Balancing individual steel flywheels

[SEDoan]

A bad thing happened to my Ariel...

Someone decided it needed a 100% balance factor!
Maybe because they thought it was a Matchless (see yellow writing).

I've repaired it by chamfering the holes then filling them with soft steel and peening the ends to fix them in place, but now it needs to be balanced and I'd like to do the drilling from the inside while the wheels are apart. Anyone got a description and pictures of the setup for balancing the wheels one at a time?

Also, any ideas on how to repair the shallow hole in the picture below? Fortunately they stopped before drilling through the oil purifier plug. My inclination is to try to repair it, perhaps by drilling it deeper, tapping for a short threaded rod, but it is probably best left alone. Any ideas?

Thanks for your help,
Shawn

[will_curry]

Before I put too much more effort into those wheels I'd make very sure that the eyes
for the big end haven't suffered. If the pins aren't a really good fit in the eyes
trouble will surely come.

[SEDoan]

Thank you Will, the crank pin holes are a good fit and the shafts are good too which is why I'm using these.

[will_curry]

Sorry, not perhaps my most helpful of posts. I can only find one set of steel
flywheels at the moment and these are from a 1938 500 but have suffered
badly from water damage. They are balanced with drillings on the inside
faces as you suggest but they still have the big end in place so measuring
them isn't going to be easy.

Hopefully someone else will be able to post the information you need but if not
I'll have a go at measuring what I've got.

[SEDoan]

I'm sorry Will, the wording in my original post was not clear. I'm looking for a picture of the setup for balancing a single flywheel at a time. I maybe just have to remove the mainshaft and replace it with a dummy shaft for balancing, but there may be another clever way to balance the individual wheels while leaving the mainshaft in place. I'd rather not remove the mainshafts or push the crankpin in and out if not necessary. There is evidence of the location of 3 of the factory balancing holes on one flywheel and 2 on the other, but its current balance really should be checked.
Searching through older posts found that a few people on here had experience balancing single flywheels but I couldn't find pictures of it.

[will_curry]

Correct stick firmly grasped at correct end, I think.

I quite agree with not pressing anything out unless it's absolutely necessary.

I think you'll find there are centres in both ends of both mainshafts.

[SEDoan]

Now there's a thought! Doh!

[nevhunter]

I think I have posted doing the flywheel balance individually on this site but I would suggest doing it with a tapered mandrel on good straight edges and get the counterweight effect exactly the same on both wheels. . There's a bit of weighing and calculating needed to get it right. The "FACTOR is 65% for that engine.. The weights you apply the "factor" to are the small end of the con rod and the piston, rings and gudgeon and circlips. Let's for convenience say that totals 1000 grammes in which case the figure you use is 650 grammes. How you the do them individually is where the head spinning occurs. It's easy to remove a crankpin when one flywheel is off. and make a turned weight that fits the crankpin hole on centre and swap it over to do your drilling of the other one Allow a bit of time. Write all figures down and check your logic. Nev

[SEDoan]

Thanks you Nev. I might try first on centers before pressing out the mainshafts.

[Mharrisbarton]

Perhaps I could add a few comments to the very good one's already made, I have replaced quite a few big end over the years, (73 now) and have noticed on almost all the steel wheels that the crank pin hole has "shaved" leaving a ridge on the nut side, the best to reduce the risk of this happening to put the new pin in the lathe (obviously protect it) and using a small oil stone remove the sharp leading edge by producing a small radius, some pins have a small chamfer still litley address it with a fine oil stone ,cast iron wheels aren't as prone to this as the steel wheels but it's still best to stone the leading edge, this may seem obvious but I don't remember removing a pin that had been stoned. an article in chevalier November 2007 by the much missed Bob Brassington on balance factors is very much worth reading! I have my copy in my saved cheval box if anybody wants a copy just send me a stamped addressed envelope an I will send it to them. the shaved holes will need to be bored and an oversized pin fitted, -005" usually does this. about 25 years ago I made a fixture that accurately oreintates and locates each half of the flywheels for boring the crank pin hole. interference of pin to hole should be -001/-0015",make sure that everything you measure is at the same temperature. 20 degrees C if possible. there is a lot more that we could talk about on this subject, but think I have rambled on enough. regards matt Barton