built91Z28

I am using a factory center chunk from an 86(?) Bronco. I am going to be putting 4.30 gears in it soon and hopefully doing a bit of racing using big drag radials. I also have a manual trans so that may put more of a shock on everything. I'm hoping to get my motor in the high 11's. I am fairly certain that I'm ok for now on a stock center chunk, but how strong are these and when should I be looking to upgrade that to a Moser unit as well?

big gear head

You are going to be at the limit for the stock center casting. When you put those 4.30 gears in it you might find that when you set the backlash that the ring gear teeth hit the boss for the pinion pilot bearing. DO NOT grind the bearing boss for clearance. This will make the case weaker in an already weak area. The correct way to gain clearance is to grind the tip of each tooth on the ring gear.

built91Z28

Thanks for the heads up. Would 4.11's be any different?

big gear head

It depends on the gear manufacturer. Some of them cut the teeth back and some don't. Most 4.11 gears that I have installed didn't need any more clearance. The 4.30 also might not need it. I just wanted you to be aware of the problem and the correct way to fix it.

AlkyIROC

I was using a stock C7AWE casting with 4.57 and 4.86 gears and pushed it into the mid 9's with transbrake launches. One day I saw the pinion support o-ring was leaking so I pulled the support to change the o-ring. That's when I saw the pilot bearing casting was cracked. If that ever breaks off, it will spit the pinion out the side of the case. I now use a Moser aluminum bolt through center section.