MTFCA Forum

I live in N. Virginia and am seeking someone who can static balance the two transmission drums. It requires a mandrill and knife edges or the tool used by machinists to statically balance items. The technique is used by Mike Bender in his YouTube Model T Tips #17. Anyone near by? Suggestions? I am at a stand still. TQ

Because of the small amount of material that typically needs to be removed, and the modest radius that the weight spins at, while balancing the drums helps, it is not a significant improvement. Balancing the flywheel with magnets on it, and the triple gears in place is a much greater bang for your buck. Most balance the triple gears to themselves, but I see no value in that so long as they stay on the same pin as they were placed when the flywheel is balanced. I number the pins and number the gears and everything stays in the same location. You can balance the flywheel within several grams without too much trouble. I typically get them balanced enough that the addition of a 1/4 - 20 nut added to the perifery will start a static flywheel rotating on a good stand.

The difference between an unbalanced flywheel and a balanced flywheel can be significant in performance. Adding balanced drums, some, but not so much.

FWIW.

I agree with what Scott says, except I have the flywheel dynamically balanced. Talk to the local engine rebuild shops for a source. I have had them done on a pair of transmission shafts. They probably will have to put a piece of duct tape around the outside of the magnets to reduce the drag from the “blower effect “ of the magnets.
Obviously check the “runout “ of the transmission shafts to ensure they are straight. Usually they are pretty good !!

Dynamic balance would definitely be better than static, even though plane separation is not much...that is a really heavy rotating mass and the 4th main will thank you for it if you do go to the effort and cost. Oh, and for dynamic balancing...the gears are not in place!!! HAHA.

I have never done this to a T and would be intrigued to see where/how the material is removed from the magnet side (?)

Les...do they actually remove material from magnet side, or just transmission side?

thanks for any info

Scott, surprised to find someone else who understands plane separation when it comes to static and dynamic unbalance (single plane versus multiple plane). Interesting to see if this creates some conversation about the benefits and techniques used to correct unbalance!

I will post some pictures of one I had done recently.
The first one I had done 40 years ago was A cranked and pressure oiled and ran nice at 4500 rpm!! No magnets of course. Since then I get ALL my flywheels done. Certainly doing them on the crank and with the transmission shaft in place is a good option as well

Joseph

I was lead engineer in the manufacture of gas bearing spin-motors for accelerometers. We balanced spin motors down to .01mg. That is the smallest amount of metal you can pick off with an exacto blade using 30x microscope. Used Schenke-Trebel balancers. That all is another lifetime ago, though...

Tom, Please post what you have found. I'm in Fredericksburg and need to get my transmission rebuilt. One of my triple gears is hitting the fly wheels. I have a 26 Touring. What are you working on? I would also join and ask your local AACA. A guy from my AACA club gave me the following recommendation. Mr. Bill Sessler in Manassas 703-368-TWO Three 67. As far as balancing everything my take is if it is affordable do it. Can't hurt. When I do mine I don't want to have to pull it out ever again. Good luck and keep us posted.

I definitely would balance the drums if given the chance, I had the engine balanced , scat crank, new rods, new pistons, flywheel and triple gears, but didn't do the drums
Figuring the engine would rune smooth but don't. Just my story, I blame it on the drums because every thing else was balanced . The engine runs smooth at times depending on where you let the clutch out.

John

I am not saying you're wrong or attempting debate...I take you at your word. As I think about this, I'm just trying to wrap my head around all of the damping you've accomplished with the SCAT, etc., and have vibration being induced by drums. I have indeed heard about drums that go in/out of sync regarding unbalance, but that was associated with an old engine and a worn out 4th main.

I'm thinking you have a speedster and are finding this at higher RPM?
did the tail shaft run dead-nuts to the crank?
ball bearing 4th main?

am asking these questions for my learning, not to question the build.

thanks

Just a few comments on the above. As one who has balanced my fair share of transmissions and related parts over the years:

1) it is not uncommon to find a triple gear that is 20 grams heavier or lighter than its two mates. (This is mostly true with the 3 piece style , but hat is not always the case).

2) I have seen some of the reproduction low and reverse drums that are out of balance and require 20-30 grams of material removal to get them balanced. I've also encountered Ford drums that are severely out of balance.

3) Flywheels with the magnets removed always need a fair amount of correction.

4) Brake drum/ driven plate assemblies can be all over the map as far as balance.

Based on all this, if you have your transmission apart, take the time to have all the pieces balanced. Choosing to balance only a few parts is really not the best route to take unless you are feeling really lucky, as it is really a crap shoot.

