Identification of crankshaft

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Model T Ford Forum: Forum 2015: Identification of crankshaft
Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave Wightman on Friday, October 30, 2015 - 07:33 pm:

I've developed a knock in my 1912 and I'm trying to learn some (a lot) before I tear the motor down. I opened up the inspection cover and the first thing noticed is there are no castle nuts/cotters on the rods. Second notice is the crank has the ford script on one throw and a "A" at the front throw. The motor is the correct one for 1912. I may be able to remove shims but if this is one of the crappy cranks maybe now is the time to upgrade..?? Any thoughts?? Thanks Dave


Top of pagePrevious messageNext messageBottom of page Link to this message  By Terry Woods, Richmond, Texas on Friday, October 30, 2015 - 07:42 pm:

If it doesn't have EE cast into the crank, it isn't one of the stronger 26-27 cranks. Of course if you have an unlimited budget, a Scat is the way to go.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Roger Karlsson, southern Sweden on Friday, October 30, 2015 - 07:52 pm:

You're lucky it hasn't got an original DB crank anymore - they're among the most crack prone. If it's a late 1924-26 crank with even width of the throws you're better off - but even if it's a '19-'24 diamond throw crank I don't think you should worry - just take up the rod bearings and run it until something else calls for a more thorough disassembly and evaluation.

The rod nuts are likely a modern self looking style. You may use these or regular nuts when adjusting the rods and then use new self looking nuts at final assembly of the rods.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Val Soupios on Friday, October 30, 2015 - 08:01 pm:

I snapped the DB crank in my '10 and replaced it with an EE but I would have gone with a Scat crank if they were being made then. I was lucky that there was no damage when the crank let go but when you consider how much it would cost to replace an early block it just makes sense to get the best insurance you can!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Roger Karlsson, southern Sweden on Friday, October 30, 2015 - 08:03 pm:

If the rods knocks in a restored engine that maybe hasn't been run a lot of miles, then there's also a risk there are other problems causing the seemingly premature knock. Check the oil pipe - the end can be accessed through the bottom inspection lid with an air gun for blowing it clean.
Another problem can be bent rods - but it's hard to see - maybe by looking under while someone cranks the engine?
If a rod goes forwards and back on its crank journal while working up and down, then it might be bent?
Another thing to check is the roundness of the crank journals. Should be less than a thousand out of round - otherwise It's time for a regrind.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave Wightman on Saturday, October 31, 2015 - 02:24 pm:

Thanks all for the information.. Any/all will help. The motor is coming out next week for my first time....Dave


Top of pagePrevious messageNext messageBottom of page Link to this message  By Roger Karlsson, southern Sweden on Saturday, October 31, 2015 - 03:19 pm:

If it's only a loose rod, you can fix it through the inspection pan under the rods, no need to pull the engine :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave Wightman on Saturday, October 31, 2015 - 04:12 pm:

Rodger.. I did open the inspection pan and the rods feel good and tight. My guess is the center main but won't know for sure until I can get to all the main bearings.. Thanks


Top of pagePrevious messageNext messageBottom of page Link to this message  By Michael Garrison - Rice Minnesota on Saturday, October 31, 2015 - 04:27 pm:

Dave, knocks from the mains seem to show up under different driving conditions than knocks on the piston rods. For me too describe the difference would end with some real confusion but I was able to simply tighten a rod bearing this last summer based on the description provided to me by a fellow moder t'er. I also know the use of plastigage was a real benefit in correcting the problem. Of course it was a benefit to be working on an engine with a 4 dip pan.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Michael Garrison - Rice Minnesota on Saturday, October 31, 2015 - 04:30 pm:

Okay, it really wasn't a moder T. It was a model t.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Paul Vitko on Saturday, October 31, 2015 - 04:53 pm:

For what its worth my T crank blew after starting with a noticeable knock that became quickly louder with a decreasing throttle in about ten miles. I stopped at home, dropped the inspection plate found nothing wrong and decided to try one more five mile drive-----mistake!---- the noise got louder until the crank broke in under two miles. The safe way is tear it down especially with an early T with expensive hard to find parts.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave Wightman on Saturday, October 31, 2015 - 05:52 pm:

Plan is plastic gauge All bearings and check end play and if we don't find it there will probably scratch my head with one hand and butt with the other....


Top of pagePrevious messageNext messageBottom of page Link to this message  By Roger Karlsson, southern Sweden on Saturday, October 31, 2015 - 05:59 pm:

There are less serious knocks that can drive you nuts - like in the crank pulley..


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave Wightman on Saturday, October 31, 2015 - 06:41 pm:

THAT's what I hoped it was as the pulley was loose, installed a new one...


Top of pagePrevious messageNext messageBottom of page Link to this message  By Les VonNordheim on Saturday, October 31, 2015 - 07:21 pm:

A close friend here in Fallbrook with a 12 touring broke the crank and it took out the rear web in the block. This also happened with my 13....same damage. Early blocks are very expensive and not easy to find....suggest installing a new Scatt crank shaft. NONE of the original model T cranks are immune from breaking.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Erik Barrett in Auburn Ca. on Wednesday, November 04, 2015 - 06:17 pm:

A Scat crank will cost a lot less than a replacement 1912 block. At the very least use a late crank, EE if you can find one, and have it magnafluxed. You are wise to remove the engine and make sure it won't break and destroy rare parts. Do it right and it will outlast most T guys.


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