Race rear disc brake options?

[Turbo6inKY]

http://www.flynbye.com/catalog/c7_p1.html

I'm going to have to call those brackets out as not good. They don't have ample material for the caliper slider bolts to thread into, and they leave out everything else. "Hassle free" means lots of hassle there. No parts list. Nothing. Just a bracket and some hardware.

 

[Boxcars]

After reading the OP, I realized this thread was years old, and went no further. My comment was just a suggestion for the OP to look and not an endorsement of those particular parts, but I do know this vendor, which I linked, sells many outstanding parts for brake upgrades of all kinds.

 

[Turbo6inKY]

After reading the OP, I realized this thread was years old, and went no further. My comment was just a suggestion for the OP to look and not an endorsement of those particular parts, but I do know this vendor, which I linked, sells many outstanding parts for brake upgrades of all kinds.

I didn't take it as such, just trying to add more information. I can come across as a dick. That's not my intention.

In other news, some wisdom on the Eldorado calipers:

Holy shartballs these things are frustrating. Mushy pedal on the first press, then they work great.

Three clicks on the E-brake pedal and life is good. Really good. Locking up the back and almost spinning good. So, I've found the issue.

There must be pre-load on the E-brake actuator for these calipers to work well. Yes, they are a ratcheting caliper, but that's not enough to get a good pedal. So, here's my guide to properly setting up these Gm Metric calipers:

1: Install caliper
2: Bleed caliper
3: Disconnect the e-brake cable from the caliper actuator bracket
4: Remove the e-brake return spring from the caliper
5: Crank the e-brake actuate arm until it stops. Use vice grips to get more leverage on the arm. Tap it a few times with a hammer. (tap, don't, hit. Tap, you gorilla)
6: Repeat 5 a few times.
7: Reinstall spring and e-brake cable
8: (the part that isn't clear) Adjust the e-brake cable (at the threaded rod ahead of the driver side rear wheel) so that the e-brake actuator just barely doesn't touch the stop on the caliper when the e-brake is released.

It should be tight enough that just four or five clicks on the e-brake pedal locks the rear brakes, and fully released has the actuator *almost* to the stop, but not quite. If you hit the stop and there's slack in the e-brake cable, there won't be enough preload on the piston to give you a good pedal on the first press. Testing is easy, just try to spin the wheel. You should not be able to turn the rear wheels by hand with four clicks on the e-brake pedal. It should stop completely with ~125# of pressure at seven to ten clicks, which is about the middle of the travel of the e-brake pedal.

Alternatively, don't do this upgrade. What a mess. Giant time sink. If I did this over again, and I might next year, I would:

Buy a rear axle assembly with outer ends that are compatible with more popular aftermarket brake set ups. Then I would buy one of those set ups.​

 

[Turbo6inKY]

Finally got these calipers adjusted. I attempted my plan above, but it didn't work.

I finally took one of the calipers off the car and got it on the bench. What I found was the e-brake actuator arm was not installed correctly at the factory. The arm had to be rotated way further than the e-brake cable would ever be able to move it for the piston to actually ratchet out.

So, on the bench, I moved the lever until the piston engaged and I saw it move. I then backed the arm off ever so slightly until the piston backed up the 0.030" it's designed to. I then undid the nut holding the arm on, and clocked the arm back towards the stop. At this point, the arm was in the proper place, and any movement off the stop caused the piston to begin to adjust out.

I then cranked the piston back in flush and re-installed the caliper on the car. Voila!

 

[Turbo6inKY]

So, an update.

While I had the calipers adjusted, they don't self adjust very well as an ongoing concern, especially the passenger side. No matter how I adjust the balance bar on the e-brake cable, I can't get much travel on that end. After a track day or autocross event, there's enough wear that I end up with a really long pedal on the first press, and the e-brake adjuster just isn't working. And since the calipers don't self-adjust without the ratcheting mechanism, I'm getting knockback just about every time the car hits a bump.

So after a few weekends of crawling under the car and adjusting them with a pair of pliers, I'm punting. I've just ordered replacement Wilwood calipers. They're cast iron single-piston replacements for this GM caliper, but do not have a parking brake mechanism. None of the things I participate in require a parking brake in the rules. Plus, being an automatic, the parking pall is way stronger than the damn e-brake ever was.

I'll report back after I get them on and get through an event with them.

 

[1986 Buick GX1]

So, an update.

While I had the calipers adjusted, they don't self adjust very well as an ongoing concern, especially the passenger side. No matter how I adjust the balance bar on the e-brake cable, I can't get much travel on that end. After a track day or autocross event, there's enough wear that I end up with a really long pedal on the first press, and the e-brake adjuster just isn't working. And since the calipers don't self-adjust without the ratcheting mechanism, I'm getting knockback just about every time the car hits a bump.

So after a few weekends of crawling under the car and adjusting them with a pair of pliers, I'm punting. I've just ordered replacement Wilwood calipers. They're cast iron single-piston replacements for this GM caliper, but do not have a parking brake mechanism. None of the things I participate in require a parking brake in the rules. Plus, being an automatic, the parking pall is way stronger than the damn e-brake ever was.

I'll report back after I get them on and get through an event with them.

I think the E-brake was invented so TR's had a way to stop when the Power Master brake systems failed.
When you have vacuum brakes or hydro boost systems E-brakes are no longer needed. Lol

 

[Turbo6inKY]

So, some shots of the Wilwood caliper next to the GM caliper.



They are considerably lighter than the GM caliper, and you can see why. Wilwood took material out wherever they could. Add that plus the lack of the parking brake mechanism and these are considerably lighter than the GM caliper.

A warning, the GM calipers have a clip on the piston that holds the inner pad in the caliper while you install it. The Wilwood doesn't have that clip, which means when you load the caliper and then try to mount it, the damn pad falls out. It took me a few tries before I managed to get the caliper in position and get the bottom slide bolt through to retain the pad. Next time, I think I'll use a piece of safety wire to tie the pad to the caliper, mount it, and then cut the wire off.

Once they were on the car, I gravity bled them. Pedal is higher, which was expected with the smaller piston, but still a bit mushy. I'll be pressure bleeding them tomorrow once I get the right master cylinder plate for my pressure bleeder. They also actually float. I think the anti-rattle rubber grommets in the GM calipers were impeding that, which I think made the knockback worse. If the rotor moved, the piston got pushed in instead of the caliper sliding. These don't have those rubber bits and move freely on the pins, so wiggling the rotor around and whacking it with a rubber mallet didn't push the piston back in, the caliper just moved with the rotor, like it's supposed to. These also require a special super-heavy-duty slider pin set. They won't work properly with the OE slider pins. They might actually fall off the car if you use the OE pins, so don't do that.

I have an event on Sunday, so by next week I'll know if this will work or if I'm going to have to quit screwing with it and install a rear end with proper facilities for axle retention and disc brakes.

 

[Turbo6inKY]

Ok, street test drive results: Much better. Good, even. I even took a few corners sorta hard to see if they'd knock back, and they didn't. Very encouraging.

Also, between the lighter calipers and removing the e-brake pedal assembly and the cables, I've now shaved 16.2 pounds off the car, a full eight off the axle because of the lighter calipers.

 

[Turbo6inKY]

Ok, ran the event today, and I can report good things. No knockback. For the first time since I embarked on this conversion, the brakes worked as one would expect them to.

Looking back, I double down on getting a complete kit from somebody instead of piecing it together yourself. It's cheaper and takes a lot less time.