I've seen this question pop up pretty often, but never seen a definitive answer. So I decided to drive to the parts store, and figure it out.
I replaced the brake lines in my Fiero with the Fiero Store's stainless steel pre-bent lines, and bought an extra proportioning valve and 3-way rear block just in case my old ones were unusable. The prop valve was fine since it was sealed in the spare tire bay, but the rear block was a corroded mess. I cut the old lines off, put the block in a vise, and used a couple Snap-On 6-sided sockets to get the old fittings out of the block. Then I cleaned it off with a wire wheel:
Now, when I was seeing how many different brake line and fitting sizes there were, I was surprised to find there were only two (not counting the two lines going to the master cylinder on top of the prop valve). The big fitting, with it's 6mm (1/4) line, and the small fitting with it's 3/16 line. So I took these to the parts store.
I hate to admit it, but yes, I went to Auto Zone. This is probably the only store in town where I could go behind the counter and do the research in the parts area for half an hour, going through all the fittings. Here's what I found:
The brake lines are European thread bubble flare. Yes, a Pontiac, built in the USA, has European brake lines. I believe this is because the parts probably came from Canada. This is an example of the lines they have:
This line is 3/16 x 08" (line size x length) (4.7mm x 20.3cm). metric thread/bubble flare. European thread bubble flare. All these lines begin with the designation PAE-3__, where the last two numbers are the line length in inches.
They also had PAB-3__ line, which is US thread bubble flare - these will NOT work on the Fiero. The fittings are a different thread.
(Again, the two lines that go into the master cylinder are different, and appear to be regular American-style double flare lines.)
Now the fittings:
First, the large fittings. size is M14 x 1.5 bubble thread size, 6mm tube size. They sell these in a 5-pack, made by the company AGS. part # BLF-53C-5 barcode # 077146372520 $3.49
The small fittings: size M10 x 1.0 bubble thread size, 3/16 tube size. Also a 5-pack by AGS, part # BLF-39C-5 barcode 077146368813 $2.99
These are right on the shelf, with the brake lines
If they don't have them, they can probably order them? Forgot to check. They're both available on their website.
I wonder if the Fiero was meant as a more "global" car at least during the early stages of development. Really wish the Fiero history wasn't buried and hidden so deep in the history of GM.
UPDATE: I finally got a hold of a used master cylinder cheap, so I could check the sizes of those lines, and the ones going into the proportioning valve. These lines have double flared ends, in contrast to the bubble flares on the rest of the lines. So the Fiero uses standard US brake lines going into the prop valve, where all the lines then turn into European lines.
At the front of the master cylinder, the line going into the prop valve is 1/4" at both ends. At the master, the fitting is 9/16 - 18, and at the prop valve, is 1/2 - 20 At the rear of the master cylinder, the line going into the prop valve is 3/16" at both ends, and the fittings are both 1/2 - 20
These fittings are all also available in 5-packs from AGS. It would be better to get them individually, since you would end up with so many extras, but they're all still available new.
Since it's a popular upgrade, I also check on the Blazer master cylinder. A 94 S10 Blazer uses the same fitting sizes, and has the same cylinder bore, 36mm. A 94 full-size Blazer uses the same fitting sizes also, with a slightly larger bore, at 1.574"
The hoses at the calipers: They all use an M10 - 1.0 thread fitting
my dad's oldmobile Eighty-Eight- from 1989 had the same crap. American and Metrrc parts on the same system. It made a giant ass pain to work on it years ago.
I just took the block off the back wheel on the car i'm working on and someone put 3 adapter fittings together to attach it. I'm saving this post to use later on this month.
I know TFS sell 84, 85-87, and 88, in line kit... They had to bend three kits, did they use different nut for some line ends?
Even if a few nuts change, we have a source for fittings. Good job. This notes/page will be added to brake section in cave.
------------------ Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should. (Jurassic Park)
The fittings above are all for 84-87 cars. If anyone has an 88 and could check and see if the sizes are the same, that would be great. I know the 88 uses a different master cylinder, but has the same fitting sizes. Not sure about the prop valve, or the 3-way block in the back.
I have this leak at the connection block over the right rear wheel. I suppose I should replace everything with the Fierostore stainless lines, but they don't have them right now and I can't even access my account for some reason. So I really appreciate your thread, especially since there is an Autozone just up the street. I see on the web they have premade lines (not prebent) and I do have benders. Do you know how long that line is? Hopefully I won't have to cut and flare as well as bend.
Is this the right line? It has a different part number "PAEX."
