Author Topic: A10 s/a clutch lever refurb  (Read 409 times)

Offline Jules

  • Valued Contributor
  • ****
  • Join Date: Mar 2011
  • Posts: 277
  • Karma: 0
  • 1956 A10 s/arm Golden Flash
A10 s/a clutch lever refurb
« on: 29.04. 2020 03:58 »
Hi all, I've been sorting through the gearbox bits and realized that the clutch operating lever is mismatched to the gearbox housing. The shaft is tapered, worn, but is too large to fit into the bush, I must have picked up another part to replace a damaged one years ago and not realized  *conf*. So I have a couple questions please...
1. are these levers "common" wrt length and diameter across models, do I have the correct clutch operating length? the shaft itself, apart from being worn appears to be ok wrt length, so was there an upgrade or something later??
2. does the operating lever arm detach somehow from the shaft (if I remember the lever is aluminium, although this one is (good) chrome), if not how do I get the shaft remachined to match the bush dia.??
all thoughts and ideas appreciated, some of you must have been through this already, I'm sure  ;)...
photo attached, cheers

Online morris

  • Wise & Enlightened
  • *
  • Join Date: Aug 2012
  • Posts: 1610
  • Karma: 24
  • Antwerp, Belgium
Re: A10 s/a clutch lever refurb
« Reply #1 on: 29.04. 2020 10:31 »
I think your problem is the gearbox cover bush. That bush is not original. I know because I did the same to my SA for the hole in the cover that had worn oval.
Your best option would be to clean up the lever shaft and make a new bush to size
'58 BSA A 10 SA
'52 BSA A 10 Plunger
'55 MORRIS ISIS
The world looks better from a motorbike
Belgium

Online berger

  • Wise & Enlightened
  • *
  • Join Date: Nov 2017
  • Posts: 1191
  • Karma: 7
  • keith.chesterfield uk 500sscafe.norbsa project
Re: A10 s/a clutch lever refurb
« Reply #2 on: 29.04. 2020 11:09 »
they do not separate , well the ones I have don't. the shaft is steel and the arm brass, the shaft and arm have a corresponding flat and I think they must have a blob of polished braze to secure them together because a rocky one I have would not come apart until I filed the dome off of the arm

Offline Jules

  • Valued Contributor
  • ****
  • Join Date: Mar 2011
  • Posts: 277
  • Karma: 0
  • 1956 A10 s/arm Golden Flash
Re: A10 s/a clutch lever refurb
« Reply #3 on: 04.05. 2020 02:33 »
ok, I've researched options and realised that the lowest risk option is to just polish the shaft up with some emery paper and a bit of valve lapping paste, then ream the bush out to suit and hope for the best, in reality its only turning 90 deg. after all....BUT I'd appreciate some opinions about what I can get away with wrt clearance/ovality because I know that the 6 spring clutch isn't the best/easiest/ lowest stress device around!
So, using just a vernier caliper, the bush (at the top) is around 10+mm, and the shaft is around 10.9 - 11.1 mm more oval than tapered it seems. If I ream the bush out so that the shaft "just" rotates ie tight fit on the 11.1 dimension, it will give a possible clearance of around 0.2mm when its running on the small side (I have no idea of where the large/small sizing relates to actual operation), which equates to around 8 thou. clearance, which seems a lot, but maybe not for this function......what do you guys think please, I know its not an ideal solution but is it workable??? thanks

Online berger

  • Wise & Enlightened
  • *
  • Join Date: Nov 2017
  • Posts: 1191
  • Karma: 7
  • keith.chesterfield uk 500sscafe.norbsa project
Re: A10 s/a clutch lever refurb
« Reply #4 on: 04.05. 2020 11:33 »
I have seen the arms work ok with loads of slop,you should be able to judge your adjustment with or without slop so just get it as near as possible in the bush. as for the 6 spring slop in the arm doesn't matter. set it up with time and patience and it is ok, well mine was when it took my bike to a ton

Offline Jules

  • Valued Contributor
  • ****
  • Join Date: Mar 2011
  • Posts: 277
  • Karma: 0
  • 1956 A10 s/arm Golden Flash
Re: A10 s/a clutch lever refurb
« Reply #5 on: 17.05. 2020 03:24 »
I thought I'd update you all on the outcome of this exercise  *sad2*… the shaft cleaned up ok and I purchased a 10.3 - 11.1 adjustable reamer. It worked well (I thought) as I gradually increased the reamer size about 0.15/0.2mm at a time, until almost there and I reduced the increments down finer to create a perfect fit. Or so I thought, until I took the cover out of the vice and realized that the boss holding the bush had broken out....  *conf* *sad2*
What did I do wrong?? unless the boss was already cracked from the bush insertion done by the earlier owner, certainly the boss wall was thin on one side....its the first time I've use an adjustable reamer and it seemed to work sooooo well, what did I do wrong, any ideas?
I've managed to locate another cover but I'm now unsure about how to size that hole in case the same thing happens - I understand that the original design just ran the steel shaft in the aluminium case, is that right? if I just open up that hole with the reamer to 11mm (assuming I can, I haven't seen the case yet) that would be better than trying to sleeve it I think, thoughts?? cheers

