AM Radio - Interference
SECTION3
GROUP
39
N0.
809
DATE
Oct. -96
AM radio interference
850
REFERENCE: NONE
AM radio interference
Symptom:
Intermittent crackling sound in the speakers (AM only). Typically the noise will diminish when brakes are applied.
Background:
Static electricity build-up in the rear wheel bearings will discharge producing an arcing across the bearings. This arcing is picked up on the AM band only.
By electrically bonding the brake rotor to the stub axle, static electricity build-up is not possible.
AM radio reception can be improved by installing an insert with a brush between the hub cap and stub axle on both rear wheels. This grounds the rear wheel hubs to the rear axle.
This Service Bulletin describes how to install the brush capsule in the rear stub axles.
Materials:
Sleeve 9191388-9
Brush 9191387-1
Preparations
- Raise the car on a lift.
- Remove rear wheels.
Removing grease cap
- Tap off grease cap.
(Use a chisel)
Drilling hole in stub axle
- Drill a hole in the center of the end of the stub axle. The hole should be
0/ 6 mm (15/64") and 16 mm (5/8") deep.
Warning!
When drilling, protective eyewear should be worn.
Installing sleeve and brush
- Install sleeve and brush as far as they will go into the hole. (The edge of the sleeve should be approx. 3 mm (1/8") outside the stub axle and the outer end of the brush should be 7 mm (9/32") outside the sleeve.)
Installing new grease cap
- Install new grease cap.
(Use tool 999 5225-1 to distribute the force of the blow to the edge of the cap so as not to deform it.)
- Install wheels.