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Just Some Dude in Jersey
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Discussion Starter #1
In a private message, Will I. Finish brought up an interesting question about using LONG flexible stainless braided brake lines to replace his front lines on his already assembled car. I thought that this would make a great topic of conversation, so I'm going to share our conversation in this thread and get input from you guys. Here goes:

Will I. Finish:
<<< After all of the comments regarding new brake lines, which I now realize I should have done that when the car was totally stripped, I am looking at alternatives and wondered what your opinion is of Stainless Steel Braid brake line from the master cylinder to each wheel. Did not see anything on the forum about this but it appears to be available out there as well as how to videos. Thanks for you help.
Best Regards, Carl >>>

Me:
<<< Considering the difficulty of replacing the front brake lines with the car put together, 3 or so foot long braided rubber brake hose sounds like a great idea. They have to pass through the radiator wall and an approximately 1/2" diameter hole at each wheel well. It's tough to bend the hard metal brake lines to pass through those wheel well holes without touching/rubbing against them. Rubber grommets are used to prevent the metal from cutting into the lines. Flexible rubber hose with protective stainless braiding sounds like a great solution for this whole situation. The only issues I see are whether the end of the hose that goes to the brake will pass through the wheel well holes and getting flexible braided hoses that have compatible ends for our master cylinders and brakes. The hole in the wheel well could easily be made bigger and adapters may take care of getting the ends to connect. This would be a great subject for a thread, so I'm going to start one on your behalf and quote both of us. :) >>>
 

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Flexible hoses, even stainless braided Teflon-lined hoses, will expand somewhat and give a softer brake pedal than hard lines.

So ideally, you would want to minimize any flexible hose lengths.
 

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Your Noble Friend ;-)
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First, do NOT use braided rubber hoses.
Braided Teflon (PTFE) hoses are the way to go. I've done it on the Jägermeister, and do it again right now on the Rekord. Even after Bob's warning. AN-3 is the right size.

Dieter
 

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Just Some Dude in Jersey
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Discussion Starter #4
Here are several responses from Facebook, where I also posted this. Todd is one of our members here:

Todd Kirby No. Don’t do it. There’s too much expansion, even in the stainless braided lines. Hard lines are there for a reason. Your pedal will be more mushy, because you’re having to displace extra fluid before the brakes start to work. The actual expansion of the hose diameter is minimal, but when it’s going across the entire length of the line, it becomes significant.

Will Roland I had a braided line built for a hydraulic clutch one time, shortly after convincing myself I had all the air bled out, I bought the correct hardline.
I could never get the clutch to fully disengage
Food for thought
 

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Just Some Dude in Jersey
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Discussion Starter #5
Member Ron Whetson made this post and picture. I like the idea of anchoring the fitting to the hole in the wheel well. He then, I presume, ran a short braided flex hose from the caliper to the fitting at the hole.

<<< I did mine a few years ago, seems like it only took about 3 hours to make and install them. But my radiator isn't in the way so that helps. When I just recently put the car back together after paint I made all new Stainless AN 3 brake lines. This time I used 90 degree bulkhead fitting thru the fender wells. Makes a clean and much easier installation. >>>

426886
 

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Hard lines are there for a reason.
I see this kind of reasoning pop up lots of places, and it's almost never valid.

The reason most things are the way they are, is because of the cost when mass produced.

It may very well be that flexible stainless lines are superior in performance and durability for all we know. They are expensive to use though, so that alone would be a sufficient reason we don't see them.

People also say things like "Oh that won't work, it's dangerous, there's a reason they're spot welded". When, yes, the reason is that spot welding uses no consumables, is a massive upfront cost but can be done hundreds of millions of times on the same machine in a factory. That has no bearing on whether it's the best or only acceptable solution for someone in a home shop doing a few mods or repairs in terms of quality, and, certainly nothing to do with whether it's still the optimum cost effective solution for a one-off.

... In this case he's probably not wrong, he's right, just not for anything to do with this reason.
 

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I wonder if having braided lines is legal in all states?
Braided lines are legal, but only if they have an FMVSS certification.
 

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Another consideration, other than cost, is that stainless braided Teflon hoses are EXTREMELY abrasive. The exterior surface is not too far off from the texture of a file.

Anything that is painted that the brake hoses touch will be ground to bare metal in short order from vibrations. Also anything plastic or rubber can get ground thru as well.

Due to the lines being more flexible than hard metal lines, they sag more. So you need to increase clamping by roughly a factor of 3. You’ll need a bunch more (cushioned) clamps holding them in place in other words.
 

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Opel Rallier since 1977
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FWIW.... I've used numerous stainless braided lines on rally cars of up to about 15" long and never had any issue with a soft pedal. In fact, pedal firmness was far superior to rubber lines, even at those lengths. 36" long? Never tried that long, but IMHO, it is worth trying. You can always take them out... it is only money LOL

Silicone brake fuild is more compressible, so I would not use that with such long lines, at least at first.
 

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FWIW.... I've used numerous stainless braided lines on rally cars of up to about 15" long and never had any issue with a soft pedal. In fact, pedal firmness was far superior to rubber lines, even at those lengths. 36" long? Never tried that long, but IMHO, it is worth trying. You can always take them out... it is only money
Yes, but you were replacing VERY expandable rubber hoses. You didn’t delete your hard metal lines altogether.

A friend of mine plumbed his rally car (VW Golf) with -3AN stainless braided hose, and it leaked everywhere. Too many junctions. Eventually he got them to all seal up, but it was also a $400 proposition. Not cheap.
 

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Opel Rallier since 1977
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Yes, but you were replacing VERY expandable rubber hoses. You didn’t delete your hard metal lines altogether.

