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Old 10-03-2003, 11:42 AM   #1
wcbjr
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Default Cheap way to get less flex in your brake lines?

A friend got a container of engines and clips from Japan recently. A lot of the clips, like half, had brakes lines on them that were completely zip tied from the caliper to the hard line. About 25 or so per line.

Is this a cheap alternative to steel lines? How much can brake lines flex and how much do the zip ties flex?
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Old 10-03-2003, 12:44 PM   #2
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Ha! I'd never heard of that technique, but I'd venture to guess that nylon zipties would flex less than the rubber lines.
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Old 10-03-2003, 10:42 PM   #3
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LOL - we found that mod here ages ago. Did not know many acutally did it though

The only reason we haven't tried it is because we all run SS lines because of the track time we do (Paul Hansen and self that is).

So, who is gonna try that on for us all?

Cheers
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Old 10-04-2003, 03:27 AM   #4
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I imagine it may help, but I doubt that it'll be as effective. It'll still expand, though... zip ties still stretch. *shrug*
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Old 10-04-2003, 12:42 PM   #5
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Funny!

You could also wrap the line in a spiral of safety wire. Or even a weave of stainless steel! Wait a minute...
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Old 10-05-2003, 01:29 AM   #6
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I don't think it'd be worth the aggrivation to put all those zip ties on
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Old 10-05-2003, 11:41 AM   #7
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that's one of the funniest things i've ever heard. do you guys understand the line pressure those things see? we're talking on the order of thousands of PSI. unless you're using carbon/kevlar composite zip-ties, they ain't gonna do isht. dang those musta been some jerry-riggin japanese dudes!!
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Old 10-05-2003, 06:03 PM   #8
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Quote:
Originally posted by Steppin Razor
unless you're using carbon/kevlar composite zip-ties, they ain't gonna do isht.
so you actually know the weight rating of a zip tie? i doubt you did. nope, instead you just made an assumption.

Anyway, I wouldn't rely on a ziptie to hold my brake lines from flexing - but they WOULD make a good abrasion-protector kind of like a bumper of sorts to protect the line.
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Old 10-05-2003, 08:01 PM   #9
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Quote:
Originally posted by nhluhr
so you actually know the weight rating of a zip tie?
i'm sitting here laughing my azz off at this clown, please tell me he is not serious!!!
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Old 10-05-2003, 11:23 PM   #10
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By the time you bought enough zipties, and spent the time to complete the job, you could have bought a set of SS lines for $90.
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Old 10-06-2003, 12:29 AM   #11
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Quote:
Originally posted by Steppin Razor


i'm sitting here laughing my azz off at this clown, please tell me he is not serious!!!
While the maximum pressure a brake line will ever see is around 2000 psi, the tensile strength of ABS plastic can be anywhere from 3000 to 6000 psi. So actually you shouldn't be laughing that hard or making fun of people "blindly" before you've actually checked it out. I find the question is actually a reasonable one, and the "idea" is not that ridiculous at all. In any type of structural design, if your material has twice the tensile strength of what is required, you're doing pretty good. You just have to make sure there is enough material available. In fact, I have no doubt that this would actually do something, although whether or not it would make a significant (or time effective) difference is debateable. Furthermore, I have seen SOME ties that actually have a thin strip of metal inside them (no not twist ties!!!), obviously reducing the elongation under pressure significantly. I think the idea (if you were to try this) would be to tighten the ties as tight as possible to pre-stress the line. How much pre stress could you create? I'm not sure, but I think most people would be surprised. If the ties did produce a noticable effect, it would probably not be for too long though. Plastic does not do well under fatique near it's limits, or heat for that matter.

