I think we should make an effort to determine if there is a statistical connection between 2-piece crankshafts and high engine speeds.
So, in the interest of Model T science (ha), lets gather a single statistical data point... and let's try to do it without arguing any points or presenting any theory's, just stick to a numerical answer and let the numbers speak for themselves.
So, if you have broken a crankshaft, please answer the following question:
How fast did you normally run your T at cruising speeds?
I run about 30-35 mph. I broke mine in 1997 just after shifting into high pulling a slight grade. It was on a MTFCI tour. Broke between 1 and 2 and was a magnaflued diamond crank in a fresh rebuild with a straightened crank case. Destroyed the camsaft.
Hey Mark. We met a couple of years ago. Was wondering if you have an email address so I can PM you...Thnaks
I was traveling about 35 mph when mine broke in my Speedster. The previous day I had enjoyed passing several model A's at maybe 50 or 55 mph (maybe faster). I believe excessive speed was a factor.
I had driven over a 100 miles and was crossing the street 1/2 mile South of my house.When it shifted to high all heck broke loose.
Ok, I'll dive in.
"Hi. My name is Bill and I am a two time member of the Two Piece Crank club."
Engine not rebuilt, but with modern valves. Car does have a modern bicycle speedometer so I do know my speeds. The car seemed most happy cruising at 38 mph. Oh, sometimes I might be around 35 and other times I could be around 40. On some roads I might choose to motor at a mere 25 or 30, but often when cruising at a higher speed and not paying attention to the speed, if I would think to glance at the speedometer the display would usually show 38.
Engine has had some work done be a previous owner; aluminum pistons, modern valves, adjustable lifters, new timing gears, maybe babbitt work-- don't know. The car does not have a speedometer yet so all speeds are "seat of the pants" estimates. I would say that most of the cruising was in 30 to 40 mph range.
My two cents worth, perhaps over valued. Bill
James, my speedster was gps clocked at 105km/h during a re-enactment of the Australian Grand Prix On the road track through Lobethal in the Adelaide hills. The crank broke two days later, taking off at traffic lights. My other two happened at road speeds od around 50km/h.
Speed was not the common denominator with my three two piece cranks. A 3:1 diff ratio was. The roadster has had a 3:1 diff and a Moore gearbox ever since it hit the road in 1986. It had done 10s of thousands of miles, the crank giving out after a long climb and probably some lugging at the end.
The speedster also had 3:1 gears and gave out shortly after the second Grand Prix event a year apart. It had a Ruckstell rear end.
My shooting brake, the only one to break while I was the driver, has a modern Warford and standard rear axle gears. However, the Warford overdrive is almost 3:1 also.
Read into this what you will.
My Duncan and Fraser wide body roadster will have a 12 tooth pinion and the 39 tooth ring gear from the speedster Ruckstell, giving a final drive of 3.25:1. That compromise between standard and 3:1, coupled with a Scat crank, should do the trick.
I hope so anyway!!!!
Allan from down under.
I never drive my '10 over 35 and usually cruise around 30. Crank snapped while starting. Pulled up on the crank, engine started and bang! Original DB crank.
Keep the information coming.... IF you are pressed for time, all I need is the typical MPH you drive on a regular basis when at cruising speed. Thanks !!
Mine liked about 35 mph.
Had a P head.
Was going up a hill about 25 when it broke.
Loudest noise I ever heard coming from an engine.
I normally cruise at around 30 mph. Stock high head, stock pistons, stock exhaust and stock intake with a Kingston L4 carb.
We were pushing ours at 35 to a little more when there was a hell of a bang!!!!!!! Engine had started to vibrate a little and uppon tear down i found a shot ball bearing 4'th main?? Bud in Wheeler,Mi.
Not sure if this counts, as I deep-sixed rod bearings 1 and 2, but got it stopped before I
tanked the crank ..... just rolled through a stop sign on a slight upgrade at about 3 mph
with about a ton of brick loaded on the back. Gearing was low Ruckstell and jumping from
low to high on the planetaries.
