How to read and understand the
aftermarket standard
SAE J2430/B.E.E.P.^Ó test report

Introduction

Brake effectiveness evaluation has always been a demanding automotive engineering task. The introduction of the SAE-J2430 SURFACE VEHICLE STANDARD in 1999 [1] and the adoption of it by the Brake Manufacturers Council as the basis for the Brake Effectiveness Evaluation Procedure for friction material used on passenger cars and light truck brake systems makes this task easier. It is a single-ended inertia dynamometer test reviewed and endorsed by the brake industry and supported by almost 1,000 dynamometer tests and 50 fully instrumented vehicle tests.

The SAE J2430/B.E.E.P. Test procedure resembles the main sections of the Federal Motor Vehicle Safety Standards 105 [2] and 135 [3]. Not having a reference material on the other axle, it gives a high degree of repeatability and consistency from test to test.

Further introduction of the Brake Effectiveness Evaluation Procedure by the BMC friction materials committee, creates a reliable framework to assess actual performance of a friction material. The acceptance criteria are derived from the FMVSS requirements and studies performed by the University of Michigan Transportation Research Institute.

Why a SAE standard for dynamometer testing

“SAE J2430 is an improvement over SAE J661/J866 as a friction material effectiveness characterization test of replacement brake linings. SAE J661 uses a one-inch square sample running against a large drum and is known to have shortcomings for characterizing the vehicle performance of different types of automotive brake linings.” [1]

A single-ended inertia dynamometer test has among others, the following advantages over other types of tests [5]:

·         Uses vehicle specific hardware and test conditions derived from detailed vehicle tests.

·         Tests only one material at a time without the influence of a reference material on the other axle that affects repeatability and accurate assessment of the material tested.

·         Specifies, in detail, control inputs and permits in-depth assessment on how the test was performed. Brake cooling, which is critical in performance tests, is also properly defined.

·         Cost-effective when compared to a full vehicle test.

·         Developed in more than 7 years of continuous testing and close analysis of results by Original Equipment Manufacturers, suppliers, consultants and friction manufacturers.

·         Takes advantage of the expertise available through the SAE committees structure and approach to develop and validate testing protocols with detailed peer reviews in an open discussion forum. Periodical updates keep standards current with the application and testing industry.

Why the Brake Manufacturers Council performance limits?

As a second phase of the SAE J2430/B.E.E.P.^Ó program, the friction materials committee developed a set of criteria consistent with the FMVSS vehicle test requirements [5]. SAE J2430 does not include acceptance or performance limits, so its applicability for effectiveness characterization required a mathematical modeling of the vehicle dynamics and its corresponding relationship with the federal stopping distance and pedal force requirements. The BMC also developed a test report format in order to present test data in a consistent and repeatable way. Performance criteria include [4]:

·         Average of ramp applications should be within the FMVSS effectiveness space requirements. Regressed specific torque within the limits allowed for stopping distance requirements, maximum pedal force and brake balance. Over-effective performance is also compared to maximum limits on pedal force and deceleration limits.

·         Cold Effectiveness and fade snubs within acceptable limits of deceleration and maximum pedal force.

·         Hot Effectiveness stops above the minimum deceleration requirements within pedal force limits.

Brake balance between front and rear axles is the basic criteria for the inertia split calculation

The BMC has external consultants to audit how a valid test is run

How a vehicle is made available for SAE J2430/B.E.E.P.^Ó testing

SAE J2430/B.E.E.P.^Ó testing requires specific test conditions and hardware information before the actual test can be performed. Vehicles to be tested should meet some initial criteria:

·         Current production on-road vehicle

·         Up to 3,500 kg gross vehicle weight

·         Be available for the corresponding floor-checks and measurements

Vehicles can be added based on BMC platform development committee request to any approved testing facility or direct customer requirement as part of their engineering or marketing validation programs. Link Testing Laboratories., Inc. also develops vehicles independently to make them available to the industry for regular testing.

Information is used to: gather hardware information to build fixtures for front and rear axle friction materials testing, define the required inertia for regular testing based on brake balance, determine the vehicle specific parameters for the control program and performance limits for the acceptance criteria shown on the report. Procedures for obtaining the vehicle information follow Federal Test Codes requirements. [5]. Vehicle data can be grouped as follows:

·         Physical dimensions and weights: wheelbase, tire rolling radius, brake effective radius, brake disc or drum dimensions, center of gravity height, gross and lightly loaded vehicle weight.

·         Hydraulic system pressure levels with and without power assist, pressure profiles for 135 N/s pedal force ramp rate, knee point when proportioning valve available, booster runout pressure, pressure levels at 667 N and 500 N pedal force for FMVSS 105 and 135 respectively certified vehicles and 1,000 N maximum pedal force corresponding pressure for the effectiveness section per FMVSS pedal force limit.

·         Brake hardware part numbers and FMSI identification for friction materials, both front and rear.

Link Testing Laboratories, Inc. performs internal testing using the original equipment friction material to fine-tune the computer control program for the dynamometer and have an exemplar data set to develop the test report format. Control program parameters, performance limits and acceptance criteria are defined based on the federal requirements, not the original equipment friction material or any other friction product.

Other options to develop a vehicle for regular SAE J2430/B.E.E.P.^Ó testing is via a testing program agreement with Link Testing Laboratories., Inc.

Customers with floor check capabilities and the proper inertia dynamometer with the technical capabilities specified in the current SAE J2430 SURFACE VEHICLE STANDARD can develop vehicles for testing on their own.

SAE J2430/B.E.E.P.^Ó test can be used to characterize effectiveness on friction materials -brake pad or brake lining- or components –rotors, drums, calipers-

What is needed to perform a SAE J2430/B.E.E.P.^Ó test

Running a regular SAE J2430/B.E.E.P.^Ó on any of the available vehicles only requires sending parts, indicating the amount of tests to be performed and arranging the test schedule by phone or e-mail. Unlike other test procedures where test conditions may vary from customer to customer, SAE J2430/B.E.E.P.^Ó test conditions are pre-defined for each vehicle.

Parts required to run a test are:

·         Friction material for effectiveness characterization. Rotor or drum and hardware used are original equipment level.

·         Rotor or drum for effectiveness characterization. Friction material and hardware used are original equipment level.

Test report is submitted in Adobe Acrobat format along with a Microsoft Excel spreadsheet.

135N/s Pedal Apply Rate

None   Instrument Check
80 km/h Cooling Curve

Within Cooling Band

200 for Front

1^st at minimum pressure from Section 0010.

1^st at 35

Within Cooling Band

200 for Front

Within Cooling Band

200 for Front