Bantam Clutch Tuning??

I'm doing this mini-article for Dave King but I some of you may learn a thing or two about making the banty clutch user friendly!! Well this is what I do and I like to pride myself on having the lightest clutch lever action in the paddock- thats certain because i've pulled everybodies clutches in!!

Clutch Drum - make/get a new one made out off slightly thicker steel and get a band brazed round the outside oppersite the circlip groove as picture.Pic1 (mine has 12 slots to save weight) You also need a groove all the way round the spring carrier plate for the cirlip to sit in.

Pic1


Plain plates - machine out the centres to about half there width. in Pic2 is a std plate and a narrow one

Pic2


Fricton plates - remove all previous burnt surflex clutch material so the plates become plain plates, and cut groves in with an angle grinder or simular kit. A good way to remove surflex material is give useable plates to Peter T and wait him to give them back with minimal material left, after a seasons hard clutch slipping He may charge you for this service?! Pic3 shows a surflex and 2 now plain plates (1 by angle grinder 1 by a machine of some sort(Ted)? Cut slots before getting plates hardened (if you are going to bother some racers don't - Alan pls comment) The slots hopefully stop them distorting! If they dish a little - no worries dish them all the same way when you build the clutch up.

Pic3


I've heard people say my clutch is slipping, I'll put another plate in! yes this may work but you will increase the clutch drag then they may put another in when it starts to slip again - increasing drag again ... When all they need to do is increase the spring pressure not add plates. The clutch needs to be 'bleddin' hot to work so warm the clutch up before you go on circuit otherwise your first two laps will be severe clutch slip.
Try to use the least amount of plates not the most and start with 6 Heavy Duty springs from Alan Brown or Rex Caunt(on ebay) then increase the number of spings (because they become weaker) or replace them.
I start with 6 then 7 then 8 then 9 then replace springs starting with 6 again. Yes you have guessed it I've got 3 spring plates 12hole (for 6 and 9) and a 7 and an 8. A 6 spring clutch is nice and light. Pic4 shows a 9 and 8 plate (12 and 7 are on the bikes)

Pic4


Hope this helps.... Mike

Great explanation and photo,s Mike .There is also a mass of weight that can be drilled out of the primary drive sprocket and hub the material it
is tough not hard.I will start to play with modifying clutch plates tomorrow .Has anybody used stainless steel pre-hardened clutch plates either water cut or laser cut?I have only used transmission oil are there other opinions using the steel to steel option any notewhorthy benifits.looking forward to the reply threads .In one photo the pressure plate in which the clutch standard mushroom pushes against has been modified ,whats that about?
regards Dave

hi dave your missing the best / most important bit, look at pic 1 again now see top right corner, now can you see how close the spocket s to the casing, now look up and left of this bit and see the original boss for the primary cover screw ! notice anything ??

sorry mike just can not keep a secret all this technical stuff got me all in a tiswas!

kind regards

Derek

oh nearly forgot great post Mike, not sure Inow how to follow that one, not sure I can, any more GEM'S

Ians got 28 bhp - sorry to bring up weight again BUT if Ian has 28 mike you need 30 peter needs 34 and i need 36 to excellerate at same speed as he does acording to Mrs cooks calcs that is, not sure it works like this but still waiting for john, to come back to me on those slimming tablets. ? LOL

Derek

Okay maybe I missed the detail in pic1 ,doesnot everyone play around with primary gear ratios at some time or another;in a 3 speed
gearbox the gaps between gears just get bigger or smaller depending on with you have changed the primary ratio; not much fun riding.Thank goodness for my 4 speed and yes I have used the 3 cr box.
The only other detail I saw was the small end crank seal boss was machined off and recessed a typical mod.
regards Dave

Exactly Dave, a typical mod!....
Doesn't everyone change primary gearing on a 3 speed bantam - No think everyone will be on 17/38!
Rex Caunt does 12and 13 engine sprockets I think?? for trails applications - no good to us.
Don't think anyone has paid for laser cut anything? on a bantam in the UK when you can do it with a hacksaw/angle grinder/file. Stainless steel ? I'm guessing to soft? Clutch mushroom has a trust bearing inside - typical mod in the UK lol
Oil some use AQF/TQF automatic transmission fluild or EP80 gear oil and I use cheap engine oil 10w40 or the like - don't use synthetic oil -clutch will slip.... And get some magnets mounted in your primary case to collect all the oily metal fillings....

Regards Mike

Hi Mike you fox " on the end seal boss being machined off, try again Dave.

Derel

Mike, does that mean the primary drive is set in closer without the outer 6203 bearing ?

bearings now ? - shussh ???

"now" john come on I need those tablets been wondering if you been, ignoring me, what about those slimming tablets please ???????????.


out of interest what type of fuel do you use down there john ? 4 start 5 star of Avgas. been looking at fuel cell,s seem the electric bike will soon be forced on us, we should alll strike for a season tke the whole season off teach these do- gooders a bloody lesson, there's power in numbers - ask the fars east dictators look what happened to them, ignored the small man to long and too often


lets stick to banatam racing tuning more interesting ? .

Regards Derek

Spot on John...

003 has a two bearing crank! the primary drive being set inboard a little. Like Derek says a picture speaks a thousand words;but only if you look at it!! (i said that bit!)