My concern would be with the possibility of the ties eventually slicing up the line, making it thinner etc. You can try what you like, but SS braided lines aren't very expensive.
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Old 10-06-2003, 01:27 AM   #12
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if you want to get down to the nitty gritty of it, and be anally retentive about it, i will show everyone that putting zip ties on a brake line is a terrible idea.

now i want to make it clear that i'm not making personal attacks or trying to hurt anyone's feelings, just show that putting zipties on a flexible brake line is a horrible idea.


one incredibly important feature of a flexible rubber (or SS for that matter brake line) is that it have the ability to FLEX. the idea of placing zip-ties around a FLEXIBLE brake line would at least have a chance at working if the rubber brake line were perfectly straight. unfortunately, in real life, that rubber line must bend. when it does so, it creates a section of tubing, the surface area of which cannot physically be entirely encompassed by a zip-tie. since some people may have a hard time understanding what i'm saying, i'll break it down into language that is hopefully easier to understand.

imagine your rubber brake line. now, take a knife and cut it width-wise so that you have 5mm thick round "slices" of brake line. you can now imagine that these are your zip-ties. now, if you have them all in a straight line, like they were when you first cut them, then there are no gaps in between them. once you arrange those slices of tubing in an arc, there is no longer any way in which they can possibly still create a seamless "hose." there will be gaps on the outer side of the arc. now, when you pressurize the soft brake line that's underneath our zip-ties, it will no longer be allowed to expand uniformly. the only places left for it to expand will be the gaps which become widest at the outer edge of the arc. what you have now done with your zip ties is placed about a hundred or so 90 degree edges (who knows how sharp the edges of your 6000 psi tensile strength zip-ties are!! ) directly in contact with the rubber brake line. not only that, but when the brake line is forced to expand around your zip ties, quite a bit of pressure will be applied to each edge of each zip tie.

the fact that there is still plently of surface area on the rubber line left open to the air shows that the line will continue to expand to whatever volume it would have in the first place. by placing zip ties around the line, you have just forced the line to expand along a much smaller surface area than it otherwise would have. in other words, there are NO performance gains to be had by putting zip ties around your brake line. not only that, but you are increasing the chances of that particular brake line failing by placing zip ties on it.

i don't laugh at people anymore. it's not nice.

Last edited by Steppin Razor; 10-06-2003 at 02:13 PM.
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Old 10-06-2003, 09:32 AM   #13
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I think that if we quit the personnal attacks and look at the two options people have already described, we'll see that this is a no win mod.

Either: the zip ties aren't strong enough to reduce flex and you've just wasted a lot of time.

Or: the zip ties don't stretch and hence create lots of dangerous pressure points between them and the bulging brake line.

I think everyone is kinda agreeing with each other, but not in the nicest way.
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Old 10-06-2003, 09:52 AM   #14
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First, Steppin you need to calm the F down. Second, you need to find empirical data to back up your claim. The brake lines to not flex that much to catch an edge of a zip tie, this is from looking at the brake line while somebody is mashing the brakes. So be quiet about that edge thing. Also, you will find that there is <1mm of gap between the zip ties along an s-curve in the line at the widest point. Third, someone from Japan actually chimed in saying it was done over there.

This was a question, not fact. Sure stainless will always be better. Maybe zip-ties are strong enough, maybe they aren't...
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Old 10-06-2003, 09:54 AM   #15
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Quote:
Originally posted by Uncle Scotty
By the time you bought enough zipties, and spent the time to complete the job, you could have bought a set of SS lines for $90.
A very small benefit would be not having to bleed the lines.
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Old 10-06-2003, 11:14 AM   #16
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gentlemen...

Rule # 7. Personal attacks directed towards other members and other websites are strictly prohibited on the NASIOC message board.
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Old 10-06-2003, 02:07 PM   #17
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alright, alright, i'll play nice.
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Old 10-06-2003, 07:12 PM   #18
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Ok, purely from an interest and engineering standpoint I will address some of Steppin Razor’s points. I would like to re-iterate though, that I think the zip ties could damage the lines, and would therefore not be a wise modification for the long term. I could be wrong about that though, and in no way would suggest that anyone would be an idiot for trying it. Especially if they were going to change the lines soon anyway. The methodology behind this idea is somewhat sound.

