[MNBoxster]

Hi,

There are so many issues with SS Brake Lines that it's safe to say the AfterMarket has over-hyped these tremendously.

First, Modern street cars with oversized Brake Boosters, plenty of available Vacuum Pressure, better designed Master Cylinders, multi-Piston Calipers and better Brake Pad material are all but immune to any slight pressure loss due to flexible Brake Hose expansion. And, the Hoses themselves now conform to much more rigerous standards of Flexibility, Expansion, Robustness and such and are thoroughly tested by the Manufacturers.

OEM Rubber Flexible Brake Hoses are not prone to failure and very few cases of such are known. The Rubber is inert to all types of Brake Fluid and are very flexible and robust. They typically use either Steel or Alloy threaded ends which are crimped to the Hose.

Stainless Steel Flexible Brake Hoses are really a Teflon Hose encased in either Kevlar or Stainless Steel Mesh (or both).

The advantage of this Teflon Hose is that it won't expand under heat or pressure and it is also chemically inert.

But, among it's disadvantages is that Teflon Hose is very Fragile and so must be encased in Mesh to protect it. These too are usually (for DOT approved types) capped by a threaded end which is swaged, or crimped, on the end. The disadvantage here is that since the Hose doesn't expand, the threaded ends must survive much higher pressures than on a Rubber Hose and so these often Do Fail.

Another disadvantage is that the Stainless end caps tend to harden with age, often losing the elasticity required for the threads to lock and they often will loosen and consequently leak fluid or admit air into the hydraulic system. For this reason, the DOT recommends replacing these SS Hoses annually - an involved and spendy practice. This is not an issue in a Racing application where they are generally replaced every season at worst.

Then there is the disadvantage of these Hoses being less flexible due to their mesh outercovering and so they are consequently longer than the OEM Rubber Hoses. This extra length can cause the hose to wear and abrade with the movement of the Steering gear or suspension.

The mesh outercovering can also be damaged by rocks and other debris and can themselves abrade the inner Teflon Hose causing it to fail. For this reason, the better DOT approved SS Hoses use a Kevlar inner mesh to protect the Teflon from the SS outermesh.

The quality of these aftermarket SS Hoses can vary greatly from poor quality materials and workmanship from Taiwan or China, to proper Aeroquip or Earl’s Hose, which are typically much more expensive.

A final disadvantage to these Hoses for Street Use is the inability to inspect the Teflon Hose itself for any wear or damage.

Now, the only ones which are truly any good (read SAFE) are those which are not legal for Street use - non DOT approved. These typically use Aeroquip or Earl’s Speed-Seal ends (also known as Fluor-O-Seal and Fluor-O-Flex respectively). These ends are best available fittings, but they do not meet the DOT specs and cannot therefore be approved - DOT FMVSS 106 specifies that "Each hydraulic brake hose assembly shall have PERMANENTLY ATTACHED brake hose end fittings which are attached by deformation of the fitting about the hose BY CRIMPING OR SWAGING." The idea is that, since crimped-on fittings can’t be loosened, the consumer won’t be able to screw with and weaken them.

Using non-DOT approved SS Brake Hoses can have many negative consequences in an accident investigation, especially in a Personal Injury action, but possibly in a State Safety Inspection as well.

The DOT specification is lengthy and all the required specs are given equal weight. As an example, an otherwise perfectly good quality SS Brake Hose can be failed because the required DOT APPROVED label is stamped in lower case instead of the required upper case.

SS Flexible Brake Hoses do give a Street Car a racier look, but are usually more expensive, less longlasting and actually underperform the OEM Rubber Flexible Brake Hose over time.

You really cannot do any better than the OEM Rubber Hydraulic Hoses - Best to leave these Race-Bred Parts where they were designed for - on the Racetrack!...

Happy Motoring!... Jim'99