Crankshaft end play ?

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Model T Ford Forum: Forum 2012: Crankshaft end play ?
Top of pagePrevious messageNext messageBottom of page Link to this message  By ken bechtel on Wednesday, August 29, 2012 - 08:42 pm:

my third main bearing has .010 end play clearance. any ideas short of a repour of the mains? thanks. Ken


Top of pagePrevious messageNext messageBottom of page Link to this message  By Doug Money - Braidwood, IL on Wednesday, August 29, 2012 - 09:02 pm:

There is a repair thread on the third main. Do a search for it. I think Ron Patterson posted it.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Bender Tulsa Oklahoma on Wednesday, August 29, 2012 - 09:16 pm:

Building up the thrust surface can be done. Doug is correct on the thread and I think there was a write up in the VF. I done a few for Mike Walker maybe he can post his thoughts.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Roger Karlsson, southern Sweden on Wednesday, August 29, 2012 - 09:27 pm:

The third main repair article can be found at John Regan's Fun projects site: http://www.funprojects.com/pdf/Excessive%20Crankshaft%20Endplay%20Repair.pdf


Top of pagePrevious messageNext messageBottom of page Link to this message  By ken bechtel on Wednesday, August 29, 2012 - 09:41 pm:

thanks for the help guys! Ken


Top of pagePrevious messageNext messageBottom of page Link to this message  By Allan Richard Bennett on Thursday, August 30, 2012 - 04:56 am:

Ken, Ted Aschman featured a repair in one of his Tinkerin' Tips books, along with a diagram. I know it works!

Allan from down under.


Top of pagePrevious messageNext messageBottom of page Link to this message  By JohnH on Friday, August 31, 2012 - 01:51 am:

Once upon a time I tried soldering brass shim to the bearing surface which certainly worked, but after about a year or two, part of it broke off - I found it in the oil funnel when I rebuilt the engine.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Chris Barker, Somerset, England on Friday, August 31, 2012 - 03:17 am:

I had success building up the front end (the end that wears) with a bar of white metal and a large 240 watt soldering iron. I used a micrometer to measure the length of the cap before I started, and having built up material, I carefully filed it down to be the required amount longer. I didn't touch the rear face.


Top of pagePrevious messageNext messageBottom of page Link to this message  By ken bechtel on Friday, August 31, 2012 - 06:53 am:

my machine shop can mill the bearing cap after the build up but i'm not sure i could do a good build up of babbitt. i think i'll buy another bearing cap and have it fitted. what is the correct way of finding the crankshaft location in the block fore and aft? the rear of the bearing does not look worn at all but not sure. thanks to all for your help. Ken


Top of pagePrevious messageNext messageBottom of page Link to this message  By Chris Barker, Somerset, England on Friday, August 31, 2012 - 01:07 pm:

If you have not disturbed the flywheel and magneto, then the correct location of the crank is where it gives the minimum desired gap between the magnet caps and the coils when pushed forward against your cap.
Note that the gap has to be greater round the bottom of the magneto to allow for vibration of the stator.
Building up the white metal with a large soldering iron was not difficult. It's just 'tinning' on a larger scale! Then, when you file it, you may find areas where you have to add a bit more. But a micrometer is essential to get the desired length over the whole surface. I aimed for 0.003" float, on the basis that it wouldn't be perfect, and that high spots would quickly wear off and then I would have about 0.005".


Top of pagePrevious messageNext messageBottom of page Link to this message  By ken bechtel on Friday, August 31, 2012 - 01:35 pm:

thanks for the information Chris but when i bought this t someone dismantled the engine and neatly stuffed it all in a box. i guess the fun ended for them and now it's my turn.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Chris Barker, Somerset, England on Friday, August 31, 2012 - 05:30 pm:

The answer is still more or less the same. When the rear main is bolted up, and the flywheel and magnets are in place, the stator has to have the right gap (more at the bottom). You can add or subtract shims behind the stator (where it bolts to the back of the block) to move or tilt it. I'm away from home, and don't have the service book, but I think the gap should be about 0.025" at the top. Unless the rear face of the third main cap looks badly worn or damaged, it's reasonable to assume that the excess end float comes from wear on the front face. This is because the clutch withdrawal force pulls the crank back, so this face is in hard contact in neutral, low or reverse. The wear allows the crank to move back, and the magneto gap to increase.
If your engine is in bits, do you have any marks to show which way round the main caps fit? If not, you may have to try to establish the correct orientation by 'bluing' the white metal and checking which way gives even marking on both sides of the crank, and allows free rotation.
Engineer's blue is also useful for testing the flatness when you file the white metal built up on the cap face.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kohnke Rebabbitting on Friday, August 31, 2012 - 08:12 pm:

Two things , the gap wider at the bottom of the coil ring, has Nothing to do with engine vibration, and has all to do with the hanging weight, of the transmission, after setting the gap on the engines nose, and then putting it in running position.

