Carraro front axle – Differential


Splitting the front axle and frame

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

Removing the wheel hubs, axle beam assembly and steering ram

Remove the wheel hubs. Remove the axle beam assembly. Remove the steering ram.

Dismantling the differential housing assembly

Remove screw B with its nut from flange A. Extract the flange and recover the seal C. This will destroy the seal.


Loosen and remove the screws from the differential housing. Remove the differential housing.
Hold the differential housing in place with a sling or other suitable device.
Loosen and remove screws A to extract the two nut retainers B.


Before removing the screws, make indelible marks to mark the position of the two half-bearings and the differential housing to avoid reassembling the wrong way round. Also mark the area between the nuts and the differential housing.
Loosen the adjusting ring nuts using the tools ref. CA119030 and CA119149. As the two nuts are different, mark their position relative to the bevel ring gear.
Remove the 4 screws A and the two half-bearings B. Check that rings C stay in place in their seatings.


Remove the differential unit. From the ring gear side, remove and recover spacer E with its set of rings D, washer F and the bearings removed with the differential unit. Be careful not to invert the bearings if they need to be reinstalled.


Recover washer G and "O" ring H from the bearing seating on the side of the epicyclic ring gear.



Dismantling the pinion assembly

Install the differential assembly in a vice. Loosen the locknut using the tools ref. CA119099 and CA715022. This will irreparably destroy the nut.
Extract nut A and recover retaining washer B.


Extract bevel gear C using a hammer. Ensure that the pinion does not fall out. Recover the washers, flexible spacer D and internal cone E from the tapered roller bearing.


Place the differential housing on a level surface and extract the external cups from the roller bearing, using a drift or a hammer.
Remove the inside cone of the pinion's tapered roller bearing using a standard puller. Recover the bearing cone and the shim located underneath it.
Check all the pinion parts for wear. The ring nut and the flexible spacer must be replaced when refitting the assembly.

Dismantling the differential assembly

Recover the differential and secure it in a vice. Loosen the screws and remove the bevel ring gear. This operation releases the two half-bearings from the differential. Ensure that the internal parts do not fall out.
Detach cover plate A from differential unit C, then extract piston B. Recover the "O" rings from the cover plate and the differential lock piston (internal and external housings).


Remove the plates, drive discs and sun gear D from the differential unit. Disassemble the parts that have been removed and examine them carefully, checking in particular for wear and ensuring that they are functioning correctly.


Use a fine punch to extract the locating pin in order to remove the long pin.
Disassemble the planet carrier and recover the parts it contains: planet gears, thrust washers, spider, sun gear. Check all parts for wear and ensure they are functioning correctly.
Extract the bearings from the half-bearings and the cover plate using a three-point puller.

Install the pinion assembly

Place the differential housing on a workbench. Install the external cups for the new bearings using special drifts ref. CA119225 and CA715092 and a hammer.
To measure the distance, use special tool kit, ref. CA119202 "dummy pinion" and CA119182 and CA119228 "dummy differential housing".
Using tool ref. CA119202, insert the dummy pinion with its bearings and nut in the newly installed roller bearing. Tighten without forcing to eliminate the backlash. Install tools ref. CA119182 and CA119228 on the differential housing supports and tighten the half-bearing screws.
Assembly diagram for tools ref. CA119182 and CA119228 on the differential housing supports. Using a depth gauge, measure distance B (between the bearing pin and the bearing point of the pinion head or bearing base).


To determine the necessary thickness S between the pinion and the bearing, subtract the value V engraved on the pinion head (V = specified taper distance) from the measured value BS = B - V
Select the required thickness S from the range of shims available and insert the chosen shim under the pinion head. Ensure that it is fitted correctly.


After inserting the correct shim with its chamfer facing the pinion, force Install the bearing at the end of the pinion pin using special tool ref. CA715004 and a press, ensuring that it is seated correctly.
Install the shims and a new flexible spacer. Systematically Install a new flexible spacer.
Insert the bevel gear assembly into the differential housing (axle beam internal side) and the second bearing cone at the end of the pinion, on the opposite side. Force Install the second bearing using special tool ref. CA715004 and a hammer. It is recommended that you exert resistance against the striking action of the tool, by using a hammer for example.

Place a retaining washer and screw a new nut onto the end of the pinion.
Screw the nut on with the wrench ref. CA119099 while holding the pinion in place with the tool ref.
CA715022. The tightening torque is determined by the bearing preload measurement.
Gradually tighten the nut. If too much tightening torque is applied, replace the flexible spacer and restart the operation. When checking bearing preload, it is advisable to gently tap both ends of the pinion with a rubber hammer to make the bearing seating easier.
Measure the torque P of the tapered roller bearings of the pinion. Shimming is carried out by gradually increasing the tightening torque of the nut, taking care not to exceed the recommended value.

All torques must be measured without the seal.
P = 1.82 to 2.72 Nm
When the torque value is reached, peen the nut with a hammer and chisel.