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Re: brake lines

Subject: Re: brake lines
From: Bullwinkle <>
Date: Mon, 09 Sep 2002 23:54:08 -0500

I believe I read somewhere that you're not supposed to put
much torque on
the bleeder fittings. True?

Most brake line fittings use the double flare which results
in a seal similar to the spark plug folded copper gasket. 
The double flare has some spring to the rolled over inner
part.  This compensates for any uneven thickness in the
material and missalignment between the cone on the brake
cylinder fitting and the matching one on the flare nut. 
Tightening the nut too much collapses this spring.

The only reference I have to the torque used for brake flare
nuts comes from a Datsun pickup manual which states flare
nuts should be tightened to 11-13 foot pounds (15-18 N-m or
1.5-1.8 kg-m).  You can do this using a flare nut wrench and
a spring scale similiar to a fish weighing scale.  If the
wrench is is 6 inches (0.5  or 1/2 feet) long from the
center of the flare nut to the pulling position of the
spring scale, a reading of 24 pounds on the scale would give
12 foot pounds.  For other lengths, divide 12 foot pounds by
the length of the wrench IN FEET to get the scale reading. 
A 5 inch wrench's usage would be calculated by dividing 12
by 5/12 ths.  It is easier to do the division if you measure
the wrenches length in mm and convert the measurement to
ft.  Don't convert it to inches.  If your lucky enough to
have a metric spring scale, the division and measurement is
much easier.

If you should happen to find a fitting that leaks after
torquing, gradually tighten it, in stages, just enough so it
MGA twin cam
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