Interpretation ID: nht94-5.5
TYPE: INTERPRETATION-NHTSA
DATE: December 8, 1994
FROM: Robert E. Fouts -- President, Earl's Performance Products
TO: Phillip Recht -- Chief Counsel, NHTSA
TITLE: Meeting with Mr. Jim Gilkey 11/05/95
ATTACHMT: ATTACHED TO 4/24/95 LETTER FROM PHILIP R. RECHT TO ROBERT E. FOUTS (A43; STD. 106)
TEXT: Dear Mr. Recht:
Flexible brake hose of extruded teflon armored with stainless steel braid have been the worldwide standard for racing cars since the mid 1960s. The reasons are two-fold:
(1) The virtual elimination of hose swell under pressure results in a significant reduction in brake pedal travel.
(2) The same reduction in hose swell gives a much firmer brake pedal feel - allowing the driver to modulate braking force more precisely.
For the same reasons there is a significant market demand for these hoses on road going vehicles, especially high performance vehicles and cars that have been retro-fitted with upgraded brake systems. There is also interest from OEM vehicle manufacturer s for limited production vehicles.
Earl's Performance Products Inc. has been the leading supplier of this type of hose, as well as other types of high performance fluid handling hoses and fittings, to the racing industry for more than twenty years.
The stainless braid armored brake hoses of teflon, supplied to the racing industry, easily meet all of the physical specifications of FMVSS No. 106 with the exception of the whip test. The whip test requires that one end of the hose be fixed to a normal end fitting while the other is attached to a disc of 8 inch diameter. The assembly is pressurized and the disc is rotated at 800 revolutions per minute. The hose assembly must endure 35 continuous hours of cycling without losing pressure.
The standard racing specification hoses typically fail at the interface between the hose and the upstream end of the swedge collar at the fixed end of the assembly. The failure is due to the aggravated cyclic stress.
Earl's determination to develop a flexible brake hose of stainless steel braid armored extruded teflon has led us to design and manufacture our own in house whip test machine to the specifications set forth in FMVSS No. 106.
After some years of experimentation and testing we have developed our "whip dampener" device which allows our hose assemblies to easily surpass the whip test. We have successfully tested hose assemblies from 9.0" to 24.0".
Briefly, the whip dampener consists of a spherical bearing enclosed in a machined housing. The housing clips into the OEM bracket where the OEM hard brake tubing joins to the flexible brake hose. The flexible brake hose of stainless armored teflon is i nserted through the bearing on assembly and cannot be removed. Suitable threaded couplings to JIC, DIN etc. standards are provided at each end of the assembly to match the OEM threads at the end of the hard lines and at the caliper of wheel cylinder. D etails of these couplings are dependant on the specifications of the individual vehicle and installation. No modifications are required (or allowed) to the threaded couplings or ports on the vehicle.
We intend to meet the marking requirements of Section S 5.2.1 by marking a clear plastic extruded overlay with the required lay lines, manufacturer's ID # etc. or by etching the same information onto the stainless steel braid.
Assemblies will be supplied with clear and graphically detailed instructions.
We met yesterday in Washington with Mr. Jim Gilkey of the enforcement division. Mr. Gilkey stated that he felt that our assembly was a reasonable approach to the requirements of Section S 5.3.3 but, since this is a new concept and no device of this natur e had been seen before, your office should be informed. We have left samples, photographs, descriptive literature and a model of the whip dampener test device with Mr. Gilkey.
Upon receipt of a favorable reply we will submit sample assemblies to an independent testing lab for certification with regard to the complete requirements of FMVSS No. 106 and proceed to apply for a manufacturer's ID #.
We are prepared to return to Washington when required. In the meantime, should you or your staff require further information please feel free to contact me at any time.