i have an 1984 Z28 with the LG4/auto combo. out back is the original 10 bolt drum brake rear with peg leg 3.23s. i just aquired a 88' GTA parts car with the 9 bolt disc brake rear (3.27 posi). i want to swap the posi rear from the GTA into my Z28. my main concern is if the brake lines from the drum rear will bolt up to the disc rear... or would i have to swap the drums onto the new diff to make everything line up? what other kinds of problems am i going to run into? thanks in advance

 

You will probably have to get an adapter fitting (or 2) from Napa or someplace to connect the brake line on the body to the brake line on the rear. I put an 87 disk brake 9 bolt in place of my 88 drum brake 10 bolt in my Camaro and had to do that. You will also have to install the disk brake proportioning valve. Other than that, it should fit directly.

Miles

 

I did the EXACT same swap, same gear ratios, years and all! My car's a 84, and now I have a 88 9 bolt in it. My rear was toast!

I changed NOTHING at all to connect the line at the rear. I changed the master cylinder and combination valve as a unit. The master cylinder IS different for disc brakes, the bore is like 1/16 larger for disc than for drum. The only thing I had to change (Other than the diff fluid) was bending one of the brake lines. One line (I think it was to the rear brakes) entered the combo valve differently. There was lots of line there, so I had plenty to bend. I can't guarentee that you won't have anything to adapt, but I didn't. It was a pretty easy swap!

I also snatched up the sway bars, the wonder bar, and a few other things. Good luck with the swap!