Flange-style Hub Locks, a.k.a. TopHats
Note the LACK of screws around the selector dial.
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TSB 88-08-17 Warn Hub Locks Inoperative
Publication Date: APRIL 15, 1988
LIGHT TRUCK: 1987-88 F-150, BRONCO
ISSUE: Inoperative front drive axle hublocks on 1987 and 1988 F-150 and Bronco vehicles may be caused by the control dial getting too hot and distorting. The hublock body is made of aluminum which transfers heat rapidly from the brake rotor to the hublock assembly. Under certain braking conditions such as brake dragging or downhill trailer towing control dial distortion may occur. Vehicles operated under these or similar conditions may not experience hublock control dial distortion but may be too hot for customers to engage or disengage the locking hub feature.
ACTION: To correct this, install a new hublock service kit that will not allow heat transfer to the control dial. Refer to the 1987/88 Light Truck Shop Manual, Volume A, Section 11-12-2 for removal of the existing hublocks. Use the 1986 Light Truck Shop Manual to install the new hublock kit, (E7TZ-1L104-A).
PART NUMBER PART NAME
E7TZ-1L104-A Hublock Kit - One (1) Required
OTHER APPLICABLE ARTICLES: NONE
WARRANTY STATUS: Eligible Under Basic Warranty Coverage
OPERATION DESCRIPTION TIME
880817A Both hubs 1.8 Hrs.
