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 Post subject: HOW TO: EXTEND REAR BRAKE LINES
PostPosted: Thu Oct 30, 2014 9:50 pm 
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Those of us with a 3.5-4 inch lift or higher should extend our rear brake lines, especially if we've installed extended sway bar links (like I did) or are running without a rear sway bar. While the stock brake hoses will be fine on the street, any significant off-road articulation of the rear suspension puts strain on them. Even when on a hydraulic lift at the shop, the stock brake lines are maxed out at full rear axle droop. The front brake hoses are long enough for a 4 inch lift and do not need replacing. Here is my KK on 245/75/R16's with JBA 4 inch springs.
Image

I could not find a How-to thread for extending rear brake lines on the KK, so I thought I would document my process. There are plenty of XJ, TJ, and JK vids and threads out there showing the process, however, our brake lines are not the same. On the Jeeps mentioned above (and the KJ too, I think), the rear brake hoses can be unscrewed from the steel brake lines and longer hoses can be swapped in without too much trouble. On the KK, DaimlerChrysler made the unfortunate design decision of permanently crimping the rear brake hoses to the steel lines, making it a harder job to swap in longer hoses. In our case, we will have to cut off the factory steel lines just before the rubber hoses and double-flare them so they will accept the threaded ends of the new brake hoses.

The rear brake pads & rotors can be done at the same time as this job. Here was the sorry state of my rear pads and rotors:
Image

Mine were definitely in need of replacement, so I followed this excellent how-to:
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?t=5142

I ran into several unexpected issues with the rear brake job that didn't come up in the how-to, and documented my problem-solving process in this thread:
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=88&t=80316

The unexpected issues included rotors that wouldn't come off easily because they were too rusty and stuck on the parking brake shoes, and caliper pistons that dragged and wouldn't let go after the brake job was completed. Replaced the calipers and all is good now.

A disclaimer about extending brake lines yourself:
Consider having this done at a brake shop if you don't have time for your Jeep to be laid up for several days potentially, or don't have a second vehicle, or if you are worried about your ability to complete the job. Brake line fittings are like doing copper pipe plumbing in the house: if they leak, you have to start all over (sometimes multiple times!), and this requires time, patience and lots of self-forgiveness! I got really good at riding my bicycle to the nearest Napa during this process! :ROTFL:

Now on to extending the rear brake lines.

Here's how it looks before getting into it.
The stock rubber brake hoses are crimped onto the steel lines at the vehicle side:
Image

They have a 90* banjo bolt fitting at the caliper side:
Image

Here are the JBA extended brake lines for comparison. They are at least 4 inches longer:
Image

Here's the equipment you'll need to do the job:

Your basic tool kit, including:
15 mm socket for banjo bolt on caliper
10 mm socket for the brake bleeder on the caliper and for the stock brake line hanger bolt
Assorted screwdrivers, wrenches, etc.
Jack stands, jack & lug wrench

Your new brake lines. The JBA lines I used are braided steel coated in rubber, so they are good quality parts. Note, I reused the stock brake line hangers so I didn't need to use the mounts and clips that came with the new lines. You can use whichever mounts you like. The new copper washers are for the connection of the hose fitting to the caliper (using the banjo bolt).
Image

You'll need a double-flaring kit. This one cost me about $20, but there are better quality ones out there for more :2cents: .
Image

A set of brake line wrenches makes the install so much easier. You don't want to have to use conventional wrenches for this job. The brake wrenches grasp the fittings without rounding them off.
You'll also need a pipe cutter.
Image

You'll need a minimum of a couple of pints of DOT-3 brake fluid on hand, or more if you make a bad flare and need to redo it and re-bleed the brakes several times. (Ask me how I know.)
You'll also need a bleeder hose. The one in the photo has a check ball in it to prevent back-flow of air and fluid into the caliper.
Image

Absorbent blue shop towels or regular paper towels are a must. You'll use up a lot of them.

