replacing all brake lines: need advice

[eljefino]

Brake lines are a great job that's really cheap for the DIY and real expensive to have a shop do. I've bought a couple $300 cars where that's all they needed.

Your mazda will have wild & crazy fittings, probably no two alike, and probably ISO bubble flares.

You can probably reuse the old fittings. Spray the threads with a touch of PB blaster then cut the lines right at the fittings (ensuring PB doesn't drip into the system) and I bet you can get a 6 point socket on there. Use a vise grips on the metal part of the hose to back up when you unthread your line nuts.

If the old fittings aren't threaded all the way to the flare they're metric. If they are, they're SAE. A 3/8" SAE nut will thread into 10mm but blow out under pressure.

You may find yourself splicing together under the van. For example running one line from the MC down under the firewall with all its twists and curves then another one that follows under the rocker panel. This is cheaply done using double flare unions. It gets crazy having a line with an ISO flare on one end and a double on the other, which kicks you out of using store bought 60 inch long pieces.

The copper nickel line is the bee's knees. If you're a first time flarer you'll do well. If you ever touched steel you'll love the stuff. If you never did you'll still think it's hard. Make sure your line nuts are on before you start flaring... easy mistake to make!

At some point you may find yourself flaring a line that's dripping with brake fluid. It sucks!

 

[windeye]

Originally Posted By: bubbatime
New brake lines on a rust bucket car worth perhaps less than a grand? No stinking way. Trade that clunker off.


A new car to replace this van cost at least 35 grand, and they have less room than the MPV! The 3rd seat in MPV folds flat and disappears into floor pan, and the 2nd row seats can be removed completely. With that, you have the cargo room that beats the new Highlander/Pilot, etc. Total cost of material and tools is going to run about $200. It's not the resale dollar value that makes me keep the car, it's the utility of it, and I have the car from day one, and have taken good care of it as much as I am able.

 

[windeye]

Originally Posted By: eljefino
Brake lines are a great job that's really cheap for the DIY and real expensive to have a shop do. I've bought a couple $300 cars where that's all they needed.

Your mazda will have wild & crazy fittings, probably no two alike, and probably ISO bubble flares.

You can probably reuse the old fittings. Spray the threads with a touch of PB blaster then cut the lines right at the fittings (ensuring PB doesn't drip into the system) and I bet you can get a 6 point socket on there. Use a vise grips on the metal part of the hose to back up when you unthread your line nuts.

If the old fittings aren't threaded all the way to the flare they're metric. If they are, they're SAE. A 3/8" SAE nut will thread into 10mm but blow out under pressure.

You may find yourself splicing together under the van. For example running one line from the MC down under the firewall with all its twists and curves then another one that follows under the rocker panel. This is cheaply done using double flare unions. It gets crazy having a line with an ISO flare on one end and a double on the other, which kicks you out of using store bought 60 inch long pieces.

The copper nickel line is the bee's knees. If you're a first time flarer you'll do well. If you ever touched steel you'll love the stuff. If you never did you'll still think it's hard. Make sure your line nuts are on before you start flaring... easy mistake to make!

At some point you may find yourself flaring a line that's dripping with brake fluid. It sucks!


Thanks... Mazda uses 3/16 inch lines with metric thread, M10x1.0. And also American standard double flare. Based on my research, and yes I did notice that the nut does not go all the way in, just to confirm to what you said. I try not to add any splice, as more connections mean more risk of leaking. I am also replacing the flex hoses, so the nut end is new. If the rear drum cylinder puts up a fight, I'll replace the cylinders, not a big dollar item...... I am rather encouraged by the collective wisdom from all your responses. Thanks.

 

[DuckRyder]

Depending on your time frame:

Inline tube can probably duplicate your lines. Doesn’t help the issue of taking the car apart, but something to consider.

 

[bdcardinal]

Originally Posted By: Chris142
Bare with me because we dont get rusty stuff here. Can you paint the lines to protect them?


That was my thought also. Maybe put some kind of undercoating spray on them?

 

[Lubener]

Originally Posted By: bubbatime
New brake lines on a rust bucket car worth perhaps less than a grand? No stinking way. Trade that clunker off.


Probably because this project is well beyond your capabilities...

 

[kschachn]

Originally Posted By: bubbatime
New brake lines on a rust bucket car worth perhaps less than a grand? No stinking way. Trade that clunker off.

Because the OP is apparently smart enough to take care of the work himslef rather than having to trade off the vehilce because he is incapable of the effort.

 

[eljefino]

Originally Posted By: windeye
I try not to add any splice, as more connections mean more risk of leaking.


This is true but you could counter it by getting a 5 footer from the parts store and re-flaring one end with your iso bubble. But then it begs the question, what is harder, one flare on a steel line or two flares on a copper one?

Splices with unions and premade flares are actually really easy-- there's lots of crush and few chances of leaks. Homemade flares are trickier but it just comes down to cutting straight and getting the tool on straight with the right depth. Practice so it looks like the picture or a parts store flare.

On the flipside you could probably get the rear by unravelling 5 feet off the "roll" and fishing that up from below the firewall, tying it off near the M/C, then unrolling to the rear. Connect to the M/C last so you don't have fluid dribbling all over.

If you get it wrong it'll leak when you bleed-- you won't have a flare that holds at 500 PSI but fails at 2k. If it holds pedal you're golden.

Remember, they put cars together on an assembly line with this system so it's at least somewhat idiot proof.

I hope you're getting your brake hoses from rockauto or similar as they're about $4 when I look.

 

[bubbatime]

Originally Posted By: Lubener
Originally Posted By: bubbatime
New brake lines on a rust bucket car worth perhaps less than a grand? No stinking way. Trade that clunker off.


Probably because this project is well beyond your capabilities...


Well to be fair, I have lived life very economically challenged, and now live on the other end of the spectrum, very non-economically challenged.

I rebuilt the engine, transmission, AND rear differential completely in my first car. Why? It was a fun son/dad project, and we didn't have a lot of money back then.

True, these days I would not bother replacing break lines on a 18 year old car. More out of economics and not willing to drive an 18 year old car any longer than any other reason honestly.

 

[andyd]

Regardless of age, To DIY this job is cheap and not too difficult. The PO asked very good questions and got lots of good advice. Up here in the rust belt, brake lines are routine maintenance in an other wise fine running older car.

PS, please post a follow up. TIA

 

[windeye]

Thanks to eljefino for the tip on rockauto.com... One other question: The torque spec on the fitting is 12 ft-lbf, how did you tighten it up without special tool over the line (i do have torque wrench but main thing is socket over the line)? I am thinking to thread the bolt until it stops, and then do an extra half turn.

 

[andyd]

I put them together hand tight to make them up. Then fill the reservoir up and chase the drips back toward the RR bleeder. I never concerned myself with assembly torque specs. You would need a set of crows feet. Open ends that go onto a ratchet. I don't feel the need for these so far. Stuff is tightened until it doesn't drip. Doing this is a gravity bleed and when the fitting stops dripping, the line is bled to the next drip. The last drip is the open bleeder. Repeat this with the other 3 lines.

 

[windeye]

It wasn't easy to reach this point and be able to make good flares repeatedly. Going on vacation, will write later. Thanks again for all the good advice.

 

[windeye]

Here is my modified approach using the NAPA tool, also with a note on the Eastwood on-car flare tool.

https://docs.google.com/document/d/e/2PA...lfgiViqM9Id/pub