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Rear Disk Brake Conversion

19009 Views 9 Replies 7 Participants Last post by  NickD
So I'm looking to change my drums to disks and I know there was the whole "you need to swap axles" thing. I was wondering if we could use the ZZP sonic kit even though it says it doesn't fit. It says the bolt pattern is different, although I am 99% sure it is the same. Does anyone know anything about this? Thanks
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Thanks Aussie I knew this had been talked about before. Honestly, except for occasionally having to adjust the drums(@every 10000 miles), I find no problems with drums vs disc and I am on my 3rd Cruze with drums. (my LS Eco and now my LT)
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1978 Cadillac Fleetwood had rear disc brakes, constant problem, Calipers were only available from the dealer at 300 bucks each, today this would be closer to a thousand. Refused to ratchet, new ones would only last about 10K miles, so to manually adjust them.

2012 2LT had the same problem, in my opinion, a dumb design, this was in the second year, refused to ratchet, nutting dealer didn't even know you had to work the parking brake to adjust them. On mine, that piston instead of screwing out, would just go back and forth. Had a three month battle to get new ones under warranty, wanted to replace them myself, but the dealer insisted on doing it, what a mess they made, to me close to a day to do the job right.

They did not put a block on the service brake pedal, so the fluid went dry, did not use a scanner to activate the ABS pump. left air in the system. My only alternative, without a scanner was to vacuum bleed them, take if for a drive between 0-8 mph, stop, switch off, and do this four times in a roll, than vacuum bleed them again. After doing this five times, finally got a full pedal.

If you want rear disc brakes, take them off an 88 Supra, caliper is 100% independent of the parking brake function, uses drums for parking. No need to work the parking brake, inherently self adjustable, why didn't GM copy this?

04 Cavalier rear drums were no problem, used a huge U shaped spring, just had to remove the drums about every 50K miles, lower anchors would rust, cleaned them off, and added new anti-seize, best lubricant ever. But did take some muscle to put that spring back on.

Cruze went back to those tiny springs you would find on a 41 Chevy, maybe too many complaints from the mechanics, not strong enough for the self adjustment to work. But have to be cleaned a lot more frequently. Hitting the brakes while backing up is what adjusts these.

Did have to redo the brakes on my 88 Supra last summer, after 28 years, the rubber dried up. Was an absolute pleasure, drum parking brakes were like new, only used when parking. It cost me four bucks per caliper for new rubber, two on the caliper guides, that ring on the piston and the boot. Had to drain it dry with ABS, just pulled the ABS pump relay, and put a jumper in there to activate the pump, that pump could run all day. With a container connected to the bleeder, ran the pump no more than ten seconds until the fluid came out clean and bubble free. Just had he rear on oil changing ramps, fronts, could do this on the ground.

Toyota came out with the torque plates, no need to use a C-Clamp, Cruze and others copied this, but not the drums for the parking brake. If you do have a scanner for the Cruze, shop manual says only to activate the pump for a very short period of time or else you will burn out the motor.

They have got to be kidding.
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Thanks Aussie I knew this had been talked about before. Honestly, except for occasionally having to adjust the drums(@every 10000 miles), I find no problems with drums vs disc and I am on my 3rd Cruze with drums. (my LS Eco and now my LT)
You'll never even notice the difference unless you're racing the car or will be in a situation with multiple, repeated hard stops. It's not like the rear brakes do much of anything anyway.

04 Cavalier rear drums were no problem, used a huge U shaped spring, just had to remove the drums about every 50K miles, lower anchors would rust, cleaned them off, and added new anti-seize, best lubricant ever. But did take some muscle to put that spring back on.
My Cobalt has that kind of drum setup - literally takes you five minutes to do a side. Super simple - U-spring, shoes, adjuster. That's it. And the adjuster can go in last, instead of having to hold everything in place and stretch the spring - which is easy with channel locks.

My '98 Cavalier had the old style with 400,000 springs, and was much more obnoxious to do.
Drums do offer shielding where calipers and rotors are fully exposed to road salt. Ha, asked my family, why are we putting up with this, kids are willing, but their mates are not about leaving their families.

But if road salt is not your problem, can go with discs, don't forgot to replaced that ABS module, different for drums than discs.

