Bantam Clutch Tuning??

Hi all

So Robbie is building an alloy swinging arm - is this legal ? " besides "No need Rob" there are another ways, although I'm not recormending them.

you should get some slimming items - I'e been taking ? Also Di suggested we go to a health place for some R&R, we went along to one such health clubs to have a relaxing day as I imagined, massage /swim! all the good things, -

"what a shock"

when I arrived they gave me lettis leaves for dinner,! a cup of tea that tasted like some just urinated in it, then prepared for my first treatment, some beautiful bird came in and stuck this tube where the sun don't shine, then hand pump a gallon of dubiouse liquid into me.

I could not possibly tell the rest, but it was not pleasant.

I have desided Im not interested in shedding or losing any more weight exercises, I am happy with my 14.5 stone besides its just
too painfull?, its esier to tune the bike to go faster or ride around at the back and have run, thats what I'm looking forward to.

see you all at the practice day, looking fitter, fatter and feeling better, ? and to have a shake down for the comming season.

regards Derek

Derek techno info :-

My drive side seal is 25x40x10 from the local bearing speclist.
Therefore shaft is 25mm, no the engine sprocket does not but aganist the bearing.
Crank is tight in bearings, end float kept to 0.00mm give or take a tolerance of 'nothing at all'.

Colonic irrigation is all the rage..... Rossi swears by it!

Mike

crank end float o.oo! " you sure mike" this is interesting, does this not overload the crankcases after hot fore sure, the crank will expand 0.002/0.004" as a natural expansion of temperature? my theory.

cheers DEREK

Back to the topic on clutches ,done a partial strip down of primary with a interesting find. the clutch was fine (2 plates stuck) but the drive side woodruff key was in two pieces.I ,ll continue with the steel to steel conversion ,it will be an interesting test.
I like .002-.003 thou(005-0.075 mm) side clearance on crank side play

I've been investigating two-stroke engines and size of bearings. They all seem to have a large drive side bearing and a smaller timming side bearing??? So perhaps you are better sticking to the standard set up? What i'll do is get Ian to get an extremely large drive side/small timing side bearing in his bike and test it for the next 11yrs see what its like??

End float? have you measured end float on a hot engine? or just a cold one??

Mike

Hi dpking - interesting subject this do you mean end float, I alwsy set side clearence on the wheel at 0.020" to 0.25" or 0.5/,6mm

Hi Mike, - no only measured cold -

just tell me what you did, what did you find when you did this hot,? what temp after a run did you measure, wilest riding /testing or just warming up the cases.

you saying the crankcases expand too "at the same rate" tell us what you found.?

Derek

Derek and others.... I thought I had 'nothing' on the crank end float because I can't feel anything,
Knowing its the same hot or cold. My thinking was the gap would remain the same or increase with temperature..

After speaking to Tom...

....... my engines do have 'end float' as this was allowed for when they were originally made (or remade)
this isn't for heat allowance but to allow for crank flex. Because the crank shafts are tight in the bearings i can't measure it.
When a motor is built up the crank is tight and won't turn over untill the crank hit from both ends (not at the same time) with some large weighty and soft sponges?!?
Then it will spin freely...

Well i've learnt something....

Mike

DaveK, sorry mate lost your e mail somewhere. E mail me direct: johnS.bantam@xtra.co.nz I am just about to get some hard steel friction plates and soft narrow intermediate plates laser cut locally. Cheaper if more done to cover setup costs.

These pictures show some of what we are using in clutch mods.

The Suzuki TS/TF100 basket is grafted onto Bantam sprocket. Ken has tried it in trials bike, may need a bit more chaincase clearance.

The other parts are heavy duty spring plate and outer cover to hold basket together.

I use 8 off Rex Caunt 110% springs in trials bike with 4 Surflex plates.
Short stroke watercooled 125 has 6 off Alan Browns's 125% type 25mm or 8 standard 28mm D14 springs with soft metal to metal in 3 plate basket.
Longstroke 175 has same set up but with 4 Surflex plates and radial needle roller pushrod bearing in 4 plate basket, less need for high revving clutch slip.

Hi John
Serious stuff - is the suzuki clutch for use in a trails bike or a racer?
Just that having no band/top plate around drum - I fear it would explode on a high revving racer.
Mainly because the bantam clutch assy revolves a just under half speed 17/38 primary drive = 2.24 :1
Therefore assuming an engine speed of 12'000 for the following bikes:-

BSA Bantam 2.24:1 clutch speed = 5'357
Honda MT125mk2 4:1 clutch speed = 3'000
Honda RSW125mk4 3.14:1 clutch speed = 3'821

The bantam's clutch speed scares me!?

The 8 spring assy I assume is for a bantam cluth drum? It looks neat and well made.

Mike

Hi Mike whats to say i haven't been testing a 2 different sized bearings already???????????????????????????????????????

Some things are just kept to ourselves until they work you should know that

pack it up you two !!! all this cloak and dagger stuff should be left for the theater.!

you either have or havent, or about too. lol" besides why do this whats the advantage" lower weight becuase the bearing is smaller?

