# Disc Brake Calipers



## DexterII (Jul 14, 2010)

I don't recall having seen one, but maybe to actuate the parking brake?


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## Guap0_ (Dec 2, 2017)

That could be. Maybe it's on threads for the parking brake.


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## Nealtw (Jun 22, 2017)

Guap0_ said:


> I've been doing brakes since 1969. We all know that the piston in a caliper has to be pushed back into the caliper, to make room for the new pads. For the first time I saw a piston that had to be rotated/screwed instead of pushed. That was last year on the rear brakes on a 2013 Honda. I presumed that it was something new. Then 2 days ago I saw the same thing on rear brakes on a 94 Grand Prix. Obviously, that's not a new car.
> 
> So the questions are: When did that start? Is it only on rear disc brakes? What's the reason, for it?


 I found an explanation.
https://mechanics.stackexchange.com/questions/21544/how-do-parking-brakes-acting-on-disc-brakes-work


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## Guap0_ (Dec 2, 2017)

Good job Neal. Thanks.


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## Nealtw (Jun 22, 2017)

Guap0_ said:


> Good job Neal. Thanks.


 I haven't seen them either.


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## Bigplanz (Apr 10, 2009)

Nealtw said:


> I haven't seen them either.


They are quite common on rear disc brakes. My Navigator doesn't use this design but the majority of rear disc brake systems do.


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## Nealtw (Jun 22, 2017)

Bigplanz said:


> They are quite common on rear disc brakes. My Navigator doesn't use this design but the majority of rear disc brake systems do.


 I have been thing about it. I don't think I have ever worked on rear disc brakes. That might explain why I haven't seen it.:vs_whistle:


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## ukrkoz (Dec 31, 2010)

Mazda has them. Out then 2008 Mazdaspeed had HELL for brakes. I had to disassemble two part pads "bracket" to get pads replaced. That's when I found about rotation. By far those were the worst, dumbest designed brakes I ever worked on. Well, that car didn't alst long in our possession anyway and totally ruined my opinion on Mazdas.


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## Guap0_ (Dec 2, 2017)

Since the conversation has taken us to emergency aka parking brakes, I remember them being used when a standard shift car was parked, to prevent it from rolling but I never knew of anyone who used it to stop in an emergency.


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## mark sr (Jun 13, 2017)

I have a 2010 Jeep with 67k miles. I had to replace the the rear pads at 55k and don't remember anything out of the ordinary. What did surprise me is having to replace the back pads first. The factory pads on the front still have a good bit of wear left.


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## 1995droptopz (Sep 14, 2010)

There are two types of disc rear brake systems commonly found in cars: Drum-in-hat and disc only.

The disc brake setup like you describe uses the caliper piston for parking brake duties, which rotates the piston to hold the brake shut. This is why you have to rotate them back in.

On a drum-in-hat brake system, there is a drum brake on the inside of the rotor near the hub, specifically for the parking brake system. This works like a traditional drum brake, but only for parking brakes.


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## Guap0_ (Dec 2, 2017)

That's correct. There was no parking brake drum on the 2 cars that I mentioned.


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## Brainbucket (Mar 30, 2015)

Ratcheting calipers came out in the mid to late 80's I believe. Going on memory here. Some were used with parking brake, some didn't. The parking brake ones had a lever and a tough spring on them. Some screw in, others you had to push and screw it in.:vs_cool:


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## SeniorSitizen (Sep 10, 2012)

Thunderbirds of the 80's era were screwed. The reason I know I still have the bent 6" heavy duty C clamp one of my sons used to try to force the piston back on his girl friends car.


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## Guap0_ (Dec 2, 2017)

The handle on my C clamp isn't exactly straight either.


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## DexterII (Jul 14, 2010)

Guap0_ said:


> Since the conversation has taken us to emergency aka parking brakes, I remember them being used when a standard shift car was parked, to prevent it from rolling but I never knew of anyone who used it to stop in an emergency.


I grew up with and had several vehicles with manual transmissions, so used the parking/emergency brake regularly, and have continued that with my automatics, not all of the time of course, but I'd guess at least several times a week when parked on uneven ground. I am not all that familiar with the inner workings of automatic transmissions, but it seems to me that something must be wearing, at least a little bit over time, when you put a vehicle in park and then watch it roll an inch or two, whatever it is, into a cog. So I try to avoid that. And I did use this brake in an emergency one time. I was driving my '88 F250 on a two lane road, catching up with some traffic that was slowing ahead, tapped the brake, and had nothing. Fortunately had plenty of room, and was familiar with the emergency brake, so feathered it in as I steered to the shoulder without incident. Hadn't noticed it prior to that, but it was immediately obvious that one of the rear brake hoses rubbed the shock as the suspension travelled up and down. Luckily was only 5 miles or so from home, with less traveled secondary roads, but I can tell you that I wouldn't have wanted to drive it much farther with just the emergency brake.


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## Guap0_ (Dec 2, 2017)

You're the first to tell me that you uses the brake for an actual emergency. What wears in an automatic transmission is a gear that looks like a flywheel. When the car is in park, there is a hook that stops the drive train from turning. That could have changed since I looked inside a transmission.


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## Nealtw (Jun 22, 2017)

The clog in the transmission does wear.
I used to park off the side of my driveway by the road and one day I grabbed the wife's car and backed into my old chevy. It started slowly backing down the Cal de sac. Kerclunk, kerclunk. I jumped out of the car and went to the old one that was still going kerclunk. kerclunk, only to find the door locked and my keys were in the first
car. It was going slow but I didn't think I had time to go for keys so I went to the intersection and stopped traffic while my car went kerclunk, kerclunk right thru and stopped in a swail beside the road on the other side of the intersection.


