MTFCA Forum

I have my 1926 TuDor engine out of the car for an inspection and I decided to check the weight of the triple gears and maybe equalize them. Here are their weights

#1 1.037 Kg
#2 1.029 Kg
#3 1.034 Kg

OK, so I would have to remove 8 grams from #1 and 5 grams from #3. This doesn't sound like much, until I figured out how much cast iron has to be removed. Maybe I made a mistake but here are my calculations.

Cast Iron has a density of about 7.3 grams/cubic centimeter. That means I have to remove a little more than one cubic centimeter from #1. 1 cubic Centimeter equals about 0.061 cubic inches, again doesn't sound like much. But here is the kicker. If I drilled a 1/4" hole 1/4" deep (assuming a square bottom) that amounts to

(0.25/2)squared * 3.14 * 0.25 Diameter divided by 2 squared, times pi, times depth
This equals about 0.012 cubic inches. So I would need to drill 5 holes like this to remove 8 grams of cast iron. OR two 1/4" holes more than 1/2 inch deep. This sounds like too much to me. Am I doing this correctly? Thanks Mike

Mike

they aren't cast iron, and unless you're using carbide drills, you won't be drilling them

I realize that to remove material from the triple gears, you should chuck them up in a lathe and take material out of the low area. I'm just trying to visualize how much material has to be removed. Mike

You'll have difficulty removing that much weight. Triple gears came in different weights. I'd guess yours are a mix from different cars to be off that much. Most I've seen is 3 grams variation.

I would not doubt that. Maybe I can find a couple of gears that are closer to the same weight, but then I have to horse around with the bushing fit. Mike

We either would take the two down by removing metal from the two heaviest, or adding weight, by wire welding, filling the two holes, to the two lightest. Easy.

Herm.

Well, OK I'm going to approach this from another angle. I'm wondering about the rotational balance of my engine. So I dragged out the grinding wheel balancer, assembled the crankshaft, flywheel with magnets on it, the input shaft and the triple gears in their proper positions. Then set it on the balancer. After a few spins I found a consistent heavy spot. I then used a 7 gram stick on wheel weight on the opposite side of the heavy spot. Now don't cry the sky is falling, the Martians are invading or some other nation emergency, I'm not installing it with this weight. I'm just looking to see if I can figure ot how out of balance my engine is. You can see the weight as the gray square on the edge of the flywheel. Obviously, I do not have the drums and clutch attached, which is a good amount of weight, but how far out of balance could it be? For that matter is 7 grams out of balance A LOT? I have no feel for what is bad, or so-so or even OK, Mike

I always balance them to within .5 grams. You can take 8 grams off- a good place is the shoulders on the edge of the counterbore on the bushing flange side. You can also turn material off the rear side on the flat face. Next resort is drilling equally spaced holes. Yea, some of them can be kinda hard , but not impossible.

Trying to balance it the way you are is a bit difficult.
If you have someone that can spin balance the flywheel you'll be in a lot better place.
Then you can contemplate machining weight of the triple gears.

What do you think is a fair charge for a balance like that? Mike