With 7:1 rear gears, the old girl got wound out pretty good going ANYWHERE. And I drove
it a LOT. Since the new engine, have not had the time to work out all the bugs, so it has been
5:1 gears, a Lincoln 3-speed, and a balanced engine rebuild are in the works to bring speed
up and cut vibration down.
I sometimes drive too fast with 3:1 and expect to join the 2-piece club eventually, just not this summer I hope
Experience gained from others tells me to avoid the "thum" speed, that's where the harmonic twistings are self reinforced in the crankshaft at somewhere between 1800-2100 rpm or 45-52 mph with std gears, depending if it's an early diamond or a late '24-'27 crank. No balancing or aligning can stop the harmonic twisting in the thin T crank, only a harmonic dampener could, should it be possible to fit one - but it isn't practical with the std style pan and front engine mount.
Here is an interesting thread where Tom Carnegie wrote about his experiences regarding the "thum" speed with different cranks: http://www.mtfca.com/discus/messages/257047/290670.html?1338075615
About fifteen miles from home I started hearing a knock. kept going slower and slower with a vary light throttle until the knock quit. Got home pulled the pan checked bearings nothing wrong so back together for a familiar test run of about two miles. On the way back blew the 22 crank at about 15 MPH. I did a bunch of weight testing on a number of different T cranks. ALL the later style cranks tested stronger then the early diamond web style. Lost the data, but as I remember the crank marked T498 like in my 16 tested poorest of all the cranks. One T498 broke in half while straightening.
Steve Tomaso did a similar survey in 2013 after mine broke. http://www.mtfca.com/discus/messages/331880/405092.html?1386244352
Here is a link to the post that I made. http://www.mtfca.com/discus/messages/331880/404531.html?1385686796
I normally drive my tudor 35 mph in town and 40 mph on the faster streets. I was accelerating at 25 mph when it broke.
I honestly don't think you will find a consistent pattern as to speed and conditions of when/where the crankshaft breaks. The newest crankshaft is going on eighty-eight years now. Who knows what stress previous owners put on them in the past.
Was rolling along about 50 mph on I-84 eastbound for Bonneville speedway in Wendover Utah. I have a Warford and 3.63 to 1 gears. Mildly built hot T motor. Everything balanced but thought I could cheap out and not mag the crank. Broke between 1&2. Running great at about 1800 rpm were I normally run it in overdrive. Suspect crank was cracked long time before it I never caught it.
I normally drive 35mph. Mine broke going about 30 slowing down for a turn.Broke between #2 and center main.
I've broken 2 crankshafts & both were diamond shaped.
The first break was in our '26 Roadster Pickup. It was a recently rebuilt engine (1 year before) and I was pulling a small trailer with snacks in it for a club tour. It started pounding at about 25 mph on a slight upgrade, and then with a bang it broke right on the back edge of the center main. It tore the entire rear main bearing right out of the block.
Our second crank break was on the first day of the big Centennial event in Richmond, IN, and was in our '14 Touring with 4 of us in the car. We were on a very slight upgrade at about 10 - 15mph in high gear and it snapped with a very loud bang. It broke just behind the first rod bearing. We had just bought this car about 18 months earlier and I know someone had worked on the engine just before we bought. It had blue rtv on the engine gaskets all over. I suspect that they tightened the center main to stop a knock, thus causing the crank to twist too much, and it eventually broke. The block was not damaged and we rebuilt it with an EE crankshaft and new babbitt and it's still running great after nearly 7 years.
Our friend Jim Hess who doesn't use a computer, broke one in his '23 Roadster. He usually is very cautions & drives at 25 to 35 miles per hour & mostly by himself. He was driving to a club event by himself and stopped for a pit stop. When he came out & tried to start the car, the crank broke right there, while parked.
This leads me to believe speed can be a factor in braking crankshafts, but not always. Metal fatigue in 80 + year old crankshafts is more likely the culprit.