AGS/3/16 in. o.d. x 60 in. ISO bubble flare metric Poly-Armour brake line with 2 pcs. M10 - 1.0 tube nut fitting for European vehicles Part Number: PAEX-360
Sorry I'm so late to respond, just saw this. That line is the undercar line, not sure how long it is, it's REALLY long, the fitting sizes on both ends is M14x1.5, line size 6mm
I had to replace the 6mm line. Good luck, nobody carries it. NAPA can order you a roll, otherwise you need to get the 6mm preflared sections azone carries, but they have wrong fittings so you need to cut off flares, get the right fittings, drill them out a little because 6mm fittings they sell don't fit over their 6mm preflared line (it is ridiculous I was so mad) I bought 2 6 foot sections of the 6mm line preflared, with one coupler that fit the lines on their, and I bought the 6mm fittings M14 x 1.5 shown in the picture at the beginning of the thread, and they did not fit over the line. Everything worked out in the end but I was really frustrated that 6mm fittings would not fit over 6mm line. I routed the line like stock.
I had to replace the 6mm line. Good luck, nobody carries it. NAPA can order you a roll, otherwise you need to get the 6mm preflared sections azone carries, but they have wrong fittings so you need to cut off flares, get the right fittings, drill them out a little because 6mm fittings they sell don't fit over their 6mm preflared line (it is ridiculous I was so mad) I bought 2 6 foot sections of the 6mm line preflared, with one coupler that fit the lines on their, and I bought the 6mm fittings M14 x 1.5 shown in the picture at the beginning of the thread, and they did not fit over the line. Everything worked out in the end but I was really frustrated that 6mm fittings would not fit over 6mm line. I routed the line like stock.
they didn't fit because of the coating on the lines. 6mm fittings fit 6mm lines WITHOUT COATING I have the same issue once, but decided to take the coating off instead.
RWDPLZ where did you get the connection block back in 2010? Is it possible to get another today? Now I have the lines, but I can't get the old connector out of the rear connection block, at least while it's on the car. It's recommended that I take the other lines off and bring the block inside to remove the fittings. The closest match doesn't have metric fittings. It would be nice to get this project complete in less than two years...lol
RWDPLZ - Thanks for all this info, you've got a positive from me. Last night, I replaced my front driver's side hardline with a 30 inch one from advance. (The 20 inch one might work but it looked a tad short) It already had the 10mm nuts on it and everything.
For anyone thinking about doing this, I would suggest buying the 6 dollar tube bender or renting the full tool set for the job. If you buy the lines with the nut and flares already done all you have to do is bend it as needed to fit. I had a little trouble with excess length, but just left it all under the master cylinder without bending the line enough to crimp anything.
I've done custom lines too, like on a Tahoe where I had to reuse the oddball-sized fittings that go to the ABS pump. It's the best way to get a good quality professional job, unless you luck out and find one the exact length you need. Problem is, the only flaring tool I've found that works well is a Craftsman one. The cheap chinese ones just don't work, and I had a Blue Point one right off the Snap-On truck break the second time I used it.
I've redone brake lines on a few cars, sometimes remedial, sometimes upgrades. Most recently I redid all the lines on my 1962 Falcon to accommodate a new master cylinder. After a lot of research I used copper-based brake line ("CuNiFeR" is one brand) and couldn't be happier with the result. The copper stuff isn't prone to rust or corrosion and is incredibly easy to form and run - getting it all the way down the driveshaft tunnel was painless. I bought a 25' roll of it from, of all places, Amazon.com but you can buy it just about anywhere that does brakes. The fittings were mostly sourced from Summit as they have a pretty good selection, but I had some leftovers from previous jobs and those were purchased from FedHillUSA, Hose and Fittings, and Pegasus Racing. FedHillUSA supplied a mess of ISO/bubble fittings when I did the lines on my XR4Ti.
FWIW, I use a Mastercool hydraulic flaring tool that was like $300 and, turns out, not such a good investment. It's nice because it's portable and great for making repairs in situ, but as a tool for cranking out multiple reliable flares it's not my favorite. If I were doing it again, I'd probably buy one of the bench-mount flarers like Eastwood sells. They're also not cheap, but some auto parts stores rent them. Related, flaring that copper tube is INFINITELY easier than steel tube, so if you just need to knock out a couple, you may have luck with one of the Harbor Freight etc. hand tools.
The 3-way block I got from someone here, in 'The Mall' section. Just made a want to buy thread.
Conventional copper tubing as brake lines is a bad idea. AGS and other companies now make copper nickel alloy lines that are DOT approved. Haven't tried them myself.
