FACTORY 79-81 DISC REAR INTO 71 OR 80 BIRD
 

After about 30 years I've finally decided to revisit swapping a 79-81 factory disc rear into either my 71 or 80 drum-rear birds and have forgotten what needs to be changed-- just the master cylinder and prop valve or also the booster as well? ...and in the case of the 71, what e-brake cables would I use, since the 74-dn & 75-up bodies are slightly dissimilar? Thanks in advance...

When I switched to factory rear discs on my 80, I didn't change the master cylinder just the proportioning valve. I used E' brake cables I purchased from The Parts Place. I installed the caliper brackets reversed (RH on LH side) and I couldn't get the cables to work. If I remember correctly the caliper bracket with the "R" on it needs to go on the LH side. Be sure to get that right and the rest was easy. FWIW the brake pedal felt crappy after the conversion and I was disappointed until I hit the brakes from 130mph and couldn't believe how much better the discs grab. However if I just street drove the car I'd be happier with the drum brake set up.

I have collected rear disc parts over the past 40 years or so and have accumulated 4 or 5 sets. With that being said I wouldn't use that system on a bet unless it was some matching numbers situation. The S10 set up far superior and if done by searching the parts can be done for about $300 bucks. I have used both and the S10 set up works great. The Ebrake on the T/A set up is nothing but aggravation unless you are familiar with how it works. JMHO.

If those are the same as the El Dorado rear brakes, then X2 on the parking brakes. Basically, they work great if you spend a couple hours every month adjusting them and NEVER park the car without setting them. I had that kit on my car, and ended up throwing it away and starting over.

Will the S-10 calipers bolt up to a 79-81 WS6 disc brake rear? Any other options that will work better than what came on these cars?

If you collect the right parts its a bolt on. Granted requires a junkyard visit and some parts collection. There have discussions all over the boards about this. I have done two myself. A straight S10 set will give you fantastic brakes. On my car (71 T/A) I have upgraded the S10 set up to 12" rotors with Wilwood calipers(Really because my aftermarket wheels have big windows). The nice thing about the S10 set up is the E brake system. IDK what your budget is like but Wilwood has a bolt on kit that goes straight to 12" brakes using 1LE baking plates. Either way you get shoes for an E brake. Everybody else's kits uses a ratcheting caliper or at least one that has some kind of lever to physically move the caliper piston. Rotors with hats are best. JMHO

Picture with old and new set up, both using S10 backing plates and E brakes.

Attachment 566409

Attachment 566410

FYI, you CANNOT run "15 Honeycomb wheels on 79-81 disc brake rear without 1/2" of wheel spacers and longer studs.
Grinding the calipers doesn't get the job done.
Note I said " Honeycomb " , NOT Snowflake.

Did it on my 72. Went with WS6 smaller master cylinder and ended up having to use either two L or two R e brake cables.

Agree the e-brake was a bitch to adjust.

Went with Kore3 C5 calipers/rotors up front.

Still don’t love the pedal feel.