Brake Line Real Talk

[PSUEng]

My question is... if the brake lines look good on the outside, do they eventually fatigue or wear out near the crimps from the suspension flexing? Should they be replaced preventatively?

I chose to have my original stock hoses replaced due to age; I used stock parts as replacements (ATE/Gen BMW). This video probably influenced my decision as well...

https://youtu.be/MHghO7DTses

Now I didn't cut my old ones open b/c I had my local shop do the job, but I should have just to see. My only reason to go to SS would be if I move forward with a front BBK later this year.

[Casa de Mesa]

Great video. Probably comes down to construction to a certain degree. I wouldn't think a Teflon lined hose would suffer the same fate as those in the vid. But perhaps then we're talking about an aftermarket line at that point then...

[PSUEng]

Great video. Probably comes down to construction to a certain degree. I wouldn't think a Teflon lined hose would suffer the same fate as those in the vid. But perhaps then we're talking about an aftermarket line at that point then...

Kent has a lot of great videos that are full of valuable info, even it's Benz specific. Our cars are getting to a point where failures based on age are something to consider--at least my car. I was in a time crunch, had the car in the shop and just had the lines done--cheap insurance and one less failure point.

[MacCube]

Thank you for posting that video. It was very informative and well made. I’ve read before that flexible brake lines can look great on the outside but swollen and clogged up on the inside and should always be replaced with age. Something else to add to my to do list.

[K-Dawg]

A bit confused by the different responses here – if OE rubber lines do not expand much when new, then is the common suggestion that SS lines improve feel simply based on the comparison to the old, worn out rubber lines they usually replace?

I think it's largely due to placebo effect, the desire to mod just for the sake of modding, and general lack of understanding of how OE brake hoses are constructed. Also, for many people, when they replace the hoses may be the only time they experience freshly flushed/bled brakes.

[maw1124]

Also for some of the rare cars, OE lines are NLA, which is why we like the aftermarket support. This car might get OE lines when the car is next in the shop and I’ll remove and keep the SS lines for down the line. I was just about to pull the trigger on SS lines for my AMG but that’ll get OE lines thanks in part to this thread.

Uncle Kent’s (as we call him in Mercedes circles) video is also a good reminder about regular brake fluid changes to keep the water content within spec. I never knew why that was an issue, and figured it had something to do with the rubber (and it probably does — water erodes everything). I had no idea rust inside the line was an issue. It’s amazing what you learn when you’re not on output only mode.

maw

[bigjae46]

The only issue with stock...long term...is heat resistance especially if you remove the splash shields and the car sees track time. They will see a lot of heat. I don't see a problem as long as the hoses are being inspected regularly.

The benefit of a braided line is it adds an extra layer of safety. As with anything aftermarket, there is the risk of quality. I bought a high-pressure PS line from Pegasus Racing who does the crimping in house and then pressure tests the hose. None of us likely have the means to pressure test a hose at its rated pressure (2000psi for my hose).

I would place a hose that is tested up to its rated pressure above an OE line. If you're paying $100 for a set of brake lines...they are not pressure tested.

[nahvkolaj]

The only issue with stock...long term...is heat resistance especially if you remove the splash shields and the car sees track time. They will see a lot of heat. I don't see a problem as long as the hoses are being inspected regularly.

The benefit of a braided line is it adds an extra layer of safety. As with anything aftermarket, there is the risk of quality. I bought a high-pressure PS line from Pegasus Racing who does the crimping in house and then pressure tests the hose. None of us likely have the means to pressure test a hose at its rated pressure (2000psi for my hose).

I would place a hose that is tested up to its rated pressure above an OE line. If you're paying $100 for a set of brake lines...they are not pressure tested.

So something tested and DOT approved, like the Goodridge or BW lines

[bigjae46]

So something tested and DOT approved, like the Goodridge or BW lines

Tested with the ends assembled. So DOT approved is not testing the actual line you are putting on your car. I'm not sure if BW tests each individual hose, doubt it.

A brake line from Pegasus is going to be $80 each corner. So $320-ish for a set with each individual line tested.

[maw1124]

So something tested and DOT approved, like the Goodridge or BW lines

These are the only ones I've used... Goodridge on MB, BimmerWorld on this car. I have some ECSTuning for another car but I'm not thinking they're going on.

maw

[cobra]

The only issue with stock...long term...is heat resistance especially if you remove the splash shields and the car sees track time. They will see a lot of heat. I don't see a problem as long as the hoses are being inspected regularly.

The benefit of a braided line is it adds an extra layer of safety. As with anything aftermarket, there is the risk of quality. I bought a high-pressure PS line from Pegasus Racing who does the crimping in house and then pressure tests the hose. None of us likely have the means to pressure test a hose at its rated pressure (2000psi for my hose).

I would place a hose that is tested up to its rated pressure above an OE line. If you're paying $100 for a set of brake lines...they are not pressure tested.

From my experience, a decent supplier will pressure test every line that comes off the line. There is a standardized machine that pressurizes it to 3000psi and they do a quick test to ensure it doesn't blow up.

[bigjae46]

From my experience, a decent supplier will pressure test every line that comes off the line. There is a standardized machine that pressurizes it to 3000psi and they do a quick test to ensure it doesn't blow up.

Do you know it’s been tested?

It is very possible that some of the lines are tested, woild be surprised if it was 100%. There is also a time aspect. I don’t think this would be much of an issue with the OE parts. More with aftermarket braided lines that are made by hand.

[cobra]

Do you know it’s been tested?

It is very possible that some of the lines are tested, woild be surprised if it was 100%. There is also a time aspect. I don’t think this would be much of an issue with the OE parts. More with aftermarket braided lines that are made by hand.

From what I've seen, it's a very quick burst test just to ensure it's not going to pop off or have a big leak. My local hydraulics shop mentioned something about being legally required by the DOT to test every line before selling it. I believe they use a fluid that evaporates, so there's no way of telling if it's been tested or not.

[bigjae46]

From what I've seen, it's a very quick burst test just to ensure it's not going to pop off or have a big leak. My local hydraulics shop mentioned something about being legally required by the DOT to test every line before selling it. I believe they use a fluid that evaporates, so there's no way of telling if it's been tested or not.

Pressure test is relative simple but getting a hose to 1000psi or more isn't. You should get a certificate with the test results if it has been tested, otherwise what's the point? I know you have to do a hydrostatic test for hazardous material service for DOT pipelines. I doubt that DOT requires a brake line to be certified and tested. DOT stamps windshields and glass...I doubt they are tested.

[terra]

https://www.ecfr.gov/current/title-49/subtitle-B/chapter-V/part-571/subpart-B/section-571.106

If I'm reading this correctly, although the lines should be constructed to be capable of meeting the tests described in 5.3.x, an individual line is only required to be tested against 5.3.1 and only one of the tests from 5.3.2 to 5.3.13. So I suspect the majority of DOT labeled lines aren't pressure tested.