Hey guys i just picked up the 9 bolt rear that i have been talking about the last couple of days. I know that RB83L69 will be able to help me but any help from anyone else will be greatly appreciated. Anyway, i picked up the 9 bolt rear for my car today. I opened the back of the rear to look what gears were in there because the seller said that they were 3.73's from the factory. But i know 3.73's didnt come from the factory in 9 bolts. There were two stamps on the ring. The one stamp looked like this 3 70 D. then there was also another stamp stamped in yellow that looked like it said 4G 14. I was wondering if you guys could help me with what these numbers and letters mean. THANK YOU GUYS!!

 

Sounds like you just bought yourself some 3.70 ratio gears What year car did they come from, 85?

 

Yeah that would be a 3.70 gear ratio. I dont know what you have not but if you went from 2.73 one leger to this rear, whew what a difference. Have fun man

 

Yeah, sounds like 3.70 gears. Nice find. The 9 bolt 3.70 rears were rare.

 

they had a 3.70 in a 9 bolt i dont remember seein that in any tech articles must have been really rare

 

These guys are right, there was a 3.70 ratio, and it sounds very possible that you have one. They most commonly (?) came in 85 T/As with L69, and might have been available as a special order item in some years and drive train combos but I don't know that for sure. There aren't a whole lot of them in the world.

If that's what it is, that's a great score. A highly sought after combo.

Count the teeth; it will be 37 on the ring and 10 on the pinion if it's 3.70.

 

YES!! 3.73's 9 bolt came from factory (Borg Warner) even with disk brakes.

 

3.70, not 3.73

 

Right; no 3.73 9-bolts from the factory, only 3.70. Very close but not quite the same. 10 & 37 instead of 11 & 41.

For some reason, the BW gear sets seem to have fewer pinion teeth for an equivalent ratio than the 10-bolts do. 3.27 instead of 3.23 (11 & 36 rather than 13 & 42), 3.45 compared to 3.42 (11 & 38 vs 12 & 41), etc.