crank shaft/piston arm question

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wmscottsutherland
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crank shaft/piston arm question

Post by wmscottsutherland » Sun May 28, 2023 8:34 pm

Checking a 17 engine and I found wear in the piston arm babbitts at the edges. Enough that I think I should replace them. The three pictures are the crank under those arms. You will see some wear.

My question is: I want to buy piston arms that are already babbited from a shop and install those and new pistons/rings and go on my merry way.

because of the crank in the pictures should I take the whole thing apart and get the crank machined and then all new babbitts for the block and piston arm? Trying to save some money, but would it be an issue down the road?

Thanks
Scott
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Re: crank shaft/piston arm question

Post by Scott_Conger » Sun May 28, 2023 9:25 pm

I see a rusty, dirty engine which has been left open for some time. There are a million bits of advice to offer, but no good place to start, sitting at a computer, so I won't offer any other than this:

1. Team up with a competent Model T mechanic or knowledgeable hobbyist (there is at least 1 other in Cheyenne) and discuss exactly WHAT you want to accomplish. There are not many differences between saving an as-is engine and all but destroying it.

2. Purchase a Model T manual (T-1) at any of the hobby's suppliers and acquaint yourself with procedures and correct nomenclature so that you and a future mechanic will be on the same page.

Good Luck.
Scott Conger

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Re: crank shaft/piston arm question

Post by Wayne Sheldon » Mon May 29, 2023 3:41 am

That is a tough one. Several marginal characteristics. The crank journal is a bit rough, and appears "acid etched". However, I have seen worse clean up really nice!
The important thing is how round is the journal, and is it straight (not tapered).
Model T crankshafts are too small to begin with. Age hasn't helped them. And turning the journals smaller makes them weaker fast!

Myself? If the crankshaft is reasonably decent? I prefer to clean up the journals with good emery tape (fairly fine to very fine). Doing so requires constant measuring and monitoring to keep it very round and very straight! But it removes the least material and extends the lifetime of a part getting difficult to find good ones. Then I hand fit the Babbitt bearings using bearing scrapers and bluing compound.

The crankshaft should be checked for cracks. I have "issues" with most people magnafluxing crankshafts as they tend to trash too many based upon faulty readings (electromagnetic fields are tricky on odd shapes like crankshafts). It takes someone that really knows how to read them to get it right.

It is also very important to make certain the connection rod is straight and runs up the center of the bore properly.

All things considered, you really should think about taking the engine apart and doing it properly.
Measuring the journals and cleaning them up with emery tape, then carefully fitting the new or replacement connecting rods to them can be done "in the car". Doing so could give you many years and many miles of enjoyment! Or not?


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Re: crank shaft/piston arm question

Post by TXGOAT2 » Mon May 29, 2023 8:11 am

That crankpin looks "flat" to me. The crankshaft appears to be heavily rusted, or else to have been welded on.

I would want to check everything about that engine using a micrometer. The crankshaft, if it isn't worn or abused beyond use, ought to be magnafluxed.

Your engine may be repairable on a budget, but if you neglect major issues to save money, you can expect to waste any time and money you do spend, and perhaps put a repairable engine beyond any practical repair.

The rest of the car's mechanical parts need to be checked over, too.

Mechanical things have certain requirements that must be met for them to perform dependabley.

If those requirements are neglected, for any reason, trouble is sure to follow.

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Re: crank shaft/piston arm question

Post by AndyClary » Mon May 29, 2023 9:18 am

I agree with Scott. Find a knowledgeable person to help with this. These decisions require first hand examination and measurements. No offense, if you don’t know the name of a part you probably need a good deal of assistance in this.

Andy


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Re: crank shaft/piston arm question

Post by Jerry VanOoteghem » Mon May 29, 2023 9:30 am

I agree with Scott & Andy. Hands-on/eyes-on inspection is needed. Hope you get this sorted out and begin to enjoy your T!