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## mark sr (Jun 13, 2017)

Guap0_ said:


> The handle on my C clamp isn't exactly straight either.


I recently bent my best 8" C clamp using it to install ball joints on the driver's front of my 4x4 ford truck. If I had just bent the frame it wouldn't have been so bad but the screw's bent too. It was a $3 yard sale find, made in the USA and a lot stouter than any of my more expensive made in China C clamps. Guess I should have bought a ball joint press!


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## Guap0_ (Dec 2, 2017)

Years ago, I started to buy the upper control arm with the ball joint already installed. At this age, why bother with pressing & banging? The banging includes our heads against the wall not just the ball joints.


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## mark sr (Jun 13, 2017)

It's a little more complicated and pricey when it's 4 wheel drive.


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## Drachenfire (Jun 6, 2017)

My 00 Silverado had 4-wheel disc with the most unusual parking brake I had ever seen.










It is a single shoe design held in place with a single clip and screw. It is actuated with a cable connected to the parking brake pedal in the truck. It holds very well and in the seventeen years I have had the truck, I have only had to replace them once.

Now my 69 VW Bug was another story. It had 4-wheel drum brakes.










Those were a PITA to change. The real danger was the level of asbestos containing dust that accumulated in the drum. One had to be careful when removing the drum not to allow the dust to blow off. We would have a plastic tub of gasoline (no Brakleen in those days) next to us in which we would place the drum after removal. We would then use a gasoline saturated brush to clean the braking mechanism.


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## mark sr (Jun 13, 2017)

My first several cars all had 4 wheel drums. Back then who knew about the dangers of brake dust? Fortunately not doing it for a living limited my exposure. My sons tell me how hard drum brakes are to replace but to me it isn't any harder but I guess it depends on what you grew up with. I have an old F1 pickup in the barn that has drums on all 4 wheels.


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## Guap0_ (Dec 2, 2017)

I've worked on 4 wheel drum brakes. Disc brakes have dust too especially the metallic pads although it's not saved for us in the drum. There is always going to be some kind of dust. The subways have steel dust from wheels grinding against the tracks plus their brakes. Even an outside train puts dust in the air. We have to stop some way or another.


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## Drachenfire (Jun 6, 2017)

A lot has to do with the concentrations of asbestos. With disk brakes you only have to deal with the residue on the mechanism. Even then all repair procedures say never to blow it out with compressed air and use a brake cleaner to clean the components.

I must be doing something right. I have been doing brake jobs since I was a teenager. Today I am in my mid-50s and knock on wood reasonably healthy.


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## Gregsoldtruck79 (Dec 21, 2017)

I got in to this situation when I changed the pads and rotors on my wife's 2003 Buick LeSabre. The emergency brake system is done through the rear brake caliper piston's metal endcap that has to be screwed inward, to collapse enough get the new pads on. I bought this tool .... and it worked well for me. 

https://www.amazon.com/Lisle-28600-Disc-Brake-Piston/dp/B0002SQUFY/ref=sr_1_18?ie=UTF8&qid=1517670447&sr=8-18&keywords=brake+caliper+compression+tool


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## Guap0_ (Dec 2, 2017)

Greg, that's the strangest brake tool that I've ever seen.

Drachenfire, I guess that I'm as lucky as you are. I also have been doing brakes for over 45 years & don't seem to be affected by asbestos. It could be because most of those brake jobs were done outside.


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## Gregsoldtruck79 (Dec 21, 2017)

Guap0_ said:


> Greg, that's the strangest brake tool that I've ever seen.
> 
> Drachenfire, I guess that I'm as lucky as you are. I also have been doing brakes for over 45 years & don't seem to be affected by asbestos. It could be because most of those brake jobs were done outside.


I could have just used needle nose pliers probably to screw the caliper cap back inwards. But how is a man ever going to accumulate enough tools to fill the oversized boxes they buy, if they keep "improvising" with the tools they already have ? :smile:


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## Guap0_ (Dec 2, 2017)

I couldn't find, well actually I was too lazy to look for the tool that spins the blade retainer on my angle grinder. The two grooves in the piston appeared to perfect for that tool.


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## Drachenfire (Jun 6, 2017)

Guap0_ said:


> Drachenfire, I guess that I'm as lucky as you are. I also have been doing brakes for over 45 years & don't seem to be affected by asbestos. It could be because most of those brake jobs were done outside.


I guess we should just count our blessings.

Today when working on brakes, I follow the procedure of spraying everything in brake cleaner. I also make use of 6-mil Nitrile gloves which is chemical resistant.


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## Guap0_ (Dec 2, 2017)

The odor from brake cleaner can't be much healthier than breathing asbestos.


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## Drachenfire (Jun 6, 2017)

Guap0_ said:


> The odor from brake cleaner can't be much healthier than breathing asbestos.


I do my repairs outdoors and try not to breathe fumes from the brake cleaner or any other similar product.


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## Guap0_ (Dec 2, 2017)

None of them are good for us.


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## Gregsoldtruck79 (Dec 21, 2017)

Drachenfire said:


> I do my repairs outdoors and try not to breathe fumes from the brake cleaner or any other similar product.


Speaking of BC....

Just a reminder to all, to NEVER spray a metal to clean it and then weld it. Bad, bad, things happen to ones health when doing so.


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