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.

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. [Source: Qingdao Gofar]