Ring and Pinion Backlash

Ken/Alabama

Ken/Alabama

Well-known member
I’ve rebuilt many early Ford rear axles over the years and have always set the backlash by feel. On the later stuff it’s easy to set up a dial indicator on the ring gear to check backlash but not so on a banjo housing. Just being curious I set up a dial indicator and measured off the pinion splines. Does anyone here use a dial indicator to measure backlash on the early Ford rears? It feels about right and I’m getting.005 measuring from the pinion splines. I put some blueing compound on the teeth and it’s drawing a good pattern across the ring gear teeth. Just curious if anyone here uses a dial indicator and what numbers your looking for at the pinion.
 

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I set the carrier bearings preload, then take out the carrier, then set the pinion preload, then I drop the carrier with the gear onto the axle tube, then fit it to the centre section with the preloaded pinion in it,I put a pile of the gaskets used to set the carrier bearing preload under the one axle tub to centre section,I ONLY PUT ONE axle tube on, THEN I have a length of threaded rod through the carrier and out through the fitted axle tube, I then tighten this up so the carrier is held firmly against the bearing in the tube, THEN you can have access to the gear and just use a dial indicator on the teeth, using the gaskets to set the preload,
when done, take the threaded rod out , strip the carrier and fit the axles and spider gears, then the other axle tube and remaining gaskets that you used to set the carrier preload.
this may seem long winded ,but its the way I do them and I do a lot of them ,
I have a chain vice set up on my bench to clamp the axle tub vertical.
Lawrie
Lawrie
 
Thanks Lawrie, I had thought about doing just as you described and wondered if it would work. The problem with this particular rear is that it’s a Columbia therefore the teeth on the ring gear can’t be accessed because of the planetary gear case. I have it standing vertically with the left housing removed so im looking at the backside of the ring gear. Thinking about sticking a magnet to the outermost edge of the ring gear and measure off that.
 
I have a little dial indicatyor (dial gauge in English)lol.
that I can stick in through the filler hole and get onto a tooth,
Let me know if you want a pic .
Lawrie
 
Another easy way to work on them is to install a backing plate on the one side and make a wooden support "box" to set the backing plate on - then you can easily work on the setup as it is supported in a vertical orientation.
 
The 1939 to 1948 Ford and Mercury Shop Manual page 261 states backlash should be checked on the splines of the pinion shaft. Never greater than 0.008” and more than 0.003”. At 0.005” you are golden right smack center. Hope this helps. I have been looking for these numbers.
 
Bored&Stroked said:
Another easy way to work on them is to install a backing plate on the one side and make a wooden support "box" to set the backing plate on - then you can easily work on the setup as it is supported in a vertical orientation.
Click to expand...

I have set them on an empty transmission case. The end of the axle housing sits on the output shaft hole on the transmission case.
 
Joe KCMO said:
The 1939 to 1948 Ford and Mercury Shop Manual page 261 states backlash should be checked on the splines of the pinion shaft. Never greater than 0.008” and more than 0.003”. At 0.005” you are golden right smack center. Hope this helps. I have been looking for these numbers.
Click to expand...

That is the way to do it. I have a large Ford literature library I inherited from my dad. There is one piece of literature I have, and I don't remember which one it was that I finally found the specs above, checked at the pinion spline. The old-timers told me the way they used to do it when they didn't have the specs was .001" for every inch of ring gear, to allow for expansion between the gears. That method is usually pretty close to what the specs are the ancient Model T guys said the thickness of a business card between the teeth. I always end up fiddling with the allowable range of backlash trying to get the best pattern.

A rebuilder of 9-inch rearends, that's all he does for a living, told me that the Artist canvas yellow oil paint from Hobby Lobby makes the best gear marking pattern compound he has ever used. I haven't tried it yet.
 
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Ken I set them to .003-.006 measured at the pinion splines and shoot for the lower number especially if they are new gears
 
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