A friend of mine plumbed his rally car (VW Golf) with -3AN stainless braided hose, and it leaked everywhere. Too many junctions. Eventually he got them to all seal up, but it was also a $400 proposition. Not cheap.
Correct.... but are we not talking about using 36" lines here? Or much longer? Or did I just dream up the 36" length? LOL That was my real point here: some length of stainless braided line is 100% acceptable. Otherwise they would never be used at all, right? What is that length? 1"? 60"?

Not a question of leaks.....they ALL can leak! Example: There are lots of complaints over on the Mopar forums from fittings from Inline Tubes (and others) leaking for their OEM replacement steel lines. Just poorly dimensioned in the flare area.
 

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Detritus Maximus
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What Bob said about being abrasive....the other thing about the braided flexible lines I've been told is that dirt and grit can work into the braid. The flexing of the braided line (where it is intended to flex) can work that grit into the rubber or teflon and act as a grinding compound. Maybe not a concern on a show car/race car where it either gets replaced occasionally or never sees dirt, but on a daily driver that sees muck and is in place for ten years?

What is the life expectancy of the braided teflon? People always say plastic lasts for years, but it doesn't.
 

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Detritus Maximus
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Correct.... but are we not talking about using 36" lines here? Or much longer? Or did I just dream up the 36" length? LOL That was my real point here: some length of stainless braided line is 100% acceptable. Otherwise they would never be used at all, right? What is that length? 1"? 60"?

Not a question of leaks.....they ALL can leak! Example: There are lots of complaints over on the Mopar forums from fittings from Inline Tubes (and others) leaking for their OEM replacement steel lines. Just poorly dimensioned in the flare area.
No fever dream, it's in Gordons post. How long are motorcycle braided lines on the front?
 

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Opel Rallier since 1977
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FWIW: Looked around and found this data point on expansion of rubber versus stainless braided lines:

"When testing volumetric expansion, Goodridge found that standard OE-type rubber brake hose expanded by 0.136 cc/ft at 1,000 psi, 0.150 cc/ft at 1,500 psi, and 0.290 cc/ft at 2,900 psi, whereas the company's PTFE braided stainless hoses expanded by only 0.0002932 cc/ft at 4,000 psi. " Here is the source article: http://www.superstreetonline.com/how-to/wheels-tires/modp-0909-brake-lines-upgrade/

So at 1000 psi (which is pretty hard brake pressure but not outrageous), there looks to be well over 100 times less expansion in this particular stainless braided line. So if 8" lines are OK for OEM rubber lines, looks like you could go 800+" on a braided stainless line and have the same pedal softness.

Now of course there are going to be other factors, and I am sure that not all stainless braided lines are equal, and not all rubber lines are the same, but even if the expansion factor is only 10 times less, then you could go with 80" lines and be no worse off than 8" OEM rubber lines.
 

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Just Some Dude in Jersey
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Discussion Starter #17
Not to disagree or agree with anyone, but I thought I would bring up the point of the lines on hydraulic fork lifts. They're very long and flexible and carry very high pressurized hydraulic fluid. Now, a car's brake system and a fork lift use hydraulics in a different way, so maybe they're not comparable.

36" is my guess of how much line would be needed to go from a GT's master cylinder to each of the front brakes.
 

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So if 8" lines are OK for OEM rubber lines, looks like you could go 800+" on a braided stainless line and have the same pedal softness.
Maybe.

I don't know why they didn't do apples to apples. Rubber was tested at 1000psi. Stainless was tested at 4000psi.

So you might say "Aha! Stainless isn't just 100x better, it's 400x better!"

Which could be true. But, maybe the extreme isn't what's important. What's important is the early pressure changes. Perhaps stainless expands a lot right from the get go, but has limited expansion thereafter. Whereas rubber is the opposite. It's very firm until you get near the peak of your braking pressures. So by using extreme numbers, (where rubber starts to show its limitations) and avoiding easier numbers (where stainless might perform poorly), they mask that behavior.

I'm not saying it does (well, rubber certainly has non-linear response to pressure, the higher the pressure the more-than-linearly it expands), but, without apples to apples it's hard to know.
 

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I have used braided PTFE lines from Inline Tube for several years without any leakage problems at all. Also their braided lines have a nice smooth clear plastic coating. Just be aware, AN fittings are 37 degrees which is not compatible with SAE 45 degree fittings.
 

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Opel Rallier since 1977
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Maybe.

I don't know why they didn't do apples to apples. Rubber was tested at 1000psi. Stainless was tested at 4000psi.

So you might say "Aha! Stainless isn't just 100x better, it's 400x better!"

Which could be true. But, maybe the extreme isn't what's important. What's important is the early pressure changes. Perhaps stainless expands a lot right from the get go, but has limited expansion thereafter. Whereas rubber is the opposite. It's very firm until you get near the peak of your braking pressures. So by using extreme numbers, (where rubber starts to show its limitations) and avoiding easier numbers (where stainless might perform poorly), they mask that behavior.

I'm not saying it does (well, rubber certainly has non-linear response to pressure, the higher the pressure the more-than-linearly it expands), but, without apples to apples it's hard to know.
Yeah, I saw the differences in the tests, Matt, and realized that one could claim the stainless braided to be as good as 1000 times better LOL. But, this may be some super good grade of stainless braided tested against the worst OEM rubber line out there; we just don't know.

I tried to look at some actual PTFE line spec sheets, but the expansion rate was never listed. Ultimately, I felt that it was reasonably safe to assume (but not guaranteed) that the stainless braided expansion was at least 10x less than rubber.

And we have to keep in mind that if the line ID is larger, then there will be more fluid volume inside the line, and the fluid compressibility becomes a bigger and bigger factor.
 
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