Brakes

Hi, Had a fail at the IVA test due to a twisted brake pipe. Rather than take the car apart to replace the complete pipe, I found this on the net. It’s very similar to a compression unit you would use for water, only designed for brake pipes, has anybody used these, are the safe/any good?

Cheers.
 

Attachments

Eddy McClements

Supporter
I don't like the idea of olives in this application; if you need to join 3/16" brake pipe there are both male and female joiners, and they work perfectly if you have the means of making a flare.

Either



or

 

Bill Kearley

Supporter
Not that type Terry, Inverted flair is the standard but see if they will let you use Swagelok, a very high end product.
 

Howard Jones

Supporter
In a word..............no.

Ya, I know that's not fair so here's why. Compression fittings are used in hydraulic systems and that is a similar application but in most hydraulic systems I have been familiar with in the rail transit industry when you see compression fittings they are being used in the low pressure or the return side of control valves to return fluid to reservoirs or for lines where pressures are fixed by design at a pressure well below the max pressure rating of the tubing and fitting.

On the other hand, the system's high-pressure side is typically controlled to 2500PSI and then modified by very high tolerance valves and electronic sensing to provide caliper pressures in the range of 500- 1200 PSI. ALL high-pressure side tubing and fittings are usually stainless thick wall tubing and stainless double flair machine formed flares. These machines are very expensive and can form flares on stainless tubing. Stainless is almost impossible to work by hand and that is why it is normally not used in the auto industry. Especially for make yourself lines.

So the problem with automotive brake systems and compression fittings is this, tolerances can not be maintained to allow compression fittings to remain stable at their rated pressures with tubing other than stainless. In addition, auto brake tubing is not meant to be used with stainless compression hydraulic fittings and the use of available brass fittings is an absolute no-no for brake systems. They simply are not strong enough. So if you use copper-nickel alloy brake tubing that is meant to be double (inverted) flared it's OD is not held to a close enough standard to be reliably used with the compression nut and they slip.

You could use the called for designed tubing (stainless) with Swagelok stainless fittings. But then you would be replacing the tubing and when you tried to work with it you would realize how difficult it is to use as well as the need to use compression fittings throughout (both ends) because you can't flare it to use your existing fitting on the other end.

So you clearly don't want the end of your brake line to blow off at the highest pressure moment because you mixed materials not intended to be used together. So.................no.

At least in IMHO. It is free after all.
 
Last edited:
Thanks guys for you answers, it looked good, but I would hate to be tearing down a big hill and go for the brakes and the system blows out. I will look at Eddie’s system going forward, great having the forum to bounce things from.

Don.
 

Neil

Supporter
Thanks guys for you answers, it looked good, but I would hate to be tearing down a big hill and go for the brakes and the system blows out. I will look at Eddie’s system going forward, great having the forum to bounce things from.

Don.
Don, that actually happened to me but it wasn't on a hill, it was in Charlottesville, VA. I stepped on the brakes and there was a "bang" and the pedal went all the way to the floor. Fortunately, I was able to pull up the emergency brake handle quick enough to stop before rear- ending the car in front of me. The brake line pressure had blown out the guts of the brake light switch. I can't blame China this time- it was A Dunlop switch in an Italian car.

AN fittings are widely available and are commonly used but with so many restrictions imposed on builders in many countries they may not pass local inspections.
 
^ jeez that sounds terrible. Do you know if this is a one in a million phenom, or is it something I should look at eliminating from my rear brake plumbing?
 

Neil

Supporter
That brake pressure switch failure was undoubtedly a fluke but it did happen. Using a microswitch on the brake pedal would eliminate that possibility but it probably would not be worth the effort to make the change.
 

Terry Oxandale

Skinny Man
That's what I utilized, and works great. Only down side is it's relative fragile nature if not enclosed, and harder to clean the area (getting around it with the vacuum nozzle). With LED brake lights, a pretty small switch can be used.
 
For brake lines I would stay away from that type of compression fit fitting. The compression olives just aren't secure enough on the pipe to guarantee against high pressure leaks or slippage.

Double flared brake lines take some practice to make, and a good double flare tool makes all the difference. After messing around with cheaper kits trying to perfect my technique I bought the Mastercool kit and it works very, very well. It's not cheap at around $300 bucks, but with a little practice you will have reliable double flares in your system you can count on!

 

Eddy McClements

Supporter
Agreed. The joiners I posted above do not use olives - they are a means of joining two pipes, each pipe to be joined must have a double-flared end.
 
Top