Denis.V

Hi,

I bought 1 master bearing kit for my 1986 Pontiac Firebird Trans Am auto with Borg Warner 9 bolts rear axle.

This kit includes the main pinion bearing with race p/n 89410 (large), but my original race Timken made in Australia is p/n 88610 (small).

What is bad with this?

Please help,

Thanks in advance

erik69&85

iTrader: (1)

Which pinion bearing are you referring to?...there are two... The inner towards the axles and the outer toward the yoke... The outer is smaller, the inner is bigger....

I am guessing by "main" you are referring to the inner... I am not aware of them ever being different...

Denis.V

The "rear" bearing. This is the bearing towards the rear axle.

For this unique rear pinion bearing, Borg Warner manufactured different rear axle housing, which requires different bearing/races as spares.

My rear axle has a 88610 race; other axles have a 89410 race (small vs. bigger).

TTOP350

iTrader: (8)

Checked specs for those and one is 3.00, the other is 2.8 ish.
I looked up the part number for the bearing in my GM parts book, there are 2 different numbers (22510042- listed as 89 and 454587-listed as 85-90) but I couldn't find specs on why.
Only guess I could have is disc/drum or gear ratio split for some reason.

Edit: the one I looked at for 89 is the 7.5 ring 10 gear and not the 7.75 9bolt. So parts book only lists one of those for the 9bolt. Maybe you got sent the wrong bearing by mistake.

Denis.V

Mistery solved?


rock auto lists the small 2.8 inch. race diameter ( 2 27/32" ) as GM S604 for PONTIAC FIREBIRD 1985-1986 only (Camaros not included).

Also, 9bolts.com confirmed to me that there were 2 sizes for these GM cars equipped with Borg Warner diffs.