does anyone know if this is the correct part no. 3967012, for a 70 chevelle
big block car with front disc brakes, these are a one piece rotor, did some of these cars have a two piece or were they all two piece rotors? thanks in advance. Jim

I'm thinking the early discs were two-piece--'67--'68. After that, one-piece rotors/hubs.

67 and 68 were two piece rotors.

I believe 70 was one piece.

Verle

Our '69s have their original two piece rotors. Replacements are one piece.

If I recall the two piece are neccessary for the four piston caliper on 67-68.

four piston calipers will not clear one piece rotors.
The rotors can be machined and/or grind on the bottom of the calipers to make it work.

Verle

69's also had the 2 piece rotors. My 69 has the original rotors and they are also 2 piece.

Our '69s have their original two piece rotors. Replacements are one piece.

69's also had the 2 piece rotors. My 69 has the original rotors and they are also 2 piece.

I learn something every day.

Do your rotors have an axial groove machined into the braking surface? That's all I remember from my '69. I was pretty sure it was a factory machining, not a matter of rivets digging into the rotor.

I learn something every day.

Do your rotors have an axial groove machined into the braking surface? That's all I remember from my '69. I was pretty sure it was a factory machining, not a matter of rivets digging into the rotor.


Mine do not. They are smooth.

I learn something every day.

Do your rotors have an axial groove machined into the braking surface? That's all I remember from my '69. I was pretty sure it was a factory machining, not a matter of rivets digging into the rotor.

If I recall the rotors on one of my Chevelles had one groove machined in the rotor about half way across the surface. I think it was an attempt to reduce noise during brake application.

I have seen several 70 SS with 2 piece rotors.

The early 70 disc brake cars did have 2-piece rotors. They were switched over to 1-piece about half way through the model year.

The original rotors from GM had a machined groove on them, both on the 2-piece and the 1-piece styles.