PTFE v Kevlar Brake lines

[BeerBudgetRacing]

Anyone have any experience/opinion on kevlar brake line?

Lighter and tougher - apparently..

Anyone know where I can find a banjo with 2 connectors sized -3 that is NOT a PTFE type?

[Rick Kirchner]

link to supplier?

[problemchild]

I wondered what problem we were trying to solve.
I figured the "kevlar" was for people that like spending money for stuff that sounds cool.

The Goodridge propaganda says
These lightweight Kevlar brake lines are stronger than braided brake lines. They will take more abuse with less expansion. Plus, these lines are smooth and will not rub off your paint like braided lines.

[BeerBudgetRacing]

Kevlar...

https://www.summitracing.com/search/...d-2/minus-3-an

Speedway sells Goodridge and AFCO

[DaveW]

BTW, the Kevlar is used in place of the SS braid. The inner tubing will still be PTFE. And the lines are "smooth" because the Aramid has to be covered to protect it from UV, abrasion, and fiber buckling.

Direct copy & paste from Yamaha R6 forum:
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Re: Kevlar vs. Stainless Steel Braided Brake Lines
The Kevlar Debate For Brake Lines
Many of our customers ask us why HEL Performance will not sell Kevlar reinforced brake lines for the motorcycle marketplace and the answer is simple.
Kevlar is an Aramid fiber introduced by DuPont in 1971. Kevlar has become a predominant fiber in the high performance racing sector for many parts such as body armour and fairings. It is stronger than steel for its weight and has a modulus that is five times greater than polyester. When Kevlar was first introduced there were two types: Type 29 and Type 49 (High Modulus). Type 49 has a 50% higher initial modulus than Type 29 and lower flex strength. Other Kevlar styles (Types 129, 149 and 159) have also been developed but are less used since the higher strength goes hand in hand with lower flex strength.

But....

Additional drawbacks of Kevlar include poor UV resistance (Kevlar loses strength roughly twice as quickly in sunlight as polyester and, when affected, the gold Kevlar fibers turn brown) and rapid loss of strength with flexing, folding and flogging.

As you can see this product needs to be covered so that UV sunlight does not effect it's strength and reliability. Therefore all brake lines which are sold as a Kevlar (or Aramid if the company does not use the original DuPont designed Kevlar and only a copy) must have a pvc cover on the outside to protect the Kevlar from UV rays.

This also means that if a stone flicks up, which when riding a bike is quite likely, and cuts or removes some of the outer protective cover the Kevlar braid will be exposed to UV and lose strength. This fact coupled with the fact that Kevlar has rapid loss of strength with flexing (and how many times will your brake lines flex with the movement of suspension) make this, in our opinion, an inferior and dangerous choice when considering the best materials for use in brake lines - After all this is what makes your motorcycle stop...

You have been warned and the choice is yours but we will NOT sell Kevlar or the unbranded 'Aramid' hoses for your motorcycles brake lines. We repeat the following statement again:

'Additional drawbacks of Kevlar include poor UV resistance (Kevlar loses strength roughly twice as quickly in sunlight as polyester and, when affected, the gold Kevlar fibers turn brown) and rapid loss of strength with flexing'.

Kevlar is great in the correct environment but not as a cover for motorcycle brake lines - You have been warned. They may offer you a few grams of weight saving but is it really worth it ? The few race teams who use Kevlar replace every line after each event so the flexing / UV issues are not valid but do you want to replace your lines every month?
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IMO, the #1 issue for us would be the fiber-buckling issue. I had experience with Kevlar (Aramid) used in air springs. Any excessive fiber flexing would destroy the Aramid in short order, leading to air-spring failure.

The #2 issue would be the low resistance to UV if a line gets scraped or otherwise damaged to expose the Aramid to sunlight. If the Aramid gives out, so would the soft PTFE inner tubing.

[Hardingfv32]

Using a short search... I see that the Kevlar is a inner layer always covered with something, often stainless braid.

Kevlar does make for great oil lines.

Brian

[DaveW]

Using a short search... I see that the Kevlar is a inner layer always covered with something, often stainless braid.

Kevlar does make for great oil lines.

Brian

The Kevlar is almost always a fiber, like SS braid. What holds in the fluid is the rubber (oil lines) or the Teflon (brake lines). The outer polymer coating is to protect the Aramid from abrasion and UV.

[BeerBudgetRacing]

I wondered what problem we were trying to solve.

2 issues. Cleanliness and abrasion. I find braided brake lines, especially those running on the corners, hold too much grime.
If you don't clean them, the grime breaks them down. If you do you need chemicals and the chemicals break them down.

