Dana differential

The crownwheel and pinion assembly containing the differential lock mechanism (Hydraulic lock) is fitted in a housing (7) comprising two half-bearings (43) fixed by screws (42). The pinion is positioned at the rear of the housing on two opposing tapered roller bearings. It is adjusted in position using shims (8) located behind the head bearing. The bearings are adjusted using shims (2) inserted between the spacer (45) (if Installed) and the bearing cone (5). Tightness is ensured by a lip seal (4) and an "O" ring (40) fitted on the pinion. The differential comprises two planet gears (38) and a pin (36). The ring gear/pinion clearance is obtained using shims (22) placed behind the cup (29). The housing and ring gear assembly preload is obtained using the spline nut (32).

Dana differential Parts list 
(1) Nut (2) Shim(s) (3) Spacer (4) Seal (5) Bearing cone (6) Bearing cup (7) Housing (8) Shim(s) (9) Bearing cup (10) Bearing cone (11) Sun gear (12) Tab washer (13) Snap ring (14) Piston (15) "O" ring (16) Friction washer (17) Spring (18) Mobile dog clutch (19) "O" ring (20) Guide washer (21) Washer
(22) Shim(s) (23) Screw (24) Fixed dog clutch (25) Half-unit (26) Half-unit (27) Ring gear (28) Nut (29) Bearing cup (30) Screw (31) Lock (32) Spline nut (33) Bearing cone (34) Centring pin (35) Washer (36) Planet gear pin (37) Spherical washer (38) Planet gear (39) Pinion (40) "O" ring (42) Bearing screw
(43) Half-bearing (44) Locating ring (45) Spacer (46) Deflector

Disconnecting the Dana front axle and frame

Drain the axle housing.
Disconnect the axle and its bearings from the front frame.

Removing the swivel housings, wheel hubs and transmissions.
Extract the steering ball joints.
Using a suitable sling, support and take off the complete right and left-hand swivel housing assemblies.

Removing the drive pinion carrier
Take off the swivel housing, wheel hub and transmission assemblies.
Remove the screws from the ram and remove the ram.
Remove the screws.
Loosen and remove the drive pinion carrier.
If necessary, remove the deflector (46).

Removing the Dana differential unit

Place the housing (7) in a vice fitted with soft jaws.
Take out the screw (30) and its lock (31).
Take off the spline nut (32) using the special makeshift wrench.
Take out the four screws (42).
Take off the half-bearings (43).
Remove the differential assembly complete with cones (33) and cups (29). Separate the cups from the cones. Remove the shim(s) (22) used to adjust the backlash. Pair up the bearing cones and cups in they are to be re-used.

Removing the ring gear – Disassembling the planet gears and sun gears

Place the differential unit in a vice fitted with soft jaws. Before disassembling, mark the position of the half-units (25) (26) and the fixed dog clutch (24) with paint for reassembly in their initial positions.

Removing the ring gear
Take off the screws (23) and nuts (28).
Remove the ring gear.

Disassembling the planet gears and sun gears

Take off the screws (23) and nuts (28). Separate the half-units (25) (26) and the fixed dog clutch (24).
Remove the sun gear (11) and the washer (35).
Take out the pin (36), planet gears (38) and spherical washers (37).
If required, extract the bearing cones (33) on the half-unit (26) and on the fixed dog clutch (24).

Removing the differential lock

Using tool MF 471 centred correctly, compress the spring (17) until the thrust washer (21) is free.
Take off the washer and gradually release the spring.
Take off the tool along with the guide washer (20) and spring.
Take off the snap ring (13). Remove the mobile dog clutch (18), the friction washer (16) and the tab washer (12).
Drive out the piston (14).
Discard the "O" rings (15) (19).

