Rear drum-to-disc E-brake cable mod

[iTurbo]

So I'm working on this '84 Plymouth Reliant that my older brother got. I'm converting it to 4-wheel disc brakes using hand-me-down parts from my '87 Shelby CSX.

Right now I have most of it all bolted on but am working on getting the emergency brake working. My original plan was to use the rear-most e-brake cable from the CSX since it was designed to work with the disc brake backing plate and e-brake drum internal to the rear rotor. That did not work because the CSX e-brake cable was about 12" too short to reach the intermediate cable on the Reliant.

So now the plan is to modify the rear-most e-brake cable that is original to the Reliant. The problem I'm running into now is the release spring is too long. With the original e-brake cable inserted into the disc back plate and hooked up to the adjuster properly, it reaches the point of spring bind before the e-brake shoes even start to move out.

I'm thinking I should start trimming the spring length down. Comparing this Reliant e-brake cable to the CSX e-brake cable, it looks like I'll have to trim 1/4" to 1/2" off. It might not be as easy as it looks though because the release springs on the end of the cable are different in the amount of coils per inch. Am I on the right track here? Anybody done this before?

[turbovanman²]

You trim the spring.

[iTurbo]

Thanks Simon. Should I worry about presetting the star adjuster before I mod the spring length? I am totally new to working on drum brakes of any sort...

Seems like I should install the rotor and adjust the star adjuster so that it backs off the shoes enough so that they don't drag on the internal drum without the e-brake cable pulling at all (reset "off" position). I want to get this right the first time because I'm sick of ordering parts and I don't want to mess up the stock cables. School me..

[iTurbo]

Tried for a couple hours tonight to get the e-brake working and no luck.

I have both the disc-brake version and drum-brake version of the rear e-brake cable removed and wrote down some measurements and then used a Dremel with a reinforced cut-off wheel to cut about 1/2" of spring from the Reliant's rear cable end. Now it is very similar to CSX rear cable (within 1/8") in terms of compressed and extended length. I installed it into the rear back plate and adjuster mechanism and reinstalled the hub and rotor in order to test it out. I left the other end of the cable disconnected so that I could pull on it while checking to see if it was locking up the rotor. It was not. So I pulled the rotor off to look at what the shoes are doing while I pull the e-brake cable. The front shoe moves out but the back one doesn't move at all. I guess I was expecting both shoes to move out opposite each other but the rear shoe doesn't move at all. Not sure if this is normal or not. I tried adjusting the star adjuster but it didn't help much. Seems like something is out of whack. I even tried testing with the unmodified CSX cable, which is the same cable that was used with this very brake setup. Pretty much had the same problem. Not sure what I'm doing wrong but didn't want to keep cutting spring either.

Next I'm going to disect the (functional) rear brakes on one of my Spirit R/Ts and see what those look like and to verify I have everything put together correctly.

[tryingbe]

The 89 + rear disc is much simpler to use and hook up to the Lbody rear.

[supercrackerbox]

The 89 + rear disc is much simpler to use and hook up to the Lbody rear.

The '89 up design is a direct copy of the '87-'88 CSX setup except for the caliper pins. The problem is he's doing this on an early K-body, not L-body.

[turbovanman²]

I'll check some shoes I have assembled on a backing plate and take a pic for you. You want to adjust the shoes so there is a light drag.

[iTurbo]

After having another pot of coffee late tonight, I decided to go out for round three. This time I got them working!

Since I had already trimmed the spring on the end of the Reliant's original parking brake cable by 1/2" on the driver side, I went ahead and did the same for the passenger side. Then I decided to assemble the cables together, and also installed the hubs and rotors to test them out just to see if they would work at all. I used a couple of lug nuts on the hub to keep the rotor tight/flush with the hub for the test.

I set the parking brake and it went all the way to the floor easily and the rear rotors could still turn by hand, although there was definitely more drag than without the parking brake set. I was hesitant to pull everything apart again and start cutting more coils off the spring, so I decided to try adjusting the star adjuster with a small screwdriver via the little rubber access plug on top of the backing plate. I only gave it maybe one turn and I notice the rotor is now really hard to turn by hand (brake still set). I turned the star adjuster on both sides until the rotors were locked up solid. Then I went in the car and released the parking brake and checked the rotors again. There is a tiny bit of drag, but from what Simon said above I take it this is normal. I then gave the star adjusters about another 1/2 turn and set the parking brake again. Rotors were locked up solid and I couldn't turn them by hand. Released them again and still only the slightest drag, so I think I'm really close! Will know for sure when I drive the car and try parking on a hill.

I still have to take things apart one more time to add a little brake grease to the parking brake lever mechanism so it releases a little better. I'm glad I did not cut off any more of the coils because it likely would have made the parking brake retraction a little weak.

[turbovanman²]

Your on the right track, I thought you'd adjusted them already, so yeah, just keep adjusting with the brake off until you get a drag, its ok, they will bed in like a normal rear drum. I like to bed them in by using the e-brake to slow it down, let them cool and readjust, anal I know.