using of dial indicator (rearend)
using of dial indicator (rearend) 
TECH Enthusiast
Joined: Jul 2003
Posts: 697
Likes: 0
From: Evansville, IN
What do you want to know? The pic is setup to check backlash. You hold the pinion and case still, and rotate the ring gear back and forth. The dial will indicate the amount of gear backlash you have.
TECH Resident
Joined: Oct 2005
Posts: 781
Likes: 0
From: Taxme, Ohio
^ He's right of course. I did mine with the differential installed because my axle doesn't have a third member like the Ford 9 inchers. There was about .005 of free movement. I also put the stem to the outside diameter of the ring to check for run-out. I saw about .004 TIR.
Anyway, that one inch travel dial is connected to a magnetic base. The dial and base have what is called universal swivel clamps. This allows you to place the magnetic base on a flat surface such as the machined housing face you see in your pic. With the swivel clamps you position the tip of the indicator stem on the face (side) of one ring gear tooth. As you can see, the indicator is near the outer edge where free movement would "show" the most easily. One inch travel dial indicators with a magnetic base and swivel clamps are so incredibly inexpensive compared to the days when I was buying my machinist tools. Something like $40 gets you a nice set-up. I paid 3 times that 35 years ago when a $5 hourly wage considered good money.
Anyway, that one inch travel dial is connected to a magnetic base. The dial and base have what is called universal swivel clamps. This allows you to place the magnetic base on a flat surface such as the machined housing face you see in your pic. With the swivel clamps you position the tip of the indicator stem on the face (side) of one ring gear tooth. As you can see, the indicator is near the outer edge where free movement would "show" the most easily. One inch travel dial indicators with a magnetic base and swivel clamps are so incredibly inexpensive compared to the days when I was buying my machinist tools. Something like $40 gets you a nice set-up. I paid 3 times that 35 years ago when a $5 hourly wage considered good money.
