Busted Crank

Topics Last Day Last Week Tree View    Getting Started Formatting Troubleshooting Program Credits    New Messages Keyword Search Contact Moderators Edit Profile Administration
Model T Ford Forum: Forum 2009: Busted Crank
Top of pagePrevious messageNext messageBottom of page Link to this message  By Chris Cansdale on Tuesday, April 21, 2009 - 05:15 pm:

Hey Guys...

Does anyone have any photo's of a busted crank and associated damage? Preferably as it was discovered in the engine during the rebuild?

I was unfortunate enough to have a knock rapidly turn to a bang, only 200 yards into a weekend rally. I don't have the time or cash to fix it for a while and am too scared to drop the inspection plate and take a look.

I'm just curious to see what I'm likely to find..

Cheers,
Chris


Top of pagePrevious messageNext messageBottom of page Link to this message  By jack daron-Indy. on Tuesday, April 21, 2009 - 06:27 pm:

Unfortunatly,there's only one way to find out...


Top of pagePrevious messageNext messageBottom of page Link to this message  By Keith Gumbinger, Kenosha, WI on Tuesday, April 21, 2009 - 06:37 pm:

Chris - You are likely to find one of two results.

If you're lucky, just the crankshaft broke and every thing else is ok.

The second possibility is when the block is destroyed in the process and not just the crankshaft. I've seen holes through the side of the block and also the entire rear main bearing broken out of the block. I'm sure there are other ways the block is destroyed also.

This is why some of us have spare engines ready to be installed when something like this happens, so that out Model T is not out of service for to long.

Fordially, Keith Gumbinger


Top of pagePrevious messageNext messageBottom of page Link to this message  By Noel Denis Chicoine, MD on Tuesday, April 21, 2009 - 07:06 pm:

Keith, do many people carry spare engines/trannys to week long events? How hard is it to swap one out in an evening to get back on the road the next day?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ted Dumas on Tuesday, April 21, 2009 - 07:25 pm:

Here are some pictures of my engine which came apart at 40 mph on the Texas T Party a few years back. I hope your damage isn't so extensive. Just lucky enough to have a fresh 26 engine on hand. Now my 24 touring has a 26 engine with the large drum transmission to go with my rebuilt large drum Ruckstell.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jim Patrick - (2) '26's - Bartow, FL on Tuesday, April 21, 2009 - 09:51 pm:

Wow! I hope to God, I never have need to take pictures like these of my engine. Jim


Top of pagePrevious messageNext messageBottom of page Link to this message  By Warren F Rollins on Tuesday, April 21, 2009 - 10:46 pm:

Ted, Did it lock the wheels or just make enough noise to let you know you had to bring it to a stop? Did clutch take it out of gear and did the transmission brakes bring it to a safe stop? I never broke one but always worry it happening at high speed.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Keith Gumbinger, Kenosha, WI on Tuesday, April 21, 2009 - 11:19 pm:

Noel - I've seen a few people that carry an extra engine to week long tours. I haven't, but wish I did at the Centennial last summer when I broke the crank on Monday morning - didn't even make it to lunch. That one didn't give any advance warning, it just went. Fortunately it didn't do any other damage. I am seriously considering carrying an extra engine along.

Difficulty in swapping one out on a tour depends. It could have been done easily at the Centennial in Gasoline Alley with a good place to do it and an engine lift available. Some tours have a good place for repairs and some don't, it varies.

Fordially, Keith Gumbinger


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ted Dumas on Tuesday, April 21, 2009 - 11:51 pm:

It sounded like you ran into a rat's nest full of pipe wrenches. I pulled off the road and the car came to a stop on its own. I don't rememember any screeching of tires on the road.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jem Bowkett on Wednesday, April 22, 2009 - 03:17 am:

If it didn't lock up, then you probably haven't torn up the block. Could get away with an ordinary overhaul with a replacement crankshaft.

When mine broke, it tore out the rear main and locked immediately. Flywheel slammed into the mag coil, smashed magnets, torn-up coil, 2 bent conrods, 2 smashed pistons, bent camshaft.

As it's an open-valve 09 I've spent several years at great expense sorting it out. Block metal-stitched, found and rebuilt an early flywheel and coil assy, new white-metal, sleeved block etc. Should be firing it up in a month or so. The metal-stitching man is a bit nervous as to how well it will work - if it fails again, then it's a museum display piece and I'll put the spare '25 engine back in for driving.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Roger Karlsson on Wednesday, April 22, 2009 - 06:52 am:

Jem, I wish you luck. The rear main part of the block was completely loose?

I would try to create some type of brackets from the rest of the block to the previously loose part & bolt in place, if at all possible to fit in the limited room there, just to relieve some of the strain on the metal stitch.
(But, as I haven't seen the repair, maybe my worry is unnecessary)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jem Bowkett on Wednesday, April 22, 2009 - 09:40 am:

I didn't actually pull it off, I thought it best to leave alone for the repairer to work on it, but the section where the main brg bolts go through was loose. I'll take some photos - the block is bare at the moment.

Can't imagine what sort of bracket you could devise which would provide any worthwhile support - I know we had a least 1 club member who had an early block successfully stitched, so I am hoping the effort will be worthwhile. But there'll be no high speed touring :^)


Top of pagePrevious messageNext messageBottom of page Link to this message  By George on Wednesday, April 22, 2009 - 04:23 pm:

Ted Dumas,

I know that I am one of the obsessive compulsive types on this two piece crank club thing...I realize they do break....I realize that every outting with a T is a chance for 'something', and I do realize that somehow, someway they are always fixable.

