Stainless braided PTFE hose to replace brake hard lines? (1 Viewer)

[Jkarow08]

Hola everybody!

Has anyone on here used stainless braided PTFE hose to replace all of their brake hard lines? I am about to do a disc brake conversion on my '72 FJ40 and the PO replaced all of the hard lines but it was poorly routed/secured and doesn't match the OE arrangement. One way or another, I need to replace all of my hard lines but I am considering switching everything to 3an braided stainless PTFE for a number of reasons including...
-Easier to route
-AN fittings seal better and are structurally stronger that 45 deg inverted fittings
-Brake line flare fittings are technically one time use, and should be cut and reflared every time they are removed...AN fittings allow for repeated easy removal and reattachment in case of maintenance/upgrade needs
-My current drum setup has 17 hard lines/hoses...a PTFE setup would cut that down to 6, meaning less joints to leak and lower fluid volume due to more efficient routing (also reduces sponginess).
-High quality ptfe brake hose (aeroquip, goodridge, xrp, etc) has a volumetric expansion coefficient that is near zero (hard steel lines do not have zero volumetric expansion by the way), 1/1000th that of rubber, meaning I would have to use about 4000ft of it to negate the improvement from eliminating my rubber lines. With high quality PTFE, the idea that it will give you a "spongy" pedal is a mathematically quantifiable myth.
-Reusable fittings like those made by aeroquip are simple to install and allow lines to be easily replaced on the trail or rerouted without having to buy new fittings (the expensive part)
-My fuzzy math says it would be cheaper than buying an off the shelf hard line kit, especially if you need any of the tee fittings (I do)
-I would think they would actually be more durable than hard steel line. A swivel at every fitting and flexibility across the entire line would reduce vibration induced leaks, and the line wouldn't permanently crimp like hard line if it comes in contact with a rock/etc.
-It would look cool.

I know it is common in the rally and F1 worlds to use whole car ptfe hoses for brakes. It is primarily done for maintenance reasons, but it can't be much/any drop in performance if they are willing to use it in those conditions. I'm curious to hear if anyone on here has any real world experience with making the switch on a 40. Thanks in advance for the info!

-Josh

 

[Jkarow08]

Malleus, not sure what part of asking a question about real world experience on a technical forum is sad but I expected a bunch of those responses. Do you have actual experience with what I'm proposing? Which one of my points do you disagree with? I know the general consensus is "just don't" but is that actually supported with examples, or just a preconceived notion based on old experiences with steel braided rubber, not PTFE. Why would professional rally and F1 teams do this if it was "sad" to even consider?

 

[steffan]

I’ve often wondered this myself. I think maybe service life might be an issue? How long does the plastic last in real world environment? Are you willing to replace the entire brake system every 10 years? Hard lines should last forever…
If you use copper-nickel lines they are very easy to form and bend and will outlast the vehicle

 

[aztoyman]

I have made my own -3 AN brake hoses but not for the entire vehicle. I used NiCopp line for most of the system and the hoses just for what needs to flex. I made most of my hoses the same length so I only need to carry one size spare hose.

IDK why you couldn't run the entire system with AN brake hose. Negatives would be It would be expensive and you can't bend the SS hose as tight as you could bend tubing. If that matters to you.

To add, Yes you can use re-usable hose ends but you have to carry extra olives since they are not re-useable.

 

[aztoyman]

Don't forget to figure in the cost of not only the hose ends, but the adapter fittings for your master cylinder, brakes at the wheels and bulkhead Tee's or straight if you want to secure them to a welded tab.

 

[Jkarow08]

I’ve often wondered this myself. I think maybe service life might be an issue? How long does the plastic last in real world environment? Are you willing to replace the entire brake system every 10 years? Hard lines should last forever…
If you use copper-nickel lines they are very easy to form and bend and will outlast the vehicle

I did some digging into longevity and it sounds like there are two factors to consider, degradation from the inside as well as the outside. From the inside perspective, it sounds like the teflon has a lower level of reactivity to brake fluid than steel or nickel/copper lines and are less likely to corrode internally, which sometimes causes old hard lines to swell and burst. In terms of external wear, I read of some third hand accounts of debris getting caught between the stainless braid and the inner teflon hose which eventually caused enough wear to put a hole in the teflon. This can be prevented by using a coated stainless braided ptfe though, usually a pvc or rubber coating, definitely a factor I have considered though. I saw goodridge ptfe achieved about 3x the life of rubber brake lines in whip tests and they warranty it for 150k miles so I think the longevity should be more than adequate for the use my 40 sees. And if the hoses started to look degraded, it would take about an hour and less than $100 to replace them if you used the reusable fittings.

I'm still on the fence, just weighing my options. I used the flexible nickel/copper to replace all of the lines when I did the abs delete and hand brake install on my Subaru rally car so I'm definitely capable of bending and flaring them myself, ptfe lines just seem like they may be even easier and better from a number of perspectives.

 

[Jkarow08]

I have made my own -3 AN brake hoses but not for the entire vehicle. I used NiCopp line for most of the system and the hoses just for what needs to flex. I made most of my hoses the same length so I only need to carry one size spare hose.

IDK why you couldn't run the entire system with AN brake hose. Negatives would be It would be expensive and you can't bend the SS hose as tight as you could bend tubing. If that matters to you.

