Laminated Timing Gear

Kenjt

Kenjt

Member
Among other problems I've had with my Model A, my mechanic found that the timing was off. He had a lot of trouble getting the timing right. He ended up asking me for the crank, thinking (I guess) that he could slowly turn the crank to help fix the timing. The next thing I knew, he was telling me he discovered that the laminated timing gear had broken up a bit. It seem very suspicious that, for a 90 year old car, this gear would suddenly fail. I doubt the crank was used much, if ever. Can someone tell me if it's really possible for this gear to fail over time or could it have been caused by my mechanic, who although very good is not an expert when it comes to Model A's.
 
Funny you posted this today, I just finished installing a new timing gear today. I ordered an aluminum gear from Berts and got a Mark made in USA gear. My fiber gear lasted a little over 20,000 miles. The aluminum gear will outlast me. When I stated the car it made a whirring sound, my heart sank, but in about five minutes it went away. It just had to bed itself in.
 
I understand they go when they go. It just seems strange it went when the car was being worked on. I don't know if he is putting in another laminated one or was smart enough to get a metal one.
 
To tell if it is aluminum or fiber take the timing out and with a mirror and flashlight, look in the hole you will see what you have.
 
The holes for the pins are slightly off of 180 degrees so the gear goes on only one way. A mechanic not familiar with Model A's can ruin a gear by trying to put it on in the wrong position, but it is really hard to do. Ford used the fiber gear to reduce noise but the aluminum gear is much more reliable and not very noisy.
 
Using the hand crank is a necessary step in the timing of a Model A. His using the hand crank will not have damaged the timing gear.
 
Years past. With each new Model A, one of the first things that I would do was replace the timing gear.

On my first Model A, that I got in 1962, I don’t change the gear. It failed within days of buying the car. Imagine how a 14 year old felt about his first car not running. That’s my reason for “always” changing the timing gear.

I have always used the fiber replacement. Never a problem since.

Enjoy.
 
Kenjt said:
I understand they go when they go. It just seems strange it went when the car was being worked on.
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The gear didn't start to fall apart "when the car was being worked on". It was already failing and that's probably why "He had a lot of trouble getting the timing right."
 
Bruce of MN said:
The owner is a real butcher, installing the new nut with a chisel; couldn't bother to learn about the right tool or use it.
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Very common to see chisel marks on a Model A timing gear. I don’t know if I have ever seen one that don’t have them.

Enjoy.
 
So, now that we’ve determined that fiber timing gears (whether laminated or not) seem to be an expendable commodity that many people deal with at some point in time of Model A ownership, it’s interesting that nobody has brought up a little know cause of timing gear failure. Most folks understand that these gears were made of some type of fiber so their wouldn’t be added noise. No doubt cost factored into it more than noise but that really doesn’t matter. This is what they came from from the factory and why would Henry accept an item in the mix that would lead to failure strictly due to its composition material. And, aside from normal wear, it’s a well know fact that an errant backfire that could ruin these gears. However, i’d ask that we consider another possible cause of fiber gear failure. That cause can be a poorly or seldom lubricated distributor shaft. I’ve taken several distributors out of running cars only to find they were dry and the shaft practically frozen in place. I had a customer who went through 3 fiber timing gears in a year only to find that a distributor was slowly but surely becoming tighter and tighter from lack of oiling. It stands to reason that, since the camshaft drives the distributor and oil pump, anything in the same line of motion might become a weak link when something else in the system “freezes up” tight. In this case, distributor becomes stuck, camshaft still turns, and then something has to break. The fiber gear at the end of the camshaft can become the weak link and breaks before something else ......... or ........... the tangs that hold the distributor and oil pump shafts into each other break and the resulting shock, much like a backfire, shatters the fiber timing gear. Easy solution ........... whether you have a timing gear failure or not ........remove and inspect the distributor from time to time, add oil through the side oiler and then work that oil in until you satisfy yourself that the distributor shaft is actually receiving that oil. Then, put the distributor back in and make sure that “oiling the distributor” becomes part of a regular maintenance routine.
 
I have noticed that the timing gear comes in various oversizes to compensate for engine wear. How do you determine what size gear is best for your car? Ed
 
Check the inside of your distributor for copper flakes remove and make sure it’s free and fully lubricated, The best gear to replace it with is a “composite” gear so that it doesn’t tear up your block when it fails next time.. it will fail eventually but it is better to rip up the shaft In a distributor and rip a fiber gear then for aluminum gear to split your block when something locks up.
 
My understanding is that the fibre gear was a “fuse” for the motor put in as a weak point to prevent catastrophic damage to the engine if a turning shaft should seize?
 
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