Just my opinion.
My crankshaft was 96 years old when it broke. I don't know what happened to it in the 95 years 11 months and 29 days prior to the day it broke. I drove the car around the block two or three times prior to it breaking. At that time I had owned the 1912 two days.
I suspect that the crankshafts will break regardless of anything that you can do or say. There is no doubt in my mind that every Model T crank will break sooner or later.
The more stress you place on your crank over its lifetime the sooner it will happen. If you have a new old stock, never used EE crankshaft that passes a Mag particle inspection and an X-Ray then it ought to last a long time no matter what you do to it.
If you don't know how old the crank is or how many cycles times how many pounds of stress it has seen, you don't know enough to make any determination of its likely time to failure.
With all other parts being good, I think you'll break a crankshaft quicker by lugging the engine than you will with speed. Ford ran stock test engines at 3,000+ rpm to show the smoothness of a well balanced powerplant. It was probably bolted down to 500 tons of concrete though.
I cruise 30-35 most of the time, it broke at that speed on a flat hwy with 4 people in it. 1914 with diamond crank, aluminum pistons, Z head about 20,000 miles on rebuild.
I was able to join this infamous club back in '76 on the Glidden Tour in Colorado. And it was purely out of human ignorance. I had one of those loud whistles you screw into a spark plug hole and it made a LOUD noise when going uphill (up mountain?) But it also caused a HUGE undue load on the crank. I threw that damn whistle off the Royal Gorge bridge into the Arkansas River. Wasn't speed - was Human Ignorance
About 62km/h on a slight downhill when mine broke. However, the growth rings around the break indicate that it had been cracked for some time.
Jim, your statistics need another column, how long has it been since the engine was rebuilt or how long has it been since you tightened the main bearings for a low budget engine repair.
Mine broke at about 35mph on a flat road.Just sounded like the fan hitting something metal. Was stock engine use as a daily driver. ripped the 3rd main out of the block.
Jim Golden... The thread has evolved and I'm no longer getting the information I was looking for anyway. I want to know how fast people typically drive their T's. I want to know their "top speed habits". That way, I can try to identify a connection between crank breakage and constant high speeds.... or debunk that theory. The stories are tremendously interesting, and I'm enjoying reading them all... but the speeds that people were running when the crank let go is not the point of this study.
Mine broke at idle sitting in my garage.
Henry never made any serious effort to balance these engines, did he ?
It seems to my more modern perspective on building engines that
getting a really good balance would go a LONG way to keep these engines
from trying to self-destruct themselves.
When I broke the crankshaft in my 1926 touring, I was going about 25-30 mph up a slight grade. The engine was all standard sizes, except the cast iron pistons were .0025 oversize. The crankshaft was marked AA . It broke between the center main bearing and #3 rod. It sure ran smooth and peppy that morning before it broke.
I have broken two cranks in my TT dump truck. One in 1989 and another in 2008. Both of the engines were built before I had the equipment and experience I now have. Both times it was on an uphill grade, no load in the back, about 25 MPH. That would translate to about 35 a model T. The last one in 2008 I was on the way home from the dump having dumped about 1800 lbs of scrap. I think lugging the engine is harder on these cranks than high RPM. As for balance, there is really no way to balance a T crank with out removing material, thus weakening it. You can balance the crank and flywheel assembly together, but it has been our experience that the T crank is so light that it is impossible for it to create vibration problems at an RPM that it can be expected to survive. I have had a bunch of T flywheels with holes drilled in them taken out of original cars, so I think balance must have been checked at the factory.
Eric, I too have seen the holes drilled in original flywheels to balance them, but they could not have been serious! They are drilled BEFORE all those magnets and keepers and screws were fitted. The big slices off some of the crankshaft throws may have helped, if they were done with the flywheel attached.
Allan from down under.
Are the statistics any better for those without magnets?
I rebuilt with an EE crankshaft and removed the magnets (magneto a mess & never used it). Surely the less weight has to be an advantage.
