stainless steel brake lines and AN fittings

[WagonCrazy]

Any functional reason why aluminum AN fittings (tube nuts and sleeves) cannot be used with stainless steel lines.

Specifically in plumbing a brand new brake system?

Can you tighten the aluminum fittings (and sleeves) enough to seal up from the high pressure that a brake system produces?

Curious...as I'm about to put a big order in for plumbing the brakes on my Nomad project. Going to use black AN fittings and polished stainless lines.

Paul

[Rick_L]

I think that in the small sizes, aluminum adapter fittings will have a strength exceeding the pressure of your brake system.

That said, I would personally want steel fittings. I know that stainless steel adapter fittings can be hard to find. But plated steel fittings are more readily available than aluminum ones. My other personal preference would be that I wouldn't want blue or red anodized fittings, but obviously that's a style issue rather than a performance issue. Even the plated vs. SS is in a practical sense.

[chevynut]

IMO the aluminum nuts and sleeves are plenty strong to handle the pressure of the braking system and I know lots of people have used them. The sleeves basically see no pressure, only the clamping force of the nut behind it. The nuts don't see the pressure either. The nuts are plenty strong to get the clamping force you need...it's not that high to make a seal.

Are you using SS fittings? Check the pressure rating of the aluminum ones of you use them, as I'm sure some types are higher than others. Hose end-type fittings might not take the pressure, but solid machined body ones should.

Here's a site with some decent prices, I think:

http://www.anplumbing.com/Adapters/B...rd+Ano-23.html

But these guys say DO NOT use aluminum fittings for brake lines....

http://www.helusa.com/info/aluminum-fittings.html

Lots of people use them, though...Wilwood being one of them:

http://www.summitracing.com/search/p...erial/aluminum

[NickP]

NASCAR allows Aluminum as best I recall. Most all sprint cars use them under USAC rules so I suspect they have been tested.

[WagonCrazy]

Thanks guys. I ordered black anodized fittings and sleeves to go with stainless hard lines and pre-made braided stainless brake lines at the 4 corners. Ill post some progress pics over on my Updates post.

Appreciate your input here.

[WagonCrazy]

I just received my order from Summit yesterday, and on the packing list it clearly says (just under the entry for the 3AN anodized alum tube nuts) "Note: Not for use on brake systems or other high pressure hydraulic applications."

And then there's a note under the entry for the 3AN Tube Sleeves: "Suggested for use on aluminum hard line ONLY!"

Makes me wonder what they know that's different than what you guys are saying.

I'm going to plumb it with these AN fittings anyway, and see if the system leaks and watch it.

Can't imagine why an alum sleeve, tightened down by an alum nut, pushing a stainless flared tube against an opposing male AN fitting wouldn't hold for brake applications...

[Rick_L]

My opinion, uness you have a bunch of unsupported 90 degree tube bends, you're fine.

We used to call those "break off fittings" on 4500 psi hydraulic systems back when I used to do work on them.

[chevynut]

I don't know why/where you would use AN3 aluminum hard line. Certainly not in a brake system, imo. If you make good 37 degree flares then sealing to an AN fitting should be no problem. As I said before, the nuts and sleeves see no brake system pressure, all they do is clamp the tube to the fitting. It doesn't take that much clamping force to seal, unless you have a flare forming problem.

[Rick_L]

Maybe I should clarify. I was referring to steel lines and aluminum fittings. (But those 4500 psi fittings were 100% steel.)

[WagonCrazy]

It doesn't take that much clamping force to seal, unless you have a flare forming problem.

Yes, I agree. And with that newfangled Mastercool flaring tool I bought myself a while back, there should be NO issue with flaring this hard stainless.

One thing I think I'll do differently is just do a single flare for the brake lines...given the 3/16 size tubing is small. I dont' see where I would need a double flare on this...like I did with the 3/8 fuel line earlier.

I'll post pics when I get done or close to having this brake system plumbed in.

Might get some time to work on it over the long weekend.
Woo hoo!