(Piston arm = "Connecting Rod")

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Re: crank shaft/piston arm question

Post by Mark Gregush » Mon May 29, 2023 9:54 am

In an ideal world, you would buy the babbitted rods in one of the standard sizes, install them and be on your way, except, it don't work that way with these old engines. Once a ballpark has been found, the rods need to be fitted to the crank. Standard on the crankshaft is 1.248, undersizes are: .010, .020, .030 and maybe .040.
I know the voices aren't real but damn they have some good ideas! :shock:

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Re: crank shaft/piston arm question

Post by wmscottsutherland » Mon May 29, 2023 11:01 am

FYI - The engine was never left open as it was full of mice. I took it apart to clean out that mess.

I think its best to move to my engine guy and get it rebuilt.

Oh and just because I called a connecting rod a piston arm does not mean I do not know my way around an engine.


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Re: crank shaft/piston arm question

Post by Original Smith » Mon May 29, 2023 11:18 am

I've never heard of a piston arm!


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Re: crank shaft/piston arm question

Post by Norman Kling » Mon May 29, 2023 11:19 am

I must tell you about an experience I had on one of my T's. I took the rods to a local member who does a good job of replacing babbit in the rods and in the block. He asked me if I had the crankshaft magnefluxed? I said "no" So I took it to a local machine shop to be magnefluxed. The machinist said it didn't show any cracks, but it was a bit crooked. I asked if he had equipment to straighten it? He said he did, but would need to regrind the bearings. Anyway, I don't think he straightened the crank. He just turned all the bearings to align them. I took the crank back to the babbit man who checked the bearing sizes and found they were 40 thousandths undersize.
I went to Redondo Beach to the SKAT company and bought a new crankshaft. Later we had a "white Elephant" auction at one of our meetings. I gave them my old crankshaft with a note attached about the size of the bearings, and someone actually bought it! Might have been OK for a show car which is rarely driven, but not on tours. We want the best running engines for tours.
Norm


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Re: crank shaft/piston arm question

Post by Jerry VanOoteghem » Mon May 29, 2023 11:24 am

wmscottsutherland wrote:
Mon May 29, 2023 11:01 am
FYI - The engine was never left open as it was full of mice.
How then did the mice get in?


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Re: crank shaft/piston arm question

Post by Scott_Conger » Mon May 29, 2023 2:12 pm

Scott

I'll reiterate my advice to find a knowledgeable hobbyist to guide you. There is a fellow in Cheyenne who knows his way around "T"s and there are some very knowledgeable hobbyists and "T" engine guys scattered south of you from Fr. Collins to Denver (and beyond).

Now, I am no way impugning the engine shop, but as far as taking it to your "engine guy", unless he has AT LEAST 1/2 dozen "T" engines purring down the road, you are taking a very serious and very unnecessary risk. These engines and particularly transmissions, are huge traps for anyone who has never delved into one and the hobby is littered with stories of new engine/transmission disasters coming fresh from the shop. Even having Model "A" experience does not prepare the builder to produce a transmission which will function without self-destructing.

Put together correctly, these things are marvelously robust, but put together wrong, they are a heartache.

best of luck.
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Re: crank shaft/piston arm question

Post by wmscottsutherland » Mon May 29, 2023 3:52 pm

I bought it from Jim (25tfire), the engine shop is rebuilding my 25 for my 25 Roadster Truck (metal bed). Not to many of those around. Oh and the engine shop has rebuilt many T engines is works closely with Gene French who is the goto guy for re babbitts in northern Colorado.


The mice got in in Jim's shop I'm guessing when the water inlet/outlet (did I saw that correctly????) was uncovered.


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Re: crank shaft/piston arm question

Post by Scott_Conger » Mon May 29, 2023 4:30 pm

No matter where you are on the internet you will find complete assholes
Whoa there cowboy...obviously, you are holding up your own very well.

