I am slowly starting to put the differential back together in Henry, and I'm making a parts list. I plan to replace the ring gear because it's pretty chewed up,
And I know it is recommended to replace the pinion along with the ring gear, but the pinion gear doesn't look too bad.
I have a suggestion. Try installing them on the loose side, ie 15 thou lash, maybe a bit more. I suspect you'll have a much better chance of avoiding gear noise.
With or without replacing both?
Luke, the wear on your ring gear is typical of there being too much backlash. If you can get hold of Ted Aschman's "Tinkerin' Tips" volume two, on page 33 there are drawings showing how the gears should mesh. You will see that backlash is not the only adjustment needed to get a correct mesh on the gears.
Hope this helps.
Allan from down under.
I put mine together just like the Ford book says!
Ford didn't have time to check backlash and thus fit the gears with a large nominal backlash so they wouldn't ever get too tight in production. We see the result when opening original rear axles - always wear on the ring gear, even on cars with seemingly low miles.
Today new gears are expensive and only sold in sets with the pinion, so no saving by reusing the old pinion unless you're really lucky in finding an old NOS ring gear or a very low miles used one.
Without the assembly line stress we can take the time to check the fit so the backlash is in the 0,010-0,020" range, thus it'll hopefully last a long time.
I put mine together with worse, You'll get 2 years driving from that crownwheel but if you get a new one it won't wear out the pinion anywhere near as fast.
Forget about backlash.
Those gears were not set-up correctly to begin with. The tooth face wear, concentrated at the outer ends of the gear teeth, indicates that you did not have proper alignment to begin with.
You can probably re-use your pinion gear. Next time you assembly everything, mark the faces of the gear teeth with a magic marker, or prussian blue, and rotate the gears. Make sure the contact between the two gears occurs evenly across the whole length of the tooth face, as evidenced by the marker being rubbed off in those areas. Then roll the gears together and note how smooth they roll with each other. You want to feel a nice smooth action with no "bump, bump, bump" as each tooth comes into contact with the next. After that, you're pretty much done. Notice, I didn't even mention backlash! Why? Because when the gears are properly aligned, the backlash will take care of itself. You don't set the backlash, you set the mesh and alignment. I don't even bother to measure backlash, just confirm that I have some.
I'll say it again: You don't set the backlash, you set the mesh and alignment.
Hooray Jerry! I totally agree with your last sentence.
Setting backlash will get the rear end to work. The time constraints on the production line meant it just had to work. Does the phrase " Near enough is good enough" ring a bell.
Getting the mesh correct is something we can do with time on our hands.
In addition to the work you suggest, there can be consideration given to getting the wear pattern in the correct place on the face of the gears. If the blue indicates that the gears mesh towards the top of the gear face, the pinion gear needs to be deeper in mesh. This can be adjusted by removing the paper gaskets on the spool. Conversely, if the wear pattern indicated is deep on the gear face an additional gasket can be used to reduce the gear mesh.
Setting the gear mesh can be a PITA, especially if the pinion needs to be deeper in mesh, but it is worth the effort, given the price of a new set of replacement gears today.
Hope this helps.
Allan from down under.
Thanks for all the replies. Now I guess I need to decide whether I want to use the gears I have or spend the money and buy new ones.