[Schurkey]

Originally Posted by grivera

Does upgrading front from 11” to 12” disc require different spindles or caliper brackets?

Originally Posted by Scarebird

yes, and only works on 1970-81 Firebirds.

For the record, the " spindle" is the steel "rod" that's pressed-into the iron casting; together they're called the "Steering Knuckle". The iron casting also includes the caliper mount, if we're talking about the OEM GM A/F/X/B/C steering knuckle design--essentially the same geometry although several different casting numbers/part numbers owing to different bearing sizes or casting revisions. The 12" knuckle/rotor system fits heaps and piles of GM vehicles including those retrofitted with the H-O Racing "Tall Spindle" disc brake conversion for '64--'72 A-body.

[grivera]

Originally Posted by Scarebird

yes, and only works on 1970-81 Firebirds.

Originally Posted by Schurkey

For the record, the " spindle" is the steel "rod" that's pressed-into the iron casting; together they're called the "Steering Knuckle". The iron casting also includes the caliper mount, if we're talking about the OEM GM A/F/X/B/C steering knuckle design--essentially the same geometry although several different casting numbers/part numbers owing to different bearing sizes or casting revisions. The 12" knuckle/rotor system fits heaps and piles of GM vehicles including those retrofitted with the H-O Racing "Tall Spindle" disc brake conversion for '64--'72 A-body.

So this means upgrading a 1st gen bird to 12" front disc brakes from a late 70's A body would require swapping in the steering knuckle - is geometry the same?

["QUICK-SILVER"]

Originally Posted by grivera

So this means upgrading a 1st gen bird to 12" front disc brakes from a late 70's A body would require swapping in the steering knuckle - is geometry the same?

I was thinking 72 was the last year for two piece steering knuckle. For first gen birds, the bolt on arm, for tie-rod, has to be retained. You swap the arms to convert from front steer to rear steer.

Seems like wheels set to the outside an inch or so further after the swap.

Clay