JSM
Active member
As I mentioned last weekend I hurt my front diff in my black truck. This is after several years of pure abuse, it was a stock unknown miles one to begin with so it doesn't owe me anything.
If you search on here, and even on the net you basically see people say they are difficult either pay someone else or buy another used one.
That answer does not sit well with me, so I thought I would start a thread to discuss in detail the inner working of these, how to rebuild them, check them, inspect them, change seals, etc. Basically whatever I come across with my truck here in the next month and welcome anything people can add.
I happened to have a spare blown up front diff at home so last night I split the case to take a look inside, learned a few things but more to come.
Notice what is left of the pinion gear.
To be continued, but in the mean time if anybody has information to add please do so.
Pictures of internal parts
Basic Information:
Used from 1983-1997 in AWD and 4wd platforms. AWD diffs have a different full time passenger side axle/tube which is easily swapped.
ZR2 option S10's in 95 time frame have a cast iron case.
Pinion Nut Size 1 1/4"
Some part #'s I found
The axles on the Bravada and Typhoon are designed for full-time four wheel drive and therefore are not equipped with a disengagement feature. With this one exception, the Bravada, Typhoon and standard 4wd front axle assemblies are very similar.
The drive axles employ completely flexible assemblies which consist of inner and outer constant velocity (CV) joints connected by an axle shaft. The inner CV joint is a "tri-pot'' design, which is completely flexible and can move in and out. The outer CV joint is a "Rzeppa'' design which is also flexible but cannot move in or out.
Axle Removal/Install:
Bravada and Typhoon
NOTE: Unless air tools are available, you must remove the cotter pin and loosen the axle nut before the vehicle is raised and supported. With the vehicle's weight resting on the tire and an assistant firmly applying the brake pedal, you should be able to loosen or tighten the axle nut, as necessary.
Wear patterns
I am also toying with the idea of building a custom solid spacer instead of the crush sleeve. As you can see in the diff I pulled apart the pinion gears are shredded. This most likely came from the lack of preload on the pinion shaft bearings. Several possible reasons this could happen (flange replacement, seal replacement, or just abuse).
Since I have machine tools available to me, making a solid spacer instead should beef up the diff some. Time will tell I guess. Heading today to get a good used diff and will tear it apart for inspection, solid spacer setup, new seal, etc.
More info to come as I collect it.
If you search on here, and even on the net you basically see people say they are difficult either pay someone else or buy another used one.
That answer does not sit well with me, so I thought I would start a thread to discuss in detail the inner working of these, how to rebuild them, check them, inspect them, change seals, etc. Basically whatever I come across with my truck here in the next month and welcome anything people can add.
I happened to have a spare blown up front diff at home so last night I split the case to take a look inside, learned a few things but more to come.
Notice what is left of the pinion gear.
To be continued, but in the mean time if anybody has information to add please do so.
Pictures of internal parts
Basic Information:
Used from 1983-1997 in AWD and 4wd platforms. AWD diffs have a different full time passenger side axle/tube which is easily swapped.
ZR2 option S10's in 95 time frame have a cast iron case.
Pinion Nut Size 1 1/4"
Some part #'s I found
- Stub Axle Bearing BCAHK4012 ~ $10.30
- Right Inner Axle Shaft Pilot Bearing BCAB2516 ~$7.32
- Right Intermediate Bearing BCAB5020 ~ $15.93
- Pinion Bearing
- Crush Sleeve
- Pinion Nut
- Stub Axle
- Shims
- Ring/Pinion 3.42
- Ring/Pinion 3.08
- Lock Right Unit 1935 ~$400
- Seals
- Axle seals (qty 2) 14039577
- Pinion seal 14039587
- Drain Plug
- Recomended Gear Oil
- Upper Housing Bushing GM 15656163 ~$15
The axles on the Bravada and Typhoon are designed for full-time four wheel drive and therefore are not equipped with a disengagement feature. With this one exception, the Bravada, Typhoon and standard 4wd front axle assemblies are very similar.
The drive axles employ completely flexible assemblies which consist of inner and outer constant velocity (CV) joints connected by an axle shaft. The inner CV joint is a "tri-pot'' design, which is completely flexible and can move in and out. The outer CV joint is a "Rzeppa'' design which is also flexible but cannot move in or out.
