You’ve got questions. We’ve got the answers—the Summit Racing tech department tackles your automotive-related conundrums. This week, we’re quieting down a noisy differential.

Q: I ordered a Richmond Gear 3.42 ratio ring and pinion set from Summit Racing for my 1989 Chevy van and had it installed by a shop I was told was reputable. They told me the gears would be noise-free. After driving the van about five miles, I could hear the rear-end whine at about 35 miles-per-hour.  When I asked the shop about the noise, they told me the gears would seat themselves after 200-300 miles, and that because Richmond gears are harder than stock GM gears, they would be noisy.

Well, after going back to the shop for new bearings and being told the noise was the rear universal joint (which it wasn’t), I have some questions to ask:

  1. Should a properly set up differential be noise-free?
  2. Could axle bearings produce a whining sound between 35-50 miles-per-hour?
  3. What could cause the whining sound under a load condition? There is no noise when the van is jacked up off the ground.
  4. Are the Richmond gears damaged?

I am in the process of pulling the gears out and checking things with my own setup gauge. I’ve already checked the backlash with a dial indicator (.009-inch). The wear pattern looks OK. I will be checking the pinion depth, which I think should be +/- 2.156-inch.

A: When installed correctly, Richmond 3-series gears like yours are quiet. Usually it is axle bearings, differential bearings, and pinion bearings that will generate a howling or whining noise. Incorrect gear mesh can also make that noise, usually the result of incorrect pinion depth.

When you recheck your setup, look for the plus or minus setting marked on the head of the pinion gear. Once you set this, the correct crush needs to be set to get the proper preload on the pinion bearings. Always use a new crush sleeve. The backlash needs to be checked in four different spots because of runout on the ring gear and bearings, case distortion, etc. After everything is set, use only synthetic gear oil. While this should cure the noise problem, you may still need to replace the existing gears due to the amount of miles on them.