Hello.

My brother's '71 442 was built in Framingham, MA and had the round cover with the 12 to 3 brow and had the 3.42 anti-slip rear axle. Supposedly, all of the Cutlasses/442's built at the Lansing plant had the round cover/brow carrier. So far, I've only seen 3.08 and lower numerically gears/codes axles with the Buick type scalloped rear cover & carrier, both open & limited slip, that was also installed that year and 1972. Could it be the ratio that dictated the carrier used? Is the Buick type carrier inferior to the Oldsmobile carrier? Since Oldsmobile offered the W-27 cover for '71 A-bodies, was the round W-27 cover only offered for certain rear axle ratios?

Anyone know the answers to these questions and the carrier usage in the '71 A-bodies?

Thanks,
Anthony

 

There were 2 castings available for the 71-72 8.5" 10-bolt.
The O-casting had a large "O" on each side of the pumpkin,between the large ribs,where the axle tubes press in.This style came with the round cover,with the brow protruding from 12:00 to 3:00. This style came in all Lansing-built cars,regardless of ratio. There might have been other plants that used them.It might have depended on location of the plants,and which one was closer.
The second type is the A-casting.This casting has an "A" on each side of the pumpkin,between the webs,and a large "A" on top.This style had the cover with the notches at 9:00 & 3:00.This style looks like a BOP 8.2",but is not.This style came under all the 71-72 Buicks,and most if the other plants that built the Cutlass/442 used this style.This style also came with brake drums that had the Buick trishield cast into them.I have had countless Cutlass/442's with this rear,and had the original Buick drums.Yes,and Oldsmobile came with Buick drums,if it had this rear.The stamped code on the tube will also have "B" for Buick plant.
The W27 cover will fit on either style if casting.
The round cover will fit in either style of casting,but the notched cover will only work on the A-casting because the O-casting has oiling holes on the outside of the carrier bearings,and the notched cover will expose these.
Whether your Brother's car had the original rear,not sure. Did he but the car new? A lot can happen to this stuff in 42 years. I know the Arlington & Fremont cars used the A-type. I don't think I have owned a Frammington 71-72. 70,yes,but those all had the 12-bolt O-axle.

 

Hi Brian,

Thank you very much for the information.

My brother did order the 442 brand new in January 1971, and was built at the Framingham plant with the 8.5 10-bolt rear with a 3.42 limited slip - round cover with 12-3 brow.

Since the Buick type rear did not have the oiling holes on the outside of the carrier bearing, were they oiled from another location?

Does the Olds installed Buick rear have the single "fin" on the carrier, unlike the Olds carrier that has the twin parallel "fins", and the Pontiac rear that has converging twin carrier "fins"?

Thanks again,
Anthony

 

Both styles of the 8.5" 10-bolt have the parallel ribs on each side of the pumpkin.
The Buick 8.2" 10-bolt has a single rib on each side.
The Pontiac 8.2" 10-bolt has two converging ribs on each side.

As for the oiling holes,the A-casting did not have them,but didn't do anything different to make up for them. In my opinion,both styles of rears get plenty if oil inside. I haven't seen any bearing issues or lack of oil issues.

 

You have to remember too the oil turns into water liquid viscosity when hot. it will get to the axle bearings + the casting is sometimes cut away behind the carrier shim that is a very common practice now to let the oil get past the carrier bearing pressed against the casting.

JUST be sure you check your oil level at least twice a year beginning and end at the very least.

You can tip the passenger side of the car up with a jack to get a few couple extra squeezes of oil in the rear too. DO NOT OVER FILL TOO MUCH just a little extra. Jim

 

Thank you Brian for the information.

 

Thank you Jim for the information.