I think we all agree that it is really important to try to maintain accurate alignment of the 4th main to the rest of the engine. And we know this can be influenced by bumps and curbs and other events. I was thinking that maybe a solution would be to make a new transmission main shaft that is connected by a spline to the plate that bolts between the flywheel and the end of the crankshaft. This would then allow it to "float" a little. I would think a very close fitting spline with no more than .0005 to .001" of clearance. Just enough so it can move a little angularily but with no perceptable slop! This might save crankshafts and other problems. I know there are smart guys out there so I wonder what there opinions are. I might try making one when I get home
I think that would be a good idea. I have often thought a U-joint or CV joint would work well right behind the crank flange or behind the flywheel.
Make a cast-steel engine pan that is about 1/4" thick.
If I follow your thinking, I believe what you want is a crowned spline. It can be a close fit but still allow angular misalignment. Not sure how it would wear in the long run however. Also, need to consider that it would allow the sun gears to move off center and may cause a clash with the triple gears, which would not move accordingly.
Actually though, if you consider all the bearing clearances involved, the T trans should have a fair amount "give" to take up a REASONABLE misalignment.
I think it would work better if the whole transmission were more rigid and connected by a universal joint. However more modern cars don't have a U joint. They are rigidly connected to the engine block. They also have a stronger crankshaft. The weakness in the T is the stamped steel crankcase with the block and the hogs head bolted to it. The improved engines of 26-27 would make it more like the modern cars. It's my understanding that the improved cars have less problem with broken crankshafts. I have 3 with the improved engine and so far have not broken a crankshaft. This doesn't mean that I won't. I have even known of Model A's that had broken crankshafts.
The Model T was advanced for its design in 1908 and has served the public well during its lifetime. The problem is drivers today expect too much from a near 100 year old machine. I had a crank break at 40 plus mph. I did not consider it a weakness but more a victim of old age and overexertion.
At .28 lbs per cu ft for steel that 1/4" thick pan will have a considerable weight. The T frame is already prone to bending where the engine arms sit. Also a new pan would be quite expensive
Jerry and Norman
I know what you are saying, but I figured to not design for very much flex, maybe 1/16" max at the 4 th main.
Modern cars bolt rigidly together and have a spline drive.
Interestingly enough Ford on the NRS had a square drive between the engine and the transmission which allowed some flex. Of course the T was very advanced for it's time. I am just pondering a idea that would be relatively cheap to make and also reduce the risk from misalignment
Worn bushings with all the transmission parts would achieve much the same thing.
Some truth, and yet it will let the drums flop around and throw things off balance and cause vibration which is great way to break parts. Admitedly the flywheel will stay in balance either way. Anyway i don't think it would achieve the same thing.
Les, good idea but the flywheel would need to be rigid unless your doing away with the magnets and mag ring. The center driven gear would need to be rigid also since it's in the middle of the triple gears.
The flywheel bolts directly to the crankshaft so it would not be affected at all. Certainly the mesh of the triple gears would be compromised a little but not more than a few thou of a inch. It is a idea I think I will try anyway, but it will be hard to judge it's success.
Yeah steel is .28 lbs per cu inch not per cu. foot, but you all knew that!
Off Topic perspective: a ton of gold would be a cube 14" on a side.
It seems to me that the most practical way to achieve a reasonable fix on the problem is stabilize the fourth main. Henry did it with two bolts. There are several other ways to do it with some success to lots of success.
I am going to try it with the cable or a band method in the next few months and test it on the stand and while driving.
I'd sure like to find one of them cubes!
Why don't you try it for about 75 years and compare the durability to the original Ford system? I'm not sure that the flex you are trying to achieve would work at high speed. With centrifugal force, you would probably find it would move to one side and then stay that way as the engine spins. I had a similar thing happen when the pin in the front of the crankshaft was loose in the hole. I'm talking about the pin which is engaged by the starter crank. At idle I had a pronounced knock caused by the pin droping from one side to the other, but at operating speed, there was no knock, because it would go in one direction and stay there until it idled again. I am thinking that would be the same way with the spline. Meanwhile it would cause excessive wear on one of the triple gears and the fourth main.