Replacing the lines:

1) Get a junk piece of steel 3/16 brake line from your nearest brake and muffler shop. Practice double flaring it with your flaring kit! I mean, practice a lot. Here is a nice how-to from CherokeeForum showing how the double-flaring kit works.
http://www.cherokeeforum.com/f51/flaring-new-brake-lines-142951/
There are also many good YouTube vids out there. I have some pictures here as well if you read on.

In order to seal properly, your double flares will need to be perfectly symmetrical. If they aren't, I guarantee you they will leak. There is a good chance a bad flare will create an off-center groove in your new brake line fitting, destroying it and necessitating a bike ride to purchase a replacement fitting from your local auto parts store. Here are some of my practice flares on a piece of junk steel brake line. The one on the left isn't too terrible, but the upside-down one on the right would definitely cause problems if I were to use it. Notice the flared end is oblong.
Image

Here is what a ruined brake hose fitting looks like. The semi-circular groove was caused when I tightened the fitting against a steel line with an off-center flare.
Image

Image

2) Loosen the rear lug nuts, raise the rear end of your KK with a jack, and support the vehicle with jack stands. Remove the tires and look at where the brake lines come from and go to. This is the point of no return. If you aren't sure about step #1 above, or are easily frustrated, have a professional do it for you. But with some patience and practice, brake line work can be learned and accomplished. Want to proceed? Read on.

3) Put an old brake rotor with a plastic bag in it, or your engine oil catch pan, under the caliper to catch spilled brake fluid. Use the 15 mm socket to loosen and remove the brake hose banjo bolt from the caliper. When you do this, a lot of fluid will run out of the caliper and the line, and that's ok. Notice the brake line end that attaches to the caliper is sandwiched between two copper washers. If your new brake lines didn't come with new washers, save these washers as you'll need to reuse them later. Save the banjo bolt as well.

4) Use your 10 mm socket to loosen and remove the brake line hanger from the frame. On the passengers side you can then reach up behind the frame and pop the steel brake line off of a plastic holder, and that will give you room to move the steel line out into the wheel well a bit to more easily work on it. On the drivers side the steel brake line is sandwiched between the gas tank and the frame. You might be able to get some play there also, but there is less room to work on that side.

5) Using your pipe cutter, cut the steel line as close to the rubber hose as possible. You'll probably lose a half inch of steel line with the rubber hose you remove. As soon as it is cut, more brake fluid will spill out of the other end of the rubber hose into your catch pan as the vacuum is broken. Remove the old line and reposition your catch pan under the dripping steel hose you just cut off. Wipe up the mess with shop towels.

6) Using a jackknife or similar implement, strip off at least an inch of the black plastic coating that is around the steel brake line. The reason you do this is because the line plus its coating is wider then the diameter of your flare nut. For the flare nut to fit on, you'll need to be down to the steel.
Here's what the passenger's side steel line looks like, cut off and stripped of plastic coating:
Image

Here's the driver's side, before stripping off the plastic:
Image

7) Slide the flare nut over the steel line like so. There will need to be at least 1-2 to 3/4 inches of line between the flare nut and the end, so that you can attach your flaring tool in a moment. If you flare the line without putting the nut on first, you'll have to cut it off again and start over.
Image

8) Attach your double flaring tool to the steel line, with the line sticking out exactly the same distance as the thickness of your 3/16 flaring disk. Make sure that the two sides of the flaring tool are perfectly flat and perpendicular against the disk (in other words, that they are exactly straight and parallel to each other). If the tool is not straight, the flare will end up asymmetrical and you will have to re-do it. So, it's good to set it up carefully and precisely at the beginning. Torque the nuts on the tool so that the tool closes down hard on the steel brake line, grasping it firmly. It needs to be tight enough so that the line doesn't slip in the tool when flaring it. Slipping is more likely too if all of the plastic isn't off the line. Be sure it's cleaned up well before attempting to make a flare.
Image

9) Invert the 3/16 disk so that the rod end goes into the brake line, like so:
Image

