to make it round again. The bush is steel of some sort ? I'm planning to make a new bush to suit the new OD, and was thinking of making it from either bronze or brass. Does anyone know of any drawbacks to doing that ? I wonder why the original was steel ? Cheers

[chaterlea25]

Hi 44
As the shaft only moves in an arc rather than revolve then a hardened steel shaft in a mild steel bush is plenty good
A soft metal bush would suffer as the force of the riders weight is very often taken by the bush

John

[limeyrob]

BSA engineers always seemed to have been quite diligent with bushes so I'll bet they decided on mild steel as better for this application. 1/2 turn, lots of force, some grit and a bit of vibration.

[berger]

most kickstart shafts i have seen over the years have a worn step on them you are better off making sure the shaft is good and making a steel bush to fit a round shaft depending on how long you are keeping the bike. i had a stepped shaft that i am using in the berger build but it was welded up and turned true then splined for the honda kickstart

[44T]

Thanks for the responses. I think I'll go with a the mild steel option as suggested. I'm certainly no metallurgist, and I reckon the designer new best.
BTW the shaft itself seems to virtually no wear at all, but the bush was totalled, and the hole in the casing was nearly 40 thou out of round at about 6 o'clock.  Cheers for now, the Turkey beckons 

[Slymo]

Iron?

[limeyrob]

This type of repair can be a pain if the hole has worn oval as you cant just put a reamer in as it won't sit on the correct centre.  Can you build up the worn side?  I once had some success on an ally cycle frame using aluminium braze.  (I also had 3 failures )

[Swarfcut]

 Couple of fixes...

  1. Set up accurately on the miller and bore a new hole, make oversize bush. Easy in theory, but a few thou out on the machining is just as bad as what you start with.

  2. Get a better cover.

 All depends if you have access to machine tools and skill, or prefer to spend rather than restore.

 Swarfy

[limeyrob]

Spend the money.....Its only £15 inc post and the bush looks good.!
https://www.ebay.co.uk/itm/116391827623?_skw=A10+gearbox+cover&itmmeta=01JGVBZKF76BB8CB4MR5FWARJW&hash=item1b197e58a7:g:SrgAAOSwd7pnJfC4&itmprp=enc%3AAQAJAAAA8HoV3kP08IDx%2BKZ9MfhVJKknYoGCQ6FWz5lHojMMfT46v6%2Fcn9tvxw1Hr2Xz06PgD9UVFFZB%2BYzZLu78ZjFykSR%2FsRWqK1wMcioMyoL8uKor818f0elTdVZY5dOEDnyQJSQ7R8HQQSbLoCaDJYw5hTmNI0FVqAoFo05ZzQSlK6EQyIQJBCtyEi3zlgYWCSUcFsXFWM1csQ5pqmL5DUth1mDqtkHOHKOT35G1TDlWdhs4ec9JVg5q%2BtROsG5z2yQWKh6OIcoLfxYawTl08oQI9gxDEmTVXlsw0LXXpUd4w%2BYxAbV%2F%2BeR3gxSIJvUeDHV4Sg%3D%3D%7Ctkp%3ABk9SR9y3_uuGZQ

[Swarfcut]

 No Rob, not that one. It's from a Plunger box and unusually does not have the grease nipple for the clutch lever shaft, even though it is a later casting with the bump at the nipple position.

  S/A Cover has raised area for the gearlever, Plunger type is recessed, Gearchange mechanisms are completely different.

 Try this   
https://www.ebay.co.uk/itm/375898615975?_trkparms=amclksrc%3DITM%26aid%3D1110006%26algo%3DHOMESPLICE.SIM%26ao%3D1%26asc%3D20200818143230%26meid%3D8fefff353c784e8c84b3ef823123d247%26pid%3D101224%26rk%3D2%26rkt%3D5%26sd%3D116391827623%26itm%3D375898615975%26pmt%3D0%26noa%3D1%26pg%3D2332490%26algv%3DDefaultOrganicWebV9BertRefreshRankerWithCassiniEmbRecall%26brand%3DBSA&_trksid=p2332490.c101224.m-1

 Other things to look for.

 Wear and cracking around that clutch lever shaft hole.

 Poor threads for the inspection cover. These are a cycle thread, not BSW as usual in alloy.

 Always heat the casting before attempting to remove speedo drive and fixed bushes.


 Swarfy

[limeyrob]

My error, I rejected loads of decent plunger ones thinking it was for a SA. Doh!
I was surprised at how many plunger gear cover there were. If it were me I'd buy one, machining does not come cheap and if the kick shaft is worn odds on the clutch lever pivot is too.

[44T]

Spend the money.....Its only £15 inc post and the bush looks good.!
https://www.ebay.co.uk/itm/116391827623?_skw=A10+gearbox+cover&itmmeta=01JGVBZKF76BB8CB4MR5FWARJW&hash=item1b197e58a7:g:SrgAAOSwd7pnJfC4&itmprp=enc%3AAQAJAAAA8HoV3kP08IDx%2BKZ9MfhVJKknYoGCQ6FWz5lHojMMfT46v6%2Fcn9tvxw1Hr2Xz06PgD9UVFFZB%2BYzZLu78ZjFykSR%2FsRWqK1wMcioMyoL8uKor818f0elTdVZY5dOEDnyQJSQ7R8HQQSbLoCaDJYw5hTmNI0FVqAoFo05ZzQSlK6EQyIQJBCtyEi3zlgYWCSUcFsXFWM1csQ5pqmL5DUth1mDqtkHOHKOT35G1TDlWdhs4ec9JVg5q%2BtROsG5z2yQWKh6OIcoLfxYawTl08oQI9gxDEmTVXlsw0LXXpUd4w%2BYxAbV%2F%2BeR3gxSIJvUeDHV4Sg%3D%3D%7Ctkp%3ABk9SR9y3_uuGZQ

All done thanks as far as bush goes. It was no good ordering a new bush, as the casing hole was enlarged and out of round. Had to bore it round again, and make a new oversize one on the OD. Luckily I have a mill, but it was my first go at boring anything. Had to set it up using the inner case as a line bore guide after fitting a new bush to that case. Cheers

[limeyrob]

Great job!  You should have explained you had a mill aching to be used.  We all understand

[a10rgs]

Hi,

I would fix the inner case to the mill and line bore the outer case to get a round hole!
If you have a suitable end mill you can use this to make a round hole for the bush!
I prefer bronze to make the bushes (kickstart, gear change and clutch lever)!

regards
Uwe

[BagONails]

Hi,

I would fix the inner case to the mill and line bore the outer case to get a round hole!
If you have a suitable end mill you can use this to make a round hole for the bush!
I prefer bronze to make the bushes (kickstart, gear change and clutch lever)!

regards
Uwe

Or even better use an indexing boring head if you have one? Bronze would be my bush material of choice certainly.