question 12 bolts Posi

The 12-bolt rear axle has anvil-like durability and is among the strongest ever to make it into a passenger car; to withstand 460-lbs.ft. of torque, it had to be. The only rear axle available came with a 4.10:1 ratio with a special heat-treated ring gear. This rear differential included a special heavy-duty Positraction case with unique parts not interchangeable with other 12-bolt cases. The code for a COPO Chevelle is KQ.

redge a écrit:Je pense que c'est juste les clutch qui sont différente

COPO 12 bolts 3916234


Here are the part numbers from the COPO differentials.


The carrier case is the standard 30174 case that has different internal machined dimmentions to allow the larger axle and pinion gears to fit properly.

3916234 Differential, w/case (special diameter)
3918831 Gear, Differential (special diameter)
3918832 Pinion, Differential; ECN May of 69
3918833 Washer, Differential Pinion Thrust; ECN May of 69
3881140 Pinion, Differential
3881141 Washer, Differential Pinion Thrust
3918834 Plate, Differential Clutch Pressure
3957939 Spring 75lb. each (natural color)

3917971 Gear Assy, 4.10 ring and pinion, speacial heat treat
3917973 Gear Assy, 4.56 ring and pinion, speacial heat treat
3917972 Gear Assy, 4.88 ring and pinion, speacial heat treat

Notes:
3918832 Pinion, : 9310 alloy to match axle gear
3918833 Washer, : has no indexing shoulder
3881140 Pinion, : 8620 alloy
3881141 Washer, : has indexing shoulder (pain the ass to assemble with these)

The "KM" is the standard duty 4.56 (3862515-3862527) rear just like the "KK" is for the standard duty 4.10.
This KQ rear has the correct 3916234 posi unit and the 3917973, HD 4.56 (3916230-3916231)special heat treat, gearset in it.

COPO/9511DT is a 1969 Camaro with 4.56 rear axle ratio
The 9511DT code is from a factory ordered L72 Camaro with 4.56 gears [(3916230-3916231)set number 3917973].
COPO/9511CB = 4.88 (3862528-3862516)