COPPER BRAKE LINES ARE THEY SAFE

[mikzjr@aol.com]

I HAVE A 29 CHRYSLER WITH COPPER BRAKE LINES SHOULD THEY BE REPLACED WITH STEELE. I HAVE BEEN TOLD THAT THE COPPER CAN SPLIT.

[1937hd45]

Lots of cars used copper lines, MG used them up till the late 1940's. If you plan to replace them use steel. The car and your passengers will thank you.

[Guest]

AACA judging standards specifically note that copper lines were used on Chrysler products in the era of your car. Therefore to be absolutely authentic, you might want to use copper.<P><B>HOWEVER</B>, I do believe that the copper tubing used on those cars was somewhat different [heavier, thicker and therefore stronger] than what we buy across the counter today at the NAPA store. I also believe it was rigid and not flexible as much of today's copper tubing is.<P>I am making <B>NO</B> recommendations, only offering thoughts based on experience. ~ hvs

[1937hd45]

Best of both worlds would be copper plated steel lines. There is some supplier in England for MG lines, that may have what you need.

[mikzjr@aol.com]

HOW ABOUT THE COPPER LINES USED IN 1929 ARE THEY SAFE TO REUSE OR SHOULD THEY BE REPLACED.

[ply33]

How safe your original lines are is a matter only you can decide. Obviously Chrysler felt that when new they could withstand the pressures required.<P>The question is: What type of metal fatique, abrasion, corrosion, etc. have they seen and how much, if any, has their strength been decreased. None of us can tell you that without a close examination of your actual parts.<P>And as for myself, I would probably not give you an opinion even if I examined them and they looked good: I am not a professional expert in estimating the strength of aged metal and would not want to assume any liability by giving an assurance that turned out to be bad.<P>I know that if they were steel I would tell you to replace them all regardless of exterior appearances. Brake fluid is hydroscopic and any car that old probably has water that was absorbed into the system. That water could very well have caused internal corrosion problems especially in any low places in the tubing. Any places with internal corrosion will be weaker than they should be and could fail under pressure. The highest pressures (most likely failure time) will be during panic stops, just when you need them the most.

[ply33]

The soft copper tubing you can find in the local hardware store would be deadly if used in hydraulic brakes. Don't use it.<P>There is a modern brake line that is a copper-nickel alloy that has a copper look. It is apparently used in some high end cars and some imported cars. It is fully certified for use as a brake line and you should be able to find it at a good brake supply company. You use the same double flare ends on it that you would use on steel lines.<P>I ended up using it, not because it was authentic on my car (it isn't) but because it is supposed to be more resistant to corrosion than steel lines.

[RoadsterRich]

I've had the same concerns as Mike. I'm no expert, quite the opposite to say the least. I am trying to learn as I go. Sometimes I come up with good ideas, sometimes with hair brain ones. Fortunately I've met some great folks via the DF's to help me either see the error of my way's, or to praise me for my ocassional lack of stupidity. So here goes my latest round...<P>Would rigging up a pressure test be of any value in checking the original copper lines? If so, what sort of pressure levels would one expect to see out of a mechanical hydraulic system. Wouldn't the pressure tend to be either a slow steady increase to represent normal braking, or a sudden sharp increase to maximum pressure to simulate rapid pedal to the floor emergency breaking? Rigging the compressor up to provide pressure to feed hydraulic fluid wouldn't be extremely difficult, but ultimately is it of any practical application at all?<P>Getting off track a little, but still in the vein of braking safety, I recall back in the late 70's, when I was playing with high performance toys while in college; a replacement junction block for the brake lines. Somehow it kept the pressure up in the other lines if one or more failed. While this wouldn't be original on a 20/30's vintage car, would something like this be worthwhile if one planned on driving their car a great deal? What sort of points deductions does one get for a safety feature at a show?<P>Rich<BR><A HREF=http://www.1930Chrysler77.com>http://www.1930Chrysler77.com</A><BR>Member AACA, WPCC

[ply33]

To hazzard a guess about the pressures involved:<ol>[*]I'd guess that in an emergency I could push on the pedal with about 400 lbs. of force.[*]On my Plymouth the brake pedal lever is about a foot long and the point where it connects to the rod from the master cylinder is a couple of inches from the pivot. That gives about a 6:1 mechanical advantage.[*]If I recall correctly, the piston in the Plymouth master cylinder is about 1&quot in diameter. That implies about an area of about 0.8 sq.in.

