Replacing a rear Brake Caliper...need some advice/help

[sad-lumina-owner]

Doing the front pads and rotors wasn't that bad, once I had the right tool (a special torx bit 65).


This is a bit different.

I opted for replacing the whole rear brake caliper (cylinder and bracket).

This is because I had examined the passenger rear pads and they looked great. hardly any wear, so I assumed they were fine.

Then, while replacing the rear tires, me and the guy balancing them noticed that the pads on the driver's side were as follows:

One pad was near-new, and the other pad was worn almost to the metal. He credibly reasoned that the sliding sleeves that allow the brake unit to shuffle sideways were rusted frozen.

this meant that one pad took all the heat and wear, (the inside one pushed by the piston) while the other pad never contacted the rotor.

He suggested I could just clean the sleeves and sand off any rust, and relubricate them (you should use high temperature silicon grease).

But I thought it better to just replace the whole thing with all new (I've already done all the lines).

I also thought this would be the simplest way to do the job too.

So I picked up a new caliper unit and pads.

Here is where I'm in unfamiliar territory:

(1) there is the emergency brake line and spring(s), which aren't obvious as to removal.

(2) I am trying to install the new pads on the new caliper now on my desk, and I am having trouble getting the inside pad to firmly click and fit, in a way that gives me any confidence that the pad won't just pop off again. There is a little metal clip (and a single cylinder).

(3) The instructions in the Haynes manual are notoriously vague about both dismount/disassembly and remount/reassembly of the caliper unit and connections.

(4) There are two (different sized) copper washers included in the kit, for which no instructions or clue as to their purpose is given. (the two larger washers I am assuming just go with the new bolts that hold the unit to the car.)

(5) I think I'm supposed to take the 'dust'(?) shield off before starting, and also drain 2/3 of the fluid for this, but I don't see the point in that since the cylinder came compacted.

(6) THere is some instructions regarding using a pair of needle-nosed pliers to "screw in" the cylinder piston, and align the cross on the surface correctly. However, the thing won't turn at all, even after loosening the nut on the other side of the cylinder that is holding the emergency brake bracket and spring.

Any help with these points by someone who has replaced a brake caliper on the rear of a /94 lumina would be greatly appreciated.

[maxwedge]

Some help here. http://www.autozone.com/shopping/rep...c152800682bfme

[sad-lumina-owner]

Okay here's an example of where I'm having difficulty with the instructions:

1. Remove about 2/3 of the brake fluid from the reservoir with a clean syringe or baster type utensil.
2. Raise and safely support the vehicle with jackstands.
3. Remove the rear wheel and tire assembly, then reinstall two lug nuts to retain the rotor.
4. Remove the brake shield assembly.

Actually this is better than the Haynes version, (they tell you you need a clean cooking baster/syringe, giving you a clue how to remove fluid from cylinder).

Not much of a clue on 4. Remove shield assembly.

I am hoping an inspection will make this fairly obvious and easy.

PART II:

1. Loosen the tension on the parking brake cable at the equalizer.
2. Remove the parking cable and return spring from the lever.
3. Hold the cable lever and remove the locknut, lever and seal.
4. Push the piston into the caliper bore using two adjustable pliers over the inboard pad tabs.

Do NOT allow pliers to contact the actuator screw. Protect the piston so the contact surface does not get damaged.

Ok here is where I really think they leave the beginner out to dry.

(1) A little more detail about how to loosen the tension, how much, and why would be good. I've never messed with an emergency brake line, and it looks kinda complicated at the back wheel with several levers and springs.

(2) Just what is the locknut? The lever/spring on the new unit looks pretty tensed up WITHOUT a cable attached and tightened. Do I need to remove this if I'm just replacing the whole caliper? What is the purpose of this exercise?

(3) The WARNING in italics is unnerving, since they give no indication of what the hell an "ACTUATOR SCREW" is. How am I supposed to avoid touching it if I don't know what or where it is?

And is this step even necessary if I am actually replacing the whole unit? The piston already seems to be depressed on the new one.

1. Reinstall the lever seal with the sealing bead against the caliper housing, lever and locknut.
2. Remove and plug the brake hose inlet fitting only if the caliper is going to be removed from the vehicle.
3. Remove the bolt and bracket to gain access to the upper mounting bolt.
4. Unfasten the caliper mounting bolts, then pull the caliper from the rotor and suspend from the strut with a suitable piece of wire to prevent brake hose damage. Do NOT allow the caliper to hang from the brake hose.

What is 9. here all about? Do I need to do that if I never removed it in the first place? Are these steps something I can just skip right over?

So much for taking off the old unit. It would be good if someone who's done this could comment on this step.

[maxwedge]

The actuating arm is probably on the reman unit, no need to monkey with it., if you back off the parking brake cable adjustment it makes it easier to remove the cable from the caliper. Forget the actuating screw issue. You must be able to move the cable further onto the lever to allow the swage fitting to clear the lever and come off, hence loosening the e brake will make it some what easier.. In actuality if you had to get the piston inboard to get new pads on your old caliper, there is a special tool designed to serve that function. Step 9 refers to a procedure required during an overhaul, once into this it will become clear.

