The Stovebolt Site Forums The Shop Area Driveline Why does the 1/2 ton truck rear end need this but car does not?

Why does the 1/2 ton truck rear end need this but car rear end does not?
Part is installed on pinion gear shaft, in front of rear bearing snap ring.
What is its purpose?

1940-1954 Chevrolet Pickup NOS pinion flange retainer, part #3653622
eBay item --- Photo

1929 - 1957 Chevrolet Master Parts & Accessories Catalog
5.468 Retainer, Pinion Flange Packing
40-42 Comm.
46-54 1/2 ton part #3653622

1954 truck rear end General Description & illustration --Snap ring & Retainer are there but not pointed out. They are in front of arrow #4.
1949-1953 Passenger car rear end illustration--Snap ring, NO Retainer ---- General Description
Passenger car drivetrain cutaway (Scroll down) It shows 5.489 Ring (Snap Ring) but not retainer.

1954 truck shop manual, Under "Assembly[/b]" 1/2 ton axle
Number 2. Thread [b]pinion bearing oil retainer.......

1949-1953 Passenger car shop manual, Under "[b]Assembly[/b]" axle
NO oil retainer mentioned.

I have just suffered a rear pinion bearing failure. I found the snap ring, and the fat roller bearings from inside that pinion bearing. Loose in the "banjo" housing. If the flange backing had been in there I would have had noise instead of chewed up and busted parts. Why in the truck and not in the car? Best guess(and this is a guess) the force and pressure in the truck is much higher.

Was your rear pinion bearing failure in a truck axle or car axle?
What year, make, and model is your vehicle?

The truck axle is made of a heavier construction than the passenger car axle.
Read Here Under
>Rear Axle Assembly, 1/2 ton and 3/4 ton trucks
>Pinion Assembly---1/2 Ton Model
>Axle Shafts

Looks like the purpose of the pinion bearing oil retainer is to slow the flow of gear lube into to the axle housing,
which helps to maintain a bath of gear lube on the front pinion (thrust) bearing.

47-51 truck rear axle. Bolted to a 52 truck. Good times inside that mess. Found the snap ring and the rollers in the pumpkin. Mostly chunks for the snap ring. The bearing rollers were whole, and chipped. Some very interesting carving where the pinion gear met the carrier body. Looks like course threads with a steep pitch angle. No real harm to the big parts. But the pinion gear and the ring gear are done. The pinion and drive shaft are free to move a lot.

In your previous Post you said that the axle you are repairing
did not have a pinion bearing oil retainer. Is this True?
According to the master parts catalog, that year of truck axle should of had one.
If that is the case, I wonder why?
Maybe that helped facilitate the failure.
I have seen those carvings in the carrier body before, but never knew how they were created. Now I know.
Carrier housing gouges
1951 Chevy 1/2-Ton pinion gear with bearing oil retainer just to left of the rear bearing.

Nice photo!

Source:--Stovebolt Tech Tip
Sweet photos, SWEET

yep. That picture is just what I have after the fail. No flat washer behind the snap ring. When the rollers escaped the race, they snagged the snap ring, and crunched it into chunks. Then the pinion moved out into the carrier. The whole thing got very loose and made the drive shaft whip inside the torque tube. Took the Bushing and the yoke with that much motion. The rest of the rollers came loose and tried to get between the pinion and ring. The only good news, I was at a dead stop. No busted teeth and no exploded bits. But the truck would not go forward. had to back it up into the street and then shuffle into the drive. Awkward. The funky grooves on the carrier were what happens when the pinion gets that far into the differential.