The Kevlar is almost always a fiber, like SS braid. What holds in the fluid is the rubber (oil lines) or the Teflon (brake lines). The outer polymer coating is to protect the Aramid from abrasion and UV.

So, if I want abrasion resistance, heat shrink wrap the offending areas?

Cleaner and lighter is a fallacy.

[DaveW]

2 issues. Cleanliness and abrasion. I find braided brake lines, especially those running on the corners, hold too much grime.
If you don't clean them, the grime breaks them down. If you do you need chemicals and the chemicals break them down.



So, if I want abrasion resistance, heat shrink wrap the offending areas?

Cleaner and lighter is a fallacy.

They ARE wrapped with a PVC cover. The issue is when the PVC gets damaged. And if an Aramid braided line gets kinked, the Aramid fibers will buckle, which usually will cause them to break (my air spring experience I noted above).

[BeerBudgetRacing]

They ARE wrapped with a PVC cover. The issue is when the PVC gets damaged. And if an Aramid braided line gets kinked, the Aramid fibers will buckle, which usually will cause them to break (my air spring experience I noted above).

I meant wrap a regular SS braided line.....

Like:
https://www.anplumbing.com/hose/ptfe....html?___SID=U

[DaveW]

I meant wrap a regular SS braided line.....

Like:
https://www.anplumbing.com/hose/ptfe....html?___SID=U

I wrap mine with electrical tape or shrink wrap (when it will fit properly) in exposed areas. The issue with electrical tape is to keep it from unwrapping starting at the "free" end. A small Tyrap fixes that. Shrink wrap is great for lines I assemble myself, but it usually can't both go over the fittings and shrink down enough with any sizes I have been able to get. If there was 3:1 shrink-ratio wrap it would be perfect.

Actually, I found some! 1/2" is $60.45 for 100 ft. 3/4" is $80.60 for 100 ft. Sizes before shrinking...
Link to source: https://www.nelcoproducts.com/store/...olyolefin.html

I'll probably buy some. Thanks for making me look!

[stephen wilson]

I also cover all my SS lines with heat shrink anywhere they are exposed to rubbing. You can also buy it in 6' lengths for McMaster Carr and other sources. The high shrink ratio type is probably required to slip over the ends fittings of assembled lines.

[Raceworks]

Heat shrink is the easiest solution. Make sure to pay attention to the starting ID & the shrink ratio. You need it big enough to get over the hose end but want it to shrink tight to the line.

The Kevlar stuff is great if you have the budget of a large Indy Car team and don't mind buying new brake lines every year.

[BeerBudgetRacing]

Heat shrink is the easiest solution. Make sure to pay attention to the starting ID & the shrink ratio. You need it big enough to get over the hose end but want it to shrink tight to the line.

The Kevlar stuff is great if you have the budget of a large Indy Car team and don't mind buying new brake lines every year.

I was willing to spend double on some lines until DaveW's explanation of the UV issues.

But that said, the high-ratio heat shrink ain't cheap! 4-1 is $20/ft
https://www.mcmaster.com/#heat-shrink-tubing/=1bhy09r


I think that is why I'm leaning toward Earls Speed-Seal hose < $5/ft which is the hose AND pvc wrapping.

[DaveW]

I was willing to spend double on some lines until DaveW's explanation of the UV issues.

But that said, the high-ratio heat shrink ain't cheap! 4-1 is $20/ft
https://www.mcmaster.com/#heat-shrink-tubing/=1bhy09r


I think that is why I'm leaning toward Earls Speed-Seal hose < $5/ft which is the hose AND pvc wrapping.

I just did some measuring and it looks like 3/4" Nelco 3:1 will work for both -3 and -4 SS braided brake lines. It's plenty big before it is shrunk, and looks like it will just shrink enough to be tight on the -3. That is $80.60 for 100 feet. $0.81/ft is a heck of a lot better than $20/ft.

I've got a question waiting to be answered by them to assure that the nominal 0.236" ID recovered size will be tight enough on the 0.250" OD SS braided -3 line.

[BeerBudgetRacing]

The difference between the PVC coated and the regular PTFE is about $1-$1.50/ft

Or is the heat shrink going to be stronger/tougher?

[DaveW]

The difference between the PVC coated and the regular PTFE is about $1-$1.50/ft

Or is the heat shrink going to be stronger/tougher?

You mean the difference between the PVC coated SS braided vs using plain SS braided with shrink wrap? If that's what you are asking, then, IMO, there will be little difference in durability and functionality between the two.

[DaveW]

I just got a response from Nelco. They are going to send me samples of both the 1/2 and 3/4 3:1-ratio shrink tubing. I'll report on how they work on -3 and -4 AN SS braided lines.