[sad-lumina-owner]

Thanks for the help Maxwedge:

Here's an update for today's adventure..


(1) I returned to the CanTire mechanic where I bought the caliper. I showed him I couldn't even get the pad to stay on with the clip.

He explained that the piston wasn't properly squared, and brought out a special tool ($40) to crank it back and align it. (Trying to do this with needle nosed pliers as recommended in Haynes etc. was a f***ing joke. There is no way you can turn that thing: the pliers will just bend or break.)

So he got the pads on for me, and I returned to the task of swapping them out.


I removed the ("dust"?) shield behind the back wheel rotor (two small rusty bolts: be careful about stripping these) with a mini-socket wrench.

(2) NExt problem was the Emerg. brake cable. As I thought, it was a royal pain. There is little room and no visibility to work.

You have to get the thing off more or less, because the bolts holding the caliper are completely inaccessable with either a socket wrench or a closed ended spanner, and you don't want to risk stripping these highly torqued bolts.

The design is so stupid that the brackets holding the e.brake line block and interfere with the mounting bolts.

The end of the cable pops off easily enough, and things looked like they should be easy, except there is a metal clip that holds the e.cable in the hole on the bracket, and that too is impossible to see and difficult to reach.

The bracket that covers the top bolt is itself covered by the spring and the other shit there. So I opted to take a hacksaw and saw off the bracket. There is a new one included with the caliper.

This made the job of removing the emergency brake cable from the bracket-piece somewhat easier, but not easy. I spent 15 minutes struggling with needle-nosed pliers and flathead screwdrivers, before finally breaking off the tabs from the retaining clip and freeing the cable. I'll have to get a new clip eventually (perhaps I'll just replace the cable - its not working anyway properly).

(3) I was able after this to free the two caliper bolts, but they were tough too: I had to add torque to my wrench by an extension, using closed wrench end so as not to strip bolt heads.

Getting the old caliper off (still hanging by the brakeline), wasn't too bad, and I tied it temporarily to the strut with wire.

On went the new caliper and pads, but I first pulled the rotor and brushed off the remaining axle/supports with a wirebrush.

(4) Getting the new bolts in was as difficult as getting the old ones out:

I had to remove the emergency brake brackets and spring. This involved taking a nut of the first bracket and unhooking spring, so that I could get a large hexkey into the bolt holding the 2nd bracket next to the upper bolt.

Then I tightened up the bolts as hard as I could (I will test torque later) and struggled to restore the brackets and spring. This was annoyingly awkward, especially from the ground with the car on jack supports in the driveway (maybe its easier on a hoist, I don't know).

(5) Finally, I reinserted the emerg. brakeline. This was easy compared to removing it, but its connection is flimsy and the e.brake itself doesn't really work at all. It pulls the lever fine, but the wheel still turns (the whole point).

The mechanic described a method of tightening the brake pads up, but it didn't seem to make any difference, and I wondered if he had just made it up or guessed at how to do it.

(6) Next, I had to reconnect the real (hydraulic) flexible rubber brakeline hose to the unit. First I had to find a way to hold the old unit (still dangling) to get enough torque to undo the bolt holding this hose on. I used a socket and a large screwdriver in one of the bolt holes to loosen this bolt.

The bolt has a copper washer on either side of a square brass block that is on the end of the hose. The mechanic thought it didn't matter which washer went on which side, but I copied the old arrangement with the larger one on the Outside, under the head of the bolt (the smaller one then goes between the brass block and the caliper body.)

There was little leaway for the rubber hose and I am not happy about that. I may try to find a longer hose (I'm using the old one right now, as I ran out of money by the time I got the caliper and pads at $170 and $25 respectively).

(7) Now I was ready to bleed the caliper. I had previously loosened the nipple slightly to make this easier. Most of this was now a joy because everything was brandnew, caliper, nipple, pads etc.).

I bled out about a 1/4 pint of brake fluid to get all the bubbles out (some were still coming out every 6 inches of fluid in my clear plastic hose I used to drain into a waterbottle.)

With a helper that took about 5 minutes.

Afterward, I topped up the master cylinder. I know there's a proper way to bleed all the lines, but I'm still replacing components, so I'm not panicking about a bubble or two somewhere in the system.

There doesn't seem to be any leaks: all the metal lines are now replaced, and the only old parts are the rubber brakeline hoses to each wheel and 3 calipers.

I got a $55 refund on the old caliper, and I kept the old pads for spares.

Total cost: $230 - 55 = about $180 for parts, and a couple of hours of my time.


I put the shield back on and the tire, and did a test-drive. All seems well, although I'd like to tighten up the emergency brake (I don't know how to do that)

[maxwedge]

Good experience gained, no one likes that job on these cars, I've done it about 20 times!