Offline Tomcat

  • Valued Contributor
  • ****
  • Join Date: May 2011
  • Posts: 398
  • Karma: 2
Re: A10 s/a clutch lever refurb
« Reply #6 on: 17.05. 2020 07:23 »
Is it possible that the original shaft was worn and turned down in size and an undersize bush fitted? Now you are trying to fit a STD sized shaft into an undersize bush?  It's not a high speed bearing and has plenty of lubrication so whatever works is good enough.
As an aside, I fitted an O ring to the top of mine by drilling a small taper at the top of the boss.
'48 A7 '59 SR '74 850 Commando TDM900

Online RDfella

  • Resident Legend
  • *****
  • Join Date: Aug 2017
  • Posts: 893
  • Karma: 8
Re: A10 s/a clutch lever refurb
« Reply #7 on: 17.05. 2020 17:03 »
Jules - can't see you did anything wrong. Have just dug out and measured a spare clutch lever and the shaft is M11 exactly, so the case you were working on must have been wrong. Maybe whoever bushed it did so off-centre? But if you have the correct cover, there should be no need to ream it out. There are different levers, as I have seen them in different shaft lengths, but as far as I know the diameter remains the same.
'49 B31, '49 M21, '53 DOT, '58 Flash, '00 Firestorm, Weslake sprint bike.

Offline Jules

  • Valued Contributor
  • ****
  • Join Date: Mar 2011
  • Posts: 277
  • Karma: 0
  • 1956 A10 s/arm Golden Flash
Re: A10 s/a clutch lever refurb
« Reply #8 on: 06.06. 2020 10:52 »
Thought I'd close this thread out by sharing my findings on my disastrous attempt at fixing my clutch lever  *sad2*….
This is what happened (see pic) when I bored out the bush that had been previously pressed into the case (by prior owner, years ago). The original bore was around 10.3 mm and I needed around 11.1mm. I setup the tool to bore out at around 0.15/0.2mm increments, which I thought at the time was “small”, but now realize my mistake. I've just found the Suttons catalogue which suggests "no more than 0.05mm increments"  *eek*....what I should have realized is that this is ostensibly a “scraping” tool, not a cutting tool perse’, so take a look at the attached pic, this is what happened…its basically “belled out/stretched” the bush as is obvious on the top, but at the bottom where the (weakened) cast boss is, its just broken out *sad2*.
I’ve just procured another case (thanks Mike) that still has the original hole in the casting (no bushing) and fortunately the bore in the  casing is not toooo bad as is....
Another lesson learned!!cheerss....

Offline BSARGS650

  • A's Best Friend
  • ***
  • Join Date: May 2014
  • Posts: 94
  • Karma: 0
Re: A10 s/a clutch lever refurb
« Reply #9 on: 06.06. 2020 21:03 »
Strange Jules it should crack like that as there is plenty of "meat" there so to speak.  Did you feel  great resistance turning the reamer?

Offline Jules

  • Valued Contributor
  • ****
  • Join Date: Mar 2011
  • Posts: 277
  • Karma: 0
  • 1956 A10 s/arm Golden Flash
Re: A10 s/a clutch lever refurb
« Reply #10 on: 07.06. 2020 02:52 »
No, BSARGS that was why I couldn't understand why it did that, the hand rotation using a tap wrench was about the same as cutting a thread really... but in hindsight, looking at the bell mouthing and researching further, I realized that its really acting as a 'scraper', rather than a 'cutter', hence the 'cut' that I thought I was making was probably stretching the bronze bush but only cutting a small amount, does that make sense??
As for the casting splitting, the 'boss' inside looks robust as cast, but when it was bored out to push in the bush, the wall thickness on one side was quite thin.....I think that if I'd done what I know now wrt the adjustable reamer, and stuck to micro steps, then all would have been ok....hence the lesson learned that I thought worth sharing, cheers

Online RDfella

  • Resident Legend
  • *****
  • Join Date: Aug 2017
  • Posts: 893
  • Karma: 8
Re: A10 s/a clutch lever refurb
« Reply #11 on: 07.06. 2020 14:46 »
Bronze, depending on the alloy, can be difficult to machine and requires a sharp tool. One that'll cut steel may not be sharp enough for bronze (and a few other metals). For a material that's not particularly hard that may seem strange, but it's almost as if the bronze would rather flow over the tool than let it penetrate. Trying to force a blunt tool through bronze will try to expand it without cutting. Maybe your reamer wasn't sharp enough? And only small cuts, no more than around  .003" at a time. Ultimately, though, the problem was the previous work. Not only off-centre but probably a massive interference fit too, when a push fit with locktite was all that was needed.
'49 B31, '49 M21, '53 DOT, '58 Flash, '00 Firestorm, Weslake sprint bike.