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'93 and earlier rear disc brakes


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Has anyone done the rear brakes on this setup? Often these cars have rear drums but mine has discs. I don't think I've ever done rear discs on this era vehicle, apparently they changed in '94 which is likely the type I have worked on. I've had the car on jack stands overnight as I had to pick up an 18mm crescent wrench to get the calipers off but I'm not sure what to expect once I do get them off. Will I need to also pick up a specific tool to retract the piston? I've done rear brakes before but I know they can differ widely between various models. On one older car I recall I was able to just spin the piston with a screwdriver or something. The ebrake is wonky and not even connected with a broken connector on one side (wonder if I can replace just the connector and just hook it up again?) so will not be worrying about it right now.

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None of the 1st gen W body's aside from the 1.5 basic model Lumina's were fitted with drums.

If yours is a '93 then it have the small rear discs that were fitted from 88 thru 93.

I won't apple pie this for you.....are you familiar with this particular brake design at all?

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If you're familiar with the actuator type caliper rear brakes like you allude to then this is pretty much the same ordeal. I use one of the rear caliper retractors that twists it back in from Harbor Freight. Works good enough I used to use one of the dumb cube things in the past as well

The biggest thing on these is that the slider pins frequently get seized in the calipers, make sure those are in good working condition, free up, clean and relube.

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It's not a terribly difficult brake job but as we all know not having the right tools on hand can turn something that should take a few minutes into not even possible.. in other words I will have to make a second tool trip! It could have been apple pie. Should have it done tomorrow anyways; am not even going to waste my time with pliers or anything.

Appears previous mechanic who worked on the rear brakes just whipped it back together without really greasing anything.. looked like a bit of grease at the bottom of the two bolts' threads but none elsewhere (you mean to grease around the bolts above the threads, yes? or do you mean elsewhere? sorry this should be obvious maybe but I want to do it right). Uneven wear on the old pads too. Bill shows previous owner paid something like $1150 for the front and rear brake job! Maybe mechanic was hoping for quick repeat business but didn't want much difficulty removing the caliper bolts.. in less than 30,000 miles and less than 3 years needed new brakes all around. The calipers were supposedly all remanned (according to bill) yet if you told me they were the factory calipers it would almost be believable for all the rust, except that the inside of the rear caliper's bolts do look new. This time used all EBC parts up front so hoping they last long; in back just putting in new old stock semi-metallic pads for now.

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You do NOT need to "spin" the caliper piston back into the bore.

REMOVE the park brake lever from the caliper--one nut and a washer, I think..  Push piston into bore with C-clamp.  The piston doesn't spin, the park brake lever rod spins.  Simple, easy, effective.  Re-connect park brake lever when you're finished, and USE THE PARK BRAKE to keep the rear calipers properly adjusted.

I've done this several times on my '92 and '93 Lumina Euro 3.4s.

 

For the record...you can pretty-much expect to need a new vacuum power booster if your car is equipped with a vacuum booster.  They get "tired" and provide only limited power assist.  Hard pedal, poor stopping power, gotta STAND on the brake pedal,.

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Depending on frequency of regular maintenance, the right rear park cable is subject to seizing up, if you live in a winter salt belt the issue becomes even moreso. The rear calipers (as Chris stated) are also prone to the slider pins seizing, If the brake fluid hasn't been changed on a regular basis moisture will get inside & work on the screw adjusting assembly, as stated it is necessary to have the park brake assembly working properly to keep the calipers adjusted up to prevent foot pedal travel. When servicing the caliper pistons to install new pads open the bleeder screw to allow fluid to escape so the piston will retract easily (this also prevents reversing fluid flow in the system...most important on any vehicle that has the PM111 system).

Back off the park brake adjuster under the driver's seat.........remove the cables at the calipers....

