JK Brake Line issues

887 Views 14 Replies 10 Participants Last post by cranbiz, 12 d ago

jmsimon211

Discussion Starter · 13 d ago

Hello, I am new to the community but I just bought a 2012 Unlimited Rubicon out of an estate. It had about 16700 miles on it when I bought it but was basically undriveable due to brake issues. When I say issues, the right front was dragging hard and generating a ton of heat. I assume it was caliper/pin related issues but as it turns out it was actually the rubber brake line itself. It appears the metal that wrapped around the line has corroded and exapanded anough to pinch the line. I swapped the lines on all 4 corners and the resolved all the issues but I did additional analysis to try to understand why the rubber line failed the way it did.

I went straight to the portion of the line that was wrapped with steel at the point where it was secured to the axle and it confirmed my suspicion that the metal was where it was restricted. See the photo of the cross section of the line. Note that the metal on the outside of the bracket has very little rust but I appears to have rusted next to the rubber and squeezed the line shut. I am sharing this as a courtesy as even if your brakes work this problem could be brewing on your unit and impact braking pressure from one brake to the next.

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Rob50lx

· #2 · 13 d ago

Thanks for sharing that!

James Rockon

· #3 · 13 d ago

Crazy! Thanks for sharing this.

jeepers29

· #4 · 13 d ago

The rubber lines are known to colaspe on themselves causing the caliper to not release. Well known issue but it never hurts to post for new members.

Reactions: 1

CMSRock

· #5 · 12 d ago

Thanks for that, things like this take a lot of time to find if somebody hasn't shared it with everyone.

Old Dogger

· #6 · 12 d ago

Welcome to the forum!

Jester1492

· #7 · 12 d ago

Welcome and thank you.

James Rockon

· #8 · 12 d ago

jeepers29 said:
The rubber lines are known to colaspe on themselves causing the caliper to not release. Well known issue but it never hurts to post for new members.

True...but what's interesting is that rust was able to form and accumulate INSIDE the steel tubing which in turn pinched the line closed.

Reactions: 2

ugmw177

· #9 · 12 d ago

road salt

jmsimon211

Discussion Starter · #10 · 12 d ago

ugmw177 said:
road salt

That could be a factor for sure but this thing only had 16K on the odometer and there was really not any other corrosion that is typical for a vehicle that is exposed to a lot of road salt. The exterior of the brackect still has its shiny steel appearance. Either way it is obvious the design and materials used is not ideal. I am sharing this as a warning to others because I am guessing there are a lot of units on the road experiencing this issue to some degree. And it is a safety issue considering it will effect brake pressure to each caliper. It was amazing how much better pedal feel and straighline braking performance I had after I replaced a 4 lines with new braided stainless. Hopefully Jeep has changed their design or materials used on future production runs. I could think of a couple ways this could easily be improved.

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jac04

· #11 · 12 d ago

jmsimon211 said:
And it is a safety issue considering it will effect brake pressure to each caliper.

Agreed that this is a potential safety issue and a design issue. This design was used on JKs through 2018, so that's a LOT of vehicles. I suppose you could report it to the NHTSA if you wanted to. Report a Safety Problem | NHTSA

I wonder how many people have had their front brake lines replaced because of this. Nobody would ever know the real problem because the new brake hose comes with the bracket already attached (see below) You can't be the only person to experience this, but you are the first one (that I know of) to section it and find this design issue. Thanks for posting this.

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cranbiz

· #12 · 12 d ago

It's not just JK's that have brake line problems. Any vehicle that uses a rubber line to go from hardline to the caliper can have the line collapse.

I just had to replace the rubber lines on my Class C. It had no signs of an issue but the drivers side caliper would not retract after applying the brakes for quire some distance.

jmsimon211

Discussion Starter · #13 · 12 d ago

cranbiz said:
It's not just JK's that have brake line problems. Any vehicle that uses a rubber line to go from hardline to the caliper can have the line collapse.

I just had to replace the rubber lines on my Class C. It had no signs of an issue but the drivers side caliper would not retract after applying the brakes for quire some distance.

I get what you are saying but this is a different type of failure that is caused by the design and the materials used. It is not a typical rubber collapsing issue because it not only impacts the caliper retracting but also impacts braking pressures at each caliper in a more impactful way because the metal encapsulating the rubber hose itself. In your situation you likely still had decent braking power and was relatively even between left and right.

jmsimon211

Discussion Starter · #14 · 12 d ago

jac04 said:
Agreed that this is a potential safety issue and a design issue. This design was used on JKs through 2018, so that's a LOT of vehicles. I suppose you could report it to the NHTSA if you wanted to. Report a Safety Problem | NHTSA

I wonder how many people have had their front brake lines replaced because of this. Nobody would ever know the real problem because the new brake hose comes with the bracket already attached (see below) You can't be the only person to experience this, but you are the first one (that I know of) to section it and find this design issue. Thanks for posting this.

View attachment 4582569

Thanks for the link. I am not one for drama but this really should be a recall.

Reactions: 1

cranbiz

· #15 · 12 d ago

jmsimon211 said:
I get what you are saying but this is a different type of failure that is caused by the design and the materials used. It is not a typical rubber collapsing issue because it not only impacts the caliper retracting but also impacts braking pressures at each caliper in a more impactful way because the metal encapsulating the rubber hose itself. In your situation you likely still had decent braking power and was relatively even between left and right.

Actually, no I didn't have decent braking power and even worse, the heat generated by the hanging caliper warped the rotor.

Moral of the story, replace your rubber lines every time you do a brake job. You can upgrade to braided stainless and not worry or just buy new rubber lines.

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