It won't cause excessive wear on any one triple gear, at most a small increase on all three but even that is highly unlikely and if anything it will reduce the wear on the 4th main as it will minimize the load that would be caused by a any deviation in the crankcase alignment. Obviously I have not explained my idea well so I will not post further on it.
I continually hear on this forum how the original Ford system has worked well for a hundred years.
How many of these cars in the last hundred years have racked up LOTS of miles? Not many of them is my guess. My car had 0.020" over bores and to my knowledge, never ran an air filter so I rather doubt that slap-worn-out thing had more than 50,000 miles on it.
Sitting around not running for 80 of those 100 years does nothing to fatigue a crankshaft, but I'd bet that running one with a fourth main not lined up with the other three does.
I was not degrading your idea Les, I think its a good Idea. As you know most of the people who read this do not have a clue. Just think its way over my head, with several unknowns to deal with.
I have thought about your suggested solution....and I agree with you. It would not be that difficult to do the modification. Machining the internal spline would be the most difficult. As a test, One possibility may be using a splined hub from a clutch disk for the internal spline. An old T transmisson shaft flange could be bored and the disk spline welded in. Making a new transmisson shaft would not be that difficult. Using a ball bearing forth main and shouldering the new transmisson shaft would limit the shaft float. Good idea!
Just a thought...
The transmision main shaft serves not only to carry the trans but also carry and stabilise the flywheel swinging about on the end of that 1 1/4 cankshaft.
Like the blokes from Tulsa, I think you need to be anal about getting the trans aligned and the brake drum assembly running true. After that it's up to Ford and the other gods of metal fatigue;) It doesn't bear thinking about the flex in a 1915 sump though.
Using 3:1 gearing I got the old mans speedster to 62mph the other day... and it wasn't about to self destruct with vibration. What would that be for engine speed??
With 3/1 gearing
Rux High/Ford High - 29.8/1000 RPM
A couple of issues come to my mind, the U joint could not just slip together, it would have to lock together with the high low shift.
The hinge point of the pan would be a few inches forward of the hinge point of the main shaft u joint creating two different plains for shaft alignment in my thinking anyway.
Les, I seem to recall a splined hub that bolted to the center of the flywheel on an OMC boat motor, about 1976 vintage. The shaft in the intermediate housing between the engine and outdrive fit in there. Something like that might work. You could probably find a picture in a service or parts manual at a boat shop.
Les V N
I have thought about the clutch and Yes I think if you use a ball bearing 4th and shoulder it so it takes the clutch thrust then everything should stay in place. Hub City makes various standard spline parts so you may be on to something. Either weld or perhaps silver braze it to minimize distortion (and keep it perfectly centred).
This way the shaft will just slip into the spline hub in the flywheel so no pins will be needed.
Thanks for the info, it is worth looking into. I figured on talking to my friend with the CNC machining centre and maybe he can machine both halves of the spline. As usual with CNC the first one would be expensive, the 2nd one cheap.
If the flywheel is balanced well it should cause very little strain on the crankshaft
My pleasure. Thank YOU for posting again on a subject that I feel centers on the T's major weakness.
The best thing about your idea is that the complete set up could be supplied as a "Kit". If produced in quanity, it would not be that expensive. Another positive plus is you could remove the transmisson without pulling the engine apart. Sliding the engine forward or the rear end back sufficiently to dis-engage the U-joint would allow removing the transmisson with only the hogs head off. With this set up, I like the advantages even if you are running a strong crankshaft. Keeps the load off the crankshaft flange as the pan flexes or falls out of alignment. Even with the 26/27 engines.....you can still have mis-alignment. The "Kit" when installed would be completely hidden. I think assembling the engine would be much easier. No more need to stand the engine on end when bolting on the transmisson. Great Idea!
