The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: Slippery Sam on 06.09. 2016 09:04

Title: A10 crankshaft spline
Post by: Slippery Sam on 06.09. 2016 09:04
Hi,
I think I have a problem *sad2*
I'm busy building my A10 (D10R) and about to fit my shiney new Bob Newby clutch.
My problem is my crank has a wide (standard?) spline on the first inch out from the engine casing - then a narrower spline out to the thread.  Basically it's not the same spline all the way through.  I have an old knackered crank in my spares box and it has a uniform spline all the way through to the thread (and would be a great fit for the crank pulley).
As it is the crank pulley will only be a good fit on the first 1/2 inch of spline (once the spacers etc are in place) with the bulk of the spline about half the width of the slots in the pulley!!!
Question is - do I have an odd crank?  Is it a different model that can be identified (maybe I can get a different pulley?).
Man I really don't want to pull a fresh built motor (with all the roller bearing conversion - blah blah) and have to replace a crank at great cost and time.
I will send a picture off to Bob Newby and see if he can help - and will post a picture here once I get home (at work already).
Any thoughts on what's going on with the spline greatly appreciated.

cheers Raymond.
Title: Re: A10 crankshaft spline
Post by: bsa-bill on 06.09. 2016 09:33
Hi Raymond
Excuse me if this is obvious and you have it covered.
what you described sounds like the crank with cushdrive spline on it, first pic is how the crankend should look like, second one is of the Cush drive assemble note part number 42-??69 (third up from the bottom) is this stuck on the crank spline?
Title: Re: A10 crankshaft spline
Post by: duTch on 06.09. 2016 10:48

  S-Sam, sounds crazy, but send us a pic too, and lets please get something else sorted; pulleys and belts, chains and sprockets  *wink2*
Title: Re: A10 crankshaft spline
Post by: beesa71 on 06.09. 2016 11:36
bsa-bill; that looks like a B25 crank in the picture I see in your post. Were you meaning to add a picture of an A10 alternator crank in your description?

Doesn't the cush drive adaptor pretty much fit flush up to the outer end of the crank before the inner end of the thread starts and therefore there is, so to speak, no spline then showing?

Paul.
Title: Re: A10 crankshaft spline
Post by: duTch on 06.09. 2016 11:58

 
Quote
Doesn't the cush drive adaptor pretty much fit flush up to the outer end of the crank before the inner end of the thread starts and therefore there is, so to speak, no spline then showing?

Paul, I'm fairly sure that the cush-nut is held hard-up against the inner sleeve to tighten up the bearing and all the shebang-bits in between, at least on my LJ (adapted to Plunger) crank which has  a slightly different setup, but works out the same; so I'm agreeing with what you say, but maybe not so 'flush', but the sleeve hanging over a bit.
 I think B-Bill just stuck the pic as an example, until S-Sam gives us a pic, we won't know for sure.
Title: Re: A10 crankshaft spline
Post by: Slippery Sam on 06.09. 2016 13:29
Yeh - this thread doesn't work very well without a pitcture does it?
Bill - the spline looks like the one in the photo - but instead of the plain shaft - the spline continues right to the thread but at a reduced width.  So the inner half of the spline is as per the photo and the spline to the thread is the same pitch, just about half the width of the spline in your photo.
The cush drive inner spline is identical to the pulley I have - and neither fit properly because they are both designed for a plain uniform spline like the one in your photo but all the way to the thread.
While stuck at work over lunchtime I trawled google again and can find loads of pictures of the A10 crank with the uniform spline - but not a single hit on one like mine - I have to say I'm concerned.  So will definately post up a picture at tea time tonight.
best I can do for now is add a drawing:

(http://)
Title: Re: A10 crankshaft spline
Post by: bsa-bill on 06.09. 2016 14:27
OK S Sam, thought I 'd just eliminate the obvious,. looking forward to the pic when you get it sent.
Just wondering if this is for an alternator crank version, never seen one in real life but someone on here will have
Title: Re: A10 crankshaft spline
Post by: Topdad on 06.09. 2016 15:27
I think Bill as already posted what I was thinking ie could this be an alternator crankshaft ,does anybody know what they look like ?
Title: Re: A10 crankshaft spline
Post by: Topdad on 06.09. 2016 15:30
whoops sorry bill typed the prev post over an hour ago and got sidetracked  pressed send without checking and there was yours :D
Title: Re: A10 crankshaft spline
Post by: Klaus on 06.09. 2016 15:56
Hi Sam,

I rum most of my bikes with a belt and its only one spline looks like new.
The others are all damaged by a losen cushdrife like you show in your drawing.

