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Flywheel Runout
#11
Hi Colin,

I too am in the midst of getting my crank assembly ballanced. One other thing to check is run out on all faces. I set mine up on the crank between centres, .002 radial run out, .018 clutch face and .018 crank case face. The kicker is the .018s were not opposite one another as I expected so my flywheel must have been machined in two ops, and would have been impossible to ballance. 

Tom

Ps old flywheel fitted to new crank, I just used blue and hand scrapped to achieve a good fit before machining
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#12
There are often discrepancies between front and rear of flywheel faces, after getting as true as you can on the taper skim back and front faces
  true 2thou or less before balancing.  Terry.


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#13
Or note runout and set up in a four jaw chuck and correct . I will always trim all faces and diameters if necessary.
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#14
(06-02-2019, 06:06 PM)Terrytuned Wrote: There are often discrepancies between front and rear of flywheel faces, after getting as true as you can on the taper skim back and front faces
  true 2thou or less before balancing.  Terry.

That looks like the most accurate way to do it.
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#15
Care is needed to avoid the flywheel pulling up against the rear main bearing instead of the taper. Perhaps supply the rear main bearing to endure there is clearance once the taper has been dressed.
Jim
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#16
I always understood the best way was to lap the flywheel and crank together in a lathe.
Flywheel in chuck check with DTI .
Crank nose in live centre in tailstock and lap taper by hand.
Not a DIY job in a small lathe you need access to an industrial lathe to do this.
It will take a lot of lapping to lock up against the rear bearing, the dished washer should be dimpled so that it will be just gripped as the flywheel is pulled up on the taper.
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#17
I had a 1934 4 seat tourer where the flywheel didn't pull onto the taper. Until I got my spare engine ready I carried spare flywheel keys and had minimum number of bolts holding it all together, radiator held only by the hoses etc. Could replace a key at the roadside in 3/4 hour. Had plenty of practice. It was the 1960s when things were simpler!
Jim
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#18
Having discussed this with Park Engineering, they proposed lapping the flywheel to the new crank and then skimming all faces true prior to balancing. Since this chimed exactly with what both Robert and Terry advised I agreed. Very helpful to have the knowledgeable advice of this forum in advance though. Many thanks.
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#19
If anyone out there has a grandchild doing Applied Maths, perhaps they could ask them to calculate  the run out couple. In my day I never got beyond railway engine wheels which, although surprising, was not the ideal to catch my interest!
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