Removing all the calipers and rotors around here is a spring time yearly job.
Just to add my $.02 worth, as a rule of thumb, the rear drums do about 20% of the braking.
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As I said adjusting the drums requires a jack t-30 torx driver and a flat head screwdriver and @ 25 minutes. and the car stops just as new again and your handbrake doesn't go as high.
The drums on my Cruze work well. I adjust them by backing up slowly and pulling the hand brake a few times with my thumb on the release button. I have checked the brake adjustment a couple times when I rotated the tires, and they were always good.

Some people are scared of drum brakes because they are a little more complicated. Others don't like them because the design was used on very old cars. When adjusted properly, they work well and last a very long time, and they are not all that complicated. Unless you are racing, the drum brakes are fine for most people.
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Symptoms of excessive shoe or pad gap is excessive brake pedal drop, pedal can go nearly to the floor. By releasing the pedal, will come up if you fan the brake pedal, pushing to the floor, releasing it, than rapidly hit it again.

Had to do this on my Cruze when the rear disc calipers refused to ratchet. With disc, car parked, all you have to do is to work the hand parking brake lever if they are working right, leave your foot off the pedal, maybe ten times, holding that button in, should get a full pedal.

With drums, have to back up, 2 mph is good and tap on the brake pedal. When doing a brake job always leave excessive gap in either the pads or the shoes. Working the hand brake with disc should bring that brake pedal up. With shoes, on my long declined driveway, just roll backwards hit the brake, stop, let it roll, then hit it again, brake pedal should come up.

Of course you look back, don't want to run over your own kids. When doing this with my kids vehicles, make darn sure my grandkids are in the house with grandma, don't let them out.

Now if this doesn't work to bring up the brake pedal, you have problems, with disc, first thing to check is that the levers are going to the home position, Cruze does use a self adjusting handbrake, really do not like this, a nut worked perfectly find, if you have excessive play, only thing to do is to replace the handbrake lever assembly, really not that expensive. If the rear caliper levers are returning to the home position, only option is to replace the calipers. This was my problem, they refused to ratchet. Is like a ratchet wrench, you have to reverse it far enough until it clicks, before it will engage the next tooth, this actually rotates the piston in the caliper on a screw, so it moves outwards. If the piston turns freely, the ratcheting mechanism is broke, only choice is to replace them. Chevy did this for me, second season, after a three month battle. Do run around 150 bucks each.

With drums, a lot easier, the shoes have got to move freely up and down and sideways, worse point is the lower anchors, does trap rust, that can be wired brush off and coated with anti-seize, nothing works better than this, that black brake grease is next to worthless, only good for a month or two. Other point is where the shoe contacts the backing plate, and where they slide into that notch on the wheel cylinder. Adjuster that thing with that toothed gear must work free. If badly rusted, dump it, not too expensive. Again the best lubricant for the threads is anti-seize, rust is the major problem. Even worse since our lovely EPA banned electroplating in our country. Either Mexico, even worse China, does a poor job.

Really not rocket science, when there is excessive play, that rear shoe goes back far enough that that little stamped steel tang on the rear shoe goes high enough to engage the next highest tooth on the adjuster. Bit more complicated with the geometry, but only happens when you are backing up.

One reason why on older GM vehicles, using that large U spring, had a lot more tension than these little coil springs, so can bet by with more shoe draq. Admittedly, had to use a large pair of channel locks and both hands to put that spring back on, sat on a stool, with my elbows on my legs to get more leverage.

Ha, with my 88 Supra, all I have to do is to pump the brake pedal, no handbrake to work, no backing up, wish all cars were this way. One hint to GM and others, that patent is long ago expired. Rear calipers are in the ten buck range, but like to rebuild them myself for four bucks.

Yet another problem with a low brake pedal, that piston with two rubber O'rings goes further forward where it has never been before with rust that wrecks those rubber rings. So you end up with a leaking master cylinder. Use to be a buck for new rings, also a boot on the rear. Do have a hone for this, one time they wanted more for these pieces of rubber than the price of a new OE master cylinder. On my 92 DeVille, no choice but to buy a new master cylinder, around a 120 bucks. Supra was 29 bucks for three pieces of rubber, but had to be done.

Ha, often make the comment, don't have to drive down to South Chicago in a dark alley to get robbed, just at my parts supplier places.
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