Here is what can happen if you are going down hill and use the reverse pedal as a brake.
Have seen this in the morning and now the owner is looking for a rear axle and drive shaft for his 1926 roadster.
That should serve as a warning !!
The RM's were not enough?!?!
RM is working great but he just made a mistake while braking and used the pedal in the middle as in his other cars.
Oh my goodness, Andre! I am astounded. That is hard to imagine, but I'll have to believe my eyes.
I will accept that using the reverse pedal was the trigger for this sad development, but I do wonder is some other problem was brewing in the rear axle or driveshaft. Please keep us informed as you conduct the postmortem and eventual repairs. Good luck with your project. Bill
Im trying to figure out how applying the reverse pedal could cause this. I would not think the forces would be much different just applying the reverse vs applying the brake. Maybe if you forceably applied the reverse till the wheels were spinning backwards. I would think just using the reverse as a brake is bad for the reverse drum, but should not matter a lot to the rear axle. All the stopping. force is applied thru the drive shaft either way. Maybe Im looking at it wrong. Ive been know to do that before. ....
Boy it took a lick to break out a rear axle like that! Must have been something going on inside the case for a while to cause this fail as it did. WOW!
I seriously doubt the use of the reverse as a brake had anything to do with the rear axle breakdown - it must have been a rear axle issue that would have happened whatever was used to brake the driveshaft - so the ordinary brake would have given a similar result. I'm glad noone seems to have been hurt.
As long as the car is rolling down hill faster than low pedal speed, pressing down any pedal will have a similar effect on the driveshaft - it'll try slowing it down. If the rear axle breaks, something is seriously wrong inside the axle and needed to be rebuilt.
It's always a good idea to be ready to pull the emergency brake at any time - it goes directly on the wheels and not through the differential.
Using the reverse as a brake is still a bad idea for other reasons, like it's the weakest drum in the transmission and that the braking force goes through the triple gears. But in an emergency, if the regular brake fails, it's worth a try while you grab for the emergency brake lever
He might have cracked the pinion gear , and the parts was forced down by the crown gear.
If I had to guess...If there was a lot of excessive backlash...the slam caused by moving to the other side of the tooth when braking has a dynamic effect of a battering ram! The gear was probably cracked anyway...or had cracked over time from practice...
Guess we will find out more when it comes apart.......
The transmission axle cracked just before the pinion gear. I couldn't see the cracked very well .
As soon as it is apart I will post photos to show.
The reverse pedal as brake had nothing to do with this. It's what can happen when the pinion gear breaks and a piece of it gets caught between the housing and the ring gear. Happened to my dad many years ago, same result.
Now I see it's equipped with Rocky Mountain brakes, so maybe the driveshaft wasn't "used to" braking forces - but still, the Model T is supposed to stand for braking forces on the driveshaft - and if it doesn't, something is seriously wrong.
Maybe it's lucky that it didn't break on a steep hill going up, stalling and rolling backwards with a broken driveshaft connection isn't easily stopped, especially with Rocky Mountains that doesn't work as good in reverse.
(A fast grab on the emergency brake is again the rescue - before it starts to gain speed backwards)
(Message edited by Roger K on November 01, 2016)
...or a broken driveshaft, as I now see Andre has confirmed.
Even though some people do it and say its safe (at low speeds), I have never used reverse, If the trans and emergency brake won't stop me, I am doing something very foolish, like going too fast.
Probably broken pinion. I've seen it before unfortunately
All that differential knows is that the drive shaft quit turning. It don't care what made it quit turning.
Well I think it does, not only it quit turning but it also wanted to go backwards in reverse while still going forwards, something has to give.
Lucky it was only the rear end, could have been triple gear pins or other transmission internals.
Wanting to go backwards and actually going backwards are two different things.
You posted: (A fast grab on the emergency brake is again the rescue - before it starts to gain speed backwards)
But...if you look again, that T doesn't have any Ford emergency brakes, no rods to the backing plate.
IMO you need the Ford internal emergency brakes even if you install Rocky Mtn. external brakes.
It will be interesting to know if it was a n original driveshaft that broke or new one. Books of the T era and Les Henry's restoration manual discuss using the reverse to reduce speed and spread wear between the bands. Have done that myself for years. But you must use finesse, not brute force. You'd kill the engine long before spinning wheels backward even if you could push the pedal hard enough. On ice it is a different story. You can make the women in the back seat wet there jumpers swapping ends by mashing the reverse on ice.
Just to clarify. He said the driver was also used to other cars (Ts?) and hit the reverse pedal accidentally (?) out of habit (?). That is an easy thing to do when you drive an assortment of unusual cars.
True, probably, the result was going to happen soon anyway. The use of the reverse pedal simply triggered the inevitable.
Use of the reverse drum as a brake should be limited to emergencies because of the fact that the reverse drum is the weakest of the three drums. At modern speeds, the stress on the drum is more than it was designed to take.
Now, to expound upon Roger K's comment about a good time to break, being not going uphill and losing the driveshaft where the RM brakes won't hold rolling backwards. This is one of my pet peeves. RM brakes should NOT be set up as the only braking system in a model T, being operated from both the pedal and the handle. Whether you want the RM brakes to be on the handle? Or the Pedal? The other one should brake independently, either in the transmission, or inside/outside the rear drums.
I am very pleased that no one was hurt. A few parts, a day or three or four of tinkering and repairs, and the car will be better than before.
Drive carefully, and enjoy, W2
I doubt the braking method was anything but the final thing
to happen. Using reverse as a brake is still not a good idea. Ever.
It all looks very dry in the rear too. You would think that some oil or grease would be dripping or smeared on the rear end.
Dennis, I started to type that and then read your post. I don't think the reverse pedal had anything to do with it. I think the lack of lubrication probably did.
That's what I think Stan, no gear oil. Look at the paint...it looks like that rear got very hot and discolored the paint finish.
Color is from exhaust blowing on the housing, see last photo.
Hey , The oil in the rear axle was checked about four weeks ago and the discoloration is due to the exhaust heat . I don't think the reason is oil or heat but more a cracked shaft that had its final crack as the driver hid the reverse pedal.
At the place where the accident happened there was a lot of oil on the road. After the accident the car was pulled behind an other car for about 10 miles to get it home. I will take it apart and will see what I will find inside the axle. Will post photos so you can all see it.
Andre, Did the car still have the old babbit washers in it? One of them could have picked this particular moment in time to go south and put undue pressure on every thing else in the rear end. There's not much room in there when things start breaking up. Jim
I don't know, I have never seen the rear axle apart.
The car came here in 2013 for the first time to make it run after 20+ years and a bad rebuild.
Every season there is something that need repair. The rear axle and brake was the last I didn't work on so it will be done now.