Second, The Majority of wear is always on the rear of the cap, not the front. If that was the case, you would have to set the motor with the transmission hanging, instead of the other way around, on it's nose, when setting clearance, and the Magnets would never hit the field coils.

I don't every remember using an even amount of shims on the 4 bolts that hold the field coil to the block. If you take your time, they can be gotten perfect.

The last thing, when the car is put into neutral, it does not push, nor pull. The flywheel does not push, or pull, as all the slop is behind the transmission shaft, and rearward. When it is in gear, all the pressure is still all in the transmission, has nothing to do with the rear main thrust, but the Magnets pulling on the coil ring does, that's where the pressure and wear, come from.

It is different with the Model A, but not with the Model T.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Chris Barker, Somerset, England on Monday, September 03, 2012 - 05:15 am:

I'm very very surprised to see Mr Kohnke's input. It would be good to see some other responses. I waited to see if any came but...
I do agree that the magnets will pull the crank forward and push on the rear face of the third main, but the force isn't great, and I certainly agree that the stator shims are likely to be different thicknesses.

But I've studied all the diagrams again, and still think that when you press the left pedal or pull on the handbrake to take the pressure off the clutch, you pull back the spring, and this pulls the crank back. It's in top gear that there is no end load - you can have the complete transmission assembled on the flywheel on the bench, the clutch will be engaged, but there's no load outside the assembly.

And if your crank is sagging when fully installed, you had better be looking for another one - you'll need it soon! The idea of fitting the fourth main with the engine nose down, is so that it is not 'sagged', and when you turn it upright, the fourth main supports it. (This does make the somewhat questionable assumption that the crankcase is rigid - probably not so unless you have a 26 car with the extra top lugs.) The Ford shop manual does mention sag, but I think it's insignificant. Certainly, if it bends enough to close up by 0.025" the crank will break very soon!
Vibration IS an issue. If you touch the stator of an HCCT coil tester (which is a car item), then when the magnets pass at the natural frequency of the plate, the vibration is quite strong. The same will occur when the firing frequency vibrations excite the plate.
Has my logic really failed me here??


Top of pagePrevious messageNext messageBottom of page Link to this message  By Doug Money - Braidwood, IL on Monday, September 03, 2012 - 05:50 am:

Yes, as Chris has pointed out, it is not engine vibration but vibration of the mag coil caused by the magnets. This will cause a resonance if you will in the mag coil assy.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ron Patterson-Nicholasville, Kentucky on Monday, September 03, 2012 - 08:15 am:

Chris
I totally agree with your analysis.
Ron the Coilman


Top of pagePrevious messageNext messageBottom of page Link to this message  By Anthonie Boer on Monday, September 03, 2012 - 12:08 pm:

Chris :
I agree with your analysis TO !!
I send you an PM
Toon


Top of pagePrevious messageNext messageBottom of page Link to this message  By Charlie B actually in Toms River N.J. on Monday, September 03, 2012 - 01:15 pm:

Since Ken's question has gotten some good responses and this is drifting a bit I've got a question: According to Chris, who I believe is correct, pulling the hand brake back pulls the crank back (spring action) so if the opposite is true wouldn't this be the real reason a T would start easier with a rear wheel jacked up and the lever forward? Most say flywheel action of the spinning rear wheel but if it closes the gap on the mag you get more voltage. This is assuming some thrust bearing wear and starting on mag with no battery.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Charles McMillen on Monday, September 03, 2012 - 01:27 pm:

I don't run a magneto. What would an acceptable amount of end play be in this case?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kohnke Rebabbitting on Monday, September 03, 2012 - 04:20 pm:

Chris, try thinking about it this way once. All pressure and movement back and forth, in the transmission assembly, from the 3340 Transmission clutch spring, is contained between the Transmission clutch spring thrust ring pin, and the thrust on the rear side of, and behind the transmission main shaft flange, or called 3331 Transmission gear shaft, and the end of the 3311 Transmission brake drum assembly in which it rides. Putting a Model T transmission in, and out of gear, will not move it in any direction, other then with in it's self. The 3 Peddles also, do not have any kind of a wearing effect on rear main wear.

