Overview
The G2 GM 8.5-inch and 8.6-inch 10 bolt aluminum cover in black (part number 40-2021ALB) is made for GM 10 bolt rear axles of those sizes. It is cast from lightweight aluminum and finished in black powder coat.
The cover protects the ring and pinion while helping cool the gear oil. Reinforcing ribs add rigidity, and the cover is heat treated and shot peened to resist direct impacts.
Black powder coat gives the cover a uniform finish over the cast aluminum, and the ribbed, heat treated construction is what gives it strength.
Key features
- Cast from lightweight aluminum to dissipate heat
- Black powder coat finish
- Reinforcing ribs for rigidity and strength
- Heat treated and shot peened
- Fully machined seal surface
Care for a differential cover
A differential cover is a simple part, but it does real work. It seals the housing, holds the gear oil and takes road debris and rock hits from below. Inspect the cover and its gasket whenever the oil is changed, looking for dents, cracks, weeping or loose bolts.
Aluminum covers are light and shed heat well, but they need careful handling during removal. Clean the sealing surface thoroughly before fitting a new gasket, and avoid overtightening bolts into the soft housing threads. Setting the cover squarely before the bolts are snug helps prevent leaks.
- Check the fill and drain plugs for seepage after the first drive
- Replace a gasket that has hardened or torn
- Use the correct gear oil for the axle and check the fill level
Specifications
| Brand | G2 Axle and Gear |
|---|---|
| Part number | 40-2021ALB |
| Axle location | Rear |
| Axle types | GM 10 bolt 8.5 inches and GM 10 bolt 8.6 inches |
| Material | Aluminum |
| Oil capacity | Extra capacity |
| Finish | Black powder coat |
Vehicle fitment
This is an axle part for GM 10 bolt rear axles of 8.5-inch and 8.6-inch size. The cover is written for the axle width rather than a vehicle, so confirm that before ordering.
Installation notes
The seal surface is fully machined, and the cover should be set squarely on the housing before the bolts are tightened.