10) Attach the stirrup-like* part of the tool with the pointed end fitting into the depression on the 3/16 disk, like so. Again, make sure it is on straight, because if it is not, you will end up with an asymmetrical flare.
*I am an ecologist, not a brake mechanic, so I don't know the correct terminology for these things! Apologies.
Image

11) Once you are happy with its placement, crank it down until the 3/16 disk is flush with the rest of the tool. What you are doing is smashing the steel pipe and ballooning it outwards. It will look something like this after you remove the 3/16 disk:
Image

12) Next, reattach the stirrup with the cone end in the center of the ballooned-out brake line. Crank it down a second time to fold the steel pipe back and create a double flare.
Image

13) The double-flare should look something like this when you're done. Examine your handiwork carefully. Is it symmetrical with the hole directly in the center? Remove any stray plastic or burs of metal from the flared end, because these will prevent a good seal with the brake hose fitting.
Passenger's side:
Image

Driver's side:
Image

14) Using brake wrenches, screw the flare nut into the fitting attached to your brake line. Make it tight but not too tight because you can ruin the seal by tightening the flare nut too much. Secure the brake line to the vehicle either by reusing the stock hanger from the old brake lines (as I did) or using the hangers and clips that came with your kit. Clip the steel line back to the frame behind the passenger's rear door if you had unclipped it earlier.
Passenger's side:
Image

Driver's side:
Image

15) Attach the other end of your brake line to the caliper, sandwiched between copper washers, using the banjo bolt. Again, tight but not too tight is the key. I used a short ratchet so I didn't over-torque it.
Passenger's side:
Image

Driver's side:
Image

16) This is an important step. Be sure your flex lines are positioned so that they bend inward with suspension travel rather than outward towards the tires. If the brake hoses rub the tires, you will shortly have a ruptured hose and possibly an accident! If you need to change the bending of the brake hose, you can loosen your flare nuts and rotate it into position. You can also bend the end steel line by hand so that the line points straight back or inward rather than outward. Another option is to bend the metal hanger, or do a combination of the above. The driver's side line in this photo needed to be bent inward towards the gas tank to move the hose away from the space occupied by the rotating Duratrac tire.
Image

17) Next I loosened the bleeder on the caliper and attached a bleeder hose, as you can see in the above photo also. The other end of the bleeder hose went to an empty bottle. Appropriately, it was a bottle of pain killers. :|
Image

18 ) Moment of truth. Climb into the Jeep and press the brake pedal down several times. Then come out and inspect your lines. Any leaks? If you have a leak, you have two options. The first is that the flare nut is not tight enough. The second is you have a bad flare. If you tighten down a bad flare you can ruin the fitting. It's your choice which option you try first. If it still leaks after re-tightening, take the joint apart and inspect the flare, looking for asymmetry and for irregularity on the contact surface, like metal burs or remnants of the plastic coating. If the flare can be cleaned up, you are in luck. If it's bad, cut it off and re-flare!* Once you can press the brakes and get no leaks from your brake lines, you are ready to bleed the lines.
*Note, it is possible to lose a lot of steel line to multiple re-flarings. Not a huge deal, because Napa sells pre-flared short steel brake line extensions and a multitude of fittings. I needed to rehabilitate my passenger's side line this way after several bad flare attempts. I also had to replace that silver fitting I showed you above, and Napa had what I needed.

19) Bleeding the lines:
First, pop the hood and take the cap off the master cylinder. During the brake-bleeding process, keep an eye on the fluid there and don't let it run dry. If it runs dry, you'll have air in all four lines up by your master cylinder, and that will cause you a lot more work. Our KK's use DOT-3 brake fluid only. Make sure to add the right type.
Image

20) You will be bleeding the passenger's side rear line first because it is the longest and farthest from the master cylinder, and then moving to the driver's side rear once you have the air out of the first line. All bleeders need to be closed except for the one you are working on. With the cap off the master cylinder and the bleeder hose with the check ball* attached to the bleeder, slowly depress and extend the brake pedal several times. If you adjust your side view mirrors down and in, and position the hose and bottle just right, you should be able to see fluid moving through the hose from the driver's seat. Continue until you get to a point where no more air bubbles come out with the fluid, and then close the bleeder.
*If you don't have a fancy hose with a check ball like I did, you can still bleed the brakes with a plain hose. Check Google or YouTube for many good instructional videos of how to do it yourself or with a partner, which is easier.

