I'm replacing the front brake line on my 2012 Suburban, and just want to confirm that the correct flare wrench for the brake line is 9/16. I have a set of metric wrenches and the 14mm didn't feel just right.

So I googled it, and the closest I could find is a post for a Silverado that mentioned 9/16. I assume it's the same for the Suburban, but thought I'd check before running to the store.

 

9/16" is close to 14mm. I wouldn't waste my time on a 9/16" as that actually calculates to 14.3mm, so a little larger. Were you trying a 6-point 14mm flare wrench????? I "thought" these were all-metric these days.

Of course our 1994 Suburban needed 3/8" allen wrench for the brake caliper bolts. Same for Mrs. Cusser's 1982 Firebird where the official service manual stated that the vehicle was "all metric".....

 

I ran out to double-check -- actually the 13mm is just a little lose, but maybe that's the right size, unless another SAE is a little smaller than 13mm. (sorry, I originally wrote 14mm--you got me thinking with that 14.3=9/16 so I double-checked the fit with my existing wrenches. I have a set of metric 6-point flare/line wrenches and I'm trying to confirm if I'm covered, or if I need an SAE set to finish up this job : )

 

1/2" flare would be a tiny amount smaller than 13mm (would be like 12.7mm).

 

Thanks Cusser. I bet that's what I need then. There's just a little bit of play with that 13mm and I've heard you want a snug fit so I don't round those corners.

I think I also read on the forum that someone likes to use vice grips with a small bit of wood (like paint stirrer cut to length) as shims so the teeth don't bite into nut. If the 1/2" isn't snug, I'll think about that. Just curious if anyone else has tried that.

 

Vise grips are not meant for removing hex headed anything. They are a last resort tool for amateur's.
Spray some penetrate and let it soak on the connections, especially on a brake line that goes through a nut as that's where they will freeze up.
Hex size will ''shrink'' due to corrosion, I've had to tap on different sized tools for a tight tool to fastener fit many times due to that. You can't own enough tools when wrenching on stuff yourself just like a guy in a shop.

 

This. nice to have both metric and standard sets for this reason.

some tips during line replacement.
make sure the reservoir doesn't empty when the system is opened. If it does...bleeding will be much more involved. wedge a pry bar between the seat and brake pedal enough to move the pedal 3 inches. This closes off the compensation ports inthe mc and stop the master from bleeding o ut.
use cupric-nickel lines. much easier to bend without kinking. will not rust. but must be properly secured to stop vibration. never run straight lines...have 2 bends in the lines. if you use steel lines...spray rubberized rocker guard on them or they will have surface rust in 6 months