***9" Axle Gurus...Ring gear dug into pilot housing!**

[chuzie]

Okay fellas, I have a situation here and am seeking further guidance as i intend to purchase replacement parts first thing in the morning...

SETUP: I am running a '74 axle housing with 4.56 USA standard gears, Grizzly locker, and 31 spline chromo axles.

This third was setup about a year ago with 100% new stuff. There were ZERO clearance issues at the time.

INITIAL ISSUE: The pinion nut backed off when driving on the interstate. It was a slow process and initially made my coast sound extremely loud. I pulled over to inspect but did not see the loose nut and continued. Later, the coast sound became exponentially louder. I then lost power and pulled over.

The pinion yoke, u-joint, and slip shaft we gone! The pinion was canted to rest at the 7 o'clock position and would not move by hand. We had a wrecker tow it home on a flat bed.

CURRENT ISSUE: I am not in Charleston right now so I had someone pull the pinion support and pinion to get an initial damage assessment.

He said the gears are obviously toast but also noticed that it appears the ring gear has worn a notch in the pinion pilot bearing housing. (see picture with arrow below).

As of now, I intend to order: pilot bearing, 2 pinion bearings, R+P, and gasket / o-ring. We still have plenty of shims from initial setup so that is not a factor.

I plan to pull the 3rd member out when I arrive in Charleston on Monday to complete the inspection and, depending if the new parts have arrived, begin the repairs.
[SIZE="3"]
My question to you gurus is... What could cause the ring gear to notch the housing like this? Are there other factors I should be considering? What am I missing here?[/SIZE]

Thanks,
Mike 8-)

[broncosbybart]

Usually on a thicker gear the case needs to be ground in that area. It is possible that the carrier preload wasn't high enough and the carrier was able to move some side to side. I'd just grind it a little more and checking clearance before re-assembly. I wouldn't be worried about it. Plan on new carrier bearings and ring gear bolts as well. They aren't that expensive.

Also, were you running a crush collar or a solid shim kit for the pinion preload? I'd get the solid shim kit. You won't ever have to worry about the pinion nut backing loose again with one of those. Get a couple of pinion nuts- 1 for setup of the preload shims and 1 to use when you get it set and finalized. You'll need a new pinion seal. Forget about the O-ring, it will be fine. I like the lube locker gaskets, too.

[chuzie]

Good info. Well, if I am going to go with new carrier bearings, I might as well well go for the full setup kit.

Thanks.

[broncosbybart]

Yep, I'd just get a full install kit as well. Just make sure what carrier bearing size you have. 2.89 or 3.06" OD. Keep us updated.

[chuzie]

2.89

I ordered everything for just about $300.00. We shall see what happens.

[broncomatt]

I bart is right on, the case if it was OE 350 would need to be ground in that area. But since you didnt notice it when setting it up means the adjusting rings backed off. It shouldent hurt anything. If you need the torqe wrench for the pinon nut or for the pinion preload (180ftlbs, 20inchlbs) or the dial indicator to get it set up. Let me know I have all of them and if you want to have me set it up just wing by with the parts.

[chuzie]

Thanks for the heads-up.

Buttoned it up today. Preload, backlash, and pattern are all spot on and she tested good on the road. Good to have the old girl back in operation; one step closer to recovering from that disaster of a weekend!

[chuzie]

BTW- I made an arm extension for the torque wrench to get it up to 180ft-lbs since its max was 150. Worked like a champ on the bench but not too fun under the truck at it is 3' long with extension and wrench!