All pullys will fit this spline. The only thing you have to do is a little regrind the sharp edges with a file.

Dont care about the lost material from the spline. The pully will sit about half an insh at the healthy spline.
You have to tighten verry well the nut and fit this with a thread lock.

Be shure the belt is in  no hard tension. Correkt tension is when you can turn the belt 90 degrees in the middle.
This seems first sight the belt is slack, but this is the correkt tension.

I use this belt drive since many years and no problems with this.
There many advantages,no oil in the primary, no chain wear, allways the same tension, no noisy rattle, no drag no slipp with the clutch.

This all worth the money you ve spend on it.

cheers Klaus
Title: Re: A10 crankshaft spline
Post by: bsa-bill on 06.09. 2016 15:57
no problem Bob, done that a few times myself, my biggest problem though is replying  and then forgetting to press post *roll*
Title: Re: A10 crankshaft spline
Post by: Slippery Sam on 06.09. 2016 17:02
Hi Sam,

I rum most of my bikes with a belt and its only one spline looks like new.
The others are all damaged by a losen cushdrife like you show in your drawing.

All pullys will fit this spline. The only thing you have to do is a little regrind the sharp edges with a file.

Dont care about the lost material from the spline. The pully will sit about half an insh at the healthy spline.
You have to tighten verry well the nut and fit this with a thread lock.

Be shure the belt is in  no hard tension. Correkt tension is when you can turn the belt 90 degrees in the middle.
This seems first sight the belt is slack, but this is the correkt tension.

I use this belt drive since many years and no problems with this.
There many advantages,no oil in the primary, no chain wear, allways the same tension, no noisy rattle, no drag no slipp with the clutch.

This all worth the money you ve spend on it.

cheers Klaus

Thank you very much Klaus - I think that's it - spline worn by dodgy cush drive.  I was pointed at this elsewhere today.  Looks and sounds exactly what I have.  It looks so neat it's hard to initially identify it as wear, but that's exactly what's happened.
I have heard of people having to loctite things on - so I will be very careful and will dress it, prepare it and will loctite the nut on.  The pulley is fresh and a tight fit so will heat before fitting to get a good solid fit on the bit of good spline I have left - and make sure I get it well home and flush.

Thanks also to all other contributors - any and all pointers welcome - I appreciate the tips and things to check and eliminate.
I'm not so gutted as I felt earlier - but will watch what I'm doing now that I have the understanding of what's going on and will keep an eye on it - easy to do with no oil flying about  *smile*

As they say "Get In!!!!"

cheers fellas
Raymond. (will post a pic later)
Title: Re: A10 crankshaft spline
Post by: duTch on 06.09. 2016 20:18

Quote
S-Sam, sounds crazy, but send us a pic too, and lets please get something else sorted; pulleys and belts, chains and sprockets  *wink2*

 I wasn't aware it is a belt drive, that's where pictures can save a lot of hassle
Title: Re: A10 crankshaft spline
Post by: Slippery Sam on 06.09. 2016 20:57
Picture of offending crank
First picture is worn spline

Next with roller bearing fitted is my old crank - needs a grind - bit ironic this one in my spares box has a good spline

Cleaned everything up and went ahead - everything fitted well and no movement.
Title: Re: A10 crankshaft spline
Post by: RichardL on 06.09. 2016 21:22
So, the wear is on the driving edges of the splne. Makes perfect sense to me, except, I think the cush drive should have avoided such deep wear. Do you know where the crank came from and if it had a functional cush drive?

Richard L.

Title: Re: A10 crankshaft spline
Post by: Slippery Sam on 07.09. 2016 08:17
Richard - no, I have no history on the crank and it didn't come with a cush drive.  There is quite a bit of wear - but it's just too big a job to address - I have to give it a go as it is.  From accounts, this is not un-common and others have successfully fitted belt drive pulleys - so onward and upward.
The pulley it's self is a good fit on the shaft (shaft diameter inside and outside the groves) and is thight on the wider section.  I got it good and tight and have a lock screw on the crankshaft end nut - so it feels good.

Will monitor and report back in a while.
Raymond.
Title: Re: A10 crankshaft spline
Post by: RichardL on 07.09. 2016 12:38
Raymond,

Sorry, I didn't mean to suggest that it was unusable. I was really just trying to satisfy my curiosity regarding how it happened. I haven't seen it before, but I'm far from the most experienced here in terms of number of bikes built. However, I may be the most experienced at apologizing.  *smile*

I wonder if anyone can comment on whether, or not, belt drive pulleys provide "cush" action.