Removing the pinion

Unlock the nut (1) (depending on assembly) and immobilise it using the wrench:
- 3376927M1 (AG 85 axle)
- 3376881M1 (AG 105 axle)
Loosen the pinion by turning clockwise, using special makeshift sleeve "C".
From the front of the housing, extract the pinion, cone (10), spacer (45), shims (2) and "O" ring (40).
Separate the pinion and seal (40), and remove the shims (2) and the spacer (45).
Extract the cone (10) from the pinion.
Drive out the cup (9) and remove the shims (8).
Remove the spacer (3), and extract the seal (4). Remove the cone (5). Drive out the cup (6).

Adjusting the position – Shimming and reinstall the pinion

Clean the components and replace those that are defective. Check that the differential lock hydraulic channel is not blocked in the housing.

Adjusting the position

Adjust the position of the pinion. The thickness of shims required to position the pinion correctly is calculated as follows: SP = C - E (d ± r)
SP: Thickness of shims required (8).
C: Value measured between the mating face of the cup and machined face "F".
d: Pinion nominal positioning dimension: 118 mm ± 0.10
E: Thickness of the bearings (9) (10).
r: Actual value marked on the pinion. This value may be positive or negative (to be added or subtracted from the nominal value d).

Using a depth gauge, measure values C and E. Ensure the cone (10) is correctly seated in the cup (9).
After measuring the values, apply the formula to determine the thickness of shims required.
Install the cone (10) up against the shoulder on the pinion (39) using a press and a suitable fitting.

Position the thickness of shims (8) calculated previously into the housing.
Install the cup (9) using a suitable fitting and shim the bearings (5) (6) and (9) (10).

In the housing (7), position the prepared pinion prepared up against the cylindrical sleeve "M" as shown in pic. Press hard on the housing while turning it several times in order to seat the bearing cone (10) correctly in the bearing cup (9). Slide on the spacer (45), with its chamfer facing towards the splines of the pinion.

Using a depth gauge, measure value F according to the formula A - B.
Press hard on the cup (6), turning it alternately to the right and left to correctly seat the cone (5). Measure value G.
Calculate the thickness of shims SP1 according to the formula: G - F.
Position the cup (6) up against the housing.
Slide the shims (2) calculated during step onto the pinion.

Install the cone (5) and the lubricated seal (40).

Grease the lips of the seal (4) and Install it home in the shoulder using a makeshift drift.
Install the spacer (3).
Install the nut (1) and immobilise it using the wrench ref. 3376881M1 (AG 105) or ref. 3376927M1 (AG 85 Dana front axle). Using the special sleeve and a torque wrench, turn the pinion until the following tightening torque is obtained: 360 - 400 Nm.
Check the pinion rotational torque.

Checking the pinion rotational torque
- Turn the pinion several turns using a dial-type torque wrench and the special sleeve. Check that the rotational torque is 2 to 4 Nm.
- After checking the torque, take off and degrease the nut (1) and lightly smear it with Loctite 270 or equivalent.

Reinstall the differential lock

Clean and check all components. Replace those that are defective.
Install the friction washer (16) to the mobile dog clutch (18). Install the assembly in the piston (14). Install the tab washer (12) and position the snap ring (13) in the groove of the mobile dog clutch.
In the housing without seals, provisionally Install the piston (14) with the mobile dog clutch (18). The pin (34) is force-fitted in the piston.

Ensure that the piston and pin slide freely in the housing. After checking, remove the piston fitted with
the mobile dog clutch.
Install the new "O" rings (15) (19). Position and fit the piston and mobile dog clutch assembly by tapping around the rim with a plastic hammer.
Position the spring (17) and washer (20) with the shoulder turned towards the spring. Compress the assembly using tool MF 471 until the washer (21) slides freely in the groove of the housing.
Loosen the tool carefully so that the spring does not jump out.

Reassembling planet gears and sun gears - Reinstall the ring gear

Check and clean the components. Replace any defective parts.

Reassembling planet gears and sun gears
If it is necessary to replace the bearings (29) (33), fit a cone (33) onto the half-unit (26) and another cone onto the fixed dog clutch (24) using a press and a suitable fitting.