Do the next with the caliper in place but the disc removed.... As stated remove the park adjusting lever when doing this process, you'll also need a wrench to fit over the hex shaped nut on the back of the stud and turn the nut as the piston retracts, you'll get some fluid out the back as this happens because the rear seal is opened by the stud coming off it's seat. When the piston is bottomed align the piston to the pad by the raised stumps on the backside of the pads & the recesses in the pistons, install the fresh pads, set the disc back into place, install the caliper, now one has to adjust the park brake lever.

Even with rebuilt calipers there is always the chance that the park lever will be out of adjustment, properly adjusted the park brake should apply full pressure when the lever is at the 75% *on* position. With the lever return spring still off & the lever retaining nut loose one rotates the adjusting stud by the lever to turn the adjusting screw to the point where the park brake applies & the rotor will not turn at all by hand....that movement should be 60% of lever travel. Release the lever, when bottomed against the stop the rotor should turn freely. Remove the retaining nut, mark the position of the lever with respect to the position on the adjuster stud,

Now one has to get the return spring back on, without anything moving slip the lever with the spring attached at both ends over the end of the stud (it will go on at a distorted angle), slowly screw on the nut, look carefully to make sure the lever hex & the stud hex don't alter their position. Tighten up the retaining screw, with a medium sized pry bar move the lever to recheck the park brake application.  Return the park cable to the levers, readjust up the park brake assembly, check the park brake application, now you can bleed the rears.

These calipers can get road crud inside the back of them where there is a dirt seal around the stud, with time that seal erodes, if the calipers are rebuilt then those chances are not as great as with original calipers.

One has to use the park brake religiously, keep the brake fluid clean and check the sliders on a regular basis.

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what the bolts pass through are the sliders, they may be stuck in the bores to the point where they seem like they're just part of the caliper casting. you'll see the rubber boots around the bolt, pull those off and you'll have access to it. Its probably what's accounting for your uneven pad wear.

The early rear discs are terrible to the point where I WISH the cars would have just came with rear drum brakes. I've converted my cars away from that to the 94+ style, while not perfect are a whole lot less terrible. Of course that has its own issues of the parking brake cables being incompatible and early steel wheels won't clear them.

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Thanks for the really helpful replies! Just to clarify things, here's a few photos of what I'm working with.

This is the driver's side where the inside pad was the most worn of the 4. So those slides are to come out going toward the inside of the car and be greased?

531004670_Driversrear.thumb.JPG.d792542bb63d999beb650649867ab103.JPG

The other has a parking brake connection issue and is just hanging there in the wind, so some of the recommendations for using it will not immediately be possible. I hope it doesn't mess things up as far as the rear brakes actually working now! Records from 3 years ago also show a new parking brake cable was paid for but I question whether one was actually installed, unless it was a really poorly made cable (I've owned the car over a year it's been like this). I do not live in an area that gets much winter weather either; it probably saw less snow where it was before.

1866683388_Passrear.thumb.JPG.8d5cef860f30ce0dfa22fe97ec427e7c.JPG

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This is interesting.....

that is the proper caliper, but I do not see the proper slider pin, nor the boot that is supposed to surround the ends of the pins that is held in place by the caliper casting which is filled with anti-seize compound to prevent the slider pins from seizing............

 

 

Pontiac GP 1991 rear caliper.jpg

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Hmm.. no idea what previous mechanic did. Bill shows it to be A1-Cardone part 174328, installed April 2017. Going to try tackling it again in a bit but am even less sure about the slides now. The inside does appear to have a boot. Next time I do this I guess it goes without saying that it will include new or rebuilt calipers. When I ordered my front EBC pad and rotor kit I had to wait about 6 weeks for them to come. In that time I needed new front brakes badly so locally I found a guy who had a bunch of brake pads he had bought in a lot at auction so at that time I also bought rear pads since he had them, so it is just those that are going in now and only cost me about $10. Have actually spent more on tools so far for this job.

