1941 Brake Pipe Kinking

[Shootey]

I’m fighting with bending brake lines. The hardest part is where they go into the distributor as there is little physical room and severe bends. I’m stuck on the short pipe from the master cylinder to the distributor and the distributor end of long one from the rear rubber hose to the distributor. 
 

I thought Cunifer would be the solution but it rather readily kinks. Would I be better off with traditional steel? The short pipe is only 9” long according to the parts book. I assume I need to bend it before cutting it so I can get leverage. But leverage doesn’t solve the kinking. What is the silver bullet on severe bends (~130 degrees) on a short pipe and no kinking?  Thanks. 

 

thomas
 

[Matt Harwood]

On tight radius bends, I've had success by both lubricating my tubing bender with a little grease so it slides over the tubing a little better, and, as a last resort, filling the tubing with fine sand to prevent the kink. It's problematic to seal up both ends of the tube to keep the sand from leaking out (on one I already had fittings installed so I just used caps, and with another I simply used duct tape).

 

There are also tight-radius bending tools, although they're dubious in their use. If you get too aggressive, they'll kink just as easily. But by going very slowly and just bending a little at a time, then repositioning the tubing, you can avoid the kink.

 

Hope this helps!

[Daves1940Buick56S]

I go with steel on the brake lines. CuNi on the fuel lines and copper on the vacuum.

[2carb40]

Having parted out a number of 'unsalvageable' 1940 Buick Supers, I have saved those particular factory lines, knowing that exact difficulty you describe. It's one part I don't mind reusing after a sufficient bath in Evapo-Rust. There are not to many other things I'd consider using without being concerned about a residual amount possibly remaining during future use. Just a couple pennies thought from doing this repair.

[Bloo]

Sand bending is going to be necessary for tight bends. Make sure the sand stays tight, keep checking as you bend. Use something bender-like with a semi-circular grroove to support the outside of the tubing as you bend. I have done this with Bundyflex and copper, but the principle should hold for any tubing. Some materials are just easier to bend than others. It may take a couple of tries. This is not a smooth process. If you need a radius tighter than the tightest die on a good bender, it is probably the only way. Good luck.

 

Edited July 30, 2023 by Bloo (see edit history)

[nat]

1 hour ago, Bloo said:

Use something bender-like with a semi-circular grroove to support the outside of the tubing as you bend.

           I bought a pair of these for a job that required a really tight 180 bend.

https://www.mcmaster.com/3382N12/

 

     Sand is a nice idea but is easier said than done.

[EmTee]

I'd probably try temporarily flaring and capping the ends with proper fittings after filling the tube with fluid (brake fluid, oil or water).  After bending, then cut-off the temporary ends, clean the tube and form the ends as required.

[Robert Engle]

I have had good luck putting one of the spring benders on the tube and then using the regular bender to make the bend. 

[Shootey]

Thanks to all. On the spring bender idea, I tried it and then couldn’t get the spring off since the bend was so extreme. 

[EmTee]

Though apparently not as original, what about using armored tubing for this piece?  That may allow a tighter bend without kinking.

 

[37_Roadmaster_C]

On 7/28/2023 at 8:38 AM, Shootey said:

Thanks to all. On the spring bender idea, I tried it and then couldn’t get the spring off since the bend was so extreme. 

If you got the bend you needed without kinking you can sacrifice the spring bender and uncoil it from the tubing with a pair of pliers.

[Shootey]

3 hours ago, 37_Roadmaster_C said:

If you got the bend you needed without kinking you can sacrifice the spring bender and uncoil it from the tubing with a pair of pliers.

 

3 hours ago, 37_Roadmaster_C said:

If you got the bend you needed without kinking you can sacrifice the spring bender and uncoil it from the tubing with a pair of pliers.

Nice idea. I’ll check it out. It may have kinked though it’s hard to tell with the spring obscuring the view. 

[Frank DuVal]

On 7/25/2023 at 7:00 PM, Daves1940Buick56S said:

I go with steel on the brake lines.

