Old Cranks?

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cannondale27 · #11 Post by **cannondale27** » Sat Nov 27, 2010 8:03 pm

20 ton press will easily handle the job. 3/4 in plate like shown is fine. Is dangerous no matter how you do it. They come apart with a bang at end.

marshall100 · #12 Post by **marshall100** » Sat Nov 27, 2010 8:18 pm

hmm, my press is rated at 6 tons, fine for case bearings, but beyond this job, and then they have to be balanced and put back together.

You want a job 27?

cannondale27 · #13 Post by **cannondale27** » Sat Nov 27, 2010 11:53 pm

I just split them. Timbo or local guy puts them back together. Saves time and shipping to Timbo if a guy splits it and then finds the bad bearing did its dirty deed already. If it vibrated definitly get it balanced also. If you want it split no problem. If its good just let me know where to send it.

marshall100 · #14 Post by **marshall100** » Mon Nov 29, 2010 2:46 pm

There must be someone in the UK that can do this? potentially I have three cranks that could be re-used/saved. I'll dig the other one out this week and get some pics of it. I have three engines and 4 cranks, a nice new crank in my road bike, the duffer pictured here, another which I think was suffering from the same problem and the one in my race bike which has largely behaved itself so far.

cannondale27 · #15 Post by **cannondale27** » Mon Nov 29, 2010 3:39 pm

Any crank builder can at least install the bearing. Balancing cranks is a specialty but is quite a few places that do it. Not any different from doing a snowmobile crank.

wayneschofield · #16 Post by **wayneschofield** » Mon Nov 29, 2010 7:41 pm

QUOTE (marshall100 @ Nov 29 2010, 02:46 PM) <{POST_SNAPBACK}>

There must be someone in the UK that can do this? potentially I have three cranks that could be re-used/saved. I'll dig the other one out this week and get some pics of it. I have three engines and 4 cranks, a nice new crank in my road bike, the duffer pictured here, another which I think was suffering from the same problem and the one in my race bike which has largely behaved itself so far.

Chris Applebee Engineering did one for me once but made a right mess of the balancing, everything on the quad shook to bits and wore away.

marshall100 · #17 Post by **marshall100** » Tue Nov 30, 2010 1:15 pm

I'll tap up the quad fraternity in the UK, I'm hopeful that my plan to do a bit of a job on my race bike can involve getting one of these cranks repaired.

I'll keep you posted.

cannondale27 · #18 Post by **cannondale27** » Tue Nov 30, 2010 3:27 pm

I think you will find what you need.Another source is Harley places.I know they are big over there and anyone who can get a Harley crank to spin at 10,000 rpm will have no trouble with our cranks for sure.

marshall100 · #19 Post by **marshall100** » Wed Dec 01, 2010 12:45 pm

I've found someone who is prepared to do it, however I'm not entirely convinced they know what it is they have to do. That crank has to be balanced to 13000 rpm right?

wayneschofield · #20 Post by **wayneschofield** » Sat Dec 04, 2010 8:16 pm

Who's that then?
They need to split the crank to remove the rod and bearing. Then press it back together and bolt a suitable weight onto the crank pin of a suitable mass, the mass depends upon the 'balance factor' used and the weights of the big end of the rod and bearing (rotating mass), and also the little end, pin, piston, clips and rings (reciprocating mass).
They also need to know what rpm you want it balanced for, as a single cylinder engine balanced for one rpm is wrong at other rpms.
Would be worth asking those in the know on here what sort of balance factor you need for stock stroke, stock rod, piston etc at typical rpms we use.