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MG MGA - Flywheel position

I want to assemble my flywheel so that it is 60 or 120 away from the original position, so the starter sees "fresh teeth". I punch marked the flange and wheel on dismantling - there is a 1/4 mark on the flywheel rim but no corresponding mark on the flange (WSM says there is).
My question is - which way should be best, 60 or 120?
(Looking at the flywheel, and intending to shift it a/c on the crank.)
Art Pearse

I would be careful if intending to move the flywheel position. With the mga twin cam the balancing method was changed in August 1959 and it could be assumed that the same policy was used on the pushrod engine. Early engines were balanced with the flywheel attached to the crankshaft. Later engines had the flywheel and crankshaft balanced separately. See CSM attached.
Are your flywheel teeth in really poor condition?
A considerable amount of wear is not usually a problem, and anyway fitting a new ring gear would be a better solution.

Mick



M F Anderson

The 1/4 mark does not mean one quarter, it means "1 and 4". This is (was) the original top point of the flywheel when #1 and #4 pistons were at TDC. I have no idea why they bothered marking it that way. I believe the crankshaft and flywheel were always independently balanced, and it makes no difference which way the flywheel is positioned. For years I would intentionally rotate the flywheel 60 degrees one way or the other for fresh teeth without changing the ring gear. Works a treat and does not cause any balance problems. Any orientation you like will do.
Barney Gaylord

Yes I know what the CSM says, but "supplied as a balanced unit only" does not necessarily mean they were spin balanced together. It could just as well mean that the factory was measuring and labeling and hand selecting parts that would be best matched together. What the CSM says is that there was an improvement in balancing methods, and you can now ignore the positions of original factory assembly when installing replacement parts. (But still check balance after assembly anyway).

In more than 40 years of dealing with MGAs I don't know if I have ever seen one that for sure still had the originally matched crankshaft and flywheel. If you can't prove the flywheel and crankshaft were originally mated at the factory, the whole idea is a mute point.
Barney Gaylord

Thanks. My lump is an Austin A60 (now MGA 1622) so outdates that CSM. The teeth are not really bad, but it would be nice to have fresh exposed. I will go 60 deg.
Art Pearse

This thread was discussed between 21/04/2010 and 22/04/2010

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