Maintenance & Technical > KX500 Original

Sleeving crank journals - good idea / bad idea?

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Captain_Chaos:
Just to clarify, the crank will be sent to the Hard Chromers assembled and trued, but without the conrod and bearing. (i.e. the stubs, webs & big end journal all pressed together)
The hard chrome platers will not disassemble the crank so they will be able to use the crank centres for the grinding. I will need to check with them if there is any possibility of distortion during the plating process.

I don?t have the factory specs on the interference fit.
Do these sound about right to you?
 RH bearing journal 30.02mm (1.1819?) ? 0.0008? bigger than bearing ID
 LH bearing journal 30.01mm (1.1815?) ? 0.0004? bigger than bearing ID
 Seal surfaces 29.99mm (1.1807?) ? 0.0004? mm smaller than bearing ID

sandblaster:
The platers will grind the journals undersize to clean up and true.
Then they will plate a little oversize and grind to finish.
That way you are assured uniformity of plating and a concentric finish...
Or something like that  :-o

DoldGuy:
Captain C,
 Your numbers are good.
DoldGuy

Captain_Chaos:
Just doing a bit of running around.
After seeing the crank, the platers told me they would get better results if the crank was split. (with the crank as a unit, one of the stubs would face down and the web would cast a ?shadow? on it)
The stubs have centers on the inside, so grinding would not be a problem.
The quote for the chrome plating & grinding came to ZAR 480.- (55 USD) so it?s quite cost effective.

On the negative side, they will only commit to a tolerance of ?0.005mm (?0.0002?), so the final journal size will be somewhere between 30.01mm (1.1815?) and 30.02mm (1.1819?). Both LH & RH journals and seal areas will be done to this size.
This is less than ideal for assembly/disassembly but is a compromise I would be prepared to live with.
I will however try to find someone who can to do the final grind to closer tolerances.

Captain_Chaos:
Got the crank halves back just before Christmas.
The results are quite disappointing.
The journal grinding is completely out (0.04mm undersize) and they decided to charge me more than double the original quote.
The crank will need to get hard chromed again.
I will need to look for an alternate supplier for the grinding once the shops open again.

With all this running about and waiting I would have been better off just ordered a new crank.

Locks like I will have to enter the first race of the season on my RM250!

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