I have a question for you, may sound off the wall, but someday my questions will all lead some place....

How easy was your car to start on magneto before the break? If you used magneto, please offer comments on the nuances you encountered. Your picture shows me that your crank was shifting forward and backward and failed in fatique, and that the break was NOT a torsional break. My guess is that if you looked at the break with the crank out, the surface would have appeared like an oyster shell. Meaning, that one took a long time coming and finally went 'tink'.

I'm working on a possible theory that too much endplay in the mains is probably the largest contributor to straight breaks...ok , so that should be and is obvious to all...but...I'm trying to get this all back to magneto performance as I do believe the two are going to be VERY tightly associated. Any help on your own experience would be much be appreciated


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ted Dumas on Wednesday, April 22, 2009 - 04:43 pm:

The magneto was in excellent working order. I had overhauled the engine about 5 years before. Royce Peterson,the father, had built up the babbit thrust for me. I had the crank out and the rod journals reground. I refitted the mains and scraped them in. The engine was bored 0.030 oversize and had aluminum pistons. I know I did not magnaflux the crank or if the crankshaft grinder did. I don't remember if I rang it out. I would guess the engine had about 8000 miles since the overhaul.

I have not torn the engine down to date. I do have a crankshaft I picked up out of a field and it is cracked in the very same place.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kenneth W DeLong on Wednesday, April 22, 2009 - 05:34 pm:

Chris,Im interested to know if you have/had a ball bearing fourth main or stock?? Mine took a total rebuild and pan straghtning.Seems nice now but it did seem great before it broke.Bud.


Top of pagePrevious messageNext messageBottom of page Link to this message  By George on Wednesday, April 22, 2009 - 08:25 pm:

Thanks for the response Ted....that sorta blows my theory all to smitherines :-)But then again may open an entirely new path in the attempt to be able to 'predict'

With a good seat thrust bearing as verified by excellent magneto performance under aparently all conditions...and a 'break' due to forward/back 'stretch' fatigue it starts to eliminate a bunch of things for your kind of break which seems to be the predominate kind reported.

When you eventually do take it apart...I'd be curious to hear more on what you find...both generally such as a nice picture of the crack surface showing reflection and specifically how 'wallowed' if at all the center cap babbit is concentricly. If it is 'true' then these sort of breaks take on an entirely 'new' set of thoughts.........

BTW for all....there was a guy on here a while ago who said he had a new process ductile iron in the vicinity of ~1000 buck crank ready for production...did I miss the follow ups on that? Was there any? Haven't seen anything on it lately.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Al Thomas on Thursday, April 23, 2009 - 02:15 am:

George, I believe this what your are talking about:


quote:

By Bill Dubats on Saturday, February 28, 2009 - 07:02 pm:

After following the MTFCA and MTFCI Forum threads on T crankshafts, breakage, counter balancing etc., reading a few thousand postings, collecting aftermarket cranks (broken and not), I decided to improve on Ford's crankshaft. It meant funding a full scale design, development and manufacturing program for an aftermarket T crank that is: counterbalanced, stock bearing dimensions, stronger and stiffer than stock T cranks, fits into stock engines with no clearance issues, dynamically balanced and Made in USA. While looking into cast steel, steel forgings, machined from billet and casting processes, I ran into a process called Austempered Ductile Iron (ADI). This lenghty heat treating process produces incredibly tough, strong but not brittle parts for high stress components for firms like Catepiller, John Deere, Columbia Gear, and many others. I was searching for a reasonable priced manufacturing approach, as forgings and billet are cost prohibitive (in the USA) and steel castings are too unpredictable.
Our initial lot of 9 prototype cranks yielded 5 finished parts, 3 of which are running in Ts now. After few design revisions to shake out producibility and function issues, we heat treated 14 new castings, which are now in machining, grinding and precision dynamic balancing.
While this crank looks similar to the BuMac, it is vastly different in many ways. The ductile iron contains optimum abounts of nickel, copper and molybdenum to obtain ideal through hardness and tempering for the best strength and toughness. It fits perfectly with no changes to block or horse shoes, and most importantly, it runs very smoothly. Not good to knock the competition, but the BuMac crank has issues with metalurgy, dimensional consistency, heat treatment, dynamic balance (and US Customs). I have a 2 page article "Why Model T Ford Crankshafts Break", which I will e-mail to all interested upload.



To read the entire thread click here


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jem Bowkett on Thursday, April 23, 2009 - 09:26 am:

My break was entirely my fault - 28 yrs ago, not knowing what I know now, I had the motor apart after it knocked out No1 rod (oil-line blocked with rubbish Scandinavia linings back then).

The pistons were .0025 oversize (yes, that's 2 1/2 thou - used to sell them to put in a well-worn std bore) which should have told me it had done some work. I didn't realise that meant the centre main would be worn more than the others so allowing the crank to flex in the centre (as depicted in Fahnestock illustration that's been often posted here).

Eventually it gave way just behind the centre main, so No3 piston went right up into the head, top ring popped out, tearing top of the piston as it tried to come back down, flywheel slammed into the mag coil, several magnets broken, mag coil buckled & bobbins torn up, several cracks in block.

Here's the block stitching:

The 2 sides of the centre web





Outside of the rear main


Inside of the rear main


Side of block, below camshaft


Outside view of camshaft side of block




And here's some of the damage:

the crank break and bits of No3 piston


buckled mag coil - early pressed-steel style


Posting is currently disabled in this topic. Contact your discussion moderator for more information.
Topics Last Day Last Week Tree View    Getting Started Formatting Troubleshooting Program Credits    New Messages Keyword Search Contact Moderators Edit Profile Administration