Re-builder friend got took this crankshaft out of an engine after the owner described the incident.
Seems the owner was motoring along normally, and T just stopped moving. Had to trailer it home. After questions, he pulled over the hand crank and engine turned, but pulling the inspection cover showed the flywheel not turning.
He had to a done something to cause that, it is a break that happens from slamming brakes, most cracks you see have been cracking for a while and it shows from the discolor through the crack, this one shows shiny all the way through so some thin cause it to stop right now! to break it.
It's a flexure break over lots of cycles, and it finally had a torsion hiccup at about the 50% cleaved point and the final 48 or so percentage gave up the ghost catastrophically
As Joe points out, I'd look at the 4th trying to nosedrive with each braking!
This could have been as simple as a radius scratch and a trying to dip 4th
Joe Bell should know. But I may have to disagree on this occasion. I think I can see the crack propagating out from the bottom of the center (machining center). I would suspect a crooked pan.
One should note, that even a pan that has been straightened can be assembled such that there will be side pressure on the back of the transmission. That is why the assembly needs to be checked carefully while the engine is put together. Nose down. Even if the pan has been properly straightened.
The radius on both ends of the journal look okay. Some friends of mine years ago had a similar experience on an Endurance Run. In their case, the tear-down revealed that the rebuilt engine in the car they had bought had sharp corners on all the journals. The break had propagated from the outside.
I type slow. George M beat me to the "post" button.
"File locking error". Probably someone else trying to beat me again?
In a way Wayne, I'd half agree with you. I tend to comment only on exactly what I see Keep posting!
I see chatter radial cracks around the periphery which is the first sign of classic flexure failure forming.
I say half agree as on my first look, my gut said torsional failure that led to final catestropic failure was center out! To really know I'd have to see it up close and personal, and that sort of thing I generally don't do anymore
Was there any mention of what type of 4'th main was used and the condition? Bud.
Yes, photos are not the best way to assess this kind of damage. Careful lighting to enhance the different shades of gray can help. But even those shades of gray can change after just a few days after the final break. Live and up close, three dimensional, and magnified shows a lot more.
Always glad to share forum space with you. Actually, all of you. Dan T, Joe B, and George M are all people who's opinions I look forward to and respect very highly.
And then Kenneth W DL slips in! Must be my day to be slow. Excellent question.
There is a way to minimize (perhaps eliminate) the risks mentioned. Dan Hatch is licensed to produce and sell my "floating transmission shaft ". It is not a substitute for a straight pan and good alignment, but it eliminates all bending loads being transferred by 4th main deflection
To my eyes the radiuses look quite small
Bent pans/out of alignment 4th mains make really good fully reversed bending demonstration machines. Then throw in some torsion, and . . . .
I don't like the looks of the radius. The radius on the other end of that journal does not appear to be a clean ground finish. Also, notice the deep pitting on the flange, which indicates to me a salvaged crank. I wonder how much undersized the journals were ground. I agree with misaligned fourth main.
Please tell us something about the car. What year is it, what body style, and if you have any modifications such as high compression or other speed equipment. What kind of 4th main and any other differences in your car.
Look at the holes in the flange,or is it a opctial dissalusion?? Bud.
Its always sad to see another crank bite the dust. But on a positive note, at least it broke in a spot that didn't destroy the block when it let go. We should all be so lucky, if and when our time comes.
Could you please explain your "Floating transmission shaft".
Floating Trans shaft
New run in the making now. Pm me for more info. Thanks, Dan
Those look very interesting. Can you explain how long these floating shafts have been used, and provide testimony's?? Meaning, how many are out there and can anyone attest to how many miles they have been successfully used? Lastly, what is the cost?
Dan, my Pm to you won't work, Could you please Pm me Price, Availability, and shipping to Sydney, Australia. Thanks....Regards Neil Martin.
They have been in service for about 10 years. I made a initial run of 10 of them. I'm not sure how many Dan has done. Being in Canada it was awkward selling to the "big market (US), so I made a arrangement with Dan. I believe some of them have close to 10,000 miles and I know one was inspected for over reasons with no evidence of wear. I still make them for the Canadian market and get them gas nitrided (about 52 Rc), for wear resistance from 4140 steel
When I launched the product, one "wise sage " said , "In 90 years we will know if it is any good "!!!
I'm not looking for vindication but your flex disk apparently proves what I have said before and the peanut gallery shouts 'boo'.
Namely, that yellow metal done right will self-lap polish to the conditions present and then stop wearing all by itself provided there is at least a reasonable amount of hardness in the mating part and a decent flush of oil.
You don't find that in todays textbooks...lol...but it was a very common design practice 100 years ago! (not only with this new thing called alloy steel but also with cast iron against 'yellow metal'. Sometimes new technology just gets in its own way...haha.
Good job on that. Following on your own anecdote joke...heck, you are over 10% there in 'ultimate proof', and already 2/3 of the way through the Model T model production life!
It's hard to say if Les' floating shafts work. All I can say is that I've had one in my 23 for about 8 years and haven't broken a crank "yet".
I'm here to say that Noel does not baby his '23 in any way, and it really GOES. We clocked him going 49 a couple of years ago when I gave up and he was still going!!!!
So far, so good for the floating shafts.
Holes in flange appear to be wallowed out. Were the dowel pins and fasteners a tight fit?
I think not.
I've got to admit it. That's probably an absolute best-case scenario when joining the two-piece crank club!