So whats the advantage of a 2 bearing crank ? Doesn't it increase crank flexibility, perhaps when we are looking for rigidity ?
Certainly would easier to change the oil seal.

Your picture does not show any primary chain oil guide, been trying to explain to my engineer what I would like, but can not quite figuire out what to attach it to ?

Then oil will not all be thrown up the back of case and I can use less as you suggested.

Day off, no work, got to stain garage door; then I can get some pictures of our clutch mods

John - Just think, do you know of any japanese two-stroke motors with 2 drive side bearings... I don't, perhaps the yamaha copy of a DKW RT125! If honda don't fit 2 bearing on the drive side neither will I. As it happens seal has to be fitted before bearing and can't be removed without splitting motor...

please clarify seal fitted before bearing ? you mean the seal s close to crank bearing on outside ? or bearing on then seal.

are you sure Mike " I thought it was me who said "a picture paints a thousand ? " , I don't want to be a cock about this, but it was me !!. LOL

spent an hr answering all these posts, so had enough now.

regards Derek

You said " A picture paints a thousand words"

I said " but only if you look at it"

The picture has had 172 ? views but how many people noticed what you did? you must have an eye for it?

Well you have since the pic(1), looked at it (2)now imagine and wonder how it was done? (3)

Happy creative thinking..... tell you tonight or tomorrow.....

Its wednesday so busy today...... will be reading MCN

HI Mike

hope you enjoyed my last post had a few replies off line can repeat on line anyway you seem to be having the desired effect well don to you both.

No w
1) I think we are getting back to the guessing and assuming ! "please "no mas"

2) on the crank seal on inside, I can think how but why ? ? come on stop this I'm going to hold my breath so please dont spend too much time keeping us all waiting,

3) what's the idea /thought /thinking behind it, sound like this could be interesting, I'm sure we all know why the bearing has gone (friction / crank wip) but the seal on the inside "why".

4) MCN Sorry boring boring boring, never imagined you looking at this may change my opinion, compared to this forum that is, and thats before I read Trevors reply.

gGreat responce and picture any more ??

John - I haven't got a chain giude/tensioner, think of the mess if it fell off. I use 10floz of oil in the common gearbox/primary drive compartment, its find no probs. My crank will flex the same both sides now and wont be held rigid on the driveside and therefore flex alot on the timing side. Its works for me and every two-stroke build in the last 40yrs. Anyway think of the weight added by a 6203 bearing and a chain guide. I like to keep thinks simple.

Derek - A lot of the time there isn't much thinking behind stuff, just think its worth a try/see. You have seen the inside of the driveside crankcase(no packing rings) and you see the bearing is up to the crank. The seal goes in the case first followed by the bearing the seal butts up aganist a 'lip' (smaller diameter) as there isn't room for a seal retaining plate before the engine sprocket.

Hope thats clear.

Mike

Mike,
Greatly intrigued and impressed with your set up and logic, I guess I have for 36 years robot like just rebuilt Bantams as they are just cos they are like that. So will be looking at two bearing setup next time sswc engine is apart. Would it be possible to use standard size RH seal from the outside without 6203 and shortened depth to boss ?

Any way of getting some more herbs to beat the NSUs and C15s.

Sorry, really did not mean chain guide/tensioner, as we use with 14T engine sprocket in trials motor; but ? "oil defection plate" set up, to redirect oil back to chain or sprockets rather than gearchange orifice !

Have enjoyed everyones interpretations of photo,s and decriptions .I am concerned about the amount of mild steel shavings floating around before they get picked up by magnets and the amount of damage that gets done to the basket.So in my case I,m going to build a Hybrid clutch first up ,one surflex plate then the 3 plate assembly after that(4 plate clutch) ,I hope this will protect the basket.
John what setup are you running and are you happy with it?
regards Dave



Going to to rip my primary case apart tonight

I have the same setup as mike on all 3 of my bantams and was used as the test dummy for the 2 bearing crank (in 99 i think). never had any problems with metal shavings not been picked up by the magnets or crank issues due to only having 2 bearings jit ust improved performance as less friction and having the clutch and drive sprocket moved in the weight is spread over a shorter distance.

Hi Ian / Mike would be interested to know how ? or what type of seal size / inner diameter you are running, and how you controlling float, does seal sit on the inner sprocket diameter, and as on most jap bikes pulling the sprocket / gear on the shft locks up to shoulder to the bearing. ?

regards Derek

With out talking to Tom I couldn't tell you as he did all the work but he is currently lieing down in a dark room preparing for robbie to come round at the weekend to build a new frame

"lying down in a dark room" and "waiting for robbie to come round, ?? you serious!


regards Derek

Robbie likes hammers and other big tools! oh and hammerite paint too, Tom prefers him to use sponges that way damage is kept to a minimum!
Robbie have a look in your photo album, i mean 'log book' i need to know a gearing for the festival??

sorry Ian I just dont get the sotherners sense of hughmer, but I get it now after Mike had to spell it out, not doing very good for the nothern cause on this "Ill shut up".

im no southerner no more i got converted nearly 4 years ago now but still can't resist the odd dig at rob even when he is making another fast bike to add to the grid next year. or is he finishing the ally swing arm project from last last year. only time will tell as he is keeping quite about his plans, well until the sound of banging metal in the morning.