Flywheel balancing
Discussion
Hi Stevie, that would be in my profile 
Cambridgeshire. Had some block work done by Ivor Searle, but they failed on the balancing, problems using my V8 crank. I have read about balancing the flywheel on its own, using a cone arangement to hold it onto the machine (a bit like wheel balancing). I am slowly running out of time to get my engine rebuilt, if I could post the flywheel to a company that would prob be my best option now, just want someone who is recommended.
The flywheel fits a small block Chevy crank just for info.
Cambridgeshire. Had some block work done by Ivor Searle, but they failed on the balancing, problems using my V8 crank. I have read about balancing the flywheel on its own, using a cone arangement to hold it onto the machine (a bit like wheel balancing). I am slowly running out of time to get my engine rebuilt, if I could post the flywheel to a company that would prob be my best option now, just want someone who is recommended.The flywheel fits a small block Chevy crank just for info.
You might want to read my cautionary tale about flywheel balancing standards out there.
http://www.pumaracing.co.uk/flywheelbalance.htm
Not saying everyone is crap but this particular well respected supposed expert my colleague was using was making his flywheels worse not better.
If all you've done is drilled evenly sized holes for the timing pickup and they're properly concentric it's likely to be fine anyway. Even serious lightening work on flywheels doesn't put them much out of balance as long as the machining is done properly as the article shows.
http://www.pumaracing.co.uk/flywheelbalance.htm
Not saying everyone is crap but this particular well respected supposed expert my colleague was using was making his flywheels worse not better.
If all you've done is drilled evenly sized holes for the timing pickup and they're properly concentric it's likely to be fine anyway. Even serious lightening work on flywheels doesn't put them much out of balance as long as the machining is done properly as the article shows.
cerealsurfer said:
I'll bet you a pound to a penny they just sell on stuff that gets made elsewhere, possibly not even in the country, and do nothing in house.Pumaracing said:
cerealsurfer said:
I'll bet you a pound to a penny they just sell on stuff that gets made elsewhere, possibly not even in the country, and do nothing in house.Can do small jobs while you are waiting if you book in advance.
They must have about 30 machines to do various tasks.... most of them fully cnc so any pattern developed can be run off again and again.
Hi Pumaracing, I had read your notes a few days ago while searching around. It did make me think some and it is very interesting what you have documented.
I have had holes drilled by a machine shop on a milling machine, so all are very accurately spaced (hopefully) and all the same depth. The only bit that will through it out is the -1 (36-1 pattern), this is made by joining two 12.5mm dia holes. I have thought about just taking a similar amount of metal away from the opposite side but wonder how accurate it would end up!?
I have had holes drilled by a machine shop on a milling machine, so all are very accurately spaced (hopefully) and all the same depth. The only bit that will through it out is the -1 (36-1 pattern), this is made by joining two 12.5mm dia holes. I have thought about just taking a similar amount of metal away from the opposite side but wonder how accurate it would end up!?
Hmmmm. If you could measure the exact volume of metal that's been removed to join the two holes and take away exactly the same amount opposite you could get close I suppose but cast iron being quite dense it doesn't take much volume to add up to quite a few grammes of imbalance. Every cc is nearly 8 grammes. Even a 1mm difference on depth on any of those 12.5mm holes is a gramme.
Also you might not be able to remove metal exactly opposite because of where other holes or bolt threads are so you have to do it with two smaller drillings either side somewhere like I do when I'm balancing. That's too tricky without a balancer I think.
I suppose if you get really stuck I could balance it for you but I'd have to make a Chevy sized mandrel for the centre hole as I haven't done one before and sod's law it'll be a different size to all the mandrels I have ready made. Probably an imperial size being American whereas most European flywheels have a metric sized hole. That local cnc place already does Chevy flywheels it says on their website so they'll be set up already and might be the best bet.
Also you might not be able to remove metal exactly opposite because of where other holes or bolt threads are so you have to do it with two smaller drillings either side somewhere like I do when I'm balancing. That's too tricky without a balancer I think.
I suppose if you get really stuck I could balance it for you but I'd have to make a Chevy sized mandrel for the centre hole as I haven't done one before and sod's law it'll be a different size to all the mandrels I have ready made. Probably an imperial size being American whereas most European flywheels have a metric sized hole. That local cnc place already does Chevy flywheels it says on their website so they'll be set up already and might be the best bet.