Derek

Yep! you are prob on your 9th season of different size main bearings, only a couple of years now and satellite
bantam riders can have the info.... such is life..... lol

Mike

Tim, no, did not make basket, it is off a TS90/100 Suzuki, plentiful, cheap as chips at the wreckers. Also, compatible for size, shaft diameters etc. Did look at an early 90s RS125 one but outside diameter and depth were too big.

Mike, conversion only tried on trials bike so far, having compared it to RS125 set up I thought it would be strong enough and internal springs would pull outer plate in. But, you are quite right about clutch drum rotation speed. No wonder SSWC motor burns out Surflex plates when getting off the line.

So perhaps a different approach. Did hear whispers of certain people that worked in aviation industry in West Country making a 5 plate clutch with a bigger drum ? That would increase clutch mass. Seems the modern clutch and conversions are large diameter and narrow plates though.
Or....... read carefully Derek; fit a 12T engine sprocket and a 20T gearbox sprocket, so I would be doing 103.14159265 mph at 10,000 rpm rofl !

Hello John ,
Great pictures did you have to space out the primary cover for clearance or was it a perfect fit.Okay I,m up for a 4 hard plates and 4 soft we can use the PM (private message) function for details of costs and postage .
regards Dave

hey - John" love the clutch, been studdying and thinking about the centre how did you do this ? you going to send us the other picture of the other side too, so we can work it our or like Mike are you going to keep us assuming and guessing.

A great post subject.


Derek

The Suzuki basket is removed form its primary gear, given a wee skim off the back and riveted to the standard Bantam clutch sprocket.

If you look closely at the second picture you will see the centre adaptor that is fitted into the Suzuki centre with a wire cut internal spline to fit the Bantam mainshaft. Easy really, but took a bit of trial and error to put together.

Dave, Ken has fitted under D7 cover with one less plate. Yes, I envisage having to space the cover out, either by welding a rim around or a deeper cover insert.

Hey john

no need to - - look at my cover ? pictures. "ahead of you my friend"


But a truly great post and well done to you, your efforts are inspirational, sure all will agree one off the best subject posts.

behind exhaust's, barrels or porting.



regards Derek

Thanks for the comments and compliments.

I am pleased I have stirred a bit of interest and provided food for thought.

Over the many years I have known you guys, your help and (s..., my dyslexia is catching up with me, or is it the two lagers before tea!) generosity has been fantastic.

Hey, Derek, quite which picture were you referring to ?

Dave, just been to laser cutters today, have a problem finding some thin hard material. Have been offered some Q ? Cu 10 coppery mild steel, might try one set, can't be any worse than plain ms. Off to find some thin band saw or cutting discs. Some suggested, others rubbished stainless steel sheet, hmm..

Hi John ,
Sorry to here about the material problems,as for the comments on stainless steel it has a higher tensile and hardness strength than mild strength ,the only catch is .One grade is magnetic and one not, usually the magnetic one is of a higher surface finish (more chrome) like typical knife and forks place a fridge magnet on s.s fridges or knifes etc.The other problem is it plays up with heat ,thats why years ago I got some rotary disc valves water cut ,no distortion.
Dave

john I agree with Dave on SSTEEL, TRY-S106 can be case hardeded AND NO MAGNETIC, but sadly is shush" classified so try your local aerospace? supplier. We tried the copper content material, and a waste of time, very difficult to ht treat/ or harden.? we just stick to the std plates the thicler once seem best and do not distort or overheat and burn, like the thinner plates.

John I want to look more at the cluch centre ? the one that fits directly to the mainshaft, has 5 or is it 6 splines.

Anyone looking at this impressive amount of re-engineereing John is doing to his clutch, its my opinion it looks great but not required for racing.

Also if you strip a 1970's MZ 125 is identical to what John is doing and is the same as a bantam fits directly ? could be easily retrofitted without the worderful work /complexinty of what John is doing, but not to say a very impresive piece of work John.

I would add that a std clutch basket in good condition, with it modified as per Mikes picture with band round the outter edge is more than sufficient to race with, and very durable, not sure other's have an opinion about this.

cheers Derek

hi mike, could you tell me when you had your new clutch basket made did you have to have it hardened? and did you have it re-riveted back on or was another method employed. best regards adam.

Adam its steel don't know what type?

Will ask the machining shop?

and its riveted together!

Mike

thanks mike adam.

johnSbantam wrote:

Thanks for the comments and compliments.

I am pleased I have stirred a bit of interest and provided food for thought.

Over the many years I have known you guys, your help and (s..., my dyslexia is catching up with me, or is it the two lagers before tea!) generosity has been fantastic.

Hey, Derek, quite which picture were you referring to ?

Dave, just been to laser cutters today, have a problem finding some thin hard material. Have been offered some Q ? Cu 10 coppery mild steel, might try one set, can't be any worse than plain ms. Off to find some thin band saw or cutting discs. Some suggested, others rubbished stainless steel sheet, hmm..

hi john you know which pictures now it took me a while to load them, they are with the brian / mike pictures - you seen the cover !

regards Derek