Hunt for a crank shaft

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Model T Ford Forum: Forum 2013: Hunt for a crank shaft
Top of pagePrevious messageNext messageBottom of page Link to this message  By Colin Mavins on Saturday, September 07, 2013 - 06:50 pm:

I have rounded up 5 cranks so far. one of our old T guys said if the crank rings when you tap it with a hammer it should be good so of the 5 I have 3 that ring. they will be off to be checked. 2 of the cranks are straight lobs but not EE The only stamp on them is ford D would this be a1925 crank


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ted Dumas on Saturday, September 07, 2013 - 08:48 pm:

If they go thud, they are bad. If they ring, then they need to be magma fluxes. You've done good.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Cameron Whitaker on Saturday, September 07, 2013 - 11:26 pm:

Good job, Colin! As I always say, the ring test is used to fail a crank, not to pass one. If it rings, then you send it off to get magnafluxed. If it doesn't ring, then you don't bother wasting the time and money because it is bad to begin with.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce in Dallas TX on Sunday, September 08, 2013 - 09:16 am:

I had five of them that ring real nice fail magnuflux check due to cracks.

By the time you purchase several cranks and pay to have them tested you will find that you wish you had purchased a new Scat crank. A new crank will save you time and money.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Jelf, Parkerfield KS on Sunday, September 08, 2013 - 09:37 am:

So what does it cost to have a crank magnafluxed? I have a few that I got cheap. Might as well keep them if they're OK.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Walker, NW AR on Sunday, September 08, 2013 - 10:11 am:

Our old-time family engine shop here in Fayetteville charges $20 to flux a crank. I've heard of other shops charging up to $40. It'll prob'ly pay to shop around.


Top of pagePrevious messageNext messageBottom of page Link to this message  By joe bell on Sunday, September 08, 2013 - 10:12 am:

Colvin, never trust the ring test, have it magged as Royce said they can ring like a bell and still have cracks. I had one that made a thud but it pasted the mag??


Top of pagePrevious messageNext messageBottom of page Link to this message  By Craig Sutton on Sunday, September 08, 2013 - 10:25 am:

I've been through this nightmare twice. Somehow every crank I find at Hershey is cracked, but the engine builders magically find them easily (and then charge an arm and a leg).

The reason I didn't want a new crank was that I didn't want the counterbalancing. I was afraid it would change the sound of the engine and other characteristics too much. Otherwise it would definitely be worth just buying new and forgetting all the bad ones out there.

Craig


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce in Dallas TX on Sunday, September 08, 2013 - 10:46 am:

Craig,

I have Dunn counterweights on one of my cars. My '15 is balanced by drilling the flywheel. In both cases the main difference is a lack of vibration. Balancing doesn't change the sound of the car at all. It just makes the engine last longer. Bearings will wear less. The crank shaft won't break so quickly, because balancing reduces crankshaft flex and harmonic vibration.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Les Schubert on Sunday, September 08, 2013 - 10:59 am:

Craig
That is a interesting concept how the counterbalancing would change the sound and characteristics of the T engine. I would expect fewer rattles and squeaks from the car. Perhaps slightly better low end torque (not sure I would want to use it though). Considerably longer bearing life (especially the main bearings).
Otherwise I suppose it would be the same. Actually I have one T with a counterbalanced crank and one without. They both drive about the same.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Les Schubert on Sunday, September 08, 2013 - 11:06 am:

Like Royce's one of my T's, rebuilt in 1978, has Dunn counterweights. I like them well enough but they were a LOT of work to put on right. They kept wanting to distort the crank, and took a lot of careful fitting to solve. And then had it dynamically balanced. Both my cars have dynamically balanced flywheels.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Colin Mavins on Sunday, September 08, 2013 - 11:47 am:

Gentle man so far I have 3 cranks to send to the machine shop he's a friend so cost is not a factor. The first crank lasted 101 years and that was a db crank so a 25-27 crank should work. My concern with a counter balanced crank is the engine relies on splash and the counter balance shaft is putting walls which will stop the splash. Also I don't put as many miles on as you guys do 500 in a year is about it, so of you guys are doing alot more. Up until now we had never nerd of a crank problem I'm the first here to brake one. I guess winter is saving Model T's Here.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce in Dallas TX on Sunday, September 08, 2013 - 12:41 pm:

The counterweights simply sling oil the same way as the crank without. It's a non issue - there's a cloud of oil droplets in there.

My dad built the engine with Dunn counterweights some time in the late 1960's - early 197o's. It's been on tour a lot both in his hands and in mine. Some day that crank will break too.


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