The flexible line:
Razor is quite right that the brake line has to be able to flex. If that need didn’t exist, the line wouldn’t be there. But how much flexing is really necessary? There are several reasons why the flex line is as long as it is. The first reason is that the last place to fix a hard line is before the suspension, and the first logical place to hook it back up is at the caliper. The second reason is to take up the travel of the suspension, and the turning of the wheels (on the front). Now do you really need 8” (this is a rough guess) of flexible tubing for the suspension travel, and turning wheels? If you’ve ever held any of this line in your hands and bent it, you would realize the answer would be no. I would contend that you could probably get away with only a few inches (at most) of flex line to accommodate the suspension travel with a huge fatigue safety factor. That is of course if the flex bit was as far as possible from the wheel. The turning of the wheels actually does not require much bending of the line, rather it requires twisting which is important for the zip tie case. Another reason for a longer line is to not make life less frustrating when you’re changing your brake pads.
So, the bending required by the line would not be significantly affected by the ties, if there was at least some space between them, and the first and last ties were not right at the hard connections (nobody said the ties had to be right against one another). The twisting of the line required for turning the wheels would not be affected by the ties to any significant degree because they are not connected to one another, and there could be some room left bare as I mentioned above. Therefore the flexing of the line would not be an issue if the ties were strategically located.

Line Length…the really important bit:
A shorter flexible line will create a firmer pedal, if the material of the lines remains the same. Why? Because pressure does not care how long the line is, the same pressure is everywhere along the line. If 1000psi causes 1” of line to increase in volume by 0.5 in^3, then 2” of line would increase in volume by 1.0 in^3, 3” by 1.5 in^3 etc. It is very predictable because the pressure acting on the internal surface of the line is exactly the same at every single point in the line. If you cover the line in zip ties which hold it rigid (the assumption for the moment), the parts in between the ties would still only see the pressure they did before. If the spaces in between only see the same pressure, then they can only deflect (or increase in volume) the same amount as they had before. This is a rule which simply cannot be broken. So the assumption that the total volume increase would be the same is incorrect. If half the line was covered in these rigid ties, then the increase in volume of the line under pressure would be reduced by half. If 90% of the line was covered in rigid ties, the increase in volume would be reduced by 90%. It is of course the increase in volume which causes the mushy pedal feel, so rigid ties would definitely help. It just depends on how rigid the ties actually are.

A simply supported beam:
I actually lied a bit in my last paragraph. I had said that the increase in volume would be the same in between the ties. For ties which are a reasonable distance apart (maybe more that their width) that would be true. However, when the distances are closer the ties actually reduce the expansion slightly. To understand this think of a long beam supported loosely at both ends with a uniform force. It will sag in between the supports a certain distance “d”. Now if you rigidly support both ends what will happen? The beam will deflect less than “d” because the rigidly supported material helps the other material in the center support the load. This as well is a physical certainty and cannot be argued. Similarly, the tube supported by the closely spaced rigid ties at either end will deflect (or expand) less than before. The effect of this in the rubber lines would not be tremendous though, but I figured I’d point it out anyway.

How rigid could the zip ties act:
Now this is something I don’t want to spend too much time on, because I’m not sure how rigid they really are. And I really don’t want to spend the time to look it up and do the math. Plus, it’s just the methodology I’m defending, not the amount of effect. And as I said in my earlier post, I HAVE seen some zip ties with a thin strip of metal in the center, which would act rigid when compared to the braiding within the flexible line itself. So I’ll just throw out some numbers to put things in perspective. How much actual force (not pressure) can the line push against the zip tie? Lets make some assumptions first; pretend the tie is ¼” wide, the line diameter is 1/8” inside, and the pressure is 2000psi. The total force transmitted to the tube in the zip tie region can be easily calculated by multiplying the pressure by the surface area affected. Please look away if you don’t like math. So…2000psi x pi x 1/8” x 0.25” = 196 lbs of force. Now the zip tie will not see all of that, because the tube will still do what it did before. The tie just has to help. As I said in my last post, the tensile strength of the purely plastic tie is 3000-6000 psi. If you get the 6000 psi kind, then you may have a chance at holding the line back a bit from expanding, as long as the material elongation is not too great. If you get the kind with a thin metal strip in the center, then it could definitely keep the line from expanding.

The most important point to take from above is that if you reduce the amount of expansion in a significant portion of the line (even half) then you WILL feel a difference. If half the line is covered in zip ties with a thin strip of metal, the expansion of the line will be reduced by as much as half (actually less though because of the spongy bit of rubber in the sandwich). Pre-stressing the ties will compress the spongy bit beforehand, thereby increasing effectiveness closer to that 50% mark. If the ties are just plastic they will still make SOME difference, just not as much.