Les Von Nordheim
I am still not clear of what standing the engine on end while installing the transmission does to line the output shaft with the mains. I just installed my transmission the other day & I had the engine vertical but it was because it was easier to do with the cherry picker. When it mates the crankshaft there are two alignment pins along with 4 bolts to line everything up. What am I missing? Nelson
What people are talking about is having the engine vertical when you install the 4th main. This way the transmission isn't hanging down. The back end will hang down some amount and basically it is bending the crankshaft. This can contribute to excessive wear in the center main and can also contribute to crankshaft breakage. I don't know of anyone who has completely analyzed the situation (crunched all the numbers) but there is plenty of anecdotal evidence as to short center main bearing life related to sprung oil pans. Whether it causes crankshaft failure is unproven but suspected.
So installing the transmission vertically is not the issue. Usually I install the transmission in pieces (first the flywheel and shaft and then assemble the rest in place). Just my personal preference as it makes it a lot lighter.
I then turn it all vertical after the pan is on and carefully dial indicate the output shaft to be sure it isn't wobbling. Then I install the 4th main and pin or bolt it in place with small machine screws to be sure it maintains it's alignment when you go to install it in the car. I don't pin it to the cover of course so you can still easily remove the cover (well sort of easily!!)
Installing the transmisson with the engine on end helps keep things in alignment and reduces the possibility of bending the crank shaft flange or warping the crank. The transmisson is heavy and if left hanging (Un-supported) in a horzental position, can cause damage. Also, with the engine and transmisson standing on end.....you should be able to bolt on the pan and then slide in the 4th main with ease. If the 4th main does not line up....you may have a bent pan, transmisson shaft or some other serious problem.
I hope my explanation did not get us lost some where in the woods. Smile!
I am using the modern 4th main. When I put the 4th main in there was no alignment problem. All of the bolts went in with no problem so it looks like there should be no misaligment. I also took the bolts out & turned the crank 90degrees & reinstalled the bolts. Still no aligment problem. I think I will go with it. Nelson
Good luck with the [modern?] 4'th main.I never knew i had one till i joined the two pice crankshaft club! All other mains/rods were in nice shape but the[modern?] one was shot.Bud.
Ken, you are not the first one to break a crankshaft with the fourth main ball bearing. Several others have had that happen and blamed the ball bearing. Another problem is that the ball bearing may have a dust seal, but not an oil seal.
I dont know if there are different style modern 4th mains. but the one I have has a pretty strong looking ball bearing. I could understand if someone had to use punches to line up the bolt holes you could put a ecessive load on the ball bearing & it would fail then the output shaft could flop around & break the crankshaft. Most ball bearings hold up pertty good if they do not have.a side load. Nelson
If the 4th main will slide in place with the engine standing on end and rotating the crank as you have done....your alignment should be good. However, with the engine in a horzental position, the transmisson should sag down due to the un-supported weight. If the 4th main slides in now....I am thinking your pan is also bent the same amount that the transmisson sag's.
It's easy to check....simply stand the engine on end and re-check the 4th main alignment.
Alignment of the fourth main has nothing to do with the alignment of the bolt holes. Just behind the flange, where it meets the convex of the cup, there is a machined outside diameter. It is that diameter that does the locating and aligns the fourth main. The machined diameter of the fourth main fits nicely in the machined diameter in the rear of the hog's head.
Also, I believe the idea behind a ball bearing fourth main causing crank breakage is not that the bearing fails. The thought is that it holds the tailshaft too rigidly, not allowing for any misalignment at all or any end play. It demands absolute alignment from an assembly that is far from absolute given the stamped steel foundation, (i.e. crankcase), that everything sits on.
The point you make is precisely why I am considering my spline connection idea. It would accomodate a small amount of misalignment with out imposing any strain.