Joining two crankshafts

[normspanners]

Hi Andrew how about this idea using a fenner flk400 type taper lock bush machine both cranks down to 25 mm ish parallel and clamp them together. first though machine the od down to match your centre brg

 

[mowersman]

The only issue there is that the shafts are 7/8", so not quite big enough!
Andrew

 

[jinjahbiscuit]

Manx norton crank ? I have only ever replaced the crankpin on a triumph tiger cub and that was simply pressed up , no crankpin nuts as used on bsa goldies for instance, but a low power engine, much as i suspect the two engines in question are.
A good few lads i know were having trouble with clutch centres coming loose on the mainshaft tapers on their bsa pre unit twins (a7 , a10) one fix is to make sure the centre is a good fit on the shaft , this being done by applying grinding paste to the taper and grinding the two parts together, just like a valve in a head, then finally assembled with one of the stronger grades of loctite.

Well, it's not a Norton, but from the same era, though this is actually brand new.

 

[jinjahbiscuit]

for those interested

And that should convince the non believers!

 

[normspanners]

Off subject a little but a few might be interested. Talkin about harmonics, I remember warming up Bill Ivys 125cc v4 yes 4 cyl's yam for him before a race at oulton, the rev counter did'nt start until 7k! and went to 24K, I think it was red lined at 22k and that was in the early 70's it didnt vibrate, it buzzed !!!------ thanks for reminding me I am sure thats where my white finger has come from!! -----Quick note to yamaha re claim !!

 

[normspanners]

Ps and my deafness!. 44bhp @18000 it hurt !!! from a 125 normally asp. wow !!!

 

[ronan]

Well, it's not a Norton, but from the same era, though this is actually brand new.

Yes but meant for manx "replica's" ? I know for the bsa goldstars there are similar products, all greatly updated and strengthened for racing. When i win the lottery i'll have them all .............

 

[jinjahbiscuit]

Yes but meant for manx "replica's" ? I know for the bsa goldstars there are similar products, all greatly updated and strengthened for racing. When i win the lottery i'll have them all .............

Yeah, me too. Dreams should come true! This one's for an AJS though. Just as sweet.

 

[ronan]

Yeah, me too. Dreams should come true! This one's for an AJS though. Just as sweet.

Ah , an ajs boy racer ? I didn't know molnar did stuff for ajs. I don't deal with them anymore , i used to buy stainless fasteners off them for bikes i was restoring, one delivery too over two months and when i rang to inquire as to why it was taking so long his wife got snotty. Not good customer service.

 

[Pete.]

And that should convince the non believers!

TBH, not really. I asked for an example and got one - ONE example from tens of thousands of crankshafts designed, and an aftermarket one at that. There still remains a reason why it's not common practice. Fair play for actually coming up with the goods though Norm.

 

[normspanners]

few more

 

[normspanners]

gettin fed up now

 

[Shox Dr]

gettin fed up now

With what

 

[ronan]

Just another point , the norton commando cranks are three piece arrangements, a central flywheel with two crank sides bolted on. The bolts are very small in diameter 5/16" as far as i can remember, and looks like the whole thing would never hold up, but it does.

 

[normspanners]

the first in the pictures is not aftermarket its a standard crank producing approx 60 bhp

With what

I put a few more pics and they disappeared

[Just another point , the norton commando cranks are three piece arrangements, a central flywheel with two crank sides bolted on. The bolts are very small in diameter 5/16" as far as i can remember, and looks like the whole thing would never hold up, but it does.

/QUOTE] Yes a lot of pressed cranks just hold with the force of the pressing mind you I have seen the ends of the big end pins tack welded for extreme power situations but never in standard form

 

[graffian]

Velocette used a taper press fit crank pin.
Suzuki welded some cranks as standard.

 

[normspanners]

Thanks for that, I have never seen one welded as standard, just tacked? tig or stick/mig?
'the only sure thing is the man that says he knows everything is a liar!!'

ps before anybody says anything that was not 'meant for anybody' it is a saying I use all the time, and it is not sexist either because we all 'know' woman are allways right!!

 

[Epicyclic]

Mowersman, you could have the pair electron-beam welded together if you can find someone to do it - Bit beyond the scope of a DIY build, but if you could get it done as a favour...

From the work we have done on this type of construction you would still have to machine the ends of the cranks to locate them, probably bore the ends out and fit a dowel to keep them square when welding. The welders would advise.

The weld finish is very good and you may get away with just polishing the journal after welding to remove any high points.

One point, and I might have missed your plan, how are you going to set the big ends to be in line or whatever you decide. I guess it will need a pretty accurate jig to be made?

Great job so far btw, enjoying the thread greatly!

 

[ronan]

Mowersman, you could have the pair electron-beam welded together if you can find someone to do it - Bit beyond the scope of a DIY build, but if you could get it done as a favour...

From the work we have done on this type of construction you would still have to machine the ends of the cranks to locate them, probably bore the ends out and fit a dowel to keep them square when welding. The welders would advise.

The weld finish is very good and you may get away with just polishing the journal after welding to remove any high points.

One point, and I might have missed your plan, how are you going to set the big ends to be in line or whatever you decide. I guess it will need a pretty accurate jig to be made?

Great job so far btw, enjoying the thread greatly!

A tool and mould makers near to where i live bought a laser welding machine as their customers were getting moulds made in china, they thought they could get some business with the welding. Fantastic thing , i seen two feeler gauges welded together edge to edge for about 4 inches and i could not see any distortion at all.