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Dynamic crank balancing...

I've started another thread on this subject to separate it from the 'Surface Refinishing' thread...

So, if anyone else knows of a company carrying out dynamic balancing for single cylinder crankshafts please post here, or if there are any other comments on the topic....

So far we have T&L Engineering, Near Bedford....Website or phone 01234 352 418....Ian

email (option): ian@wright52.plus.com

Re: Dynamic crank balancing...

I just rang T&L and they are closed until May 4th....I'll ring them then to determine what balancing services they can provide...Ian

email (option): ian@wright52.plus.com

Re: Dynamic crank balancing...

Can anyone explain how difficult it is to statically balance a crankshaft in a home workshop, or more specifically adjust the balance, and the difference between static and dynamic balancing?

email (option): tomillward@hotmail.com

Re: Dynamic crank balancing...

I use Andrews Precision, Bromsgrove. https://andrewsprecision.co.uk/

I spoke to them about dynamically balancing a crank with a roller big end and it would have to be assembled without the rod etc and trued up, then they'd balance it as usual, then you'd have to take it apart and assemble with the rod and bearings. So setting up the crank twice.

email (option): horror@blueyonder.co.uk

Re: Dynamic crank balancing...

Tom Millward
Can anyone explain how difficult it is to statically balance a crankshaft in a home workshop, or more specifically adjust the balance, and the difference between static and dynamic balancing?
A good number of years ago i static balanced a crank with a new set of flywheels that i had made for a vintage engine. I used the information out of Tuning for speed by P E Irving. Text was easy to understand and it worked quite well on this engine. I know it will be nowhere near as good a professional dynamic crank balancing but it may give you an idea of how far out your crank is in the first place.
Don't really like the thought of having to split the flywheels twice as Horrors thread, as past experience show that the flywheels eventually loose the grip on the pin after repeated dismantling.

Tim W

email (option): t.j.walker@btinternet.com

Re: Dynamic crank balancing...

Tim W
Tom Millward
Can anyone explain how difficult it is to statically balance a crankshaft in a home workshop, or more specifically adjust the balance, and the difference between static and dynamic balancing?
A good number of years ago i static balanced a crank with a new set of flywheels that i had made for a vintage engine. I used the information out of Tuning for speed by P E Irving. Text was easy to understand and it worked quite well on this engine. I know it will be nowhere near as good a professional dynamic crank balancing but it may give you an idea of how far out your crank is in the first place.
Don't really like the thought of having to split the flywheels twice as Horrors thread, as past experience show that the flywheels eventually loose the grip on the pin after repeated dismantling.

Tim W
Sorry Tom, meant to explain the differences between static and dynamic balancing. Static at home is just done on knife edges or between centres. Dynamic it is done on a proper machine and spun at speed. A lot more accurate than static, but it all depends on what you are going to do with your engine and what engine speeds you are going to run it at.

Tim W

email (option): t.j.walker@btinternet.com

Re: Dynamic crank balancing...

['I spoke to them about dynamically balancing a crank with a roller big end and it would have to be assembled without the rod etc and trued up, then they'd balance it as usual, then you'd have to take it apart and assemble with the rod and bearings. So setting up the crank twice.']....

That was also the procedure with Basset Down and would be with anyone dynamically balancing a crank....

The crank can't be rotated for balancing with the con rod in place, so a weight is clamped around the bare crank pin to simulate the percentage of the weight of the conrod, big end assembly and piston that is being used...

Assembling the crank twice is a chore but shouldn't really cause any issues with pin to flywheel fit...A set of flywheels could have multiple big ends fitted over it's normal lifespan....If the flywheel tapers are worn (in the case of a BSA assembly) there are remedial strategies to deal with that fortunately...

If a parallel pin is used and they are worn to the point where fitting a pin twice would compromise them then I guess it's time to consider replacing them or to investigate oversize crank pins....Ian

email (option): ian@wright52.plus.com

Re: Dynamic crank balancing...

I've stood there for ages listening to the old bloke at Andrews Precision, explain about balancing, and almost understand it when he's talking. I had my mate's 850 Commando crank done there recently, I recorded what the bloke said so I didn't have to explain it all again. I was asking how he'd do a roller big end and had an hour talk on that subject too. Very clever bloke.

email (option): horror@blueyonder.co.uk

Re: Dynamic crank balancing...

I have never gone through the complete details of the dynamic balancing procedure and wouldn't regard myself as any kind of expert...

I've picked up a bit about the basics here and there talking about the various jobs I've had done with the chap at Basset Down...As I'll probably never get to see the whole procedure from start to finish first hand or get any hands on experience I'd have to read up on it to find out more...

It must have been interesting to hear it all from the chap that's doing it...Ian...

email (option): ian@wright52.plus.com

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