Author Topic: Flywheel Balancing Questions  (Read 2375 times)

dieselspanner

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Flywheel Balancing Questions
« on: June 22, 2015, 08:43:25 PM »
Hi All

I'm slowly getting on with the rebuild of my 3/6/8-1 bitza

The spec plate indicates it started life as a 3-1 hopper cooled version around 1933

It camr to me with the larger bore cylinder and a piston with 4 standard rings and no scraper, although the bottom ring sits in a groove that has been machined in a similar fashion to an oil control ring. (the oil control ring I have won't fit in the bottom - or any other - groove)

Whilst cleaning off the flywheels - they appear to be a pair - I found a '3' stamped on one of the spokes and what may be a badly stamped 3 on the other wheel.

I've finally found someone to regrind the big end, next is balancing.

My questions are......

Is there a difference in 3-1 and 6-1 flywheels (to allow for the mass of a bigger piston)?

If there is a difference, is it too large to overcome with additional weights? - I intend to use the stick on type used on Mag alloy wheels

Is there any merit in using an aluminum 8-1 piston, (less mass), I'd ideally like to end up with a 6-1

I've aquired a pair of ball bearing  'axle' stands and there's loads of info on here that should get me through the balancing stage once the crankshaft returns, the big question is 'Can it be done with what I have'?

All help, advice and comments welcome!

Cheers Stef

Tighten 'til it strips, weld nut to chassis, peen stud, adjust with angle grinder.

dieselgman

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Re: Flywheel Balancing Questions
« Reply #1 on: June 23, 2015, 12:23:58 AM »
There were a lot of different flywheels in use for these models. Since yours already had the larger bore piston installed, I would have to guess that the balance was already close enough to pass.

If you want to run 650 rpm, I would stay with the iron 6/1 piston as originally designed. The alloy 8/1 piston becomes a necessity at higher speeds (850rpm).

dieselgman
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dieselspanner

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Re: Flywheel Balancing Questions
« Reply #2 on: June 23, 2015, 08:45:01 AM »
Thanks for that,

Nice to have confirmation that if I am guessing then I'm not going down a dead end whilst wearing rose coloured glasses!

Sadly some one sabotaged the motor years back, by pouring sand into the sump and the previous owner had no details of it's previous existence. It doesn't appear to have done a lot of hours since it was last rebuilt (from the most disparate pile of bits and pieces imaginable). Maybe it was a show engine, or maybe the sand was the result of some one's frustration when the odds and sods would barely run. 

We're quite busy on the B&B front over the summer, but eventually I'll get the balancing underway and will doubtless be looking for more advice!

Cheers Stef
Tighten 'til it strips, weld nut to chassis, peen stud, adjust with angle grinder.