Automatic Hublock - Diagnosis/Service Tips
Article No.95-5-18
03/13/95
^ LOCK HUBS - 4WD - AUTOMATIC HUBLOCK INFORMATION - SERVICE TIPS
^ FOUR-WHEEL DRIVE (4WD) - AUTOMATIC LOCK HUB DIAGNOSIS
LIGHT TRUCK:
1983-90 BRONCO II
1983-95 RANGER
1991-94 EXPLORER
ISSUE:
4X4 system diagnosis can be difficult at times due to system complexities.
ACTION:
For general system operation and diagnosis: Refer to TSB Article No. 92-1-8.
For specific automatic lock hub diagnosis and service: Refer to this article.
HUBLOCK DIAGNOSTICS
WHEEL END CONTAMINATION:
^ All compact vehicle hublocks have an O-ring seal between the hublock and wheel hub to prevent contamination. Whenever the hublock is removed, the 0-ring seal should be checked for damage.
^ If contamination is found in the wheel end, the path must be determined and corrected. Path possibilities are through the hublock seal, the wheel bearing seals or the axle spindle seals.
WHEEL END NOISE (BUZZING) IN 4X2, AFTER UNLOCKING HUBS, SHORTLY AFTER FOUR-WHEEL DRIVE USAGE:
^ Noise concerns in two-wheel drive shortly after shifting from four-wheel drive and unlocking hubs, can occur if one of the hublocks fails to disengage. As the vehicle moves forward, the one (1) hublock that has failed to disengage will rotate its axle shaft through the differential and attempt to rotate the other axle shaft in the opposite direction. This is called differential motoring torque. As this torque attempts to turn the other axle shaft through the differential gears, that shaft's hublock will attempt to engage which will result in a ratcheting or buzzing noise.
^ This type of noise concern is usually found on axles that have incorrect front axle differential lubricant or very few 4X4 miles on them.
^ Verify that the front axle differential lubricant is F1TZ-19580-A. If incorrect lubricant is detected, extract the old lubricant using a suction gun.
NOTE:
BREAKING THE CARRIER SEAL IS NOT A RECOMMENDED METHOD OF EXTRACTING THE LUBRICANT.
1. Refill the front axle with 56 oz (1.66 L) of lubricant F1TZ-19580-A using a suction gun.
2. As the front axle accumulates 100-200 miles (161-322 km) of locked hublock operation, the axle will break-in, thus reducing the amount of differential motoring torque significantly.
3. If a front axle requires breaking in, refer to the Front Axle Break-In Procedure in this article.
4. If the front axle has been broken-in and the differential lubricant is F1TZ-19580-A, however, a wheel end noise (buzzing) in 4X2 is still experienced shortly after four-wheel drive usage. It is advised that the hublock which is not ratcheting be replaced as it is not disengaging correctly. When this condition occurs on any 4X4 Ranger, Explorer, or Bronco II, built from 10/89 through model year 1993, it is advised that both hublocks be replaced as the ratcheting hub is likely to become damaged.
FRONT AXLE BREAK-IN PROCEDURE:
^ To break-in the front axle, engage four-wheel drive and then shift out of it without disengaging the hublocks.
^ Thereafter, continue to drive the vehicle with locked hublocks until 100-200 miles (161-322 km) are accumulated. This will break-in the axle. Should the vehicle be backed up during this time period, the hublocks will disengage and will have to be locked again by repeating the engagement procedure.
WHEEL END NOISE (RATCHETING) IN 4X2 AND HUBS UNLOCKED:
^ This condition could occur during turns or when the suspension is stroked. It is more prevalent in cold weather, with new front axles. It is usually caused by high motoring torque at the axle shafts or by incorrect axle lubrication.
^ Verify that axle lubrication is F1TZ-19580-A. If the front axle is not broken-in, 100-200 4X4 miles (161-322 km), proceed to do so following the outlined front axle break-in procedure in the Hublock Diagnostics section of this TSB article.
WHEEL END NOISE (BUZZING) WHILE ENGAGING 4X4 (TOUCH DRIVE) WHILE MOVING:
^ Refer to TSB Article No. 91-15-10.
POPPING/BANGING SOUND WHILE IN 4X4:
^ If the system slips under load, find what has broken or is slipping. To locate where slip is taking place, put marks at various possible slip points (Figure 1). Test drive the vehicle, then check to see if marks at different points are still in the same relationship to each other. This will help you determine where the slippage is taking place or where to look for broken parts, if any.
^ On vehicles with automatic hubs, find a place where you can do your test, mark the components, then drive without backing up. Stop and check the marks to see if they are in the same relationship to each other. If you back up before checking your marks, the hubs may reindex and not reveal the problem.
^ Reindex component should be serviced.
INSTALLATION PROCEDURE
1. Remove old hublock; remove key from bearing retainer nut and then remove nut.
2. If replacing a manual hublock with an automatic hublock, also remove the three-piece wheel bearing nut assembly.
3. Remove the new wheel bearing retaining nut from the cam assembly and install on the threaded spindle.
4. Using Hex Locknut Wrench (T70T-4252-B), torque the wheel bearing retainer nut to 47 N-m (35 lb.ft.) while rotating the wheel assembly. Back nut off 1/4 turn and retighten to 1.8 N-m (16 lb.in.) of torque.