If someone wanted to try this, I would suggest only covering about half the line with the thin metal strip plastic covered ties. You could strategically place them by watching where your line flexes the most and then avoiding those areas. This would significantly reduce (but not eliminate) the possibility of slicing the line. You could also taper the edges of the ties to reduce the cutting action. This is a lot of work though, and really you would just be better getting the SS ones.
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Old 10-06-2003, 08:49 PM   #19
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Interesting discussion but it seems we have overlooked a significant point: the holding power of the zip tie will be limited by the strength of the buckle not the tie itself.

While the plastic of the tie may well be 3000-6000 psi, the actual contract area of the buckle is CONSIDERABLY smaller than the cross section of the tie itself giving a yield load that will be a fraction of the full tie strength.

Still, I give the inventor a hearty thumbs up! You can buy a huge bag of zip ties for a couple of bucks and (as pointed out above) you don't need any brake fluid or other supplies.
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Old 11-24-2003, 08:02 PM   #20
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so...anyone try this?

just for fun, im thinking about it.
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Old 11-24-2003, 10:54 PM   #21
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Old autoX Trick...I have had it done now for about 2 years....works as advertised....Stiffer lines...I had done way back when I raced in Stock Class and you couldn't change the lines out....just the rears are done now as I have since put stainless lines on the front...(Came with the Calpers...)....they are definately stiffer than stock...not a stiff as regular stainless lines...but it works non the less... Next time I have my rear wheels off...oh..and the zip ties...the small ones...I got out a 9.99 Sams club special ...used 35 ties a corner.. spaced about 1/4 in apart all the way down the line...

Hope that helps..

Bill
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Old 11-25-2003, 03:44 PM   #22
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I'm dubious. Not about whether there's a decrease in volume with a stiffer line but about whether that decrease is palpable.

I changed to SS lines and didn't notice any difference. Not on the street or the track. Doesn't mean there wasn't a difference. It just means I didn't notice it. If I didn't notice it, it doesn't make a difference.

When is someone going to actually measure, with precision instruments, the change in stiffness between OEM rubber lines, SS wrapped lines and even zipped tied lines? This can't be too hard to do for a manufacturer that has equipment to test the lines.

Wouldn't there be a difference in piston travel within the master cylinder from one line type to the next to achieve a given PSI?
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Old 11-25-2003, 04:35 PM   #23
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Quote:
Originally posted by ITWRX4ME
Wouldn't there be a difference in piston travel within the master cylinder from one line type to the next to achieve a given PSI?
In theory yes.....however in real life....the difference will be pretty much negligible IMO. That statement however will depend on the stiffness of the original and SS lines.
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Old 11-25-2003, 04:53 PM   #24
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Quote:
Originally posted by legacy777
In theory yes.....however in real life....the difference will be pretty much negligible IMO. That statement however will depend on the stiffness of the original and SS lines.
Negligible. Exactly.

So, what's the point in spending $$ on SS lines? I did and I regret it. They have a psychological affect. I understand that they should be stiffer. But do my brakes actually perform better? More importantly, am I more effective at braking because of the 'negligible' difference?

The thing is, if there really was a significant, measureable difference, manufacturers and vendors would include those statistics in their sales pitches. "We're the best because we guarantee to improve stiffness by at least x%!!". Hmmm...sounds more like a Viagra ad.

Last edited by ITWRX4ME; 11-25-2003 at 05:00 PM.
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Old 11-25-2003, 10:04 PM   #25
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You have to remember too what I said....it will depend on the state of your original lines too.

On my car with lines that had 160k miles on them....the SS line upgrade was most likely a more pronounced & beneficial then let's say a car that has just rolled off the showroom.

Other issue is the point at which I think SS lines become most noticable or effective will be at the edge of lock up or in more extreme conditions. So most people are not going to notice the benefit right off the bat......

You can nit pick this topic to death, and a lot of it is subjective to the driver as well. I just don't think the added stiffness can be be repeatedly or quantitatively measured. Like you said....if it was, they'd probably put it in the marketing campaign.
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