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The issue I see with that design is the ends of the pins are exposed to the elements, the ends can & will corrode and seize in their position preventing the caliper from sliding. Taking a *closer* look .....the casting bosses around the pins are somewhat different than what would be OEM.

Odd.......the proper Cardone # should be 184327 & 184328,

Edited by 55trucker
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Alright, got the one side all buttoned up. It isn't much different from my '99 Pontiac's brakes now that I remember.. I recall having to adjust the slides when putting it back together. Will need to do the other side and a tire rotation before putting it back on the ground for a test ride. Thanks again for all the info; and yes 184328 is right, typo'd there with a 7.

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9 hours ago, 55trucker said:

 the caliper casting which is filled with anti-seize compound to prevent the slider pins from seizing............

Not "Anti-Seize".  Use genuine brake caliper grease.  There's many different brands and grades.   This is what I bought.

https://www.amazon.com/Sta-Lube-SL3303-Caliper-Synthetic-Grease/dp/B000CPIOAG/ref=sr_1_8?dchild=1&keywords=Brake+Caliper+grease&qid=1607154017&sr=8-8

 

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This has just become a little nightmare. The right side had the slide boots and they slide fine. I actually should have just left this side given the pads looked pretty good as now I can't get its piston to retract, at all. I can't even get the old pads back on. There was some confusion as the driver side retracted counterclockwise and apparently the passenger goes clockwise (and everything I've read says they should be both the same? trying this made it go out instead of in and now it won't go in again). Removing the bleeder didn't help.

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As we stated to your earlier one doesn't *turn* the piston, one removes the park lever, then one uses a piston retractor & with a wrench one turns the nut on the end of the stud to retract the piston to bottom it out.

Trying to alone *turn* the piston will cause you fits.

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Thanks for the reminder. Since I've already opened the bleeder I suppose I don't mind taking things apart more given I'm also sort of thinking of ordering new calipers anyways. Will spend another while looking at it again before deciding. I'd feel kind of stupid putting on new calipers just in the rear and with old metallic pads and unturned rotors. If it came to it, will the piston push itself out if the brakes are applied? Maybe it has a burr or something.

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One problem with trying to turn the piston back in to bottom it out is........

one has to get the alignment of the piston face recesses to the backside of the pad just so or the pad will not align properly. Turning the piston & bottoming it doesn't guarantee a good alignment. Remove the park lever, don't turn the piston, & push it back in with a piston rewind tool

 

s-l1000.thumb.jpg.3ff52183c00277fde6b64ed2e0fd3265.jpg

 

 

 

& turn the nut on the screw at the backside of the caliper. It's less of a headache, true one has to get the lever back on but that's not as frustrating as fighting with the piston trying to turn it.

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I spent quite a lot more time with it, and just finished ordering new calipers. Wasn't happy with the slides on the finished side anyways and now the piston has come out the passenger side's caliper and doesn't want to go back in (couldn't even get it to do a test seat with both spring and stud removed, so ended up putting a screwdriver through the seal so I wouldn't be tempted to waste anymore time on it). Spending $100 on calipers wasn't in the plan and really bad timing for the extra expense in December, but at least they were fairly well priced through Rock Auto. Took the opportunity to order some parking brake hardware as I was turned off looking the last time when the hardware and park cables had to be shipped from multiple warehouses, so since these were in the same warehouse as the calipers I can have them on hand. Also finally bought a locking gas cap and impossible to find GE 892 back up bulbs. Oh well.. another day owning a near 30 year old car, another day spending money on it! Still cheaper than making payments on a new car, maybe..

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Once upon a time Autozone made the mistake of selling me lifetime warranty rear calipers. I got MANY sets over the years. Eventually I got sick of replacing them and just moved to 94+ ones. I had one fail over the years since then.

Was it garbage reman calipers, maybe, was it a garbage design, absolutely. So who knows the root cause.

I will second that replacing the booster did help massively. However on another car I had the brakes felt like trash no matter how many reman boosters I threw at it.  

