I've read that the 4th Gen rear end's bolt right in to the third gen cars. But if your 3rd gen is drum in the rear do you have to change anything for the new disc brakes on the 4th Gen rear end?

 

HAVE TO? No. Some will change out the proprtioning valve too, some won't. It's a LONG standing "arguement" here on TGO to do it or not, that will never be solved!

 

yea someone needs to do some kind of controlled test w/ a drum valve and a disk valve, but that still wouldn't end it

 

I swapped in LS1 rear disks about a year ago and firured what the heck, might as well try it with the disk/drum prop. I had a disk/disk prop sitting there anyway. I made a trip around the block and immediately pulled the disk/drum off and put the disk/disk prop on. The car didn't stop for crap, even with the 13" wilwood brakes I designed and built for it on the front. Was a major difference with the 4 wheel disk prop valve.

 

Change the proportioning valve for the best braking performance. Proportioning valves were designed to optimize specific systems: disc or drum. While the car will stop without the appropriate valve, the system won't be at its best, and if the system isn't going to be at its best, why swap in bigger/better brakes at all.

To the OP, check the following FAQ for more info on what you'll require for the swap:

https://www.thirdgen.org/forums/tran...-10-bolts.html

JamesC