MTFCA Forum

Hi all. The rivets have failed between the tail shaft /output shaft to the driving plate of my 1921 Touring.

I heard strange pinging noises from inside my transmission and was very lucky to have made it home with ONE very loose rivet still in place. The rest had sheared off and caught up in my aftermarket transmission oil screen.

Can anyone tell me what may have caused them to fail. Am I being too heavy-handed with my shifting (or maybe too heavy-handed with shifting the Ruckstell whilst in motion)?

As much as I'd like to repair this, I'd really like to get the car back on the road for Christmas light touring season with my 6 year old son and his friends. Does anyone have a complete pre-riveted assembly they might sell me?







James

Misalignment of the "fourth main" can cause tailshaft rivet failure.

Seen that several times in re-builds that come in and usually it's due to bad driving habits of not backing the throttle off when changing from low to high.

With an eye on Christmas light tours, it is possible to change (or remove, repair, replace) the output plate and shaft without removing the engine. Tricky, but can be done.
However! Carefully collect all pieces of rivets and anything else loose! Count them all and make certain you have ALL pieces. One little piece of a rivet that may have escaped the filter screen, avoided the flywheel magnets, and hidden out of sight after the oil was drained, can later shake loose and end up in the transmission gears or wedged between spinning magnets and the field coil and blow the entire transmission to pieces!

To do so, if you choose to accept the assignment? The hogshead and fourth main cap must be removed, and your choice depending on preferences and available facilities (blocking, hoists, jacks etc.) either the engine must be moved forward a few inches, or the rear end moved back a few inches.

I did it on a speedster (easier access) in an afternoon one time years ago when a piece inside the clutch broke. At least I didn't have to count out a dozen broken pieces of rivets!

Thanks Erik. Since posting I read that a misaligned or worn 4th main can cause this issue, and I'll check it tomorrow in daylight.

Wayne - I have actually pulled the engine a few inches to remove the output shaft and driving plate.

My engine has oil slingers and no mag coil, which I believe it partly what saved the rivets from destroying the transmission. I'm pretty confident that there is no extra metal in the bottom of the pan.

Usually if there is misalignment between the 3rd main and the ball cap you get one of two results.
One is loose or broken rivets in the driving plate.
The other result is broken crankshaft.
See Floating 2 piece Transmission shaft.

Checked the 4th main / ball cap. It looks like I might need to address it also

No surprise.
Thats also caused by 4th main misalignment.

You might want to have the crank checked for cracks.

Also, pan needs to be checked on a pan jig for straightest.

And a thorough cleaning! Looks like a lot of sludge to me!

That much damage would come from a horribly aligned crankcase.
However, as you reassemble the motor ensure the transmission center shaft has no run out.

Do you have a Friend close by with a T that could help you out for the event? I hate it for the kids but I don’t think your engine is going anywhere soon. Who knows though maybe some one has a working engine on a stand somewhere close by for a quick swap to help out. Hopefully so.

I appreciate the thought. I don't know anyone with a car locally. Our neighbor does have a cool old fire truck that he uses for the same task so it's no big deal to miss it this year.

I did go and buy a new drive plate and ball cap from Chaffins in Lake Elsinore, CA. Unfortunately I didn't bother to inspect the remainder of the transmission, and it was only after I was home, having decided to push things around with a pry bar a bit, that I noticed the drums have lots of axial play on the transmission shaft.

I think it's time to pull the engine apart and go through it. Real shame.

I love working on engines and I'd love to do this myself, over time, but to avoid this becoming one of those "ran when parked" situations, can anyone recommend a good engine shop in Southern CA or AZ to do a refresh?

Here is some information from Herm on transmission rebuild.
viewtopic.php?t=2114

It might be a bit farther than you want to go? However Erik Barrett up in Auburn CA does very good work.
I know there were a couple people in the greater L.A. area that were quite popular with the Southern California folks, but I don't know their names offhand. Members of the area model T club chapters should be able to give you current information for them.

Check the drive plates carefully as we have seen alot through the years that the iron of the plate is crumbling around rivets and forms a crack between them. May not be the rivets that failed it could be the plate itself.
I was not able to see your images but wanted to point this out as well.
As with anything this old, i would strongly suggest getting it crack inspected as i have shown in the pictures.

I have to second what JM says about checking for cracks.
I have seen more with than without.
Lucky there should be a source for NEW reproduction ones soon. Saw the prototype at Luray this year. Looked like a #1 job. Dan

I see a lot of speculation here.

I’ll add something that hasn’t been mentioned yet.

The holes are really ovaled out badly. In order to get ovaled out that bad, the rivets and shaft had to be loose for quite some time. It likely was not a sudden failure. It is possible that drive plate could have been installed with just barely loose rivets tens of thousands of miles ago and it took a long time for it to totally fail. The failing shaft connection would have also destroyed the fourth main bearing.

