Trailer Brake Question for Performance Auto Guys

[Peter]

I have an aluminum traier with stainless steel Kodiak disc brakes. The brakes need service. Part of that is the flex lines are cracked and should be replaced. The hard tube is stainless steel and is in good shape.

So I looked into braided stainess steel brake lines, but they generally use a different standard than common brake lines.

Fo rthe uninitiated the performance guys use -x AN flare fittings on the ends of their tubes. (The "x" is a nuber like "3" or "4") This is a 37 deg flare and is different than the usual 45 deg double or "inverted" flare found in most automotive applications.

OK.. I can easily source the braided stainless flex lines with various -X AN fittings from lots of places.... but I need to adapt the rest of my system to them. The caliper end seems easy as I can find 1/8 NPT to -X AN elbows. But I am not sue what size AN flare I would want to use....-3 or -4 or something else?

Next: the other end of the hose where things connec to the sst hard line is a puzzle so far. It looks to me like the "factory" set up is some sort of compression fitting to an adaptor nipple (compression to NPT?) to another adaptor union (NPT to standard flare?) to the 3/16 MIF rubber line fitting.... (BTW 3/16 MIF uses a 3/8-24 thread, so said flex lines are often described as having a 3//8-24 fitting)

Now compression fittings in a brake line are a no-no... but that isn't to say it isn't done. Or maybe it isn't a compression fitting but is something else like 3/16 FIF or even some sort of AN nut I do not recognize. But the nut looks too short to be a flare nut of any sort.

Right now I am considering getting the right AN tube nuts and an AN flareing tool and just re-doing the flare at the end of the SST tube.

Question: What size AN should I be using (each end)? How hard is it to flare the sst hard line? I have made countless (single) flare fittings in copper tube and done some some inverted (double) flares in mild steel brake lines, but I hear SST lines are different. Would I need to buy a very expensive AN flareing tool to do the sst? If the tool is very expensive would I be able to put a standard inverted flare on the hard line (using a tool I already own) and adapt that to the AN fitting?





Peter

[Rawleigh]

I would not attempt to flare SS tubing without an expensive hydraulic tool. keep the existing fitting on the SST and find an adapter would be my advice.

[mike ohlstein]

Why bother? Just replace the hoses and bleed the lines. It isn't a race car....

[Peter]

Why bother? Just replace the hoses and bleed the lines. It isn't a race car....

Because the existing hoses are only 5 years old and are shot, and so far the sources I've found for rubber repplacement hoses will charge me 80% of the cost of converting to stainless....

So far I can find adapters to go to -3AN in stainless steel for the caliper end, but not much luck on the other end. What I can find to eliminate the existing kludge of parts is not stainless steel or brass, only mild steel. No point to that. I can find a part to kludge onto the kludge in stainless, but.....

So you may be right. At some ponit you just gotta hear Vic's mantra:
"Perfect is the enemy of good!"

Peter

[Bruce]

For a short time in the 70's I worked for Crane Carrier on the frame assembly line bending and installing stainless brake lines for a run of garbage/snow plow trucks for the city of NY. Stainless can be a bear to the novice and an expensive learning curve.

I would go with Swagelok not standard compression. They can be had in stainless instead of trying to flare stainless tubing.
Then just use stainless flex break lines to your calipers from the frame points.

[RAWicklund]

I've used hand flaring tools for SS.... company supplied so I don't know cost but I assume they are expensive. They work with an eccentric guide as compared to a concentric guide solid cone used with a standard 45 SAE flare tool.

Even if I had the tool available I would go with swagelok as suggested earlier. Sort of fool proof
We used to have trouble with slippery gasses ( helium and hydrogen) using swagelok but very seldom a leak using any fluids.

JIC and AN are the same thing for your purpose ( both 37 degree flare) #4jic is 1/4" and #6 is 3/8"... I would think that the #4 would be more then adequate for trailer brakes. A hyd. shop should have what you need but it's always cheaper to go fishing online if you know exactly what you want.

Ray

[Peter]

Ray, Thanks for the tip on the JIC /AN equivelency. I was able to find a lot more stainless stuff at reasonable prices by knowing I could use them. It got me out of the speed shops into general hydraulic stuff.

Summitt has stainless steel braided brake tubes that are -3 AN, -4 AN, FEMALE both ends and also 1/8 NPT MALE both ends. That last one eliminates some adapters if I was going to go Swagelok or compression on the hard lines.

I still haven't made up my mind what I will do just yet. The brake tubes in stainless are actually a little less than the replacement rubber ones, but the elbow for the caliper is expensive in either 1/8 NPT to JIC/AN or even in 1/8 NPT male to 1/8 NPT female. About 20 bucks in stainless, but still about ten bucks in brass...

I'll probably just crack open the wallet and go all stainless. It is about double the cost of just replacing the rubber, but then it is done for the rest of the life of the trailer.

Peter