Free Auto Repair Advice by Professional Mechanics
How
Does it Work /
Brake Flex
Hose
How Does a Brake Flex Hose Work?
Introduction:
A brake flex hose
is designed to transfer hydraulic force from the car
frame to the
brake caliper,
wheel cylinder or junction block. Brake flex
hoses are also used on some hydraulic clutch systems. The purpose of a flex hose
is to allow movement of the suspension and
steering systems of the car. These components
move as the car is being driven over bumps and as steering action is performed.
These brake flex hoses are constructed with specialized rubber, reinforced with
nylon. Some brake hoses include a Teflon tube used as an inner liner for added
strength. All brake flex hoses should be inspected whenever a
car service is performed. If brake fluid is present at any part of the brake
flex hose it should be replaced immediately. Once the brake hose been replaced
follow normal
brake system bleeding procedures. These hoses are connected at either by a
double flare fitting and a copper sealing ring. It is recommenced that the
copper sealing washer be replaced anytime you disconnect or reconnect a brake
flex hose. The double flare does not need to be replaced when service is
performed, but the flare does need to be clean before re-assembly. It is
recommended using a semi boxed end wrench (flare nut/line wrench) when servicing
the brake flex hose. This wrench is made to grab the fitting more efficiently to
avoid stripping the hex fitting.
Brake Flex Hose
It is recommended using a flare nut/line wrench when servicing the brake flex hose.
This wrench is made to grab the fitting more efficiently to avoid stripping the
hex fitting.
Line Wrench Used for Brake Lines
A brake hose can cause one of the hardest to find problems known to technicians
everywhere. When a brake hose malfunctions internally it can cause a small part of
the inner hose liner to become dislodged and act like a one way check valve
that will either hold full brake pressure from getting a particular wheel or
not allowing the brake pressure to bleed off. This condition with cause the
brake to not work as hard as the other wheels or cause the wheel to drag and
not fully release. Either of these conditions will cause a brake pull
condition. If you suspect this problem use a pocket IR thermometer
laser temperature reader. Drive the car for a short distance with repeated
braking then park the car and use the pocket IR thermometer to test each
wheel. You must test each wheel in the exact same place (I like to use one
lug nut on each wheel). You are monitoring temperature differences from side
to side, not from front to rear. Front to rear temperature differences are
normal, side to side is not. (both front or both rear wheels) If a
measurable amount of temperature differences exists replace both brake hoses
involved. (Note: most brake pull problems of this nature are
front brake related). Example: if both front wheels are tested and the right
temperature reading is 190 degrees and the left side is 80 degrees, there is
a problem with the 80 degree brake side.
Pocket IR Thermometer Laser Temperature
Reader Replacing a Brake Flex Hose:
- Loosen but (Do Not Remove) the lug nuts of the
wheel to be serviced
- Support car in a safe position high enough to remove the brake flex hose
- Remove the lug nuts and wheel
- Loosen the hydraulic brake flex hose at the caliper or junction block, do not remove
- Loosen flex hose at the frame or body mount, remove retainer clip
- Continue the remove the hydraulic brake hose
- Clean all mounting/sealing surfaces
- Re-Install new brake hose
- Tighten all mounting bolts and flange nuts to seal the brake hose
-
Bleed brake system as needed
- Inspect brake flex hose connection for leaks, if brake fluid leaks
exist repair as needed
- Reinstall wheel and lug nuts, lower the tire onto the ground the finish
tightening lug nuts
- NEVER MOVE A CAR WITHOUT NORMAL BRAKE PEDAL OPERATION
For manufacturer replacement or service procedures consult a
car repair manual
Common Problems
- When replacing a brake flex hose make sure the sealing washer is not leaking
- If a brake flex hose fitting has seized use an anti-rust solvent such as wd40
or equivalent to help loosen.
How to Remove a Brake Caliper Video
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How to Change Front Brake Pads and Rotors
How Does it Work
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Brake Flex
Hose
Check Manufacturer Specific Brake
Flex Hose Question and Answers
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