Brake System Evaluation

NOTE:
IT IS IMPORTANT TO PERFORM THE BRAKE DRAG TORQUE MEASUREMENT ON THE VEHICLE IMMEDIATELY FOLLOWING THE ROAD TEST (BRAKES MUST BE HOT).

WARNING:
USE EXTREME CAUTION WHEN HANDLING THE WHEELS AND BRAKE COMPONENTS WHEN PERFORMING BRAKE DRAG TORQUE MEASUREMENTS. THESE COMPONENTS WILL BE VERY HOT.

**NOTE:
THE LAST BRAKE APPLY BEFORE PERFORMING THE BRAKE DRAG TORQUE TEST (STEP 3) SHOULD BE MADE WITH THE LEAST PEDAL TRAVEL POSSIBLE SO THAT BRAKE PRESSURE IS AT A MINIMUM.**

1. On 4X4 vehicles that DO NOT have a functioning axle disconnect, shift the transfer case into neutral.

2. Raise the vehicle on an appropriate lift.

3. Measure the Drag Torque of each front hub/rotor assembly. The measurement should be taken with either a dial or beam type foot pound torque wrench and the rotation must be in a forward direction (Right Side = clockwise - Left Side = counter clockwise).

a. For all 4X2 vehicles and 4X4 vehicles equipped with the Dana 44 front axle (all 1500 series 4X4 and 7500 lb. GVW 2500 series 4X4), the measurement will be taken with a torque wrench attached to a lug nut. The torque wrench must be perpendicular to the spindle.

b. For 4X4 vehicles equipped with the Dana 60 front axle (8800 lb.. GVW 2500 series 4X4 and all 3500 series 4X4), remove the cotter pin that secures the hub nut to the axle shaft. The measurement will be taken at the hub nut with a torque wrench. The hub nut on a Dana 60 front axle is a 1-11/16 inch hex head nut.

4. Rotate the hub/rotor assembly in a forward direction. The initial torque required to get the hub to rotate is called "break away torque." The break away torque will be higher and should be disregarded. **Measure and record the rotational torque of the left front wheel. Then, measure and record the rotational torque of the right front wheel. The difference between the left and right side rotational torque should be less then 20 Nm (15 ft. lbs.) of torque.** If the measured torque exceeds the maximum specification, remove the front wheels and proceed to the next step. If the measured torque is within specifications, remove the front wheels and proceed to Step 6.

5. **Remove the caliper assembly from the side of the vehicle that has the higher drag torque and rotate the hub, bearing, and rotor assembly in a forward direction.**

WARNING:
USE EXTREME CAUTION WHEN HANDLING THE WHEELS AND BRAKE COMPONENTS. THESE COMPONENTS WILL BE VERY HOT.

The break away torque will be higher and should be disregarded. The rotational torque should be less then 20 Nm (15 ft. lbs.) of torque. **If rotational torque exceeds the specification (with calipers removed), the bearing/hub or differential should be repaired or replaced.** If the rotational torque is now less then the specification, replace caliper assembly. Refer to the 1997 Ram Truck Service Manual (Publication No. 81-370-7108), Groups 2, 3, and/or 5 for proper caliper, bearing/hub and/or differential service.





6. Using a feeler gauge, measure the clearance between the caliper slide surface and the knuckle mounting arm (both top and bottom) (Figure 1). Take separate measurement at inner and outer portions of both top and bottom slides.

**The total for inner and outer clearances should add to 0.010 in. to 0.026 in. (e.g. top left inner + bottom left inner = 0.010 in. to 0.026 in., top left outer + bottom left outer = 0.010 in. to 0.026 in., etc.). If the total clearance is within specifications, but an individual measurement is low, the knuckle rail can be lightly filed to increase the clearance. If the total clearance is out of specifications, replace the caliper and/or knuckle assembly.

NOTE:
IT IS POSSIBLE TO HAVE NO CLEARANCE ON ONE END (EITHER THE TOP OR BOTTOM) OF THE CALIPER AS LONG AS THE TOTAL CLEARANCE ADDS TO 0.010 IN. TO 0.026 IN. FOR THE INNER READING AND 0.010 IN. TO 0.026 IN. FOR THE OUTER READING. THIS CAN HAPPEN AS A RESULT OF RAM TRUCKS USING A FLOATING CALIPER AND WHAT OCCURRED TO THE BRAKES JUST PRIOR TO CHECKING THE CLEARANCES.**





7. Record the caliper to slide clearance.

8. Install new cotter pin into axle shaft.

9. Remove the rear wheels and brake drums. Perform an inspection of the rear brakes. Verify that there is no differential grease leaking from the rear axle seal or brake fluid leaking from the wheel cylinder onto the brake shoes and linings. Repair any rear brake components or rear axle seal(s) as necessary and adjust rear brakes. Refer to the 1997 Ram Truck Service Manual (Publication No. 81-370-7108), Groups 3 and/or 5 for proper brake and/or differential service.

10. Verify that the proper size wheel cylinders and calipers are on the vehicle. Wheel cylinder diameter is cast in the outside surface of the wheel cylinder barrel (a cast 4 = 23.8 mm and cast 7 = 27 mm). Caliper sizes can be identified by measuring the length of the lower caliper slide rail. 86 mm caliper slide rail measures 4.75 inches, 80 mm measures 4 inches. Using a tape measure, measure the length of the lower slide rail.





11. Inspect the combination valve in front of the booster housing to verify that the correct valve has been installed on the vehicle. All Dodge Ram trucks are equipped with a metering valve and a differential pressure switch located internal to the combination valve. Only some trucks have a proportioning valve. If the truck has a proportioning valve, it will have a hex visible with a rubber plug over it on the rear side of the combination valve. Refer to the chart for identifying correct brake components.

12. Reassemble the rear brakes and install all four tire/wheel assemblies.