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Re: 350 Model 8 clutch basket
Posted: Tue Aug 22, 2017 2:36 pm
by Janet
SPRIDDLER wrote:Janet wrote:Now where did I put the tent?
Well I doubt that you lent it to your predecessor, Roy Blagit...........
If I had, it should come back unused -er- I mean undamaged.
Re: 350 Model 8 clutch basket
Posted: Tue Aug 22, 2017 9:22 pm
by Ozmadman
clanger9 wrote:I had a go at trying to make sense of all the Lightweight gearbox & transmission variations.
Link here:
https://1drv.ms/x/s!Au7XMUF8xm1UkBPuy8KOlpb2M4uS
[this should open in Excel Online - not sure if it'll work for everyone, but I can't post Excel attachments here...]
What do you think? It's probably full of errors, but it's almost beginning to make sense to me...
This is a compilation of what I've been able to obtain from Christian's archives, plus the insights and advice on this here forum (especially from Ozmadman and John Jarrett), plus my own corrections to the more obvious mistakes in the factory parts lists and workshop manuals.
Anybody spot any obvious errors? There's definitely something amiss with the 1966 CSR gearbox part numbers, because these are supposed to be close ratio, but I can't find these part numbers anywhere. Also, if anyone could provide teeth counts or other identifying marks, or just check the info against their own bike that'd be ace!
Excellent work as usual... Haven't had a proper look through it as yet but no doubt it will be pretty accurate. Don't seem to have the time to delve deeply into things at the moment so good to see another lightweight owner willing to take on the task of unravelling the complexities of these great bikes and passing their knowledge on. Regarding the "close ratio box" on the later CSR's TBH I didn't even know there was such a thing until Rob I think posted a sales picture of one where it mentions this... the hunt for part numbers is on... who will be the first to find them.. Not too much to ask for a late CSR owner to take his box apart and count all the teeth for us is it??? ha ha only joking
Re: 350 Model 8 clutch basket
Posted: Tue Aug 22, 2017 9:29 pm
by clanger9
Thanks Paul - and I even figured out the "close ratio" CSR box!
All they did was change the 4th layshaft gear to 19 teeth (from 18). Because of the way the gearbox works, that effectively narrows all the ratios. I added another tab to the spreadsheet to explain this.
Hopefully the spreadsheet is useful for the next Lightweight owner that dares to tackle the transmission.
Part numbers are useful. Having actual parts, rather more so...
Re: 350 Model 8 clutch basket
Posted: Tue Aug 22, 2017 9:52 pm
by Ozmadman
Sounds like the standard of British engineering back in those days, who would notice that??? maybe we are all riding round with "close ratio" boxes??
Re: 350 Model 8 clutch basket
Posted: Wed Aug 23, 2017 6:32 am
by Janet
clanger9 wrote:Thanks Paul - and I even figured out the "close ratio" CSR box!
All they did was change the 4th layshaft gear to 19 teeth (from 18). Because of the way the gearbox works, that effectively narrows all the ratios. I added another tab to the spreadsheet to explain this.
Wouldn't they have to reduce the corresponding gear on the other shaft by one tooth? As far as I know the total number of teeth for each pair of gears should all be the same. Made up numbers but for example 20 + 10 == 30. 18 + 12 =30.
Re: 350 Model 8 clutch basket
Posted: Wed Aug 23, 2017 7:55 am
by clanger9
Janet wrote:clanger9 wrote:Thanks Paul - and I even figured out the "close ratio" CSR box!
All they did was change the 4th layshaft gear to 19 teeth (from 18). Because of the way the gearbox works, that effectively narrows all the ratios. I added another tab to the spreadsheet to explain this.
Wouldn't they have to reduce the corresponding gear on the other shaft by one tooth? As far as I know the total number of teeth for each pair of gears should all be the same. Made up numbers but for example 20 + 10 == 30. 18 + 12 =30.
Yes, I thought that too. However, the only part that is listed as changed is the layshaft gear. The mainshaft gear remained unchanged.
As a guess, I worked out the gear ratios with a 19 tooth layshaft gear and - hey presto - it matches the quoted gear ratios.
I can only assume they found a way to machine a gear with an extra tooth in the space available. Is this even physically possible? Presumably it has slightly shallower teeth? It's possible my bike has this gear (it's a late CSR), but I'm not going to take the gearbox to bits again to have a look...
Re: 350 Model 8 clutch basket
Posted: Wed Aug 23, 2017 9:48 am
by SPRIDDLER
clanger9 wrote: I can only assume they found a way to machine a gear with an extra tooth in the space available. Is this even physically possible?
That set me thinking over my bowl of Shreddies. (I'm more of a practical than an academic chap).
Am I right in concluding that.....
If a tooth is added to the mainshaft gear the pitch and depth of the teeth must remain the same or they will not mate with those on the layshaft gear.
If a tooth is added to the mainshaft gear at the correct pitch the circumference of the gear must be greater than before, and
de facto its diameter must be greater than before.
If the diameter of the mainshaft gear is increased, the diameter of the layshaft gear must be reduced or it won't fit.
Re: 350 Model 8 clutch basket
Posted: Wed Aug 23, 2017 11:15 am
by Ozmadman
Correct as far as my thinking goes apart from the fact that they added the tooth to the layshaft gear ( same principle though). I had a similar problem when rebuilding my Yamaha RD box. Got two S/H gear box internals from the same year bikes and was trying to replace one of the worn gears from my original box with one of the ones from the spare boxes but couldn't get the two gear clusters to sit down properly in the engine casing even though everything looked ok. On finally checking after scratching my head for about an hour I realised that the gear I had replaced had one extra tooth on it so it was half meshing with the corresponding gear. My box is a USA 6 speed box and the other two spares were Europe six speed boxes and the ratios on two of the gears are slightly different!! Moral of the story... always check your teeth!!
Re: 350 Model 8 clutch basket
Posted: Wed Aug 23, 2017 4:00 pm
by Janet
Obviously I don't know anything about the mechanicals but if it got you all thinking...............
Re: 350 Model 8 clutch basket
Posted: Wed May 12, 2021 6:44 pm
by Red Gauntlet
I have looked through the archives to try and find an answer to my clutch problem, with such scant info on LW clutches I find that my G5 clutch does not appear to conform to the pictures that Paul posted on 1/9/17, in as much as my one looks more like a CS with duplex than the G5. basically it has a cage depth of 1&3/16" but fitted with the correct 9 plates inc the stepped back plate 043342 the plates are too shallow unless I use the deeper pressure plate 040365, however when configured as a CS clutch it seems correct visually but not according to the drawings Paul has submitted. The configuration that works is the back plate 043194 3x friction plates 043192 4x plain plates 043191 and the single sided plate 043193 before the thinner pressure plate 043362. I will run with the latter config as it should work but any ideas?