So, will be interesting to see how long it lasts.
The one common thing here is those that drive their T's are those that have broken cranks! It is a recreational hazard. I broke mine,(the first and only) after many miles in many different T's. Broke on flat road at about 35mph in Warford overdrive. As long as I continue to drive I am sure I will break another one even with all the good engine rebuilding knowledge and preparation that we have learned!
I think maybe it could be assumed that on the assembly line, each trans was built with magnets from the same batch and could be expected to weigh the same? The same could be said for the attachment hardware.
I have never had a crank break that I had properly inspected, magnafluxed, and reground.
We broke one coming home from a movie. It broke in the 2nd rod journal and stayed in the rod. We drove it very slowly home 3 miles, low gear slow. We quickly tore it down and found a crank with the same dimensions and reused all the babbitt including that rod that held the crank together.
James, your question makes no sense when trying to correlate it to crankshaft breaks. That's why no one has answered it yet.
It makes plenty of sense Ken...
My theory is that people who are breaking them are pushing their engines a little harder than was originally intended by Henry back in the day.
The Model T was advertised to be able to do 40 MPH. That doesn't mean you should run it that hard on a regular basis. Heck, a modern Camaro will do 140... same applies there.
The roads on which the Model T ran in the years of 1909 - 1927 were mostly dirt. No one back then was running the T as hard as we are for the duration that we are.
So it's simple, if folks who are breaking them (on average) have a habit of driving their T's on the road at speeds of 35mph or above (again, on average), then it would appear that T owners who keep the speeds lower have far less to worry about.
So there's plenty of sense in the question... I just can't everyone to answer it correctly.
James,I think there is a lot of merit in your question as it gets people to think!! I think trying to reason the how and why makes sense rather than installing some modern engine?? Bud in Wheeler,Mi.
Anyone that has been involved with the Montana 500 want to chime in on how many have broke during the race?
Your premise is logical, however, it makes no account for manufacturing flaws or the time the crankshaft spent prior to the current owner's ability to report. Therefore I believe you have great intentions but no possibility of anything useful statistically.
I suspect 50% of Model T crankshafts built of vanadium steel were defective the day they were made. Most of those probably have already failed and are not in any of our engines. Again, this is only unsubstantiated wild assed guessing, but none of us has anything better to offer.
Here's how to avoid a broken crankshaft:
Here is the picture that was supposed to appear:
One problem with the question is that almost no one knows how their car/crank was driven when previous owners drove the car. Who can say how the car was driven during the first 10 years of life?
Also just based on the number of cars that finish the Montana 500 with no problems, speed does not seem to be a big factor in broken cranks. Based on the posted results from the Montana 500 lost rods seem to be a bigger problem for the few that do not finish then broken cranks. I wonder it anyone has kept more detailed records on the exact cause of cars that did not finish.
Your data will be flawed. As Jim points out, most don't know the history of the crank. It could have come out a car that was run to death or sat unused since new. Basing the data on the average speed it's driven on tours/sport now makes no sense because that may not be the speed at which it broke nor is it an indication of past care or abuse.
It's already apparent from past polls that speed is not the governing factor for broken cranks.
I agree with those that say your data will be flawed. Spend your effort putting in a new Scat crank and get on with life.
I spent too many years working with Statisticians ......what number do you want to try and prove your point? Smile!
I have to think that age is the determining factor in why cranks break. These cranks are 80 to 100 years old and have far exceeded their originally intended useful life. The only solution is a new crank and the Scat cranks fill that bill. If I was doing a engine over today I wouldn't think of using an original crank, even an EE crank. I only wish they were available when I broke my last crank several years ago and did not have that option.
I'm with Ken. The problem with studies, is that they look at data to draw a conclusion, (which is usually preordained). A proper experiment has controls and variables so a logical conclusion can be made.
