What grinds your gears?
Is it prematurely worn or chipped teeth? Or an ominous clunking sound?
These symptoms can be signs of a fairly serious problem with your ring and pinion gears, so it’s time to consult with the doctor—the gear doctor. In this case, the gear doctor is the Summit Racing technical department, which helped us compile this quick guide to diagnosing common ring and pinion issues.
Before we get into the specific symptoms, it’s important to determine whether you’re using the proper gears for your vehicle. Here’s a breakdown of the three specific types and their intended purposes:
- Street Gears (OEM type): These gear sets are designed for mild performance applications in which comfort is a factor. They are cut like an OEM gear to keep gear noise or whine to a minimum but are made from a higher grade alloy than OEM.
- Performance Gears: These gears have teeth that are cut differently than the OEM version to make them stronger; however, they are often noisier than OEM.
- Pro Gears: These gears are for drag racing only and cannot be used on a street vehicle. Produced by Richmond Gear, Pro Gears are made from a softer, more malleable alloy to resist breakage under harsh conditions.
Once you’ve determined that you’re using the proper gears for your application, you can start looking at other causes for premature wear or unusually noisy performance. According to Summit Racing, here are some of the most common problems and causes:
Problem: Gears make excessive noise.
Possible Cause #1: It’s possible this noise is just normal, depending on the gearing you have. Remember, numerically higher gear sets (3.73 or higher) are typically noisy by nature because they use a pinion gear with very few teeth and are cut differently than street gears.
Possible Cause #2: Excessive noise can also be caused by improper spacing. Because aftermarket gears can require different spacing than the OEM set, you can’t use the old shim spacing. To ensure proper installation, you’ll need to determine the proper spacing by using a pinion depth setting too .
Possible Cause #3: If spacing is correct, it’s possible that improper tooth contact could be to blame for excessive noise. After the gears are installed using a pinion depth setting tool, you should always check the wear pattern using a marking compound. You should see the wear pattern closer to the toe of the tooth with most gear sets.
Problem: Teeth on the gear set are excessively worn, chipped, or broken.
Possible Cause #1: As mentioned above, aftermarket gears can require different spacing than the OEM set, so you can’t use the old shim spacing. Again, you’ll need to determine the proper spacing by using a pinion depth setting tool to ensure proper installation. Improper gear spacing will lead to wear and damage to your gear set.
Possible Cause #2: Worn carrier or pinion bearings can create excessive play between the gears and produce an uneven wear pattern or chipping teeth. Check for worn bearings and replace as necessary.
Possible Cause #3: Incorrect backlash can lead to damaged gear teeth. The backlash setting, which affects how much fluid gets between the teeth of the gear set, should be set between .006 and .009 inches. If this setting is not correct, it may cause overheating or damage to the gears.
Possible Cause #4: Improper break-in will lead to premature wear. Make sure to always follow the break-in procedure outlined in the manufacturer’s instructions. As a rule of thumb, new gear sets should used lightly for the first 20 miles and then allowed to cool down. If driven too hard, the gears will wear early and cause excessive noise.
Problem: Gears “clunk” from a dead stop.
Possible Cause #1: Does the “clunk” sound only occur when your vehicle starts to move? In this case, the gears typically aren’t the problem at all. Instead, it’s often a loose pinion yoke, bad U-joint, or worn transmission making the noise.
Possible Cause #2: A second possible cause is the crush sleeve. If the crush sleeve is not crushed properly, the pinion yoke will be loose and the pinion bearings will not be seated correctly. Keep in mind, it typically takes 300-400 ft.-lbs. to effectively crush the crush sleeve.
Problem: Gears have been getting louder with time.
Possible Cause #1: Improper break-in can cause gears to become louder with repeated use. As we outlined above, new gear sets should used lightly for the first 20 miles and then allowed to cool down. If driven too hard, the gears will wear early and become increasingly noisy.