Sonny_T

Thanks to thirdgen members for infos that helped dare to take on tasks that I have never done before. Little past history. I had once BW 370 posi that went bad, and ended up replacing (not my preference) with 373 non posi 10 bolt form another firebird. Lately I found an 89 thirdgen BW 370. Once received and opened up, it ended up being 373 but rest were all BW 370 posi. Thirdgen member ‘Sofakingdom’ said that this 373 was aftermarket installation as BW did not make 373 for those cars on those days. Makes sense.
Bought the Australian posi (Part # tlvl) from ‘Supa F’ at Sydney Australia. Installation was simply a breeze. New bearing was installed by a machine shop. I had not needed any pinion gear head shaving. Total cost was below $1k (rear-end: 0$, rear-end shipping: $325, Australian carrier with shipping: $495 us dollars, shims and bearing: $60, bearing pressing: $10, dial test indicator: $25, other items like marking, gear oil, thread locker, gasket, sealant were another $70).

Few info that I gathered:

-The old and new carrier are amazingly identical when comes to weight, length & shape. I was told by the Australian guy, that any gear ratio in 3 range may not need any pinion head shaving.

-9 bolt BW rear-end has ring gear attached to carrier by 8 bolts. I went through a mini situation when I first opened the new carrier and seeing it had 8 bolt hole instead of 9. Well… I learned.

-Carrier bearing and Race: LM102911 (race) / LM102949 (bearing). Know that LM102910 is not the right race.

-My backlash average: 6/1000 (*gears being old, I thought it would be little more, but will take 6).

-Gear pattern: Matched for a used gear setting.

-I end up using old shims as is. Had no use of new shims. It made sense as I had deeply compared the new and old carrier of its entire length and ring gear location, and they were amazingly same to mm. I did try to add/subtract shims to see if it changes the pattern and actually it was going off.

-Gear oil used 85W140: 1.7 quarts. Thirdgen member ‘General Disorder’ said 85W140, and his logic made sense.

-Ring gear bolt torque was done via installing it in housing and placing rear-end on floor, putting a towel between ring and pinion, holding u joint with one foot, and torquing it in star pattern. Of course with each bolt tighten, I rotated ring gear to maintain star pattern. It took some time but was able to complete the job. I did not want to put in any jaws. These bolts are reverse threaded.Before putting together make sure both surface are super clean.

It is all set to be installed in car.

Sonny_T

Installation completed and have been driving since, with no issues. Car felt as original as it was, and definitely faster. 1K well spent.