A coat hanger will break from continuous flexing. A T crank breaks in much the same way. There are many things that can cause a crank to flex, such as:
Mis-alignment - either of the pan (4th main) or the main line of the motor itself. People will take shims out of the center main only, for example, which causes the crank to be bowed. With every revolution the crank bends back and forth the amount of the mis-alignment.
Imbalance vibration - Imbalance is well understood by most I think.
Torsional stress - The bending of the crank from the power strokes. Simple torsional stress is maximized at the period of highest engine torque. Around 35 mph for most T's. Torsional vibration is caused from the crankshaft wrapping up and unwrapping from the power strokes. There are speeds that the harmonics of the vibration can amplify the stress on the crank. The so called "thrum".
Of these causes, my gut reaction is that pan misalignment is the major exacerbation of crank breakage.
Even today engines still break crankshafts and it could be any make even international and JD.When our 14 was rebuilt i used the later EE and had the crankshaft/flywheel assembly ballanced.I do not drive our T over 30/35 anymore so how long will it last?? A new larger journel ballanced crank makes sense but it's expensive! Still i think almost anything is better than using a modern engine!! Bud.
This is hilarious.
I am employed at NASA, Goddard Space Flight Center as Optical Engineer, whose primary expertise is consultant and technical problem solver for space flight hardware and instruments.
Yet according to this forum, I don't know the first thing about what I'm doing when trying to build a failure analysis.... which ALWAYS begins with one data point - and expands from there.
This was indeed a waste of time. Instead of providing the single data point, so we could move on to the next column (as alluded to by James Golden) the thread devolved into chaos and inaccurate opinion of the structure of my analysis, proving only that we couldn't even answer one simple question... How fast do you normally drive your T?
Two digits is all it took to answer the question... Two simple key strokes. Then we could have moved on to the deeper details and maybe learned something as the matrix unfolded.
What a waste of time. I certainly won't do this again.
Well my 1926 crank did not break on a recently rebuilt engine, but I took out the Second Main Bearing and got a loud knocking noise like it had broken.
My wife was following me modern with the 4 way flasher going for safety.
The knock started at about 25 miles and lasted the last mile of that trip.
The car was trailered home.
I told my wife that new engine had a lot more power, but I could not tell the speed for sure.
She said most of the time I was only going 55 MPH but I got up to 60 and 65 MPH on some of the down hill stretches.
I was actually following another T owner with a 1923 Touring that was driven coast to coast with no problems and the speed was no problem for him.
That was 30 years ago when I was younger and dumber.
That lead car driver may have been a little crazier than me.
James, it's a bit like trying to herd cats - we T owners are also independent minded and have our own opinions on most things, but I still don't think this and other crank shaft break threads are wasted - lots of experience and ideas collected here.
Wish you would continue, I enjoyed reading the comments and the large number of replies to your original question:
...."So, if you have broken a crankshaft, please answer the following question:
How fast did you normally run your T at cruising speeds?"
You received many comments on the speed those were driving when the crank broke...
I didn't reply to your thread as for my driving speed, as I haven't broken a crank (yet )...but others did who have experienced busted crankshafts.
James, you have asked a question that cannot be answered easily, if at all.
I normally drive my T just under the speed limit. I often drive it from every speed from above zero to 72 mph. There is no two digit number that I can say accurately describes how fast I "normally" drive my T. Anything I (or probably any one else) said would be a guess and likely meaningless.
I do however appreciate your trying to discover something. Sorry I couldn't help.
Its because those that are hearing you are hearing the premise that driving the car fast contributes to crankshaft failure.
I am thinking they don't want to contribute to the premise.
I think your question can easily be answered by someone with no skin in the game.
For instance..."who thinks its hotter this year than last year?" or "Who thinks the earth is warming?" Essentially the same question, but..
Gather all the data points you want and then do like the Government does,take the lowest bid.
Here is a photo of crankshafts supplied to an engine builder from customers. They are all cracked.
Get 5 crankshafts and check them and most will already be cracked in an earlier life. You will be lucky to get one which is not cracked.
