“This will not be over quickly. You will not enjoy this.”
This started as a 10-minute job to replace the flex hoses for my front brakes and install a new caliper on the driver’s side. It tuned into a messy job involving several days of research and ultimately flaring the hard lines. Here’s what I learned along the way.
After 14 years in Chicago, my brake lines were frozen solid. Wrenches rounded off the nuts. Vise Grips shredded the nut. A blow torch did absolutely nothing. I had to cut the nuts and replace them.
Here’s the tools needed for this job:
Bubble flaring tool kit – not a single flare or double flare, but a bubble flare.
3/16 in. tube size to M10 - 1.0 thread bubble flare European steel tube nut – one per line
Flare wrenches – 8 mm, 10 mm, 11 mm, 12 mm, 14 mm and 15 mm
Small hacksaw blade - no more than 3/8 inch wide
3/16-inch tube bender
Small section of 3/16-inch tube – used for practice
A good supply of shop rags
Small bucket - to catch old brake fluid
Brake fluid – at least one 12 oz. bottle per nut you’re replacing.
Large bucket with soapy water
Safety goggles
Mechanics gloves
Power bleeder or a friend who knows how to push on the brake pedal.
Small tubing for bleeding the brakes. Length needs to go from the bleeder valve to the small bucket.
First off, this is going to be messy. Did I mention that already? Yeah, it needs to be repeated. Plus, the brake fluid makes everything slippery so I strongly suggest wearing mechanics gloves for this, to help hold stuff.
Flare Wrenches: I was surprised that I used so many sizes. I used 11 and 14 mm for the hard line to flex hose connection, 14 mm on the old flex hose at the caliper, and 10 mm for the bleeder valve on the passenger-side caliper which I did not replace. For the new drivers-side caliper, the bleeder valve was 8mm. The new flex hose itself used 15 mm at the caliper and 14 mm at the hard line connection.
- These are Flare Wrenches
“3/16 in. tube size to M10 - 1.0 thread inverted flare Japanese steel tube nut”
“3/16 in. tube size to M10 - 1.0 thread bubble flare European steel tube nut”
- European (left) and Janapese (right) Nuts
Also, 3/16 line is also known as 4.75 mm line.
If you’ve never flared a line before, use the small section of tube and practice a few times. My first attempt was misshapen and I knew I had some more practice to do. After trying this a few times, try holding the pipe clamp in a position similar to what you’ll experience on the car, just to get a feel of how awkward it’ll be to twist the bolt. I did six before I felt good enough to try it on the car. Once you’ve done a few, you’ll get the feel for the tool and you can whip through them in no time. When I was done with each one, I inspected it mounted in a nut. I even torqued one down into the new flex hose so I can see what happened to the flare once it was inside coupling. This gave me a good understanding of where the metal was compressed/stretched and how it created a seal.
Prep:
First off, it would be a good idea to get the rotor and brake pads out of the way. This way, there’s no chance of fluid or scratches getting on the parts. In my case I was replacing the rotors and pads, so they were already off the car. It made it easier to get in there. The sway bar link was the biggest obstacle with the strut being next.
Remove the ABS cable and tuck it out of the way.
- ABS cable out of the way
- Rag & Bucket to catch the dripping fluid
Next, make sure all of your tools and parts are in reach as you’re sitting at the wheel well. You don’t want to start searching for something as fluid is dripping out of the system.
I STRONGLY SUGGEST placing the nut on top of the flaring clamp, just to make sure you don’t forget to put it on the line before you start the flare.
- Nut is on the clamp for a good reason!
First, begin cutting the line. Using the small hacksaw blade, begin cutting the line inside the spring, as opposed to cutting the line on the back side of the nut. Cutting on the inside of the spring will help improve the flatness of the cut as well as provide a little extra length of the pipe. Using a gentle pressure will allow the spring to help guide the blade in a straighter line as well as preventing the blade from binding as you cut. Once you cut the inside of the hose, fluid will start to leak out. Things will get slippery very quickly. Once you cut through the hose completely, the hose will spring apart and fling fluid around. This is where the safety glasses are important – you do not want that stuff in your eyes!
- Cutting the line on the inside of the spring clip
- Hard line has been cut
Depending on the bend of the tube, you’ll want to use the bender to straighten out the hose – if possible. Since my bender didn’t make it easy to straighten the hose, I gently straightened the hose by hand and then pushed and wiggled a nut up the hose. Vice Grips helped to firmly push while my other hand held the hose firm to prevent kinks. The tube has to be straight enough to get the nut, clamp and the length for the flare, so you’re looking to have about 1.5 inches straight enough for the nut to slide up.
Remeber to place the nut on the hose so the threads are pointed towards the flare you will create!
Place the clamp on the hose and check the gap for the proper distance from the end for the flare. When clamping the hose, start by tightening the nut closest to the hose, and then clamp down the far nut. This tightening doesn’t have to be painfully tight because of the clamp I used. It has small teeth inside the hole and will grip the hose very well. Use the twisting handle on the nuts and it should be fine. Tighten it too much and you’ll screw up your washers – which I did during my practice time.
Place the flare bolt on the clamp and tighten it, making sure to hold the clamp very still, otherwise you’ll place tension on the hose and possibly kink it. Take your time to make sure you’re applying steady pressure. When the flaring nut has stopped moving, you’re done.
- Flaring the hose
Also make sure your caliper is within reach. Install the flex hose onto the caliper and place the caliper in its normal operating position. This is important so you can install the hose properly.
- Attach the Flex Hose to the Caliper First
Time to remove the flaring tool and bend the hose back into place. Take your time so as not to kink it.
- Carefully bend the hose back into place
- Spring Clip in place and ready for connection
- Groved Bracket for Flex Hose
Begin by holding the flex hose in position and pushing the new nut into it. Becase the spring clip is in place, it may take a bit of effort to get everything aligned and connected.
- Hoses connected - no more dripping fluid!
With everything looking good, I reassembled the rotor, brackets, calipers and pads. Don't forget to reinstall the ABS cable. I kept the newspaper in place and stomped on the brake pedal again for one last test.
- One last pressure test
During the bleeding process, I discovered something odd. The bleeder valve on the old caliper had a 10 mm nut and on the new caliper it had an 8mm nut – both were Volvo calipers, but maybe the new one was rebuilt with a different valve. Although it was new, I still used a flared wrench for the bleeding process.
The final step was cleanup. Using the large bucket of soapy water, I dropped in all of the tools, gloves and rags I used to clean the brake fluid off. After I dried the tools, I sprayed them with WD-40 to prevent rust and wiped off the excess. I also used a rag to ‘swab the deck’ of any fluid that missed the bucket.