We have an older Stewart Warner hard bearing balancer that we upgraded with new software and electronics a few years ago that is incredibly sensitive and does a fantastic job and takes all the guess work out of balancing, but you can single plane balance transmission parts with a static balancer and improve things considerably.

I always went with a width of 4 or 5 inches as a cut off for single versus two plane but that's just me...

[image][/image]
I see this one was pretty good. Only required a bit of help on the magnet side

In regards to drums, it looks like I’ve been lucky (which I will take any day)!! Maybe Ford Canada drums were made better. Certainly no guarantee of that!!

I am balancing transmission drums today and tomorrow. I have a static balancer, the type with rwo sets of wheels on two triangular stands and two mandrels I made. The low speed drum was 11 grams out, the slow speed 12 grams. Getting is perfect is a neverending battle, but the two are better than 2 grams out so far. I'll probably try to get it closer tomorrow, but it seems once you get one heavy side balanced, another pops up in a different place. I'll get it as close as I can without going bonkers.

The above looks like a new drum which I am thinking might be a different story then original drums. I would think removing any material from an original drum might be dicey, after all they are already 93+ years old. New drums would be nice, but for some of us, that isn't in the cards. Now I am not saying not to, but to think about it first.

Hi Scott, This was a 1926 engine for my father. The balance is pretty good, but could have been better. Fourth main only ran out .0015 and aligned perfectly with the pan. Just saying that the drums appear to be the culprit and I wouldn't take a chance again.

The drum pictured above is an original drum which has been trued and polished. I've never had a problem balancing original drums. Re the low speed and reverse drums I did today, it was a matter of enlarging the holes. The brake drum/diving plate assembly is different of course, but I don't anticipate a problem.

Thank you, John

As a neophyte, I may be wrong on this, but it seems that the flywheel would be the most important part of the drivetrain to balance. It is large in diameter, and if not balanced would be hard on all the bearings.

Did Ford balance the flywheel and magneto in engines before they were assembled?

But, I would also want the transmission drums balanced if I were to run over 1600 rpm. Otherwise it could be very wearing on the forth main.

I wouldn't worry about it if I were only going to do parades and drive under 35 mph, but balancing and vibration control have to be a major factor in a strong and long running engine.

If I am going to pay for a rebuild, I want it balanced.

Interesting to get all the info on dynamic balance. I balance all parts on knife edges. As a test of our work, I sent out two flywheels to have spin balanced after static balancing here. One with magnets, one without. They came back with two additional 1/4” holes drilled about 1/4” deep. This is an amount of weight removed completely insignificant in the rpm range the model t flywheel will ever see, in my estimation. Opinions will vary. We balance transmission drums on the same equipment. While the weights involved and correction radius are not large, consider there are three of them and they do not always come up in the same orientation to each other every time the clutch is engaged. In the event all the heavy spots come up together, it could be noticeable. Such an engine will balance differently after every stop sign.

For the speed range the cars I work on I use the knife edge for the flywheels. I have found the cast type need more work done then the later (1926-27 ish) fully turned type.
Richard thanks for the correction on the drum in the photo.

One of my other hobbies is industrial anthropology through the years. When we look back on something...I like to put on the mindset of the 'then' and try to think things through.

What most do not realize is that often time in that era it was not individual mental power, but collaborative notes reduced to consensus 'black books'. (How many of you 70+ guys in engineering remeber the white hairs of your youth having this 'book' that was usually under lock and key?)

I collect these books whenever possible as a few always escape the farm and I'm amazed at some of the instruction sets found from time to time.

Just for kicks because Dan mentioned computer aided decisions...I was going to post a 'nomogram' of how balancing worked in those good old days when the most sophisticated calculator was a slide-rule....then decided to post the section for an old line manufacturing company view towards 'balance'

Not to take anything away from previous posters...I'm in favor of spin balancing of all if you have access to it 'cheap'....also obsessive compulsive to static balancing anything else-just because

I use the Sunstrand balancer like Richard posted above - flywheels I balance - drums not so much unless the customer expresses interest and $'s !

My brake drum bolted to the drive plate oriented to give the least tail shaft run out is 18 grams out of balance. Thats a bit of material to remove but its doable. The last flywheel I checked was less than that.
My plan is to have the flywheel and crank dynamically balanced. The other rotating parts static balanced. Got to be careful about who you choose to do the balancing. One guy I was referred to darn near ruined a crankshaft from an earlier rebuild by grinding too close to the fillets.