I might see if I can use a press to open it up and examine the crack surface. If it has the good old tide marks of a classic fatigue failure, I will not be recommending that anyone rebuild old harmonic balancers

cheers
michael

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the world is a book, and those who do not travel read only a page
66 Mini Minor sponsored by http://www.lifeonthehedge.com.au/ The Dog Harness Specialists
It was a pleasure ausmini. I'll miss all you misfits and reprobates

It's only grey cast iron, so if you press into it you will get 2x 1/2 pieces- all the better to look at!

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Hey michael, sorry here mate but I suspect that you may have mis-understood my point. I have NO doubt that you assembled it correctly as per workshop manual etc.

Just the 'normal' harmonics produced in the crank can have an effect that may make fasteners screwed in to it loosen off.

oh I forgot to mention that it took a lot of effort to unscrew the bolt because of the loctite

_________________
the world is a book, and those who do not travel read only a page
66 Mini Minor sponsored by http://www.lifeonthehedge.com.au/ The Dog Harness Specialists
It was a pleasure ausmini. I'll miss all you misfits and reprobates

Yer, it's bloody good stuff...

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

When Tuffbond rebonded my damper they broke it getting it apart so they turned up another out of steel

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David L


My greatest fear in life is that when I die my wife will sell my Mini and tools for the price I told her I paid for them!

Thinking about harmonics, vibrations, movement, etc...
How good a fit is the timing chain sprocket on the crank? (assuming you are running a chain)

And something for the real experts, could an aggressive camshaft and a slightly slack crank sprocket get angry enough to loosen/damage the harmonic balancer?
Could a belt drive reduce the harmonics? (could a single row chain do the same thing for a shorter time!)

I know that the early Cosworth DFV and the Repco 4 cam used to do nasty things to cam followers until Cosworth came up with a fancy damper in the gear train.

yours might last a bit longer then?

_________________
the world is a book, and those who do not travel read only a page
66 Mini Minor sponsored by http://www.lifeonthehedge.com.au/ The Dog Harness Specialists
It was a pleasure ausmini. I'll miss all you misfits and reprobates

A better fit than the damper apparently. I checked that and there was absolutely no slack there.

_________________
the world is a book, and those who do not travel read only a page
66 Mini Minor sponsored by http://www.lifeonthehedge.com.au/ The Dog Harness Specialists
It was a pleasure ausmini. I'll miss all you misfits and reprobates