To add, Yes you can use re-usable hose ends but you have to carry extra olives since they are not re-useable.

I read today that the olives have to be replaced if you reuse the fitting, thankfully it looks like every fitting manufacturer offers replacements for a reasonable price. I'd definitely throw a few in my toolbox just in case, but it sounds like the reusable fittings are very reliable so I wouldn't expect any failures unless I caught a line on a rock or something.

 

[aztoyman]

Or if you screw up making your hose. I bought a few spare olives to have with me in addition to a spare brake hose assembly.

 

[Jkarow08]

Don't forget to figure in the cost of not only the hose ends, but the adapter fittings for your master cylinder, brakes at the wheels and bulkhead Tee's or straight if you want to secure them to a welded tab.

I've been running the numbers for a few different manufacturers and setups but here's my fuzzy math for aeroquip hose/fittings...

40' of hose (should only take about 25'): $110
Reusable 3an straight female fittings 12 @ $12 each: $144
3an tee with mounting lug 2 @ $15 each: $30
10x1 inverted male to 3an male 90 deg 2 @ $15 each: $30
1/8x27 npt (wilwood) to 3an male to male 4 @ $5 each: $20

Total: $334

It looks like I can push that number up or down about $100 depending on the hose/fitting brand and if I end up with a caliper with a bango fitting that will change it slightly as well. Pre bent hard line kits are basically the same price, not including the tees which aren't cheap for oem. It's not nearly as expensive as I expected it would be to go full ptfe.

 

[Jkarow08]

Or if you screw up making your hose. I bought a few spare olives to have with me in addition to a spare brake hose assembly.

A guy could make up a spare of the longest hose (master to rear axle), and in a pinch it could be used to replace any of the 6 hoses either as is or easily cut down to size.

 

[pb4ugo]

It sounds like you've already made up your mind. It's your vehicle, do what you want. I bought roll of ni-copp and some fittings for cheap. I replaced most of my lines. You won't have as many individual lines when you go to disc. I ran steel lines on the axles housings.

 

[aztoyman]

I just looked for the best deals. I bought some from Pegasus Racing, some AN fittings from hydraulic suppliers on eBay had good prices when getting more than a couple fittings.

I prefer steel over stainless. It galls.

I also found I could tuck banjo fittings in closer on my calipers than putting a 90 on an adapter.

Good luck with your project. Follow up please so we can see how it turns out.

 

[Jkarow08]

It sounds like you've already made up your mind. It's your vehicle, do what you want. I bought roll of ni-copp and some fittings for cheap. I replaced most of my lines. You won't have as many individual lines when you go to disc. I ran steel lines on the axles housings.

I definitely haven't made up my mind, just considering all options and hoping to hear from someone that has done what I'm proposing and their experiences, either good or bad. Part of the consideration is I'm here in Nicaragua and my flaring tools are in my storage unit in WI, it would pi$$ me off to have to buy new flaring tools and pay to have them shipped down. Because of that I'd probably just buy a set of pre bent hard lines if I go that route, but ptfe has always intrigued me as an option, especially now with the reusable fittings that are available to DIY it.

 

[Jkarow08]

I just looked for the best deals. I bought some from Pegasus Racing, some AN fittings from hydraulic suppliers on eBay had good prices when getting more than a couple fittings.

I prefer steel over stainless. It galls.

I also found I could tuck banjo fittings in closer on my calipers than putting a 90 on an adapter.

Good luck with your project. Follow up please so we can see how it turns out.

Pegasus is a dealer (with good prices) for goodridge and it looks like goodridge is about as good as it gets for ptfe. Plus goodridge makes a tee with 2 reusable fittings and one 3an male, which would work perfect on each axle and eliminate 2 fittings (less to leak). Goodridge is probably the most expensive option though, would cost about $100 more, maybe we'll spent though. I'm not worried about mixing brands when it comes to tee and fitting joints, but I'm guessing you want to use the same brand reusable fittings as the hose correct?

I'll definitely post a thread with my project, I'm about to do a full suspension refresh (new springs, shackles, bushings, pins, etc), 4 corner disc conversion, and likely install an aussie locker in the rear. My old bastard child has a lot of kinks to work out, but I'm excited to finally be able to do some serious jungle wheeling!

 

[aztoyman]

Some hose ends are "said" to be hose specific but the hose specs seem to be the same. I did notice that different brand hose ends required their own olives. I compared them and there were definitely differences.

Jeg's and Summit Racing sell olives and list what brands they will fit.

So I stick to same brand hose ends and olives at least.

 

[73FJ40]

Does the Teflon hose expand under pressure? I've seen it move (straighten out) when compressed air is supplied.

 

[Jkarow08]

Does the Teflon hose expand under pressure? I've seen it move (straighten out) when compressed air is supplied.

It does, but only a tiny amount. According to Goodridge's testing, they found it only had a volumetric expansion of 0.0002932 cc/ft at 4,000 psi. Standard rubber lines in comparison expanded 0.290 cc/ft at 2,900 psi, about 1000x more. I haven't been able to find the volumetric expansion data for hard lines, but I know it isn't zero. But even without knowing that, the math says that a full PTFE system will be significantly better than any system that has a rubber line in it in terms of pedal feel.