A10 plunger clutch problem

[paulbsa54]

Hi Guys ,
              i have a 54 A10 plunger , checked the primary chain for tension and noticed the clutch was loose on its mounting. Took the cover off and the clutch basket has been rubbing on the primary cover and crankcase side. I see there is a roller bearing on the drawing which must be worn , is there anything available to repair this ?. I presume a bearing coud replace the rollers but am a little unsure where to go with this.

[Brian]

First thing is to take the pressure plate off and check the nut that holds the clutch centre on hasnt come loose.

If it is the bearing then thats a problem. As far as I know a replacement bearing isnt available for the plunger models. You can replace the rollers but the inner race is part of the clutch centre, the outer is a replaceable ring but not available. It would probably be worth contacting someone like C@D's to check but there was nothing available a couple of years ago whenI searched.

I did a modification to mine using a sealed bearing and it seems to work well but I have only done about 2,000 miles on that bike which isnt really enough to see how its going to last. I sleeved the inner to the ID of the bearing and bored the outer to the OD of the bearing. Unfortunately I cant remember what the bearing number was that I used but It wouldnt be too hard to work out.

[paulbsa54]

Hi Brian ,
               thanks for the reply , i see where you went with the mod , i could repeat that as i am an engineer by trade . The centre nut is not loose by the way as i stripped it down today. The primary chain is at maximum adjustment and is still too loose so that needs replacing . I will get the bearing book out when i get back to work and see whats needed.

Thanks very much for your help and nice bike you got there.

Regards Paul

[Brian]

The concern I had when I did this mod was that the bearing would not be up to the job but so far so good. I would have liked to have used a bearing that had a lot higher load ability but I couldnt find anything that would fit in the space available.

If your inner surface if still ok you could possibly make a outer ring and get it hardened. In my case both inner and outer where well and truly beyond any form of repair.

The bike in the pic that appears with my posts is my 50' Star Twin. Here's a pic of the bike that has the clutch mod in it. Its a bitsa, a mix of 51' and 52' bits plus a few extras.

[BSA_54A10]

The bearing is only in use when the clutch is dissengaged .
When you pull in the clutch lever the pressure plate will move out and oft a basket that is too big will foul on the cover.
I would suspect the main shaft if it is  loose or bent you will get rubbing on both side of the chain case.

that was a nice mod to the clutch.
When i was some what younger a speedway rider replaced the double row ball bearing on my swing arm clutch with a leaded gunmetal bush.
Very nice and it taught me to select neutral & not ride the clutch as if held in for too long it would expand and grab.

[shuswapkev]

i think i may try that bearing mod...

my centre race is very pitted and quite soft... i can file it quite easy...i reckon it should be as hard as supermans head...

back doown to the bearing shop tomorrow...

[BSA_54A10]

Way back when i was in my teens a "local hero" speed way rider fitted my A10 with a leaded gunmetal bush replacing the clutch rollers.
Worked really well and taught me not to ride the clutch because if you held it in for 2 minutes ( average traffic light cycle down here ) the bush would heat up and bind.

[shuswapkev]

Brian

i have a semi unit clutch that has both roller faces worn out...
lookin at your modification... looks terrific
 went thru a few books today ...cant find any bearing that comes close...i,m thinkin i need 5/16 max width or...8mm..
 hole centre is way too small and the outer isn,t even close...

any help would be appreciated...my outer race is easy enough to replace with a a hardened bush...but the inner is pretty bad and quite soft...

[Brian]

The bearing I used was a 6807. Thats 47mm OD, 35mm ID and 7mm wide.

The bike I did the mod to has done about 3,000 miles now and so far no sign of any problem.

It might be worth contacting someone like C@D's as there might be a bearing available to repair the original set up. When I did mine there was nothing available but that was a couple of years ago.

I bored the basket to take the OD of the bearing but you have to make a sleeve to go over the inner to bring it out to the 35mm.

[orabanda]

Brian,
Great work as usual!!

Hey Shus, just an idea; why not get in touch with Alpha Bearings (UK) and ask them to make a new bearing assembly. They did a great job of making a new B/E assembly for my 1927 Ariel. The bore in the rod was oval (the outer race fell out; it should have been a light interference fit). I sent them the rod and old B/E. They machined (ground) the rod until the bore was true, then machined a new (oversize) outer race. Co-incidentally, it is approx the same size as the outer bearing race in the A10 clutch!

Richard

[shuswapkev]

brian

 the problem with my clutch centre..its not round...maybe +.010 oval..definetly not as hard a supermans head...i can file it pretty easy.. sooooooooo  i think its at the end of the road...unless i can apply some metal enthusiasm... the ball bearing looks like the go for me.. otherwise i have to turn th ecentre down and press a hard bush over and then make another for the basket...my concern s reducing the splined end at the business end..soon as i finish this note i,l be googling up that bearing
and as it usually works,  by the time i get most the way thru i,ll have 3 more good ones either here or on their way...