I can't recall anyone becoming nastier, quicker, nor anyone being blocked on my end so fast. You're one of only two.

You no longer need Good Luck, you need a new attitude. No one here was poking at you...you asked for advice and you got it. Obviously it did not meet with your expectations.

Goodby Scott
Scott Conger

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Re: crank shaft/piston arm question

Post by Jerry VanOoteghem » Mon May 29, 2023 5:19 pm

wmscottsutherland wrote:
Mon May 29, 2023 3:52 pm
I bought it from Jim (25tfire), the engine shop is rebuilding my 25 for my 25 Roadster Truck (metal bed). Not to many of those around. Oh and the engine shop has rebuilt many T engines is works closely with Gene French who is the goto guy for re babbitts in northern Colorado.

OK ASSHOLES I get it It was late, piston arm popped into my mind and you wonderful people cant look past it.

No matter where you are on the internet you will find complete assholes!!!!!!!!

The mice got in in Jim's shop I'm guessing when the water inlet/outlet (did I saw that correctly????) was uncovered.
Oh, very nice. Please don't bother coming back here.


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Re: crank shaft/piston arm question

Post by Kerry » Mon May 29, 2023 5:32 pm

Although I've never heard of the term piston arm for a connecting rod before. but need to be broad minded as we are talking to people all around the world that may use different names for parts, if you google it, guess what comes up.


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Re: crank shaft/piston arm question

Post by TXGOAT2 » Mon May 29, 2023 5:55 pm

Duck tape. Just duck tape it and git on down the road.

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Re: crank shaft/piston arm question

Post by AndyClary » Mon May 29, 2023 5:56 pm

I suppose what I said may have come across as condescending, it was not my intention. I’m glad you were able to get you motor to someone who knows what they’re doing.

Andy


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Re: crank shaft/piston arm question

Post by wmscottsutherland » Mon May 29, 2023 6:52 pm

Thanks - Wayne, TXGOAT2 (especially the duct tape), Mark and Norman

You guys are right I will do what I did with the power plant for my 25. Took it apart and had it ground, cleaned, magnaflux, all new babbitts ..... professionally. It goes back together much easier at this point. All the magnito parts I am getting rebuilt from langs and sending in my old stuff. The transmission drums look good, meaning no cracks so I will use them as is. This is for a speedster so if I need to redo the transmission I will know it when I have a running chassis.

I do understand the power plant is the key to these. Outside of that they are very simple cars.

I consider this thread closed.

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Re: crank shaft/piston arm question

Post by Craig Leach » Tue May 30, 2023 12:23 am

Gentlemen, Gentlemen,
We all know the piston arm is what goes between the crank pin & the gudgeon pin! This was Scotts 17th post give him some slack. Scott every
day have a attitude lets hope its a good one OK.
I had no idea mouse piss was that corrosive.
Craig.


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Re: crank shaft/piston arm question

Post by Jerry VanOoteghem » Tue May 30, 2023 6:40 am

Craig Leach wrote:
Tue May 30, 2023 12:23 am
Gentlemen, Gentlemen,
We all know the piston arm is what goes between the crank pin & the gudgeon pin! This was Scotts 17th post give him some slack. Scott every
day have a attitude lets hope its a good one OK.
I had no idea mouse piss was that corrosive.
Craig.
Took him only 17 posts to call well meaning people "assholes". Sorry. No slack given.


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Re: crank shaft/piston arm question

Post by TXGOAT2 » Tue May 30, 2023 9:27 am

Mice are capable of completely destroying an automobile, and they delight in doing it. One of their specialties is removing the stuffing from upholstery and packing it into doors and body crevices, then defecating and urinating on it. This creates a durable, moisture-attracting, foetid mess that is as corrosive as battery acid. They also like to put upholstery stuffing, acorns, and the bodies of their dead into radiators, crankcases, and fuel tanks. Their dedication and skill at destroying automotive electrical systems have no equal. Mice and rats will chew up radiator hoses, wiring, wooden body parts, and rubber items, leaving stinking, corrosive heaps of confetti behind.