21) While you're back there looking for air bubbles in the hose and closing the bleeder, check the flare nuts again for leaks. A little dampness is ok because they had brake fluid on them before, but dripping is not. Go up front and check the brake fluid level in the master cylinder. Add fluid if necessary.

22) Next, bleed the driver's side following the same procedure (21 & 22).

23) Top off the brake fluid in the master cylinder and re-cap it. Press the brakes several times to bring the system up to pressure. If the pedal feels squishy or goes down to the floor, you still have air in the lines and will need to re-bleed the system. Go back around and check your handiwork for leaks again. No leaks? You are better than I was my first time!

24) Put the wheels back on. Before lowering the Jeep, check to make sure the lines are in no position where they could rub on rotating wheels! Again, that will cause brake failure in short order.

25) Road test at slow speeds in your neighborhood. Squishy pedal? Bleed again. Check for leaks. No leaks? Great! Next, try braking at higher speeds on an open road where there is very little traffic. Pull over and check for leaks again. If no leaks* and you like the braking performance, you are good to go! :JEEPIN: :rockon:
*You may have a little wetness of brake fluid left over between your flare nut and steel line that works itself out in the next day or so. Don't freak out, it's probably not a leak. Dry it up with a paper towel, or it should evaporate eventually. Leaks, on the other hand, drip under pressure and don't go away.

26) Recommended: Have a trained mechanic check your work. I did, and I was happy to have the peace of mind of knowing everything is in good working order! Even with paying a mechanic to check your lines, you have saved hundreds of dollars by doing this job yourself. Congratulations!

_________________
2008 Liberty Sport 4x4 Automatic
Image
Jeepin By Al 4" Lift Kit
BFG KO2’s 245/75R16
Full MOPAR skid plates
Rock Lizard Skink Super Sliders
AtTheHelm Front Recovery System & Roof Rack

M116A3 Trailer build thread: viewtopic.php?f=72&t=77997


Last edited by lfhoward on Mon Sep 24, 2018 9:37 pm, edited 2 times in total.

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 Post subject: Re: HOW TO: EXTEND REAR BRAKE LINES
PostPosted: Thu Oct 30, 2014 11:14 pm 
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Joined: Fri Sep 09, 2011 9:14 pm
Posts: 2377
Location: Lindenhurst, New York
Great write up!! I want to go bigger, which means these will be a must(pretty much there now lol). Hopefully my old man has done this before and he can help out.

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2011 Deep Cherry Red KK - Skyslider - JBA/Bilstein Adjust-A-Strut set at 3.5" - OME 731 Rear Springs - Bilstein Rear Shocks - Al's A-arms - 245/75-16 Duratracs - Rock Liazard Super Sliders


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 Post subject: Re: HOW TO: EXTEND REAR BRAKE LINES
PostPosted: Wed Apr 29, 2015 8:28 pm 
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Joined: Sun Oct 23, 2011 7:32 am
Posts: 3100
Location: Philadelphia, PA
NAMoulton recently found a set of rear brake lines made by Crown, which might be a less expensive alternative to JBA's. More info here:
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=88&t=81956

_________________
2008 Liberty Sport 4x4 Automatic
Image
Jeepin By Al 4" Lift Kit
BFG KO2’s 245/75R16
Full MOPAR skid plates
Rock Lizard Skink Super Sliders
AtTheHelm Front Recovery System & Roof Rack

M116A3 Trailer build thread: viewtopic.php?f=72&t=77997


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