Flange-style Hub Locks, a.k.a. TopHats
Note the LACK of screws around the selector dial.
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Today's free-running hubs are very simple to operate and feature seals that prevent the entry of dirt and moisture. Automatic locking hubs are used in many applications. They use the front axle shaft rotation to actuate a cam that locks and unlocks the hub.
There are two types of front hubs currently in use on Ford Trucks:
^ Manual (or free-running) that require the driver to get out of the cab to either lock or unlock them.
^ Automatic locking (they lock automatically when the axle shaft begins to turn).
The vehicle operator doesn't have to wait until the last minute (or when stuck) to lock the hubs. It makes sense to plan ahead and lock them at a convenient time. The hubs can be left in the locked position all the time if desired. For example, if the vehicle is constantly going from the highway to off the road conditions and back, it's not necessary to lock or unlock every time. If the vehicle is equipped with a manual shift transfer case and manual locking hubs, low range can be selected when the vehicle's front hubs are unlocked. This is useful for short distances if very low, creeper gearing (but not 4WD) is needed. For example, backing an empty boat trailer down a launching ramp is best accomplished in 2WD. Once the boat is loaded, 4L (low) can be selected to help pull the boat up the ramp. The hubs don't have to be locked for this purpose, and being in 2WD will prevent driveline windup while maneuvering in the boat ramp parking lot.
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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.
![hublocksflange.jpg Flange-style Hub Locks, a.k.a. TopHats
Note the LACK of screws around the selector dial.
-----------------------------------------------------------
Today's free-running hubs are very simple to operate and feature seals that prevent the entry of dirt and moisture. Automatic locking hubs are used in many applications. They use the front axle shaft rotation to actuate a cam that locks and unlocks the hub.
There are two types of front hubs currently in use on Ford Trucks:
^ Manual (or free-running) that require the driver to get out of the cab to either lock or unlock them.
^ Automatic locking (they lock automatically when the axle shaft begins to turn).
The vehicle operator doesn't have to wait until the last minute (or when stuck) to lock the hubs. It makes sense to plan ahead and lock them at a convenient time. The hubs can be left in the locked position all the time if desired. For example, if the vehicle is constantly going from the highway to off the road conditions and back, it's not necessary to lock or unlock every time. If the vehicle is equipped with a manual shift transfer case and manual locking hubs, low range can be selected when the vehicle's front hubs are unlocked. This is useful for short distances if very low, creeper gearing (but not 4WD) is needed. For example, backing an empty boat trailer down a launching ramp is best accomplished in 2WD. Once the boat is loaded, 4L (low) can be selected to help pull the boat up the ramp. The hubs don't have to be locked for this purpose, and being in 2WD will prevent driveline windup while maneuvering in the boat ramp parking lot.
--------------------------------------------------------------------------------
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.
[url=http://www.supermotors.net/registry/media/470240][img]http://www.supermotors.net/getfile/470240/thumbnail/flangehublocks.jpg[/img][/url]](https://www.supermotors.net/getfile/556280/fullsize/hublocksflange.jpg)