Richard L.
Title: Re: A10 crankshaft spline
Post by: bsa-bill on 07.09. 2016 15:55
Think I read somewhere a cush drive was NOT recommended with a belt drive.

However I do read things with varying degrees of accuracy.
I also read things and miss the obvious (like Raymonds mention of his belt drive) *roll*
Title: Re: A10 crankshaft spline
Post by: RichardL on 07.09. 2016 16:30
Bill and all,

I am making the assumption that the belt is not stretching to simulate the cush function. You wouldn't want the belt to stretch anyway. So, if you don't need cush for a belt, why have it for a chain? As I take it, the purpose of the cush is to keep clunks and thumps at the clutch (from hard shifts, etc.) from being reflected back to the engine. There is probably a better way to  describe this and I am sure I am missing something. If I'm correct, the belt does nothing for this. Also, it seems to me that a dry clutch is more likely to need cush than a wet [or somewhat wet] clutch.

Dunce cap at hand and ready to be schooled if I am all wrong.

Richard L.
Title: Re: A10 crankshaft spline
Post by: Slippery Sam on 07.09. 2016 16:56
I do have to hold my hand up - after re-reading the original thread start - I mentioned Bob Newby clutch and pulley - but failed to mention belt in the initial post - so my appologies.
There is no way to have a cush drive on the BN system - the pulley its self is the full width of the old spring drive.  Other sytems may well be different.
I do think the belt does provide a little cushioning - they are tough and don't stretch all over the place (and in fact you have to be careful they don't end up too tight or that causes problems, especially when hot) - but will cushion more than a chain though - but not a lot.
The motor, gearbox and rider's gear changes are going to be so silky smooth - it won't need a cush drive  *smile*
I guess there are hundreds of millions of bikes out there with no cush drive, including race bikes and direct drive with a lot more power (160bhp more power) that manage okay without a cush drive - I'm sure we'll be fine.  I'll be riding like a nun anyway  *eek*
Raymond.
Title: Re: A10 crankshaft spline
Post by: bsa-bill on 07.09. 2016 19:35
Quote
I do have to hold my hand up - after re-reading the original thread start - I mentioned Bob Newby clutch and pulley - but failed to mention belt in the initial post - so my appologies.

Thank you for that Raymond, my senility put back for a little while (perhaps)
Title: Re: A10 crankshaft spline
Post by: RichardL on 07.09. 2016 21:07
...but will cushion more than a chain...

I was aware of the configuration on the Newby clutch. I don't think I want to debate whether or not a cush mechanism was ever necessary. Maybe it isn't/wasn't. Also, no debate over smooth shifting [though shocks can come back to the engine with the clutch (not lever) engaged]. However, I don't think I agree with the quoted line above. The belt can't be designed to stretch and, to my understanding is woven (or "belted) with steel wire to assure it does not. This said, completely envious of your Newby clutch.

Richard L.
Title: Re: A10 crankshaft spline
Post by: chaterlea25 on 07.09. 2016 22:53
Hi All,
Sam, Who did the roller conversion? and why did they not see the worn splines?

Worn splines are very common,  *sad2* resulting from the cush drive nut not being tightened properly
I have had several crank splines repaired by SRM

The debate on cush drives could go on forever?
All modern bikes have cush drives usually in the rear wheel
Even shaft drive Beemers and guzzis have them either in the gearbox or drive shaft
My 1925 Chater Lea has one built into the clutch drum using rubber discs

Belt drives are rigid ! no give in them  *eek*
SRM did offer a conversion converting the cushdrive to pulley
Some belt drives retain the Triumph type clutch inner drum that  incorporates a cushdrive

John
Title: Re: A10 crankshaft spline
Post by: kiwipom on 08.09. 2016 00:05
hi guys, just looked up `Chater Lea` never heard of them but very impressive in their day, cheers
Title: Re: A10 crankshaft spline
Post by: RichardL on 08.09. 2016 00:49
John,

Thanks for confirming my thinking regarding the belt. I don't think I've seen the insde of a Newby clutch, so, as far a I know, the cush could be built in there.

Richard L.