[BLS]

When I made new -3 SS braided brake lines I used clear heat shrink on all of them including the long one from front to rear. I put the heat shrink on before the fittings, folded it back at each end then cut to final length after the fitting was put on. The long one was a real pain to slide on the whole length but it worked. I bought the shrink from amazon in a 50 or 100 foot spool fairly cheap. 20- 30 bucks as I recall. Still looks good on my now sitting in the garage car...

When I get a chance I'll see if I can find the spool and specs. from memory it was 1/2" 2:1 shrink. It was just large enough to slide over the braid, but the long line probably took an hour of pulling/pushing to get it on.

[DanW]

I bought this stuff from B.R.I.T.S. in Sonoma several years ago. A bit spendy @$7 a foot compared to uncoated, but its very abrasion resistant. It might also be available from others.

[DaveW]

I just got a response from Nelco. They are going to send me samples of both the 1/2 and 3/4 3:1-ratio shrink tubing. I'll report on how they work on -3 and -4 AN SS braided lines.

I received the samples this morning and evaluated them. Results below:

Both sizes expanded have ~ 0.012" wall thickness .

Nominal 1/2" (NP-203-1/2)
Expanded, fits fairly easily (close fit, but slides on easily) over 7/16" hex (-3 AN hex size).
Shrunk onto a 1/4" (0.248") diameter bolt ( slightly smaller than the -3 AN SS braided which is ~ 0.255" OD), the final OD ~ 0.290, i.e., wall thickness ~ 0.021".

Nominal 3/4" (NP-203-3/4)
Expanded, it is nominally 0.709" ID, so fits easily over 9/16" hex (-4 hex size)
Shrunk onto the same bolt as above, final OD ~ 0.320, i.e., wall thickness ~ 0.035". It had no wrinkles and fit snugly, but takes a bit more heat and diligence to shrink to the 1/4" ID than the 1/2".

Obviously, 3/4" (NP-203-3/4) will work well on -4 AN SS braided.

For -3 AN SS braided tubing there is a choice. Either the 1/2" or the 3/4" will work . The 1/2" will fit over the 7/16 hex on -3 AN SS braided. After shrinking it will likely be tighter and a bit more flexible than the 3/4". If you want more wall thickness for better protection, the 3/4" may be a better choice with its heavier post-shrinking wall.

For -4 AN SS braided, only the 3/4" expanded size will work on a line with fittings installed.

I am undecided on whether I will buy 100' of each size, or just 100' of the 3/4" because it will work on both -3 and -4, plus offer more protection on the -3.

If I order 100' of each, I will likely be able to sell some of each size and still have more than I will ever use.

[EricP]

Dave,

Thanks for posting the detailed info. Is this where the line starts? I'd buy 10 feet from you when you decide...
(But I'm not sure what I prefer either. I think I lean toward ease and thickness of 3/4)

E

[DaveW]

I'm not "taking orders," but...

When I order it, if I decide to sell some, I will put an ad in the "Open Classifieds" section. It will be a couple of weeks before I do that.

If you post in this thread to let me know you want some, it could influence my buying decision (one or both sizes, which size, etc.).

[B Farnham]

I'm not "taking orders," but...

When I order it, if I decide to sell some, I will put an ad in the "Open Classifieds" section. It will be a couple of weeks before I do that.

If you post in this thread to let me know you want some, it could influence my buying decision (one or both sizes, which size, etc.).

Id take some, I'm local too.

[DaveW]

I am planning to place an order Monday, 3/5. If you are interested in buying any of it from me, let me know before that so I can decide how much to buy.

If there is enough interest, I would buy enough to be able to sell some 1/2" for ~$1 per foot and some 3/4 for ~$1.25 per foot. Minimum quantity would be 10-ft length combined between the 2 sizes.

I will place an ad in the classifieds when I have it. Shipping within the US would be by USPS flat rate envelope ($6.70).

[EricP]

I am planning to place an order Monday, 3/5. If you are interested in buying any of it from me, let me know before that so I can decide how much to buy.

If there is enough interest, I would buy enough to be able to sell some 1/2" for ~$1 per foot and some 3/4 for ~$1.25 per foot. Minimum quantity would be 10-ft length combined between the 2 sizes.

I will place an ad in the classifieds when I have it. Shipping would be by USPS flat rate envelope ($6.70).

I’d do 10’ if each size.

[DaveW]

I just ordered 50' each of the 1/2 and the 3/4 for the same price per foot as 100' each. It will likely be here near the end of the week.

So I am not looking for additional buyers over the 2 who responded above.

So EricP and B Farnham, I will sell you some. Respond to the PM I'm going to send you.