I got this gift from my 1912 van, as a reward for a heavy braking effort in city traffic.
From the upper picture you can see that the gear was cracked for some time, and finally let go under brakes, leaving me to coast round a round-a-bout and into a side street, all this of course with no brakes and a heavy clunking as the wheels drove the broken gear.
Normally, I would just undo the six nuts holding the Torque tube to the diff and pull the driveshaft assembly. But with the gear expanded to this size, it would not come out of the hole, like a 13 tooth pinion on a 3:1 gearset.
It got quite complicated! I had to be able to split the diff halves. To do this I had to get the pinion housing off. That meant the following steps.
* Remove the universal joint, so the torque tube could be slid off.
* Undo the six nuts on the studs and slide the pinion gear spool off. No go. It was bound up on one or more of the studs.
* Wind nuts back onto the studs, lock one against another and wind out the studs. The last one I removed was the bound up one!
Finally I was able to split the diff halves and check out the damage, which was not as bad as I feared. The gears had been in near perfect mesh. The chipped teeth must have been as a result of the mishap. The crown wheel was unmarked. There was slight ding in the keyway on the tailshaft which I worked out with a dremel tool. I had a good original Ford replacement pinion gear and to get the mesh correct a slightly thicker gasket between the spool and the diff was used.
She's now back on the road, but I need a couple of rear axle seals and a new spoke or two in a Hayes wire wheel to have her back in ship shape.
For your interest.
Allan from down under.
This explains why the transmission brake was superceded by wheel brakes, in fact I amazed the concept even lasted into the 1920s.
Ricks will be online telling you to get a set of front brakes any moment now :^)
I’m sorry that happened to you and I am very thankful that you are alright. It is nice that the T came out “ok” also. I always appreciate when folks share failed parts and/or potential accidents – especially when the failed part contributed to the potential accident. Sometimes we may not see any “lessons to learn” and other times they jump out at us. And if it only happens once – then it isn’t as big a concern as when we see several of them happening to members and their Ts.
I looked in my files but I did not find the discussion from several years ago about some then recent deferential pinion gears having some issues of failing prematurely. From memory (not as reliable as finding the posting and reading it again) I think the key way on the pinion was machined in the wrong location or something. I’ll try to search for that one some more later or perhaps someone else remembers it and can post a link. It may or may not be related to your pinion’s failure.
Clearly producing a new car today with rear brakes only and that braking through the band on the transmission would never be approved. There are many single points of failure for that system (axle key could shear, Babbitt thrust washer could fail, u-joint could fail, etc) that would result in the normal brake system no longer working. But with the Model T – that is the system we have – and when serviced with good parts it normally functions as originally designed. Do you have any additional thoughts on why the pinion failed? Do you know if it was a modern replacement part or an original Ford part (you commented it did not have any marking on it – but if you know or think one way or the other – please let us know.)
What type of emergency brake shoes did your Delivery Van have? From the description I would guess the “cast iron” brake shoes – but that is just a guess.
Did you apply the emergency brakes? (Some folks are thinking of course anyone would do that – but sometimes things happen so fast and driving the car to avoid things might be done first and the brake is done later).
Do you think a lined emergency brake would have helped in this situation?
I would think a set of external brakes (Rockies, etc.) would have probably prevented the failure as they would have taken part of the braking load off the pinion. But even if it did fail properly adjusted auxiliary brakes should have stopped the T with or without the normal transmission brake.
Depending on how much we drive our T, what type of traffic we are in, I think having some sort of back up brakes (the lined rear brake shoes for the 8 inch 1906-1925 rear hubs or the later lined 1926-27 rear axle and hubs) is a smart investment. Has anyone lost their transmission brake and used only the cast iron parking brake shoes to stop? And if so – how did that work out?
I think for a T that is driven a lot – the external brakes (or the rear disc brakes) adds a margin of safety. And of course for any of the auxiliary transmissions or rear axles that can get stuck in neutral – they are really needed.
Again, I’m so glad that you were not hurt and that the car was also ok.
Hap l9l5 cut off
"Ricks will be online telling you to get a set of front brakes any moment now :^)"
Thanks, Jem.. I try not to recommend, just state facts and what I've done with them.
Yes, there are too many single point failures on a driveline brake. However, I think it is more common for a single rear wheel to lose traction, such as a flat tire, or one wheel in wet or off the pavement.
The driveline brake stopping distance will increase with loss of traction to one wheel, but it will keep the car going straight ahead. With rear wheel brakes, the one wheel still with full traction will tend to spin the car out of control; or to keep going straight, the driver has to quickly compensate with reduced pedal pressure and cross steering - a double challenge.
Front wheel brakes do the same thing with uneven traction as rear wheel brakes, but the rear brake, be it driveline or wheel brake, is still there helping to stop.
Someday I will deactivate the hydraulic rear wheel brakes and actuate the tranny brake with a hydraulic slave cylinder. Then the next time the reared is pulled, I will replace it with stock, save for safety hubs.
From the looks of that pinion, it doesn't look like it was genuine Ford. If it was, that never would have happened.
Allen, glad to hear your alright, things like that can go bad in a hurry.
Very glad everything turned out okay! As a recent survivor of a pinion key shear, I can relate (actually, the timing of mine had me in no real danger, but?). When driving any sort of real antique, one must always look ahead and consider possibilities.
I have always recommended using some sort of improved emergency brake. I know from a couple cars I have had, that the lined cast iron shoes inside the the small drums are adequate IF they are in good condition and properly adjusted. The center-door sedan I had could lock both wheels easily, and controllably. Of course, outside brakes are even better. However a couple of my cars, I am after the aesthetics of factory.
Do drive carefully, and have a very HAPPY NEW YEAR! W2
Fellows, thanks for your concerns and good wishes. I will answer your queries, in no particular order.
Both the broken pinion gear and the replacement I fitted are genuine Ford old stock.
The brake shoes fitted were lined cold rolled steel accessory shoes. The left one was a bit oil soaked and the right deformed at the pivot point, so I had little braking effect there. I intend to replace some oil seals and fit a new set of Snyders lined shoes.
In the situation I was in I did not brake at all. I coasted around the round-about and rolled to a stop in a side street. The round-about is a notorious two lane affair in Adelaide, just east of the CBD on flat ground. I was doing OK keeping the van rolling, when a Volvo driver entering on the right in the inside lane wanted to cut across my bows into the outside lane to go left in front of me. She missed.
The Bennett brakes on my 1917 shooting brake may have prevented the pinion breakage, by taking the load off the gear. I have fitted my own design of safety hubs to the van and they do a good job, but I do need to replace the inner oil seals.
I do a daily drive of some 60 miles each time I take the van out for a promotional run, 40 miles of which is in the city, traffic lights, idiot drivers etc all part of the picture. On a good day I rarely have to brake hard, keeping my distance and watching the traffic well ahead. I tell those who ask it's like driving an 18 wheeler. I can stop and go as well as that.
I put the failure down to a 100 year old part just quitting. The crack has developed from the sharp corner in the keyway, a natural stress riser. It eventually let go under an unusual load. I fitted the gear some years ago when another shed a tooth. That one still drove with just the 10 teeth, without any complaint until I went to trailing throttle on slow down.
For your interest.
Allan from down under.