So... (400 * 6)/0.8 = 3000 psi.<P>Remember this is only a guess. Pick your own numbers. I know for compressed gas cylinders, the hydrostatic pressure test is often at 200% of working pressure. I don't know if that would be true of this or not. I also don't vouch for what damage happens to the components if you over pressurize them.

[cmj]

McMaster and Carr supply, besides nuts and bolts also carry thickwall hydraulic copper tubing, except you have to get 50 feet at a time. <A HREF="http://www.mcmaster.com/catalog/107/html/0096.html" TARGET=_blank>http://www.mcmaster.com/catalog/107/html/0096.html</A>

[ply33]

<blockquote>From: "Gary"<br>To: tod-aaca@FitchDesign.com<br>Subject: Brakes<br>Date: Thu, 3 Jan 2002 15:33:19 -0600<br><p>I read your post on the Antique Auto site regarding copper brake lines. You got my attention. I hope you have time for some Questions.<br>I have a 29 Chrysler. The gentleman that assembled the chassis ended up using off the shelf copper for the brake lines. I had new steel lines but he couldn't get them to seal at the brass fittings on the rear wheels. He said the fittings were slightly damaged by the steel. I ask about the wisdom of brass and was told the only danger was the possibility of puncture. I haven't felt good about this. Now<br>Is there a probability of rupture?<br>Are there special fittings for steel lines to brass fittings?<br>Why are double flares used on steel?<br>JC Whitney has a brake line kit, steel with copper plating. Would this be better if I have to change?<br>My car seems to have a mix of 3/8 and 1/4 lines. Is this normal or how should it be?<br>I am more concerned about safety than authenticity.<br>As you can tell, I need basic Hydraulic brake training. My other cat is a Model "T" ALMOST NO BRAKES AT ALL.<br>Any guidance you can give will be very much appreciated.<br>Gary Cleveland</blockquote>Gary,<br>I am replying to you on the forum rather than directly to keep with the concept of open communication and allow others to read and comment on this.<p><span style="font-weight: bold">Disclaimer: It has been decades since I got my mechanical engineering degree and I have been working in fields unrelated to mechanical engineering for nearly as long. These opinions are not from a qualified, currently certified professional engineer working in this area.</span><ul>[*]I would not use "off the shelf copper" in any car I wanted to ride in.[*]A previous poster gave a link to copper tubing from McMaster-Carr. I did a search for the ASTM spec that the catalog entry listed. It seems to have sufficient burst strength. But I am still leary of it. For one thing it sounds like it is the wrong size to use standard brake flared ends and tube nuts.[*]I would only use tubing that is sold for use in automotive brake applications.[*]All the brake fittings on my car are brass. All the brake fittings I recall seeing in the auto supply and brake supply store are brass. Steel tubing works fine with brass fittings. When you make the double flare on the tubing there might be some ridges or roughness left on the inside of the flare by the tooling. At least there is with my <BR>tools. I clean those off before assembling the tubing onto the car. I have found that I cannot make a leak free connection without that clean up step.[*]I used new brass fittings where ever I could. There was only one fitting on my 1933 that was not available at my local brake supply company (a extra long "T" that extends through the frame). Replacing all the fittings I could meant that I did not have to closely examine the old ones for bad sealing surfaces or microscopic cracks. Basically peace of mind.[*]The copper-nickle tubing was available at the local brake supply store where I used to live. It came in 10 foot lengths and handled about the same as steel tubing. It was perhaps more rigid that steel brake tubing. I would use it again.[*]Copper plated steel tubing should be fine. As well. I would only use it if it were sold for use as brake tubing.[*]As best I know, a double flare end makes a better high pressure seal than a single flare or a compression fitting. That may have changed with newer technology on compression fittings, but at the time our cars were built I believe it was true. Since, as far as I know, the auto industry is still using double flare fittings I suspect it is still the best way to go.[*]Your car may have come with a mix of tubing sizes. One way to find out is to get the parts book and study it closely. Another is to contact the appropriate technical advisor of a marque specific club for your car. On my car all the brake lines are one size.