Axle Removal/Install:
Bravada and Typhoon
NOTE: Unless air tools are available, you must remove the cotter pin and loosen the axle nut before the vehicle is raised and supported. With the vehicle's weight resting on the tire and an assistant firmly applying the brake pedal, you should be able to loosen or tighten the axle nut, as necessary.
- Disconnect the negative battery cable.
- Unlock the steering column so the linkage is free to move, then raise and support the front of the vehicle safely using jackstands.
- Remove the tire and wheel assembly.
- Remove the cotter pin and retainer from the hub end of the axle shaft.
- Hold the hub from turning and loosen the axle nut. Once the nut is loosened unthread it and remove the washer. The hub may be held by installing two lug nuts and using a large prybar.
- Place a jackstand or a floor jack under the lower control arm for support.
- Remove the lower shock absorber retainers, then reposition the shock for access.
- Matchmark the output shaft flange, then remove the output shaft flange-to-drive axle bolts. If necessary, hold the hub from turning using the prybar or insert a drift through the opening in the top of the brake caliper into the vanes of the rotor.
- Using an axle driver/removal tool such as the Posilock Puller Model 110, or equivalent, drive the axle shaft from the hub.
- Remove the drive axle from the vehicle. If the boots are not being serviced, take care not to damage or rip the CV-boots during removal. To install:
- Install the axle to the vehicle, taking care not to damage the CV-boots. Insert the shaft end into the hub.
- Install the washer and retaining nut, then tighten the nut to 180 ft. lbs. (245 Nm).
- Install the retainer and a new cotter pin over the axle nut. If necessary, tighten the nut additionally in order to insert the cotter pin, but DO NOT back off from specification.
- Align the hub flange, then install the retaining bolts and tighten to 59 ft. lbs. (80 Nm).
- Reposition the shock absorber and secure using the retaining bolt.
- Install the tire and wheel assembly.
- Remove the jackstands and carefully lower the vehicle.
- Make sure the ignition is OFF, then connect the negative battery cable.
- Remove the right drive axle (halfshaft) from the vehicle. For details, please refer to the procedure located earlier in this section.
- Remove the support bracket-to-frame nuts and washers.
- Remove the tube-to-carrier retaining bolts.
NOTE: Before removing the shaft and tube assembly, position a drain pan to catch any escaping fluid. - Attach a slide hammer to the output shaft and pull the shaft free, then remove the shaft and tube assembly from the vehicle. To install:
- Thoroughly clean the mating surfaces of the carrier and tube.
- Apply a bead of sealer such as Loctite(r)514 or equivalent to the carrier sealing surface.
- Install the shaft and tube assembly to the carrier.
- Install the tube-to-carrier bolts, then tighten to 35 ft. lbs. (58 Nm).
- Install the support bracket nuts and washers, then tighten to 55 ft. lbs. (75 Nm).
- Install the right drive axle to the output shaft.
- Remove the axle tube and output shaft assembly. For details, please refer to the procedure located earlier in this section.
- Remove the shaft along with the deflector and retaining ring. Strike the inside of the shaft flange with a brass hammer to dislodge it.
- Remove the shaft seal and bearing using a slide hammer and axle tube bearing remover such as J–29369–2. To install:
- Lubricate the seal lips, bearings and bearing surfaces using axle lubricant.
- Install the bearing using J–33844 or an equivalent bearing installer.
- Install the seal using J–33893, or an equivalent seal installer.
- Install the shaft to the tube taking care not to cut the seal with the splines.
- Install the axle tube and output shaft assembly to the vehicle.
- Pinion Bearing Preload (NEW) 11-14 Inch Lbs
- Pinion Bearing Preload (USED) 6-7 Inch Lbs
- Ring Gear Backlash .006-.010"
- Ring Gear Bolts to Case 60 Ft Lbs
- Side Bearing Caps 60 Ft. Lbs
Wear patterns
I am also toying with the idea of building a custom solid spacer instead of the crush sleeve. As you can see in the diff I pulled apart the pinion gears are shredded. This most likely came from the lack of preload on the pinion shaft bearings. Several possible reasons this could happen (flange replacement, seal replacement, or just abuse).
Since I have machine tools available to me, making a solid spacer instead should beef up the diff some. Time will tell I guess. Heading today to get a good used diff and will tear it apart for inspection, solid spacer setup, new seal, etc.
More info to come as I collect it.
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