Brakes - Shudder While Braking
83ford19 Article No. 83-7-19SHUDDER DURING BRAKING - SEMI-FLOAT REAR AXLE
LIGHT TRUCKS 1981-83 F-250/350
A brake shudder condition may be caused by the wheels warping the brake drums as well as brake system causal factors. The following procedure will assist in determining the probable cause and appropriate service actions.
Verify the condition by road test.
^ Make sure tires are warm to eliminate "cold flat spots".
^ Drive vehicle on smooth road at varying speeds between 30 mph and 55 mph. Determine whether a vehicle shudder condition exists during this evaluation.
^ If a shudder condition exists during vehicle operation without brake application, service should be handled per Section 18-01 of the Light Truck Shop Manual. If shudder exists only during brake application, the following diagnostic procedure should be continued.
^ Apply brakes at varying brake pressure at speeds between 30 mph and 55 mph. Determine whether a shudder condition exists.
^ Using parking brake only, apply the parking brake at varying intensity between 30 mph and 55 mph. Determine whether a shudder condition exists.
NOTE: The parking brake release should be held in the "release" position to permit modulation of the parking brake pedal.
^ If the condition occurs during service brake application, but not during parking brake application, this condition is isolated to the front brake area.
^ If the condition occurs during both service brake and parking brake application, the condition is isolated to the rear brake area.
After verifying that a shudder condition exists during brake application, perform the following operations in sequence:
^ Inspect tires for any obvious damage.
^ Inspect wheel lug nuts for looseness. Correct torque is 85-115 ft.lbs. (nominal - 105 ft.lbs.) for the F-250 (under 8500 GVW) and 115-175 ft.lbs. (nominal - 145 ft.lbs.) for the F-250 HD (over 8500 GVW) and F-350 (single rear). Torque wheel lug nuts to specification if necessary and retest vehicle. If condition is still evident, proceed to next step.
^ Remove all wheel/tire assemblies and apply light coat of paint to the surface of each front rotor/rear drum that contacts the wheel, Re-install the original tire/wheel assemblies and torque each wheel lug nut to 85 ft.lbs.
^ Remove tire/wheel assemblies and inspect for evidence of contact between wheel and front rotor/rear brake drum at all wheel lug locations. This is done by observing the pattern on the paint applied above.
^ If the wheels make full contact with the rotor/rear brake drum at all lug locations, proceed to section "A" if the condition is isolated to the front brakes or to section "B" if the condition is isolated to the rear brakes.
^ If the above procedure indicates wheel does not make contact at all lugs, locate another similar vehicle that does not exhibit this condition and switch the tire/wheel assemblies between the two vehicles. Repeat the above paint procedure to the front rotors and rear brake drums. Check each wheel to rotor/brake drum contact pattern at all lug locations.
^ Road test vehicle.
^ If the shudder condition has been eliminated, the original vehicle wheels should be replaced with the following wheels which incorporate improved uniformity discs.
NOTE: Reinstall the tires from the original customer unit:
Original Replacement
16 x 6K 16 x 6K: E3TZ-1015-S
16.5 x 6
16.5 x 6.75: D5TZ-1007-F
16.5 x 6.75
^ If the wheels make full contact and the shudder condition has not been corrected by the above tire/wheel replacement, refer to Section A for the front brakes and Section B for the rear brakes.
Section A
^ Check front wheel bearing end play. If excessive, reset per Section 11-10 of the Truck Shop Manual, and retest the vehicle for shudder.
^ If not excessive, or if the shudder still exists, remove the front brake calipers.
^ Sliding surfaces of caliper and spindle caliper support should be wire brushed to remove all scale, rust, and foreign material. A light uniform coating of lubricant D7AZ-19590-A should be applied to both sliding surfaces.
^ Inspect brake linings and if excessively worn, replace.
^ If not worn, hand sand inner and outer linings and both inner and outer braking surfaces of the rotor. Use garnet paper 100A (medium grit) or aluminum oxide 150J (medium grit). Wipe lining and rotor surfaces with a clean, dry rag.
^ Reinstall caliper, ensuring that caliper is free to slide on rails. Be careful not to get any lubricant or grease on the brake surfaces. Retest for shudder.
^ If shudder still exists, remove caliper, and remove rotor from vehicle. Check and record rotor runout and thickness per Section 12-24 of the Truck Shop Manual. Refinish or replace rotor if out of specification.
^ If shudder still exists, replace wheels.
Figure 13:
Section B
^ Check for excessive runout on rear axle wheel bolts, flange face, and drum pilot. Refer to Figure 13. If the dimensions are out of limits, the axle shaft should be replaced.
^ Check rear brake drums for cracks or for out-ofround condition. Runout of brake contact surface should be 0.007 TIR maximum. Replace or machine as required.
^ If shudder still exists, replace wheels.
PART NUMBER PART NAME CLASS
E3TZ-1015-S 16 x 6" Wheel A
D5TZ-1007-F 16 x 6.75" Wheel A
OTHER APPLICABLE ARTICLES: None
WARRANTY STATUS: Reimbursable within the provisions of the Warranty and Policy Manual.
OPERATION: Applicable Standard Labor Operation and/ or M Time (Actual Time) as defined in the Warranty and Policy Manual.
DLR. CODING: Basic Part No. All charges to be coded to the identified causal part.
Article No. 83-7-19-S
SHUDDER DURING BRAKING - SEMIFLOAT REAR AXLE - UPDATE FOR TSB 83-7-19
LIGHT TRUCKS 1981-83 F-250/350
IMPORTANT SAFETY NOTICE CORRECTION TO TSB 83-7-19
TSB 83-7-19 outlines a service procedure for brake shudder. That article contains an error which, for the safety of technicians, should be corrected immediately. On page 30 of the TSB, the text correctly instructed the technician to replace original 16.5" x 6" or 16.5" x 6.75" wheels with 16.5" x 6.75" wheels, identified as part number D5TZ-1007-F, using the original (16.5") tire. On page 31, however, the parts block incorrectly identified part number D5TZ-1007-F as a 16" x 6.75" wheel.
WARNING: MOUNTING A 16.5" TIRE ON A 16" WHEEL OR VICE-VERSA CAN RESULT IN AN EXPLOSIVE SEPARATION OF THE TIRE FROM THE RIM AND IN PERSONAL INJURY TO THE TECHNICIANS OR IN SUDDEN AIR LOSS WHILE DRIVING. THE ERROR IN THE PARTS BLOCK ON PAGE 31 OF TSB 83-7-19 SHOULD THEREAFTER BE CORRECTED IMMEDIATELY. PART NUMBER D5TZ-1007- F IS A 16.5" x 6.75" WHEEL, NOT A 16" x 6.75" WHEEL AS INDICATED IN THE PARTS BLOCK.
Because 16" and 16.5" wheels and tires appear similar in size, be sure to compare the sizes on both the wheels and the tires to ensure proper matching before mounting the tires.
TSB 83-7-19 should also be amended to indicate that when changing from 16.5" x 6" wheels to 16.5" x 6.75" wheels, the wheel cover adapter rings should be changed.
OTHER APPLICABLE ARTICLES: 83-7-19
WARRANTY STATUS: "INFORMATION ONLY"