I hope this helps a little.....

[ronbarn]

ply33 - Thank you for staying on the DF with your response. While most of my cars have mechanical brakes (no hydraulic lines to worry about) your comments were certainly helpful. You get one atta-boy for staying on the DF. Father Ron

[Rick Hoover]

I agree there has been some very good responses with this thread and Tod sure has been given a work out on this one. Good work Tod!<P> However the reason I'm jumping in on this, is that it may have been over looked that the AACA Judging Manual states that all copper brake lines used on these early Chryslers were painted black. (something I don't quite agree with, but so be it.) Being that, why not just go the safer route and use steel or even stainless steel lines and paint them black as stated in our Judges Manual? You will have captured both the safety and no deduction of points in judging as the Judges will never know what material was used. (Trust me) Anyways, and I believe Father Ron might back me up on this, that the use of steel lines would not receive a point deduction if used in bare form. This I was told by a VP of Class Judging years ago.<P>I personally would not have copper lines on my own driver cars. As for restoring a show car and going for authenticity, then yes I would and have done so. I know of several early Chryslers products on the road today that have never had a problem with the copper. It's just that I wouldn't do it.<P>Rick<p>[ 01-03-2002: Message edited by: Rick Hoover ]

[Guest De Soto Frank]

Mike,<P>Do you plan to drive this car on the road? <P>If the answer might ever be "yes", I would not trust the original lines.<P>A '29 Chrysler can be capable of 50-60 mph,and it's not the lightest car on the road; a brake failure would be tragic! <P>If you want to win a senior trophy yet still have safe driving, the copper-nickel stuff may be worth the investment.<P>Whatever way you go, don't throw those old lines away; they're valuable as patterns at the very least.<P>Ply33 makes a very good point about brake systems corroding from the inside out; I've had "good looking" brake lines blow-out without warning on 30 year-old cars; if in doubt, play it safe and replace it. Flex-hoses too!<P>Consider the question this way: which is more cost effective in the long run? Replacing brakelines or trying to repair the car and survivors after a wreck?<P>I don't wish to incite panic, but I've been lucky thus far: all my brake line failures have been either in the garage or the driveway; so now I plan a total brake plumbing replacement on any old car I get and plan to drive.<P>Good luck on source for "correct lines"!

[RoadsterRich]

With regards to Gary's inquiry on mixed brake line sizes, I checked my 1930 Chrysler 77. The supply line from the master cylinder to the distribution block (one line in three lines out) is 3/8", from the distribution block to each of the front wheels, and to the rear of the car is 1/4". Mine appears to be original, though given what I have found on this car everything is suspect. <P>Rich

[Peter J.Heizmann]

For what is is worth, guys, my company makes quite a few pressure vessel castings. All that I am aware of are tested 2-3 times the operating pressure. York International, for instance, performs hydrostatic pressure tests up to 5,000 p.s.i. for an airconditioner compressor that operates under 1,200 p.s.i. in the field.<P>Personally, I would either take the existing lines to a test lab and have them pressure test them, or, buy new ones designed for cars and make damn certain they were tested at the the manufacturer (which they probably were, but...).<P>Regards,<P>Peter J.