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2015 Mazda3 S GT Hatchback 2013 Kia Optima SXL
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Discussion Starter #1
Recently I needed to replace my driver side parking brake cable. While replacing it, I noticed that the rearmost driver side brake tubing is quite rusted. I want to replace it before it fails. But nowhere can I find any info on the size of the tubing. To anyone who knows, is it 1/4" or 5/16"? Metric or standard? Double flare or bubble flare? Any info will be a tremendous help.

Don
 

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Discussion Starter #2
Okay, the best I could figure is it is 3/16" line with a bubble flare. Right? Now a new question. Do I double flare the existing brake line to match up to a bubble flare on the new brake line? Or will I be cutting off the new lines bubble flare, making a double flare, and using a union?

Don
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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:rolleyes: Dadillac, IMHO, trying to marry steel brake lines is fraught with danger. You would probably be safer and have an easier repair if you went to ????? GMPartsdirect ???? or some such and got the whole rear line setup. I betcha that, somewhere back there, there's a crossover connector coming from the engine room mounted brake proportioner rear line.
 

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Discussion Starter #4
:rolleyes: Dadillac, IMHO, trying to marry steel brake lines is fraught with danger. You would probably be safer and have an easier repair if you went to ????? GMPartsdirect ???? or some such and got the whole rear line setup. I betcha that, somewhere back there, there's a crossover connector coming from the engine room mounted brake proportioner rear line.
Upon my initial inspection, each rear wheel has its own dedicated brake line. So the driver side line has to be at least 12 to 15 feet long. So even if I could get a prebent replacement, how would I get it home?

Anyway, I think I got it figured out. I am almost certain that the line is 3/16". I do remember that it is extremely small in diameter. I bought two lines today, one a standard thread, one a metric thread. I will keep the metric thread for the car, as I am pretty sure that is what I need. I cut up the standard thread line, and practiced flaring and bending it. I will use the bubble flare at the caliper end, cut off the other end of it, and do a double flare. I will install the standard fitting on that end. I will double flare the existing line, and install the other standard fitting. And put a union between the two lines. As long as I am leak free, I should be good to go. I am doing this job on Saturday. Hoping for the best.

Don
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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:thumbsup: Yeah, looked at the FSM, and you're not in for an easy fix. Darn Seville has more pipe than the Hoover Dam.
 

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Don,

Pre-formed brake line comes in huge boxes with "shipping bends" to allow the whole piece to fit in the box. Upon arrival, you unbend the line and everything unfolds. They try to use a large radius on the shipping bends so the line doesn't kink during unpackaging.

In almost all cases, factory braking systems are designed to use 3/16" line at calipers and/or wheel cylinders. For rear brakes, there is usually one line that runs from the ABS unit or combination valve to the back of the vehicle, where it then splits to feed each rear brake. The single line that runs down the length of the car is usually 1/4", because it has to move enough fluid to handle two brakes. The lines that split are 3/16", just like the front brakes.

Anyway, that's just what I've seen on every car I've worked on. I'll admit, I haven't actually crawled under my Eldorado to see how they did the brakes. I really need to get that car up on a lift one of these days...

So, there are separate lines for each rear brake that run the entire length of the car? If that's the case, I'd say they're 3/16" with bubble-flared (ISO) ends. My FSM doesn't state whether the threads are standard or metric.

Making a hybrid double-/bubble-flared line sounds like the easiest way to do it, if you're comfortable with flaring your own tube (short of replacing the whole thing). I did that on my '86 Camaro when I was running a line lock. Everything worked fine, as long as the flares were made properly.

Good luck. I could think of about a million better ways to spend a Saturday than flaring brake line. :bonkers:
 

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2015 Mazda3 S GT Hatchback 2013 Kia Optima SXL
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Discussion Starter #7
Good luck. I could think of about a million better ways to spend a Saturday than flaring brake line. :bonkers:
:alchi:Ain't that the truth. The hardest part that I think I will have is trying to get the new line in place after bending it into shape. These brake lines from the factory were definitley put in place before anything was put onto the car. I have to navigate through, over, aroung the exhaust, rear cradle, wiring, etc. Not going to be fun. Plus being only about 12" off the ground isn't going to help any. The flaring should go okay. I did about a dozen flares last night to practice up. Not too difficult. I will post back with the results when I get it done.