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Actually the brakes felt fantastic, especially since installing the EBC kit in the front. The only reason I wanted to change the rear pads (sigh) is because of an ever worsening squeal. There was some life left so I should have just pulled the squealer back but since I had pads on hand, the 2 bolts on each side weren't supposed to be much trouble (and then two trips for tools had to be made.. and so on) and it wasn't supposed to cost anything either! I guess I wasn't sure of what I was getting in to but it seems from what you're saying, one sort of takes a gamble with these calipers as to whether they'll go back together nicely or not during what otherwise should be a simple brake job. I don't want to say the mechanic who installed the calipers 3 years ago removed the inside slide boots (where they can't just fly off either) on the driver's side, but for some reason they're not there and there's no doubt it's the reason the single pad wore out while judging from the rest these brakes should have had a few more years in them.

When I did the rear pads and calipers on my '99 Grand Prix, I had no idea those slides were supposed to move. Am pretty sure they were put back together all seized up. Despite this the brakes never gave me issue in years, except for when driving beside highway barriers a whooshing noise associated with such rotors. This was a cheap cross drilled and slotted gold hued rotor kit with ceramic pads from eBay and they were surprisingly fantastic brakes on all 4 wheels; never had to touch them again. I almost wish I had ordered '94+ calipers now that I think about it though I do want a working parking brake.

Local auto stores are sort of limited for me as far as availability and pricing unfortunately, even with a decent discount at a few of them (two calipers would have cost about double). When I have been able to make it to O'Reilly's etc. I wasn't particularly impressed with the quality nor brands of most of the parts, though they did honor a warranty full refund on a blower motor ("VDO?") that worked for me for less than a year, even though it probably took something like 5 years to find the opportunity to return it after I had already found and installed a scrapyard OEM domestic made blower motor instead (and the problem was probably a resistor anyways). They might even have lifetime warranties on calipers also but I'm not sure; they seem to on many items. Places with these warranties seem to make so much money selling this cheap foreign made stuff that when it breaks they can just replace it and still be doing fine, which makes it impossible for domestic companies that might actually make decent parts to compete.

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I've installed a couple of those parts-store reman calipers like you have. Yes, it would have had boots, but it probably wouldn't have mattered much. Those reman calipers rust/seize very, very quickly. It's unreal. The parking brake also does not actually work on them even when new out of the box. so plan on living without that. I don't think new calipers are available anywhere. As others have said, the 94+ swap, while a lot of work, is so much better.

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Quick update.. waited a week and just received the calipers. In the "rebuild" process they did not really seem to do anything with the slides and there are no boots at all on any side!? The ones pictured on Rock Auto do show them to have 4 boots for the slides. The slides are better on the old one on the car with the boots! I have no choice on the passenger side but it's tempting to not even replace the driver's side and just send it back given the seized slides on the "rebuilt" one are no different. I have really been put out by this so no choice but to probably just install them and then try and get in touch with Cardone and inquire as to why the rebuild was so awful and if any warranty claim can be made. Rock Auto is awful to deal with on returns; buy a new one and send these ones back later for a refund taking a chance after already ordering that "maybe" they'll pay for return shipping. I'll pass on that ordeal. I have had good luck with Cardone calipers in the past (and also bad luck on another order but they made it right in the end) but I can see why the original issue with the missing boots on the old calipers is there.. unreal.. they rebuilt them properly on one side but not the other. Now they're not even doing it at all; at least it's consistent(ly bad) I guess.

Edited by Regal
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RockAuto.. they are absolutely awful rebuilds. What choice have I got? The car has been sitting in a garage that's not mine on jackstands for a week and the parcel arrived 5 days late. I can't sit around waiting for another order hoping it might arrive before Christmas. I have been occasionally been very upset with RockAuto and their return process is unacceptable. It's tempting to do a chargeback to be honest but I know they wouldn't ship future orders if I did (though I'm not even sure why I'd want to make another at this point).

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