MTFCA Forum

I need to change a timing gear. The fiber gear of many years ago and thousands of miles has given up. Just looking for opinions on timing gear. Aluminum, Bronze, Nylon??? I don’t think I want to do another fiber type gear. I’m interested to hear from experience. Thanks

I run the bronze gear on the Rajo. I run aluminum on everything else. Be sure to check the clearance, Dan makes undersized gears if your mesh is too tight.


Andy

I have tried all three plastic aluminum and bronze. I like the plastic the best it is definitely the quietest. And very reliable haven't had a failure yet. Mike

I only ever replace existing gears with a new aluminium one, preferably with a new steel crank gear at the same time. I'd use bronze,but can't justify the additional expense on a road car.
Allan from down under.

I used the bronze one. You are going to need the tool that takes the special nut off.

https://www.youtube.com/watch?v=F3Vspt_A3ks

My ‘26 coupe turned 96 years old this month and I have never changed my original cast iron timing gear. It’s noisier than nylon or fiber, but is much stronger and reliable and is almost indestructible. Jim Patrick.

DMC bronze are the best on the market, the aluminum ones are a little more noise, the fiber and nylon I do not like with the generator, what if a bearing goes out in the generator? it will take them gears right out. Just my thoughts on this, I am too old to remember the 69 Pontiac 400 with the nylons timing gears in them!

Thanks for all input. The next question. Are all distributors selling gears made by the same people? I’m leaning toward aluminum. Are they all made by the same manufacturer? My crank gear seems to be in good condition as the fiber gear didn’t wear it (there’s one good thing about fiber). Should I consider the .003 oversized for wear? It is in a ‘26 with a generator. Thanks!

Modeltmike wrote: ↑

Mon Mar 01, 2021 9:18 am

Thanks for all input. The next question. Are all distributors selling gears made by the same people? I’m leaning toward aluminum. Are they all made by the same manufacturer? My crank gear seems to be in good condition as the fiber gear didn’t wear it (there’s one good thing about fiber). Should I consider the .003 oversized for wear? It is in a ‘26 with a generator. Thanks!

I’ve probably installed around fifty Aluminum cam gears in the last ten years. My actual experience is there are/or have been at least 3 manufacturers, maybe 4 in that time period. The McEachern gears have his name cast in them and have a good reputation. There is one that is machined all over that is usually pretty decent and there are some that show rough casting in the center that can be real hit or miss, sometimes okay, but occasionally have too much runout to use. There are good and bad ways to measure runout on a gear. Measuring off the tips of the teeth with a dial indicator is a rough measurement. I buy gears five or more at a time I keep std, .003, and .005 in stock and Generally in “repair work”, I just try them for lash and see what fits best. Crank gears can be non-concentric too for a couple reasons (manufacturing, journal wear, grinding error).

...very reliable haven't had a failure yet.

I have. It was in a Chebby, not a Ford, but when the nylon timing gear failed it caused considerable inconvenient and expensive damage. Is a nylon gear quieter? I suppose so. But is a little reduction in normal Model T noise worth the risk? Not for me.

I agree - if you can hear the valve train gear noise over that dang planetary, Id be surprised UNLESS you had your head under the hood !!!

I ordered and received aluminum gear. My cam dowel pins are .010 bigger that the holes in the gear. Not a big to slightly ream. Is this unusual?

If you aren’t a machinist, you probably can’t fix that yourself and end up with a gear that has acceptable runout. Send it back and get a better one.

The dowel pin holes in a cam gear should measure slightly bigger than .375" We machine ours to .3770/.3775.

It looks like my measurements are similar to yours. I had a friend with a shop and he expanded the holes it went on tight and is running again. We will see how I get along with it. Thanks for all info!