So if an original crank is used it most probably will have developed a crack already so any additional running may lead to eventual failure.
How many motors have been put back into commission with no check as too its condition?
For some reason, James' question reminds me of something that I believe Royce Peterson's Dad said, which was words to the effect that if you drove your Model T at a speed of 28 mph, it would last a lifetime.
I take that to mean that with a lifetime of Model T experience, Royce Peterson, Sr. believed as I do that Henry Ford and his engineers expected the Model T to be driven mostly at speeds of 25 or 30 mph max on what were mostly gravel roads at the time. And he probably also believed that most engineering of the Model T produced parts (including crankshaft) that were expected to drive at such speeds,....probably NOT Montana 500 speeds.
Forgot to answer the question,....I try not to drive over 35 mph, and frankly, I really enjoy just puttering along at about 25 mph, if I can find roads that allow it. Not easy nowadays though.....
... and Harold nails it...
James,I think that is how most of us learn!When a question is asked many respond and we all get to pick everyones thoughts!! Bud in Wheeler,Mi.
Actually, documentation would indicate Ford expected the cars to be driven at 20mph. (As in setting the generator.) And few roads had any topping. Most were dirt except in large cities.
James, as an engineer I suppose you've learned more about metal fatigue than what was known by 'ol Henry and the others who designed the crank shaft at Piquette avenue in 1907.
The type of failure we can expect in our crank shafts is called high cycle fatigue, and the factors that affect when cracks may have grown until they break are among others: the number of load cycles, the geometry of the part (radii at the end of bearing surfaces), the surface finish and the environment where it rotates.
The speed of the cyclic loadings isn't among the factors that affect how many load cycles a part can stand.
Thus, Since most T's has the same rear axle gearing and they're driven in high most of the time, both a fast and a slow driver would get about the same amount of miles before it breaks all things equal (which they're not in the real world, of course)
The cyclic loading on a crank shaft can be in two planes, both bending strain and twisting from the power impulses, but there's only one of them we can do anything about - the bending strain, by building the engine correctly and by connecting the top of the hogs head to the block like in the improved engines. The twisting loads can only be minimized by avoiding certain "thum" speeds when the impulses are magnified by resonance, 1800 to 2000 rpm depending on if it's an early or late style crank.
The late '24-'27 cranks weren't just redesigned in the throws - the radii at the rod bearings were also made larger to be the same as at the main bearings, so a late crank is preferred.
One factor that actually can make a difference that hasn't been discussed much is the surface finish of the crank at the throws between the bearings.. It would be a major job to grind a crank smooth enough to make a difference, though. Shot peening and laser peening is discussed in the wiki article, it can create a compression in the surface that makes it a little more resistant against developing cracks. But could it be practical to use on a good crank to make it live longer?
(Message edited by Roger K on June 11, 2015)
Well stated but you failed to mention one important fact. Model T crankshafts made prior to about 1925 were made from vanadium steel alloy. Later crankshafts (E-E and beyond) were made from a much more durable carbon steel.
When trying to find a good crankshaft to replace the broken one in my '12 we bought and paid for NDT on 5 crankshafts. (On top of the price of the crankshafts and shipping ) All five of them passed the "ring" test. Four of them failed fluorescent mag particle inspection. All were E-E cranks.
The new "SCAT" cranks are made from a high nodular "crankshaft grade" cast iron. They have full counterweights so the crankshaft can be dynamically balanced to reduce vibration which will lead to failure. It will save you money in the long run.
I find it interesting that so many of us do not have a speedometer, so we do not know how fast we are going. I drive whatever I feel comfortable on that road, at that time, on that day. One day I might go about 25 and the next 45. Hard to determine a set average speed.
When I bought my SCAT crank from Tom Lieb, I was told the cranks are machined from a forged billet of 4340 steel. Have they changed to cast iron?
By golly you are right, the Model T crank that I bought and Ross Lilleker installed for me is forged 4340 steel. I build Ford FE engines and the SCAT cranks for those are cast. My mistake!