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Crankshaft Taper

Is it possible, or practical, to have the tapered portion of a crankshaft "built up" by some means and then turned down to produce a smooth, correctly-sized taper? If it is, does anyone know someone capable of doing the job?

Rick

Location: Deepest Norfolk

Re: Crankshaft Taper

Metal spraying and machining should work. These people do that kind of stuff along with other related machining.
http://www.thurstonengineering.co.uk/general-engineering.php usual disclaimer -only a customer etc.

Location: N W Kent

Re: Crankshaft Taper

Thanks, Stuart.

Rick

Location: Deepest Norfolk

Re: Crankshaft Taper

I guess you have followed this forum sufficently long to appreciate that, if an origianl crank, crack testing worthwhile before spending.

The taper spec may be on the drawing which appeared some months ago, although more simple to machine to suit flywheel. For the flywheel to fit so it just grips the slinger does not allow much machining or fitting tolerance. Were original slingers gripped or just a tight fit on shaft? Flywheel hub thickness may have been reduced at some time.

Location: Auckland, NZ

Re: Crankshaft Taper

Yes check it isn't cracked first.I'd try carefully,lightly filing any marks off the taper,and out of the flywheel and lap it on. .002" off the taper will move the flywheel about .060" up the taper which is about as much as you can get.
If you do this check the flywheel doesn't go on further than the shoulder at the end of the taper as the nut won't tighten it up unless you fit a recessed washer behind the nut.
I had a crank metal sprayed years go on a 1450cc mini,Taper flywheel but it only lasted a couple of years.

Re: Crankshaft Taper

Good advice, guys. If I decide to have it sprayed and reground, I shall certainly crack-test it before investing any money!

Rick

Location: Deepest Norfolk

Re: Crankshaft Taper

I have tried this in the past. It's success was only good for a year or so.
Finally the crank broke it was crack checked beforehand.
I have always since believed that a tiny fractional difference from the front to the back caused a slight hormonic which in the end resulted in the eventual disaster.
Given that there are various new cranks available and still plenty of secondhand ones if budget is an issue, I would strongly recommend that you consign your current crank to the bin.
It's a lot of work and damage to put right if it breaks, not worth the risk in my view.

If you do decide to take the plunge with a new crank, I would strongly recommend that you get it dynamically balanced as I have never had one that was (even though they supposedly are).

Hope I do not sound too negative, but I wanted to share my experience with you.

Location: The Centre of the Universe

Re: Crankshaft Taper

Thanks for all the good advice. New crankshaft now fitted and engine rebuild in progress.

Rick

Location: Deepest Norfolk

Re: Crankshaft Taper

Hope you have good success

Location: The Centre of the Universe