5. Align scallop of the wheel bearing retaining nut with the center of the spindle keyway by advancing the nut clockwise.
6. Install the retaining key into the spindle keyway. With the garter spring inboard, align the key on the cam assembly with the keyway on the spindle.
7. Firmly press the cam assembly on the wheel bearing retaining nut.
CAUTION:
DO NOT PACK THE HUBLOCK WITH GREASE. TOO MUCH GREASE WILL CAUSE IMPROPER HUBLOCK OPERATION AND MAY DAMAGE THE HUBLOCK.
8. For Ranger and Bronco II, model years 1983-90 (through build date 10/4/89), using the DANA 28 Axle, install the thrust washer set onto the axle:
a. First, the plain steel washer.
b. Second, the needle bearing.
c. Last, the spline washer.
9. For model years 1990-94 (begin build date 10/5/89), DANA 35 Axle, install the one-piece spline washer. Install the "C" clip into the axle groove. It may be necessary to push the axle outboard from the inboard side of the knuckle.
10. For 1995 Ranger, install the thrust washer onto the axle:
a. First, the plain steel thrust washer.
b. Second, the plastic unsplined thrust washer.
c. Last, the steel spline thrust washer.
CAUTION:
ENSURE THE RETAINING RING OR "C" CLIP IS SEATED PROPERLY IN THE AXLE GROOVE FOR STEPS 8, 9, OR 10.
11. Check to ensure 0-ring seal on the flange face of the hublock body is not damaged and is properly positioned in its groove.
12. Install the hublock body assembly into the vehicle hub and rotor assembly. The hub may have to be rotated to line up the three (3) prongs of the cam follower (found internally to the hublock) with the cam assembly.
13. Install retainer flat nuts on wheel studs.
NOTE:
DO NOT FORCE THE HUBLOCK ASSEMBLY. IF THE BODY ASSEMBLY WILL NOT FIT, RECHECK THE ALIGNMENT OF ALL COMPONENTS. INSTALL SPEEDNUTS ON WHEEL LUGS TO RETAIN HUBLOCK. THEREAFTER, INSTALL THE WHEEL AND TORQUE THE LUG NUTS TO 136 N-m (100 LB.FT.) (FIGURE 2).
HISTORY AND TIMING
The Warn Automatic Hublock (Model M350) was used on the DANA 28 Axle (Bronco II and Ranger) from model years 1983-90 (through build date 10/4/89). The Warn Automatic Hublocks (Models M350A and M350B) were used on the DANA 35 Axle (Bronco II, Explorer and Ranger) for model years 1990-93 (begin build date 10/5/89). Starting with model year 1994 the Warn Automatic Hublock (Model M350C) used on the DANA 35 Axle (Explorer and Ranger) was introduced.
The Model M350 is black and Model M350A, M350B and M350C are argent (white silver) in color. The Model M350 can only be replaced by Model M350 service parts. The M350C service kits should be used as replacements for the following:
^ M350A hublocks released 10/89 as model year 1990 running change.
^ M350B hublocks released 4/92 as model year 1992 late running change.
^ M350C hublocks released 8/93 as model year 1994 Job 1 change.
When automatic hublock servicing is required for any Ranger, Explorer, or Bronco II built from 10/89 through model year 1993, it is advised that both hublocks be replaced.
NOTE:
IF AN M350A OR M350B HUBLOCK REQUIRES SERVICING, ALL THE HUBLOCK COMPONENTS MUST BE REMOVED AND REPLACED WITH SERVICE KIT F3TZ-3B396-B, WHICH ESSENTIALLY IS THE SERVICE KIT FOR THE M350C AUTOMATIC HUBLOCK. THE CAM ASSEMBLY OF THE M350A OR M35OB SHOULD NOT BE USED WITH AN M350C AUTOMATIC HUBLOCK BODY NOR SHOULD AN M350A OR M350B AUTOMATIC HUBLOCK BODY BE USED WITH AN M350C CAM ASSEMBLY.
For model year 1994 (and beyond) 4X4 Rangers or Explorers, replace automatic hublocks in accordance with the automatic hublock Service Manual procedure and additional diagnostics procedure outlined in this TSB.
IDENTIFYING AUTOMATIC HUBLOCK MODELS
A stamped code found on the rear of the automatic hublock flange face can be used to identify the automatic hublock type, in addition to the model year summary described above. Examples of the three (3) different codes which correlate to the automatic hublock model type are outlined in the chart:
THE ABOVE PART APPLICATION CHART IS FOR 1983-90 (THROUGH BUILD DATE 10/4/89) BRONCO II, RANGER, DANA 28 AXLE, HUBLOCK MODEL M350:
THE ABOVE PART APPLICATION CHART IS FOR:
^ 1990-95 Ranger (begin build date 10/5/89)
^ 1990 Bronco (begin build date 10/5/89 through end of production)
^ 1991-94 Explorer (through build date 11/18/94, DANA 35 Axle, Hublock Model M350C)
OTHER APPLICABLE ARTICLES: 92-1-8
WARRANTY STATUS: INFORMATION ONLY
OASIS CODES: 508000, 509000, 590000