The hoses at the calipers: They all use an M10 - 1.0 thread fitting
I've never worked with brake line before, so this will certainly be a learning experience.
The different thread fittings have me boggling. I know that eventually I'm going to replace all of the lines, but for now I'm simply trying to fix the brakes on the rear passenger side.
I removed the wheel well liner to access the water pump (which, as it turned out, did not actually afford me additional access) and it got hung up on the brake line. I went to unbolt from the wheel well and push it slightly out of the way, and it sheared off at the T. I barely touched it!
Then I went to unbolt the T, and the head sheared off on that, too. Again, barely touched it.
From my understanding, the hose from the caliper is an M10 1.0 thread - but, what kind of flare?
It's which leg that matters... there is a 1/4"/6mm pipe that runs to the front of the car, and a 3/16"/4.75mm line that runs to each wheel. So, one big and two small. Hopefully it's not the big one, as that would be a pain to replace. Of course, if the pipe is in otherwise good shape, you could always cut it back and use a union to splice a new section of pipe in. Be aware, a compression fitting is NOT a suitable way to splice brake lines. You need an actual flare union.
Fed Hill (the site you linked to) has a good variety of brake fittings. You may also be able to re-use what's there if it's in good shape. If there's any concern about rust, etc., I would replace as much as you reasonably can.
[This message has been edited by thesameguy (edited 01-28-2021).]
It's which leg that matters... there is a 1/4"/6mm pipe that runs to the front of the car, and a 3/16"/4.75mm line that runs to each wheel. So, one big and two small. Hopefully it's not the big one, as that would be a pain to replace. Of course, if the pipe is in otherwise good shape, you could always cut it back and use a union to splice a new section of pipe in. Be aware, a compression fitting is NOT a suitable way to splice brake lines. You need an actual flare union.
Fed Hill (the site you linked to) has a good variety of brake fittings. You may also be able to re-use what's there if it's in good shape. If there's any concern about rust, etc., I would replace as much as you reasonably can.
It's the bottom of the "T" that broke. It's pretty gnarly.
it looks like the lines The Fiero Store carries don't include the line that goes to the front of the car, according to the diagram.
I'm going to have to remove the "T" completely, and I'm praying that I don't break any of the other lines trying to do that. The one on the bottom that broke did so with very little effort.
I wish it wasn't so cold here. It's like 15. I would just use the torch on the T, but it'll cool down way too quickly.
It's the bottom of the "T" that broke. It's pretty gnarly.
it looks like the lines The Fiero Store carries don't include the line that goes to the front of the car, according to the diagram.
I'm going to have to remove the "T" completely, and I'm praying that I don't break any of the other lines trying to do that. The one on the bottom that broke did so with very little effort.
I wish it wasn't so cold here. It's like 15. I would just use the torch on the T, but it'll cool down way too quickly.
Well, here it is three years later, and I'm finally getting around to replacing the rear line. The subframe requires replacing, so since it's grounded, it seemed like a good time.
I've learned a lot in the last three years. Ended up making flares for a bunch of the existing lines because the PO didn't make them correctly. Completely created and replaced lines for a completely different Fiero than the one I referenced above.
So I was feeling really confident about replacing the line on my Fiero "Ginger". The ones going into the rear "T" at least.
The lines were seized into the T, with the exception of the line on the bottom I'd replaced two years ago. That one came out easily.
I tried so many techniques to break the bonds, but all I ended up doing was slowly rounding off the corners on the hex on the fittings.
Finally threw up my hands and decided to break the rear line off (which was as delicate as the bottom one which disintegrated when I looked at it), and cut the frontward one (the 1/4" one) with a line cutter. It was THAT one which gave me most pause.
Interestingly, it's been replaced before. When I was examining the lines, I found a fitting about halfway between the nose and tail, just sitting there. It's not connected to anything. Theory is PO chose a premade line that on one end went into the proportioning valve fine, but the end with the T was a different fitting, so they slid the fitting back a ways, and put on a new end.
All of the other lines I made, bent, and installed, but now I have to see if I can dig up a metric M14 fitting easily.
oh, right, to actually remove those seized fittings, I ended up welding nuts to the fittings and using a 1/4" impact to shock them out. I've gotten so much better with this technique. First time I ever tried it, it took me 12 nuts (this was a couple years ago) to remove ONE of the first bleed screws.
This took me four, to remove three fittings - and, it would have been three! Except, the weld stuck to the old line on the 1/4" fitting, instead of the fitting itself. The line just spun in the fitting. So, an angle grinder with a cutting disc, and two minutes of time to get to bare metal, and out it came.
Replacement lines are much softer.
