Changing rear end gears.

[A/Fuel]

Back when a lot of cars I worked on had the old 9 1/2" rear, the pinion would crack just like that. Every week I was putting togather a new center section. The race gears have a higher nickel content that makes them softer, and in the catalogs they are usually labled. Driving them on the street for a long perriod of time will cause them to get hot and the lash will change. Lots of gear manufactures make street gears which hold up fine.

[TC]

I've seen that happen on several sets of OEM GM gears. I think race gears usually are softer so they won't fatigue crack like that, but they will wear faster on the surfaces of the teeth.

The pinion there is a Moser unit which is made by US Gear and they are race gears....... I think the difference is the OEM gears that do that have 10's of thousands of miles on them, where these Moser gears only made it 10-15 thousand miles......

[TC]

Back when a lot of cars I worked on had the old 9 1/2" rear, the pinion would crack just like that. Every week I was putting togather a new center section. The race gears have a higher nickel content that makes them softer, and in the catalogs they are usually labled. Driving them on the street for a long perriod of time will cause them to get hot and the lash will change. Lots of gear manufactures make street gears which hold up fine.

The thing that got me was that for the same gear ratio(3.73) the GM gears were physically bigger in size than the Moser gears where...... Put it this way the guy at the shop that redid the rear actually called the dealer to make sure they sent him the right gears because the size difference was so extreme.........