Edit: So I looked at the pictures and no cush. Saw a couple of pictures of belt sprockets converted with inserts and, also, one setup here on the forum where the belt sprocket is tagged to the original chain sprocket so the ramp-and-spring action is still happening.
Title: Re: A10 crankshaft spline
Post by: Klaus on 08.09. 2016 09:05
Hi at all,

this BNR belt has no steelliners, such as from Norton belts. Cuchdrive,  Cluthabsorbers or any other dampers in wheels.
What the heck, I can tell having no problems with BNR or NEB belt drives at all my bikes. Riding thousends of miles, plug, play and forgett, I does nt care about, its still running.

There where only three times a belt was broken on the Racebikes, the primary is open, and so the belt collect small stones and give them a perforation and so the belt tear like a cut.

I have seen other belts looking like clutter with damaged pully and clutchbaskets.

Dont think about, ride it. Belt is a good decision *yeah*


cheers Klaus
Title: Re: A10 crankshaft spline
Post by: muskrat on 08.09. 2016 10:41
I agree with Klaus.
 With the amount of (or lack of) tension recommended for the belts is enough to give a little chush. Mine gives no snatch on roll off, snap on throttle.
Cheers
Title: Re: A10 crankshaft spline
Post by: RichardL on 08.09. 2016 14:33
Well, maybe I should stay out of this, having zero belt-drive experience, but my curiosity continues.

Question for Klaus (or anyone) regarding steel wire reinforcing of the belt. It seems Klaus is saying no steel in the belt but I'm not completely sure that's what he means. I AM sure the belt is not supposed to stretch.

Then, there is the point of belt slack providing cush. Isn't the belt always in tension, either on the top or bottom run, and doen't this apply to chains, as well? In any case, I'm having trouble seeing yanking on the belt or chain as equivalent to cush.

Finally, there is the issue of what I think is an unusual amount of spline wear that I have guessed is due to lack of cush. Anyone disagree that this is the likely cause?

Finally, finally, the experience of two race riders with regard to the benefits of cush, or lack thereof, might be very different from us joy riders. Is it unreasonable to think that race riders have an expectation of frequent engine and clutch rebuilds on their race bikes?

Finally, finally, finally, I am not ignoring or disagreeing with Klaus' heavily experinced recommendation for belt drives, just curious about open questions.

Richard L.
Title: Re: A10 crankshaft spline
Post by: Greybeard on 08.09. 2016 18:19
...no snatch...
No snatch!?  ;)
Title: Re: A10 crankshaft spline
Post by: Klaus on 09.09. 2016 08:12
Well, maybe I should stay out of this, having zero belt-drive experience, but my curiosity continues.

Question for Klaus (or anyone) regarding steel wire reinforcing of the belt. It seems Klaus is saying no steel in the belt but I'm not completely sure that's what he means. I AM sure the belt is not supposed to stretch.

Then, there is the point of belt slack providing cush. Isn't the belt always in tension, either on the top or bottom run, and doen't this apply to chains, as well? In any case, I'm having trouble seeing yanking on the belt or chain as equivalent to cush.

Finally, there is the issue of what I think is an unusual amount of spline wear that I have guessed is due to lack of cush. Anyone disagree that this is the likely cause?

Finally, finally, the experience of two race riders with regard to the benefits of cush, or lack thereof, might be very different from us joy riders. Is it unreasonable to think that race riders have an expectation of frequent engine and clutch rebuilds on their race bikes?

Finally, finally, finally, I am not ignoring or disagreeing with Klaus' heavily experinced recommendation for belt drives, just curious about open questions.

Richard L.



Hi Richard,

for you I read in the producktion line from the belts I drive.
They are lined with a glascord tensioncord, to avoid streching
Norton or Triumph belts, I gues they are Harvards have stainles steel wire cords inside.

I m lucky if a belt fails, that there is no wraping the wire cord around the clutch or the pully.
It s only a few minutes to fit a new one.
In my tankbag is every time a spare belt but all the years I dont use a one.

About the tension, I mm sure in other engieneering the tension is much stronger.
But in case driving on a cluth the tension had to be low.
By running the engine and chlutch get hot and so the pully and the chlutchbasket, its minimal in extension but the belt get tighten.

Finally, this spline wear can only be done by a losen chush drive.

Finally, Finally...hmmm I do a hight amount of milage every year ( about 20.000 miles) with my beesas, and I think its a big advantage to drive the belt.
For rider how only puddle around the block, with a low milage can save the money for this goody.

Finally, Finally, Finally, hope I could wash away any doubts.


cheers Klaus
Title: Re: A10 crankshaft spline
Post by: RichardL on 09.09. 2016 12:44
Thanks Klaus.