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Re: crank shaft/piston arm question

Post by ModelTMark » Tue May 30, 2023 4:33 pm

Magnafluxing T cranks is a must and the cost is insignificant as compared to the cost of an engine rebuild. Also, crank ringing method is not a good test of whether or not a crank is broken. Here some pics to consider:

In Pic # can you spot the issue?
Pic1
Pic1
Here's a Pic of the same crank after magnafluxing, can you see the issue now?
Pic2
Pic2
Mark
Vintage Engine and Machine

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Re: crank shaft/piston arm question

Post by AndyClary » Tue May 30, 2023 11:53 pm

Sounds like Pat may have an opinion on rats. They get into places you’d never believe and the mess is disgusting. There’s always little dead rats in the nest too. Not a pleasant memory.

That’s an excellent example of a hard to find crack, Mark. If available, wet magnaflux is definitely the way to go. Cheap insurance.


Andy

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Re: crank shaft/piston arm question

Post by JTT3 » Fri Jun 02, 2023 12:08 am

Mark just curious has the crank been spray welded and turned down?


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Re: crank shaft/piston arm question

Post by DHort » Fri Jun 02, 2023 1:39 am

I wonder if piston arm is a Midwest term. I have heard that before. Lots of immigrants here.


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Re: crank shaft/piston arm question

Post by Allan » Fri Jun 02, 2023 2:26 am

How does having the water outlets missing allow mice access into the bottom end of a T motor?

Allan from down under, where solder is NOT pronounced sodder,

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Re: crank shaft/piston arm question

Post by Mark Nunn » Fri Jun 02, 2023 8:11 am

Allan wrote:
Fri Jun 02, 2023 2:26 am
Allan from down under, where solder is NOT pronounced sodder,
So down under, the "l" in solder is not silent?
Then down under, is the "l" in flux silent?

Lord, I apologize. Back to relevant discussion...


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Re: crank shaft/piston arm question

Post by Allan » Fri Jun 02, 2023 9:34 am

That's right Mark. The l in solder is pronounced as in sold. Not pronouncing it in solder is nonsensical. To be consistent, as you fellows age you get odder? You put paperwork in a fodder? In winter it gets codder? I think not. Language is always changing but some changes are odder than others.
Allan from down under.


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Re: crank shaft/piston arm question

Post by Jerry VanOoteghem » Fri Jun 02, 2023 11:51 am

Allan wrote:
Fri Jun 02, 2023 9:34 am
That's right Mark. The l in solder is pronounced as in sold. Not pronouncing it in solder is nonsensical. To be consistent, as you fellows age you get odder? You put paperwork in a fodder? In winter it gets codder? I think not. Language is always changing but some changes are odder than others.
Allan from down under.
So, what do you folks do the first "L" in "colonel"? Colon-el? As in, having to do with, or pertaining to, the colon?

"To be consistent, as you fellows age you get odder? You put paperwork in a fodder? In winter it gets codder?"

Sorry to say, but as English usage in the U.S. continues to decline, this may in fact be the norm. Most millennials have already thrown out many of the "T's" from most words, For example, they vacation in the "moun'ains". (It's coder there...)


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Re: crank shaft/piston arm question

Post by TXGOAT2 » Fri Jun 02, 2023 12:55 pm

qikdnfrtyrtnrtf8f
Last edited by TXGOAT2 on Fri Jun 02, 2023 12:58 pm, edited 2 times in total.


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Re: crank shaft/piston arm question

Post by TXGOAT2 » Fri Jun 02, 2023 12:55 pm

It was like vacay WOOOO!!! and so weyall went to the mounans an it was not coal it was like coder then HEKK!!! So weyar going to somplace like Vaygas nxt time!! Vaygas is WAYYYY coal!!

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