Assemble the half-unit (25) in the dog clutch (24), according to the marks made during disassembly.
Position the washer (35) on the sun gear (11) and position the assembly in the half-unit (25), while inserting the washer tab into one of the half-unit holes.
Position the planet gears (38) and washers (37) on the pin (36). Next, position the assembly in the half-unit (25), while turning the tabs of the washers (37) into the holes of the half-unit (25).
Install the other washer (35) on the other sun gear (11). Install the assembly in the half-unit (26) according to the position of the tab of the washer (35).
Position the half-unit (26) assembly on the half-unit (25) according to the marks made during disassembly.

Reinstall the ring gear
Any replacement of the ring gear (27) automatically entails replacing the pinion (39). The same number is engraved onto the pinion and ring gear. They must be fitted as pairs.
Clean the mating faces of the ring gear and differential unit.
Degrease the new screws and nuts and smear the threads of each screw with Loctite 270 or equivalent.
Secure the two half-units (25) (26), fixed dog clutch (24) and ring gear using screws and nuts (28) tightened to a torque of 82 - 90 Nm.

Reinstall and shimming the differential unit

Position the cups (29) on their cones (33).
Install the shims (22) recovered at disassembly up against the washer (21).
Place the ring gear assembly in the housing (7). Check that the locating rings (44) are present. Position the half-bearings (43). Moderately tighten the screws (42) so that the cups (29) fit freely with no play.
Install the unit horizontally in a vice with soft jaws, with the ring gear facing upwards.

Before shimming the differential unit, check that the ring gear is not constrained on the pinion.
Position a dial gauge. Tighten the nut (32) and turn the ring gear (27) several turns to correctly seat the cones in the cups. Retighten the nut to eliminate the axial clearance.
After eliminating the axial clearance, tighten the nut (32) three more notches to obtain the correct

Checking the backlash

Check the backlash using a dial gauge, moving it both ways around the ring gear without causing the pinion to turn. Take three readings at three equidistant points. Calculate the average of the three readings to obtain a backlash between 0.18 and 0.23 mm. If the value measured is too high, reduce the thickness of the shims (22), and if it is too low, increase the thickness of the shims to obtain the correct backlash. Repeat the differential unit shimming operation.
Remove the screws (42) one by one from the bearings, smear with Loctite 270 and tighten to a torque of 115 - 127 Nm.
Reassemble the lock (31) with the screw (30) smeared with Loctite 270 and tighten to a torque of 16 - 25 Nm. Lock the nut (32) by folding the lock tab into the corresponding spline.

Piston tightness test

On the differential lock supply union, Install a pressure gauge fitted with a valve whose tightness has been checked beforehand.
Supply the system with compressed air at a pressure of approximately 5 bar and check the reaction of the piston (14). Lower the pressure to 0.3 bar and close the valve. No drop in pressure should be recorded on the pressure gauge for approximately one minute.
Remove the pressure gauge and valve assembly.

Reinstall the drive pinion carrier

Check and clean the components. Replace any defective parts.
Check for the presence of the rings on the axle housing.
Smear the mating face of the differential housing on the axle housing with a sealing product, Loctite 510 or equivalent, and tighten two diametrically opposed guide studs.
Reinstall the drive pinion carrier. Take out the guide studs. Install and tighten the screws to a torque of 125 - 140 Nm.
Reinstall the steering ram. Smear the screws with Loctite 270 and tighten them to 180 - 200 Nm.

Reinstall swivel housings, wheel hubs and transmissions

Using a suitable sling, support and then refit the complete right and left-hand swivel housing assemblies.

Assembling the front axle and frame
Connect the axle and its bearings to the front frame.
Top up the oil level in the front axle housing and check the oil level in the final drives.
Carry out a road test for the front axle and differential lock control.
Check tightness:
- of the seals and the differential housing mating face
- hydraulic unions