timing gear backlash

Pilotdave said:
Okay, basic education time! How DO you measure the timing gear backlash? Thanks!
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I just find a spot where I can 'rock' the cam gear against the crank gear [ in other words, no tension between the two] and just use feeler strips between the teeth.
Once the the clearance gets in the .010" range, the noise starts.
 
Thanks, Patrick. So the cam gear tooth is touching the crank gear tooth on one side and you measure the space between the two teeth on the other side? Seems straightforward enough....though do you take the measurement at the base of the teeth? Tips of the teeth? Or does it not differ much? Thanks again.
 
H. L. Chauvin said:
Hi Tom,

I had my crank counterweighted by Mr. Ron Kelly in TX, whereby he always replaces the crank gear with a new one made by Mr. Dan McEachern.

I next installed the same fiber gear with a metal center because it met clearance specs & was not at all loose. Sounded great initially, but after maybe 50 miles, ticking started & it got worse.

I called Mr. Dan McEachern who knew Mr. Kelley used his crank gear & Mr. Dan recommended his aluminum gear. He thought my new Stipe IB increase cam lift "may" have loosened the metal/fiber gear.

I changed the timing gear out to aluminum, & the engine immediately stopped ticking & was totally noiseless.

On my next engine I will get a Mr. Dan McEachern crank gear with his perfectly "matching" aluminum timing gear. This gentleman is truly a perfectionists.

Furthermore, looks like every time a Model A fiber timing gear breaks a few teeth, it happens like on a Christmas Eve morning, 792 miles away from home, in the middle of a Christmas Parade, with two (2) dogs, a wife, & two (2) grandkids in the car with everyone having to go the bathroom; plus it is raining so hard, the "Rain-X" washed away .

I'll never use a Model A fiber gear again -- one fiber gear failure is enough. LOL
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Right on, Mr. Henry !!!!!!!
 
Cam gear should be checked in 4 places. Reason is a lot of the cranks have been ground off from the true center line. This causes the cam gear to run out.Which makes it tight in some places and loose in some places. It also cause the flywheel to run out. Both are not good, but seems to be the way things are going in today's world.
 
Tom- with regard to your phone call last week, I've been thinking how you could have .009 backlash in one place on your gear set and the only conclusion I can come to is that when the cam gear nut was tightened, the crank was prevented from turning with a block or ? and the cam gear was tightened using the crank gear to prevent cam rotation, damaging the gear teeth in the contact region. Again, if you are replacing a cam gear, do not use the crank gear to keep the cam from turning- remove the side cover and clamp a block to the back side rim of the cam gear and let this absorb the torque of tightening the cam nut. I hope this helps. Dan
 
Dan McEachern said:
Tom- with regard to your phone call last week, I've been thinking how you could have .009 backlash in one place on your gear set and the only conclusion I can come to is that when the cam gear nut was tightened, the crank was prevented from turning with a block or ? and the cam gear was tightened using the crank gear to prevent cam rotation, damaging the gear teeth in the contact region. Again, if you are replacing a cam gear, do not use the crank gear to keep the cam from turning- remove the side cover and clamp a block to the back side rim of the cam gear and let this absorb the torque of tightening the cam nut. I hope this helps. Dan
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Dan:

Thank you much, looking forward to your new cam and crank gears showing up on the doorstep.

Tom Endy
 
Hi Tom,

FWIW:

Before I installed my aluminum timing gear a few years ago, Mr. Dan warned me about this Model A, age old religious heresy, written & preached everywhere in our Model A Religion for years........... i.e., he said, "Do "not" use a rag between the gears to hold the timing gear when "tightening" the timing gear because it can place lots of stress on just a few timing gear teeth ........ instead, clamp a piece of wood to the timing gear to hold it steady."

Sounds about as intelligent as a one (1) tooth bar tender trying to open his customers' beer bottles with his one (1) tooth .... at close to 100 foot-pounds on a timing gear, something has to give.

In my opinion, just because the rag trick is written all over both Model A Forums, (maybe even also in our Model A Manuals), this tooth stress heresy may make as much sense as our former ancient World learning institutions preaching for centuries that the earth was flat.

Besides avoiding timing gear vibration ticking noises on bent timing gear teeth, Mr. Dan appears to be not only a timing gear expert, but maybe could teach one tooth bar tenders to use bottle openers. LOL

Just a timing gear parable experience..
 
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i think clamping the cam gear is an excellent idea. However, I have not been able to make it work; the gear still turns under the clamp no matter what
 
Mr. Tbird,

Same wood slipping experienced here when first tried because of lack of friction.

However, I next carved out two (2) approximately 1/2" wide arches, (same diameters as that of the timing gear x approximately 3-1/2"), across two (2) separate either 1x4's or 2x4's, & allowed the timing gear outer front & rear protruding arches to fit in the carved out wood arched areas.

Like brake shoe bands working on the principle of square inches of contact, these arches allowed an increased frictional contact area of wood to aluminum.

Also, when the outer ends of the two (2) clamped wood pieces contacted a solid object, the concaved arches applied a torsional force to the circumference of the timing gear, acting somewhat like a pry bar resisting the torsional force applied by the torque wrench.

Hope this helps someone installing a timing gear with clamped wood.
 
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