Most of the other speculation offered draws some reasonable conclusions too. The only way to know for sure is to completely disassemble & do proper inspection of all your engine & transmission parts, pan, etc. The filthy condition of the parts leads one to believe nothing has ever been done to it and therefore fear the worst. However, that filth can also just be a characteristic of a couple decades use of non-detergent oil too.

In terms of checking for cracks; you really should pay a professional to check the drums and drive plate. Something of great importance is to also crack-check the driven gear sleeve on the brake drum (brake drum shaft). This is usually overlooked by many rebuilders and is something that can fracture and cause major transmission issues. If any cracks show up it should be discarded. Pay special attention to the edges of the keyways and around the oil holes. Remove the bushings and look inside. Anything visual inside that looks like big fissures is an indication of a poor quality forging and more prone to failure.

James to Adams points with that probable long term problem effect on the many transmission components a really good inspection of the 3rd main. In the past year I’ve seen a few engines come in that have the 3rd main crack or totally cracked out. It would really sux to do a lot of good work on the transmission only to have a catastrophic failure with the block. Best John

Guys, thanks for the replies.

I decided to pull the engine out of the car, split the block from the pan and pull the transmission in order to take a look at it.





Through a process of the above, and speaking to Dave at Chaffins (he's very helpful, and generous with his time), I was able to work out that the brake drum is missing one of its two bushing - there's only one installed, at the end closest to the flywheel, and it's kind of galled. Dave said some builders just choose to do it that way because the drive plate bushing carries the other end of the drum assembly on the transmission shaft. Except when it doesn't, as is the case with my unit.



The transmission shaft is a bit ripped up.



I dropped the center crankshaft journal, just to take a look. I seem to remember the previous owner saying that the engine had been recently overhauled, but he was at the age where 'recent' could have been 20 years ago. As it stood, the babbitt looked decent, and looking up inside the engine, there are still cross-hatchings visible in the cylinders. Based on the power this engine makes, and the components inside (aluminum pistons and oil dippers), I don't think it was long ago someone was in here. I wonder if someone rebuilt the engine and left the transmission well alone on the basis that it worked OK at that point in time.







The crankcase oil tube was absolutely filled with crud.



I pulled it, blew it out and reinstalled.

My magneto pickup external oil feed line is also plugged solid. I've ordered a Texas T oiler to install whilst the hogshead is out.

So my plan is this - fit new brake drum bushings (two, this time), polish up the transmission shaft on a lathe, reinstall the lot and see how we go. Gonna miss the Christmas lights, but hey.

I will inspect the drums and brake drum shaft for cracks, thanks Adam. The brake drum is a newer replacement (has the clutch shoes found on the late-model cars).

If you will look in the Service Bulletins in 1925 you will see a Bulletin from Ford that the second bushing in the brake drum is not needed. That was not the cause of your problem.
Most likely it is misaligned of pan, 4th main and crankshaft.

Also if that 1.215 is the size of the crank, it is a broken crank waiting to happen. It would be a boat anchor in my shop. A small boat’s anchor.

Dan Hatch wrote: ↑

Fri Dec 08, 2023 3:57 am

If you will look in the Service Bulletins in 1925 you will see a Bulletin from Ford that the second bushing in the brake drum is not needed. That was not the cause of your problem.
Most likely it is misaligned of pan, 4th main and crankshaft.

Also if that 1.215 is the size of the crank, it is a broken crank waiting to happen. It would be a boat anchor in my shop. A small boat’s anchor.

It's not waiting to break so much because of its size as it is because of the sharp corners at each end of the journal.

Thanks Dan and Jerry. Well, the good news is that I didn't pay much for the car and I've so far it has been one of the most fun vehicles I've ever owned. The bad news, for me, is that most of the advice I've received on this forum has turned out to be absolutely spot-on, so I will, from hereon in, drive with the expectation that the engine is going to grenade.

The body of this car is kinda beat to death, so I don't want to start a major overhaul on anything. I'll reassemble it, drive it, maintain my AAA membership, and keep an eye out for either a keenly-priced spare motor that I can have on standby.

jamlip wrote: ↑

Fri Dec 08, 2023 10:44 am

Thanks Dan and Jerry. Well, the good news is that I didn't pay much for the car and I've so far it has been one of the most fun vehicles I've ever owned. The bad news, for me, is that most of the advice I've received on this forum has turned out to be absolutely spot-on, so I will, from hereon in, drive with the expectation that the engine is going to grenade.

The body of this car is kinda beat to death, so I don't want to start a major overhaul on anything. I'll reassemble it, drive it, maintain my AAA membership, and keep an eye out for either a keenly-priced spare motor that I can have on standby.

That sounds like a good plan. Knowing what's under the hood will most likely guide your future use and will also most likely extend the life of the motor.