Cunifer is good enough for Volvo brake lines, then it is fine with me!👍

 

I've been using it for over 20 years for brake lines. I got tired of replacing steel brake lines (and of course the driving through red lights that go with brake failure, never seems to happen in the driveway on daily drivers) multiple times (the same line on the same vehicle) due to salt rust. Never a failure yet with Cunifer. You people that trade daily drivers in every few years just wouldn't understand.😁

.

Curious, how does one get the sand out of the bent pipe, I mean every grain, so it does not end up in a wheel cylinder?

 

That "brake line armor" shown in EmTee's picture is available in stainless steel from Summit racing, and probably others too. It makes a great looking brake line when placed over Cunifer.👍 GM used a lot of this armor on the rear axle of vehicles, to prevent stone damage.

Edited July 31, 2023 by Frank DuVal (see edit history)

[Bloo]

55 minutes ago, Frank DuVal said:

Curious, how does one get the sand out of the bent pipe, I mean every grain, so it does not end up in a wheel cylinder?

Good question. Brake cleaner, compressed air, and a prayer I suppose. Mostly when I have needed bends that tight it has been in fuel lines but not always. Heat would help, but I never do it because I am afraid I would melt the sand, and how would you get THAT out? Also how would you know if you got it all out? A sand bend on a long line would be a giant pain for all sorts of reasons. I have one good bender and a collection of cheapies, and also a fancy pliers thing for tight bends that doesn't work at all. In my opinion, when replacing all the brake lines on a car (something we almost never do up here in WA), you want a big pile of benders. Borrow every el-cheapo bender you can get your hands on. No one bender can do everything, no matter how high quality it is, especially if there are compound bends. Usually a pile of benders, one really good one and a bunch of cheap ones will get the job done. I have only resorted to sand a few times.

 

I think If I were sand bending a line now, I would braze a nut on one end for a bolt that would fit inside the tubing, so I could retighten the sand at will. I am a bit skeptical but intrigued by @EmTee's idea of using liquid. I want to try it. If that works, it solves a bunch of problems. The last time I did it I substituted salt for the sand. It worked, but don't do that. It was a mistake. It crushes and is almost impossible to keep tight. The "sand" only works if it is really tight. Salt made a lot of unnecessary work.

 

 

[EmTee]

Liquid is uncompressible, as evidenced by its use in hydraulic systems.  It should be better than sand for bending, as there will be no voids (air space) like those between grains of sand.  The trick will be capping the tube so that it doesn't leak.  That, however, should be possible using appropriate caps on ends of the tube that are prepared just as they would be for installation in the brake system.  Start with a piece of tubing long enough to fabricate the entire piece (with allowance for the temporary end fittings) and form the tightest bend first.  Then make the other bends working toward each end.  If brake fluid is used as the fill, then no cleaning would be required before installation.

[Shootey]

2 hours ago, EmTee said:

Liquid is uncompressible, as evidenced by its use in hydraulic systems.  It should be better than sand for bending, as there will be no voids (air space) like those between grains of sand.  The trick will be capping the tube so that it doesn't leak.  That, however, should be possible using appropriate caps on ends of the tube that are prepared just as they would be for installation in the brake system.  Start with a piece of tubing long enough to fabricate the entire piece (with allowance for the temporary end fittings) and form the tightest bend first.  Then make the other bends working toward each end.  If brake fluid is used as the fill, then no cleaning would be required before installation.

I was advised by a smart person who shall remain nameless that he fills up the pipe with solder, does the bending and then melts out the solder. Of course the capping would be necessary although I suppose capping temporarily might work since the solder would be allowed to harden. 

Edited July 31, 2023 by Shootey (see edit history)

[Frank DuVal]

I've carefully hand bent 3/16 cunifer around a 3/8" socket. On some benders I can get close bends by installing the flare nut, flaring the end and then placing the "reaction plate" between the flare and nut so that is the straight section, just enough straight for the nut.

 

In any case, you need a "mandrel" to bend against, air bending gets kinks readily.😲

Edited July 31, 2023 by Frank DuVal (see edit history)