What does have an effect on real main wear, is a main fit with over .003 thousandths, and up, dirty oil, to thin of oil, carbon, steel filings, glass beads, or sand, Aluminum off the pistons, and when every thing else is right, Starting off with to much end play. After it gets .006 thousandths, it wears faster, and also hammering the rear thrust.

Here is the kicker, for those who think different then this. If putting the Transmission in gear moved the Transmission forward, the only way it could push its self ahead and do that , the tail shaft would have to have a thrust at the ball cap area, but as it is, if the transmission assembly could get longer, and it can't, except from heat, the extra length would only go rearward sliding, in side the ball cap.

And if your crank is sagging when fully installed, you had better be looking for another one. "END QUOTE"

Chris, Flanges on crank shafts on, ALL CRANKSHAFTS FLEX, that is the nature of the beasts. Take any Model T motor, in a rebuild, and after you get the Mag., and transmission set, with out the hogs head and ball cap, just the pan bolted on good, and while on a motor stand, with nose down, and Transmission up, bolt a Dial indicator to the pan, and put the indicator on top of the tail shaft. Then turn the Motor level, with Out touching any thing, and see if the indicator is still Zeroed out??

The idea of fitting the fourth main with the engine nose down, is so that it is not 'sagged', and when you turn it upright, the fourth main supports it."END QUOTE"

Chris, Putting a motor on its end, to install a ball cap will make no difference in assembly. I know what you are thinking, but it don't work that way, and here is why. When you bolt a pan on the block, if it is a straight pan, it will always come out straight. If the pan is bent, it will always come out bent, and all spec's will stay the same , unless you changed the pan in bending.

When you install all the pan bolts, and tighten them down, they will pull the pan into the same place EVERY time, and the ball cap will come out the same place.

Now just think it DID make a difference, which it won't, the only way you could keep it there, is to tighten the 4 bolts, in the ball cap, and the end of the pan, OK, when you put the engine in, you have the engine in, it is in the frame, How are you going to hook up the drive shaft, you have to take out the ball cap bolts, and then you have nothing to hold the transmission weight, what ever it flex's. Short answer Chris, it doesn't make any difference.

I know some have put pins in the ball cap, and into the pan thinking they are really doing something, but it makes no difference at all in alignment.

The last thing, The Magneto Gap has nothing to do with vibration, it has all to do with weight of the transmission! Pictures Below!

I started this post this morning, and I found these pages out of Ford Service, for Reference for you, about 10 minutes ago.

P.S. Ron, Ron, Ron.

Read the last 4 lines, in the second picture!





Top of pagePrevious messageNext messageBottom of page Link to this message  By JIM WILSON, AMORY, MS on Monday, September 03, 2012 - 04:56 pm:

I have an accessory center cap that can be adjusted to take out the end play. Has anyone tried this devise?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kohnke Rebabbitting on Monday, September 03, 2012 - 05:10 pm:

Not True, Charlie, According to Chris, who I believe is correct, pulling the hand brake back pulls the crank back (spring action)"END QUOTE"

When the transmission is put in neutral, the only effect is about 1, to, 2 seconds, on either side of the main thrust, as long as it takes for the lever going from forward, to neutral center. If there was pressure on it, your car running neutral, would soon take out the rear main! The only reason to not leave your car left running in neutral, is the clutch plates!

After that in Neutral, the Transmission, while under pressure, from with in, holding the driving plate fingers in, and lets the clutch pass the two kinds of clutch plates.

So now, setting in neutral, the transmission is not pushing, or pulling, as it sets and floats, on 3400 Transmission clutch release ring, and 3344 Transmission clutch Shift. It is not pulling, or pushing, just floating.

Jacking the driver side rear wheel up, is the Flywheel effect only! It works, other wise I Wouldn't say it.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kohnke Rebabbitting on Monday, September 03, 2012 - 05:21 pm:

Jim, it all depends what condition your rear main thrust is in. If pushing the crank forward still leaves the right air gap in the mag., you can put the thrust to the front of the motor, with your center cap, but you have to look at the way the crank is centered, as you can push the rods out of center, either direction. Every rear main cap is different.

I have poured a few of those caps, but not for my self.


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