The OE brake hoses have what are known as bulkhead fittings on the ends that attach to brackets. Their function is to positively secure the ends of both the hoses and the rigid lines. They are secured by a spring clip under the rigid line flarenut shown here on the rear subframe:
On my rear subframe the cutout in the bracket is large enough that the ER end fitting (which is not strictly a bulkhead fitting) slips right through, so it is not secured by the clip:
On the front brake lines the brackets are a bit tighter and the ER fitting just jams into the cutout, securing it almost as if it were a bulkhead fitting:
On the rear intermediate lines at the forward end, the cutout is also tight enough to secure the line. As you can see the fitting is barely secured, versus the positive security provided by the bulkhead fitting on the OE hose:
Stoptech appears to make their hoses the same way as ER, but their kit contains washers. A 1/2" washer prevents the ER hose fittings from passing fully through the subframe bracket, giving them some of the properties of a bulkhead fitting, so I have to assume this is their function. The thickness of the washer does result in over bending of the clip though. Also, the fitting is not prevented from rotating, so a second wrench is required to prevent the hose from twisting while tightening the flarenut. The OE hose bulkhead fitting engages the star-shaped cutout and prevents the hose from twisting, so only a single wrench is required to tighten the OE hose:
For a bit more security the same washer approach can be taken at all the brackets when using the ER hoses. Here is the front brake hose bracket with a washer (although the flarenut is not fully tight in this image):
The washer idea came from an image I found on line of the Stoptech hose kit:
Hose suppliers whose kits use a true bulkhead fitting include Techna-Fit (direct), Agency Power (following image):
and UUC:
The ECS, ER and Stoptech kits can be described as a kluge. Their female fittings are clearly wrong for the application and the washer is a poor fix.
Noun
"A system that is constituted of poorly matched elements or of elements originally intended for other applications."