Does anyone know to what degree the factory did balancing of engine parts during assembly?
I've seen flywheels with balance holes drilled along the edge, but I cannot recall reading that pistons, connecting rods, crankshafts and other parts were subject to any sort of balancing.
If this is true, could it be that the manufacturing process was deemed good enough so that virtually every piston or crankshaft came out nearly identical? (To the required precision of the day). Even all magnets were "close enough" ?
Related, I doubt that wheels were balanced at all. Is that right?
Lots of jokes about Model T's vibrating the fillings out of the passengers, but to what degree is this true for factory-original cars?
Thanks for your thoughts.
I believe an attempt was made to balance the that the naked flywheel casting. Iron castings tend to have heavy sections. I do not think they were balanced with magnets. I have never seen any other engine parts that showed any sign of being balanced.
Time spent balancing parts would add an expense to the process of making the cheap car.
At some point the pistons and rods were grouped by weight so 4 rods/4 pistons that were close in weight were installed in the engine at least that is what I recall reading somewhere.
Given that the roads of the were either natural surfaces (dirt, stone, sand, etc.), or maybe brick or cobblestones...how could you ever tell if it was the engine vibrating the car or the surface it travelled upon? I can't imagine high pressure clincher tires absorbed much road shock either. Unless you were at idle, the car would be bouncing, rattling, and vibrating all the time on the road anyways.
You are correct about the pistons and rods being sorted by weight (at least during some of the production – I don’t have any documentation on earlier or later production). On page 145 of Bruce McCalley's (R.I.P.) "Model T Ford" he has 3 photos of the piston and rod assembly area. He states, "One of the two piston and connecting rod assembly tables. Six men do the assembling, and the seventh inspects and sorts them according to weight. It took less than a minute and a half of one man’s time to assemble and inspect each assembly. The photos are located in the 1913 section of his book and were published in the July 1914 issue The Engineering Magazine: . The photos below are the same photos but are from page 21 of the Jan-Feb 1988 “Vintage Ford” and are used by permission to promote our hobby.
From that Jul 1914 article in “The Engineering Magazine” it states:
The finished weights of Ford pistons vary ----
maximum, about six ounces. Each piston is
weighed and marked on the head by a centerpunch
used without a hammer, with one, two,
three, or four center marks, dividing the pistons
into four weight classes, maximum weight
variation in each class three-quarters of an ounce.
After inspection, the inspector places the assemblies
on one or another of four shelves, according
to the center marks on the piston head, and the
pistons are paired for weight on opposed crank throws
by the motor assembler.
Hap l9l5 cut off
Many Model T crankshafts have grind marks, suggesting some attempt was made to balance them.
Oops, I forgot about the crankshafts. I have seen many that have been ground on the throws in an attempt to do some balancing. Trent is right, I have had a senior moment.
Maybe it was just cleaning up the raw forging?? Is there any way to balance a crank without a spin?? How would one know where or how much to grind?? Maybe there was extra to be removed before fitting in the fixture for turning/grinding?? Respectfully Submitted,Bud.
Hmmmm, early documentation in Arnold and Faurote says that there was a disk-balance stand and an emery-wheel stand used for crank balancing...one man / 40 cranks per hour / close balancing...
So the guy had 90 seconds each to both mount the crank on whatever the disk-balance stand was...check it for complying balance...grind a correction for those that were out...and check it a second time. I usually laud and support Ford methodology...but this pace sounds super-extreme of any sort of really close balancing...makes me wonder how many cranks actually were in balance zone on first check? Must have been a bunch which would imply to me that close wasn't really all that close! (If I had to guess I would strongly suspect it was a knife edge stand, it had a disk as a tailstock that picked up the 0.441" locating holes from a previous operation, the guy gave it a measured 1/4 turn and let it go, and how slow it went through bottom dead center, or how high on the other side it rose was 'close enough' for a pass fail...he didn't have time to do anything else!)
Trent or Jack...can you describe the evidence you guys have seen? I'm curious as others may be too. Some cranks/many cranks show way too aggressive snagging was done on the throw forge split line and it is that very same snagging 'roughness' that causes the weak link in a throw failure at endurance. (smooth v. alligator chewed snagging is on the order of a 3::1 change in endurance life all else the same. I'm not sure they understood that yet in the era...)
Interestingly, while I've handled a whole bunch more AA cranks than EE...I also don't recall ever seeing an EE that has had aggressive snagging on the throws...can/could someone confirm that?
I'll get beat up on my next comment, but I am now convinced that the triple gears were self-balanced as part of a very complex machining operation and control of many associated dimensions to the 4th decimal place in actuality. My view, I'll stick to it, your own opinion may vary.
Finally, there is a bit of irony in balancing a Model T engine for we all know it runs better and smoother...yet if you find the American Treble nomograph set of the era (The biggest spin balancing guys for the longest time...) one would conclude that based on weights and RPM, American Treble recommendation would have been to not consider the burden/cost of spin balancing...just don't spin balance at all, and also probably dismiss most of static (knife edge) balancing! Boy, have things changed in 'thinking'
Balancing your Model T engine is money well spent. You will have a noticeable improvement in smoothness and the engine will last much longer, particularly if aluminum pistons are used to reduce reciprocating weight which is lost power.
Just another thought,is that Ford straightened crankshaft's with sledgehammers so ?? Bud.