I plan on swapping out my 2.73 limited slip rear end for a 9 bolt posi with 3.27's. my question is do I need to change the master cylinder or was in the same in all models of the iroc?

 

Swapping complete rear axles....All you will need is the Proportioning valve and the parking brake cables from the 9-bolt. The master cylinder dose not need to be replaced.

 

If you're swapping disc to disc (82-88), you need do nothing where the combination valve or master is concerned. You'll, of course, need to change to drive and/or driven gear to make the speedo read correctly.

JamesC

 

2:73 10-bolts in most cases did not have rear disc brake and he will need the Proportioning valve. I know, been there and done that swap.

 

If that's the case, the OP will indeed require a disc combination valve. Perhaps he'll chime in and tell us exactly what he has so that guessing is no longer an issue.

JamesC

 

If the change involves a change to or from the cast-iron calipers, to or from ANYTHING else, a new combo valve will be required.

If the change is from drums to PBRs (aluminum), the existing one will work fine.

The key here is not "9-bolt" or "3.27"; it's the calipers, both the new and the old.

 

I have the complete rear end. It doesnt currently have disk breaks, and the 9 bolt does