Lotus Elan

Some questions on the rebuild

PostPost by: Craven » Tue Feb 06, 2018 1:32 pm

+1 with 2cams70 comments, it?s generally true that material is removed but sometimes it?s necessary to add weight, this happens quite often in balancing the clutch cover/pressure plate where material may be removed in one position BUT extra weight added at some other point.
It may be of interest that the latest dedicated balancing machines include the display of location and calculate the depth of hole needed to remove the imbalance weight.
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PostPost by: 512BB » Wed Feb 07, 2018 11:54 am

Craven wrote 'Why, if you limit your pictures, post an irrelevant and possibly misleading one'

How was it irrelevant? I posted a picture of a flywheel, matched to a clutch cover, after balancing, to show how it had been marked to ensure the two parts were mated together in the same position on assembly.

The thread is about a flywheel being mated to a crank boss, and the necessity, or not, of reassembling the two in the same position as they were taken apart. If you are not able to make the huge leap to associate my picture with the tread, that is no concern of mine, but please do not diss my post because of your own inadequacies.

I wont even bother with 'possibly misleading'. I am sure that the OP can decide if he feels he has been mislead.

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PostPost by: 2cams70 » Wed Feb 07, 2018 12:26 pm

512BB wrote:Craven wrote 'Why, if you limit your pictures, post an irrelevant and possibly misleading one'

How was it irrelevant? I posted a picture of a flywheel, matched to a clutch cover, after balancing, to show how it had been marked to ensure the two parts were mated together in the same position on assembly.

The thread is about a flywheel being mated to a crank boss, and the necessity, or not, of reassembling the two in the same position as they were taken apart. If you are not able to make the huge leap to associate my picture with the tread, that is no concern of mine, but please do not diss my post because of your own inadequacies.

I wont even bother with 'possibly misleading'. I am sure that the OP can decide if he feels he has been mislead.

Leslie


Whoa steady on guys!! I think all Craven has done is make an innocent mistake thinking the picture showing the painted marks on flywheel and crank was posted by the OP rather than 512BB. Thus leading to the assumption that the OP was being a smart arse by asking a question which he knew he didn't need to ask because he had already marked them prior to dissassembly. Must admit that's the way I read it first time around too.
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PostPost by: Craven » Wed Feb 07, 2018 4:13 pm

dlb 123
Take a close look at your flywheel, if work has been carried out that requires it?s fitting in a specific orientation then it will have been marked. Here are typical marks that indicate this, they align with Top Dead Centre position of the No 1 crank pin.
p1030299.jpg and

p1030300.jpg and
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PostPost by: elj221c » Thu Feb 08, 2018 1:28 pm

rgh0 wrote: if you do it right when assembled its fully in balance. If its not some component is not central and that problem needs to be corrected and not to do this by balancing the whole assembly. thus I believe balancing individual components is all you need to do if you do it properly

cheers
Rohan


This was QEDs approach when I had my components done.
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PostPost by: Craven » Thu Feb 08, 2018 4:23 pm

As the precise axis of the crank and or flywheel are unknowns then balancing components around another, separate machine axis, will not provide optimum balance.
Moving the position of a flywheel axis is a totally impractical proposition.
Would you accept a balanced flywheel off another engine?
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PostPost by: 2cams70 » Thu Feb 08, 2018 10:51 pm

Craven wrote:As the precise axis of the crank and or flywheel are unknowns then balancing components around another, separate machine axis, will not provide optimum balance.
Moving the position of a flywheel axis is a totally impractical proposition.
Would you accept a balanced flywheel off another engine?


I assume that's the way Ford would have balanced the engine originally - i.e balanced the crankshaft in a dedicated crankshaft balancing machine, balanced the flywheel separately in a dedicated flywheel balancing machine, etc.

From a mass production point of view it's too difficult and time consuming to do things the way you would with an individual engine build - i.e balance crankshaft itself first, bolt flywheel to crankshaft and balance assembly and so on. Similarly for an individual build it's just not practical to do things the way Ford would have done using individual balancing machines for each individual component.

That's why it's recommended to balance an engine even for a road build. As Craven said the factory balancing no matter how good for the components individually does not allow for the fact that there might be slight misalignment of the central axis of each individual component when assembled.
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PostPost by: Craven » Thu Feb 08, 2018 11:42 pm

Ford acknowledge the outcome of machining tolerances in their engine data,
Flywheel run-out Max Lateral 0.004?
Starter ring-gear Max Lateral 0.016?
Run-out is probably caused by an accumulation of tolerances rather than a single component.
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PostPost by: rgh0 » Sat Feb 10, 2018 3:00 am

The critical assembly is the crank to flywheel. This should be a light press fit. If the hub on the crank and the spigot on the flywheel are both concentric to the axis on which the individual components were balanced. then on assembly there will be no imbalance as their axis will align

There are a few other critical dimension such as the flywheel face being at right angles exactly with the cranka xis so there is no axial wobble in the assembly.

if you have a standard iron crank and flywheel then correcting issues in any of this can be a problem as any machining and you loose the press fit of the crank and flywheel. If the crank hub and flywheel spigot are not on the same axis then you do need to decide what to do. Either fix the axis problem or balance the crank and flywheel as an assembly.

cheers
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