misdiagnosis based on assumptions

Mike Peters

Mike Peters

Well-known member
Today I finally got around to finding out why the rear wheels on our 28 Tudor are no longer taking orders from the engine up front. This very sad state of affairs began last fall a hundred miles from home going around a corner when we heard a distinct "clunk". After that, no forward and no reverse. It resulted in a ride home on the back of a rollback truck. Embarrassing wasn't the word for it.
The car is equipped with an old Borg Warner overdrive, and I, in my wisdom blamed the overdrive. A fellow club member blew out his Borg earlier that year and had no forward and no reverse, so I ASSUMED mine had failed as well.
I started the car and put it in gear after removing the left rear drum to see if the overdrive still worked. It did indeed turn the axle. Between last fall and now I have hated and cursed Borg overdrives, and so now I have egg all over my face. The photos indicate a broken left rear axle shaft.

Moral of story...Never make a diagnosis until you have ALL the facts.
 

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Moral of story...Never make a diagnosis until you have ALL the facts.
Now THERE is a lesson for Fordbarn. So many times broad claims are made based on very very thin evidence and the poor sod who tries to follow the advise from the "seasoned experts" ends up chasing his tail. Anyway, glad you found it, we always seem to jump to the worst case scenario it seems!
 
Tell me about it. Got in a hurry a week ago Friday to take my daughter to coffee so she could thank a prayer group that has been praying for her and her battle with pancreatic cancer. We were almost late and we jumped into the coupe, the one I had written an article about for the last Restorer. I started the car shoved it into reverse, let the clutch out and nothing, engine revved up and we sat there. Out and into the roadster and got her to coffee and made a bunch of friends happy for us and all that. then I came home and pulled the rear end with the B/W O/D and proceeded to disassemble it only to find this unit looks very nice inside, with no missing or damaged anything. Come to find out that for the first time in my life I had put the transmission in reverse with the O/D handle pushed into the engaged position. The end of the story is that tomorrow I get to put it all back together and am now aware that with the solenoid not engaged and the O/D mechanically engaged you can put it into reverse and let the clutch out. The free-wheeling feature will save you from ruining your overdrive. Never knew that, so with egg on my face I have created a learning experience for myself over and above my brilliant comments on a fail safe switch.
 
Has any one else ever suffered a fracture axle shaft? I thought Model A axles were practically indestructible ( until now!)
 
Back in the day my Dad's (now mine) '29 Tudor had the same 'no-go' symptoms, and my Dad immediately though clutch slippage, or transmission issues. He was going to pull the engine to start work when I noticed the speedometer was still registering, hence the drive shaft must still be turning.... A quick check of both rear hubs showed one pinion key had sheared in half. Easy fix from there......
 
Mike, I'm going to make you feel like a genius. I along with many mechanic friends ASSumed that I had burnt valves on a dodge 318 engine. On the gravel drive,,, I mean the hi tech shop, I crawled up in the engine area and removed both heads. I'd never done anything like that before. It was a 4x4 so I did climb as mentioned, didn't have hardly any tools and very little knowledge of what I was doing. I forget the price of having the heads worked but along with a lack of tools, shop, knowledge, garage floor I also had a lack of money. I'd still like to thank all of the mechanic friends who always knew exactly what they were talking about, never ever just "didn't know".


Turns out the distributor cap was cracked. :(. But I did learn a lesson.
 
Sounds like it worked out ok then, other than a busted axle! I too did something probably dumber. Many years ago (my mechanic abilities are minor, but even less back then), I was on vacation with the family at the beach, about 3 hours from home. Came out from a restaraunt and the Jeep G Cherokee gave a bit of a kick and died. Car was pretty new. Guy came out and said 'those things are notorious for blowing a crank, piston, etc.' whatever it was he said i panicked and called a tow truck. Car towed 3 hrs back home, pop brought me a spare vehicle to use for the rest of the weeks vacation. Got home to find out it had a dead battery!!! I only take mechanical advice now from my trusted mechanic.
 
Never take advice from a mechanic with clean hands and a fresh manicure...
Glad you got it figured out... Chap
 
I had a cracked axle on my 29 Roadster that was WELL on its way to braking off. Fortunately a lady in a convertable pulled up beside me as I was getting ready to make a turn and told me I had a rear wheel wobbling. Creeped home and put it on jack stands. Sure enough when I turned the driver side rear axle there was almost it was almost 1/8 inch wobble. Took the rear end apart to find a crack that was almost half way through the axle. Did a show and tell at our local club and a gentleman who had worked on model A's almost 50 years said that was the first one he had ever seen but it sure as heck was cracked!! Glad I found it when I did.
 
Never broke an axel shaft, but did shear a drive shaft once. It broke at the groove tht holds the keeper ring for the speedo drivegeaar. Had to drag the coupe home with a chain. Thats embarassing. Chased the problem for weeks before I found the hiccup.
 
Assumptions based on experience is a part of troubleshooting,no one can see through steel.As a field service mechanic I always ask for the most detailed symptoms from the person calling for service,gain advantage by thinking about the problem,resist tearing in without using logic.
 
Just some food for thought, since I purchased a Magnaflux crack detection machine, I have learned that there are a bunch of items on our Model-As that failed a 'mag test' yet the owner had no idea. Items like axles, spindles, steering arms in the threads, etc. can have fatigue cracks that could potentially cause a part to fail on a restored car.


On the other hand, it seems many restored cars likely go years & years with those defects without ever experiencing a failure, so I don't know what the answer is. Kinda like a bunch of my friends & I go off-roading in our buggies, and we do some nighttime trail riding. My son made the comment one night while we were riding that it would be cool if we had some night-vision goggles to wear. At first that seemed like an great idea until we got to thinking that we may not want to know what is out there! :eek:



 
Getting spiritual now,cant tell you how many people run complex machinery and processes based on pure faith and ignorance.,Its called Providence...or the the devils hand,depending upon the task at hand..
 
Crystallization of metals through work hardening (metal fatigue) and resulting catastrophic failure is unavoidable.Doesn't matter how good the assembly is,transmit vibration or torque through it and it will ultimately fail.
 
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