MTFCA Forum

While driving the 1923 Coupe. Everything was fine until I pulled out at the red light .I pushed the couch in and nothing.I got home on a trailer. I released the brake lever all the forward, and I could push the car back and forth no resistance. I thought a broken u joint. I pulled the rear and everything looks fine so I thought the transmission. I took the trans cover off, everything looks fine. And then looking at the back of the transmission where the square slot for the driveshaft fits in turns with brake lever all the way forward and cranking it by hand. What can I check next?

John,

A couple of ideas: You stated you "pulled the rear". Does that mean you open up the differential? My first thought was failed babbitt thrust washer in the differential. My second thought is broken axle. Along this line of thinking, maybe a failed axle key at the wheel hub(s).

If you can turn the drive line when cranking the engine, the problem would appear to be in the rear end.

Good Luck,
Terry

I had the same symptoms. It was a broken axle. happened as I put the pedal down to cross an intersection. Click! No progress.

Allan from down under.

Same here, broken axle shaft. Started off from a stop and heard a pop! The engine ran, but the car wouldn't move in any gear. I called a flatbed and got a tow home. Gave me a good excuse to install the Ruckstell rear axle that I had built.

This had the same symptom, broken pinion gear.

Put the rear end up on jack stands. Diagnostics. Both sides, pull wheels outward. If they dont come out, rotate. Opposite wheel should rotate backwards. If so, axles/ diff are ok. Could be sheared ring gear bolts or the more common pinion gear key sheared. You can look in the diff. fill hole with it running in gear for ring gear movement or not. If you have gotten this far. Now its the pinion gear or drive shaft.

-
John,

Here is a heads up. That wonderful Norm Kling in Alpine, CA helped me replace my rear axels and, among many other lessons that weekend, I learned something the hard way.

Here it is; When breaking down a Model T rear end the first thing you might want to do, after removing the rear end from the car, is go around the housing and torque all 6 of those bolts/ studs. I recommend this because you don't want to find out that one of those is stripped "after" you have reassembled your fresh rear end. Typically, you would have to take it completely apart again to correct this problem. So, a minute spent checking can potentially save you a day's work.
-

NorthSouth wrote: ↑

Fri Jun 18, 2021 11:27 am

-
John,

Here is a heads up. That wonderful Norm Kling in Alpine, CA helped me replace my rear axels and, among many other lessons that weekend, I learned something the hard way.

Here it is; When breaking down a Model T rear end the first thing you might want to do, after removing the rear end from the car, is go around the housing and torque all 6 of those bolts/ studs. I recommend this because you don't want to find out that one of those is stripped "after" you have reassembled your fresh rear end. Typically, you would have to take it completely apart again to correct this problem. So, a minute spent checking can potentially save you a day's work.
-

Are you talking about the 6 DRIVE SHAFT bolts/studs?
During a proper rebuild those 6 holes should be inspected & threads chased. Along with removing/cleaning the old grease & dirt. Maybe you find that housing crack. As in a motor overhaul, address all threads

Steve Jelf wrote: ↑

Fri Jun 18, 2021 12:07 pm

Sudden free wheeling and a suddenly locked up rear wheel can both be symptoms of the same malady.

http://dauntlessgeezer.com/DG79.html

If you are saying, a lost thrust washer can create a "freewheeling" NOT POSSIBLE. The thrust washer is .187-.200" thick. The diff assembly does not have that much side to side room. Even if it did, the ring/pinion gear mesh is deeper than .200". The D/S bearing/sleeve would also have to be gone & there would be a continuous nasty noise from the gear mesh overrunning.

Best "guess" is sheared axle or pinion issue. A little testing will narrow it down.

could be anything from the transmission output shaft to the rear wheels. Most often would be the driveshaft, or the rear axle. Next would be the gears in rear axle. Easiest to find would be a broken axle. Unless you have safety hubs, a broken axle would pull right out if you jack up the car.
Norm

DO NOT CHASE THOSE BOLTS UNLESS YOU HAVE THE CORRECT TAP
-
[/quote]
Are you talking about the 6 DRIVE SHAFT bolts/studs?
During a proper rebuild those 6 holes should be inspected & threads chased. Along with removing/cleaning the old grease & dirt. Maybe you find that housing crack. As in a motor overhaul, address all threads
[/quote]

Norman Kling wrote: ↑

Fri Jun 18, 2021 4:11 pm

could be anything from the transmission output shaft to the rear wheels. Most often would be the driveshaft, or the rear axle. Next would be the gears in rear axle. Easiest to find would be a broken axle. Unless you have safety hubs, a broken axle would pull right out if you jack up the car.
Norm

If the axle broke beyond the outer machined race area, it probably would not pull completely out untill the bearing is removed.
The axle would still pull out far enough to confirm a break or departure from the drive gear.

Mark is dead-on, the studs are 7/16 X 16 not a common tap or die. .4375 X 14 threads per inch is standard.

That is not correct. Measure them again. The correct thread is 13/32-16 .406 dia.

none of the above

13/32" x 16 thread is what was done at the factory.

Anything else is a bastardization of the correct diameter and pitch

And there is now proof that John K types faster than I.

I stand corrected.

I had a similar situation, pulled into the driveway. Opened the garage door and no drive……
I jacked up the rear end and I could turn both wheels and the other would rotate in the opposite direction. I looked inside the transmission and the clutch plate was turning with the crank. So I deduced it was either the UJ or broken pinion gear.
Out came the axle but everything was lust fine.
How could that be possible?????
I poking around I removed the fourth main bearing and the shaft from the clutch was loose??
I pulled the motor and found the problem.
The rivets holding the drive shaft from the clutch plate to the UJ had all pulled out
In my simple mind it’s a real defect with the design in that the rivets are not formed on the clutch side, they are just pressed in and sure enough mine just pulled out. I fixed it by countersinking the front of the clutch plate and spread the rivets while nice and hot.
I know Ford built at least 15,007,033 transmissions but mine failed due to a what I consider a design defect.
I really not sure how to diagnose this failure without pulling it all apart.