measure and set differential backlash ?

[riverbend]

1940 H. I'm elbow deep in the guts of the back half of my H. The neighbor is going to machine for the worn bull gear hubs and make matching shims. While I'm waiting for him, I'm going to reset the backlash for the ring and pinion in the differential.

Using a feeler gauge is going to take a lot smaller hands or some clever way of reaching down along side the pinion shaft. Using a dial indicator is off by some 15 or so degrees due to the thickness of the gauge stem interfering with the next tooth. How is it supposed to be done ?

Best estimate, the backlash is <0.007 and should be closer to 0.010. I read that moving shims from the left to the right increases the backlash. How do I figure out how much to move the bull pinion carriers to get 0.003 more room ? Or should I move a thick, thin, or medium shim ?
Thanks
Greg

 

[Janicholson]

If this gear set has been operating as it is and shows no abnormal wear, and has been pretty quiet (none are without noise), do not change anything. you will be making things much worse. Running at .007 is just fine. The gears are worn into mesh where they are. They are happily married!!! to change them would be like wearing the wrong shoe size because they looked good. Jim

 

[rustred]

X2 do not touch that diff.! the gears are already worn in. its a one time operation . and when removing a crown and pinion to be reused u check the old backlash setting and set it back to the way it was. maybe do something else while waiting on him, like a christmas cheer!

 

[Duner Wi]

Tooth pattern for me is far more important than backlash. Especially true for used gears.

 

[riverbend]

The reason I want to adjust it is that several years ago I broke one of the bearing mounts off the differential and replaced it, using the original gears. I didn't think that measuring the backlash on a busted differential would produce a useful measurement. So it is noisier than it used to be. I'm back in there...

These things are never simple.

 

[rustred]

you cannot get an answer till u check you gear pattern. then post that pattern. this is eyes and hands on stuff. pattern and backlash go hand in hand.

 

[Janicholson]

Several years if used even weekly is enough to let it be. The bearings and noise associated with the bull gear issues you are tackling are more than enough to cause noise. I am an experienced differential mechanic, and recommend you to not mess with it. Your intention is OK, but the reading of gear patterns is a thing learned from experience and solid hands on teaching. This is a simple bevel gear system, but even then it is easy to make very much worse. Jim

 

[gbs]

you can lessen the noise by using unless straight 140wt gear oil instead of multi-viscosity type unless you are in a cold climate. also be careful as some of the gear oils may not be the wt claimed, I remember Daddy filling up the old m farmall with 140wt Sinclair brand and it poured like thick syrup on a cold morning even it was summer day, I was able to find some straight 140wt but don't remember the brand several years back that has worked ok in our h Farmall.

 

[Janicholson]

85-120 gear oil will provide a good compromise between the hot 140wt thickness, and 85wt cold behavior. Jim

 

[riverbend]

What is a DIY alternative to red lead or prussian blue ?

 

[Janicholson]

Tooth paste with food coloring. Blue or yellow. Clean it well! Jim

 

[D Slater]

Which side was broke? If left side and you put right side back like it was, backlash should stay the same. If right side was broken it's a best estimate or reading of pattern or leave like is.

 

[BarnyardEngineering]

Rustoleum. Just dab some paint on and create the pattern before the paint dries. Wipe it off with a rag.

 

[riverbend]

It was the right side. I put the shims back as they were but it whined right away.