Don
 

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Discussion Starter #8
Well it is done besides cleaning up. Everything that could go wrong did go wrong. I removed the old line easily. Bent up the new line easily. Flared the ends easily. SOB leaked at the union. Go to auto store and buy a compression fitting. No leaks. Time to bleed. Dam bleeder screw frozen in caliper. Two hours later bleeder is out, off to auto store. Major thunderstorms in NJ today. Took two hours to return from auto store. Everything back together, brakes bleed, time to test drive. Brakes work beautifully, but, there is now an annoying squeak. Took tire off, caliper off, found nothing. Put back together, still squeaks. Screw it, whatever it is will clearance itself. Started at about 1 pm, ended at 8:30:alchi::bighead:. Clean up is tomorrow.

Don
 

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Started at about 1 pm, ended at 8:30:alchi::bighead:. Clean up is tomorrow.
Boy, do I know THAT feeling.

I hate to say it, but you should never, ever use compression fittings for reattachment of brake lines. They just aren't designed to handle the pressure of a hydraulic braking system (upwards of 1000 psi, often more!).

The union leaked because the flare wasn't properly seated. It sometimes takes a few iterations of tightening and loosening to get the steel line to match the brass seat. I've also seen homemade flares destroy the seat of a brass union if the flare isn't perfect -- and I mean PERFECT. You'd be amazed how little an imperfection can cause hours of frustration.

Even if you don't blow a line during normal driving, you're probably going to have to do it the right way before long. I doubt any service garage will put an inspection sticker on your car with that compression fitting in place. For fuel and transmission lines they work great, but the fluid pressure is a lot lower. It sucks, I know...

As for the squeak, maybe you got some brake fluid on the pad or rotor?
 

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Talk to a Midas mgr. See if he will give you a flat rate to do job. Worst he can do is tell you $1 million. On other hand, he might be reasonable. Or he might have a mechanic who moonlights at the shop at nite.
 

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Discussion Starter #11
I am going to give it another shot. Nothing is leaking, just trying to do the repair correctly. Bought another line and some more brake fluid. This time should go much easier though. I was able to locate a metric union that takes bubble flares. Last time I used a double flare union, and it leaked badly. Making the bubble flare is far easier than the double flare. I am expecting the repair to take no more than an hour, and be leak free. I have alot of other work to perform also (right rear brake caliper replacement, right rear parking brake cable) so it should take about all morning (fingers crossed). Hoping all the parts are here by Saturday, otherwise, it gets put off until the following weekend. Wish me luck

Don
 

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Discussion Starter #12
Brake line is officially repaired. I bent up the new line (I had to be creative as the new line was 60" long, and the repair only called for about 55"), bubble flared the existing line, used the metric bubble flare union, bleed the brakes, and no leaks. I got it up to about 25 mph and hammered the brake pedal several times. The neighbors are probably still asking themselves what is wrong with me. Drove back home, checked for leaks, and the repair is bone dry. I took one extra step this time and wrapped the new line with electrical tape. Hopefully this will delay rusting in the future. Now if my other parts would just get here.

Don
 

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Nice job!! :thumbsup: I have never been successful at removing my parking brake cable from a caliper setup. Is it only on the right side? Any special tricks? I have a sneaking suspicion it is not releasing all the way now causing the brake to 'drag'. It now sounds like there is no pad left.
 

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Discussion Starter #14
Nice job!! :thumbsup: I have never been successful at removing my parking brake cable from a caliper setup. Is it only on the right side? Any special tricks? I have a sneaking suspicion it is not releasing all the way now causing the brake to 'drag'. It now sounds like there is no pad left.
Brake bleeder screws have been changed with new ones laced with anti-seize. Remaining parking brake cable has been installed. Tires have been rotated. Now just have to wait for new caliper to arrive to complete the job.

As far as the parking brake cable is concerned, if you grab the end of the cable with a pair of pliers, and pull it outward, you will get enough slack to remove it from the caliper. It is much easier than you think. Until I changed the cables, I had no idea you could do that.

Don
 
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