Thread: Brake lines and fitting sizes.

Hey Everyone, I could use some help here. Apparently the local parts stores around here don't know anything anymore.
I need to replace a right front brake line on my 2004 Grand Prix GT2. It rusted out under the heat shield and was spraying fluid all over my driveway. It seems they no longer make a preformed brake line, probably haven't for years, but that just goes to show how long it's been since I've had to replace one. Anyway, I'm trying to find out a few basic things so I can get this back together.

1. What size is the line? (3/16" I'm assuming)
2. What thread sizes are the fittings on the caliper side and then on the antilock brake (master cylinder) side?
3. Has anyone had any experience with the Poly-Armour brake lines?

Thanks!

Originally Posted by ItHurtz

3/16 yes

m10-1.25? just cut the nut off and bring it in and test fit on the nuts dont confuse double vs bubble flare fittings, if the nuts are not rusted junk piles I would reuse them.

I have nicopp lines on all four corners, easier to work with. Poly will work fine, but tougher to bend a tight radius if needed and may kink.

3/16" is what I thought, thanks for confirming
The nuts aren't junk, and if they are the same size as the thread in the caliper then they are m10-1.5.
Sitting here without the line in front of me I don't recall any sharp angles, nothing over 90 degrees anyway. If I use the poly I'll have to join on the middle which seems easier to me than trying to run one solid line all the way down and behind the engine to the other side of the car.

Thanks for the info!

I did a little more digging and here's what I found, for anyone else who needs to know.

The line is 3/16" but it's a "metric" line.
The flared ends use a "bubble flare" and the fitting threads are M10-1.0
I'll try to find out if the local parts stores sell anything metric.

That's what I did too. It rusted through where the heat shield went over it so I took one half out the wheel well on the passenger side and the other out through the engine compartment. I couldn't get my fitting loose on the ABS block so I had to cut the line and use a socket so I won't be able to keep the flex line. Advanced Auto sells Poly Armour metric lines and fittings so I think I'm all set. The sad thing is, they have them, but don't know they have them. I had to dig and find part numbers before they could even help me out! Good thing for the internet and forums. Thanks for your help!

I got it all back together and it's working good.
Here's the break down:

The line is 3/16" but it's a "metric" line.
The flared ends use a "bubble flare" and the fitting threads are M10-1.0
Poly Armour lines and one connector.

PAE-360 60" line
PAE-340 40" line
BLU-8C connector

If I were to do it over I think I might be able to get away with a 51" line instead of the 60". The advantage if the 60" I guess is that it gets the line further away from the exhaust. The junction ended up being just under where your foot would rest next to the gas pedal.

Thanks everyone for your input.

Good info, now l have a 2001 Grand Prix, just got it and somebody did a shoemaker job splicing a line in.
I have good brakes but there is a leak at both places.
I just have to make sure my brake fluid remains full in the meantime.
If I can use the lines and connectors that you mentioned above I may just run the whole line eventually.
Do you or anyone know if the 2001 would use the same part number lines and union?
However it seems like they're always has to be something I ran across a YouTube video where the follow was changing a line or showing you the where the lines go but he stated the line at the ABS unit under the hood, and the line at the rubber brake hose were different thread sizes on the fittings.
Did you find that to be the case on the 2004?
I know I did a complete brake line replacement on my 2002 Oldsmobile Alero and the fitting size at the ABS unit under the hood and the fitting size at the brake hoses were indeed the same size.
Do you have any idea if the fitting sizes for the ABS unit and the brake hoses on the 2001 Grand Prix are the same?
Thank you.

On my 2001, the fittings were different sizes. I ended up reusing all that I could.