Volume of metal removed is:
V = pi * d * ((((R + r)^2 - (R - r)^2)/36) - r^2)
where:
V = volume of metal removed
R = radius of circle holes are on
r = radius of each hole
d = depth of holes/connecting slot
You could remove the same volume of metal at radius R dead opposite the connecting slot to balance it... but this would leave a hole which would bugger up the signal from the sensor, so you need to do it at a different radius R1... drill a hole of radius r to a depth D...
D = ((pi * r^2) / V) * (R^2 / R1^2)
If D works out to be deeper than the thickness of the flywheel then drill two holes radius r depth D/2 symmetrically disposed about the "dead-opposite" line at radius R1. Or three holes depth D/3, etc.
This assumes that r is negligibly small compared to R
Still open-loop so not as accurate as a closed-loop method but if you want ultimate accuracy you could always drill the holes fractionally shallow and close the loop later
V = pi * d * ((((R + r)^2 - (R - r)^2)/36) - r^2)
where:
V = volume of metal removed
R = radius of circle holes are on
r = radius of each hole
d = depth of holes/connecting slot
You could remove the same volume of metal at radius R dead opposite the connecting slot to balance it... but this would leave a hole which would bugger up the signal from the sensor, so you need to do it at a different radius R1... drill a hole of radius r to a depth D...
D = ((pi * r^2) / V) * (R^2 / R1^2)
If D works out to be deeper than the thickness of the flywheel then drill two holes radius r depth D/2 symmetrically disposed about the "dead-opposite" line at radius R1. Or three holes depth D/3, etc.
This assumes that r is negligibly small compared to R
Still open-loop so not as accurate as a closed-loop method but if you want ultimate accuracy you could always drill the holes fractionally shallow and close the loop later
[quote=Pb3]Can anyone recommend who could balance a flywheel for me. I do not require a full engine balance, I have modified the flywheel with timing trigger holes for use with an EDIS-8 and just need it balanced before it goes back on the engine.
[/quote
Try to give Steve from http://www.vibrationfree.co.uk/ a call, he specialise in balancing.
Bo
[/quote
Try to give Steve from http://www.vibrationfree.co.uk/ a call, he specialise in balancing.
Bo
rev-erend said:
I believe it's normal practice to also add the clutch housing to the flywheel otherwise you are just wasting your time. Both would be individually balanced then balanced together.
Then you may as well add crank..rods, pistons, pulleys....There is nothing wrong with balancing the individual components.
rev-erend said:
I believe it's normal practice to also add the clutch housing to the flywheel otherwise you are just wasting your time. Both would be individually balanced then balanced together.
How on earth could anything be balanced both individually and then together? The second operation would by definition make the first redundant.Anyhoo. Clutch pressure plates are individually balanced to very fine tolerances at the factory as you can see from the OE drilling marks on them and certainly don't need any further work just because the flywheel has been modified or because they're being fitted to a different flywheel.
Only if the pressure plate locating dowels and bolt holes on the flywheel weren't concentrically located could a pressure plate be out of balance once fitted but then you've got a defective flywheel to replace not a defective pressure plate.
Pumaracing said:
How on earth could anything be balanced both individually and then together? The second operation would by definition make the first redundant.
Anyhoo. Clutch pressure plates are individually balanced to very fine tolerances at the factory as you can see from the OE drilling marks on them and certainly don't need any further work just because the flywheel has been modified or because they're being fitted to a different flywheel.
Only if the pressure plate locating dowels and bolt holes on the flywheel weren't concentrically located could a pressure plate be out of balance once fitted but then you've got a defective flywheel to replace not a defective pressure plate.
The idea behind balancing components individually and then as an assembly is to minimise the initial unbalance of the assembly which can then be corrected with minimal material addition/subtraction. This also permits the replacement of individually balanced components without taking the assembly outside of the balance limits. If the individual components are finely balanced then the assembly unbalance mainly results from mismatch of the components from the assembly centreline.Anyhoo. Clutch pressure plates are individually balanced to very fine tolerances at the factory as you can see from the OE drilling marks on them and certainly don't need any further work just because the flywheel has been modified or because they're being fitted to a different flywheel.
Only if the pressure plate locating dowels and bolt holes on the flywheel weren't concentrically located could a pressure plate be out of balance once fitted but then you've got a defective flywheel to replace not a defective pressure plate.
Pumaracing said:
cerealsurfer said:
I'll bet you a pound to a penny they just sell on stuff that gets made elsewhere, possibly not even in the country, and do nothing in house.
Almost everything they sell they make in house, or in one of the buildings on their site. They do do balancing but with anything they do you will need to keep chasing them.Gassing Station | Engines & Drivetrain | Top of Page | What's New | My Stuff