Features

Replacing a Discovery 3 front differential - pictures

by: Auto Express team

27 Sep 2017

Go to: Replacing a Discovery 3 front differential

Detating the axle shaft : With the vehicle securely supported, the engine undertrays are removed, exposing the diff (close to the chassis rail) with its aluminium support tube.
When drained out, the differential’s oil looked black, discoloured and contaminated. The oil also had a burnt smell about it.
When drained out, the differential’s oil looked black, discoloured and contaminated. The oil also had a burnt smell about it.
The propshaft bolts are difficult to access and remove once they have been undone. Here, a magnet helps with their removal.
Using a bar, the propshaft is pryed away from the flange, then it is lowered and secured with a cable tie clear of the crossmember.
The crossmember under the front diff is unbolted, and then completely removed from the vehicle.
With the road wheel off, the axle stake nut is removed from the driveshaft, and the shaft tapped inward to free it from the hub splines.
The caliper assembly: pads, caliper and carrier, is unbolted and tied clear of the hub so as not to strain the brake hose.
With care, as it is easily broken, the securing screw is undone from the wheel speed sensor, before removing the sensor from the hub.
The steering rack track rod end ball joint’s securing nut is undone and then the ball joint is split from the hub knuckle.
The ball joint locating the upper arm and the knuckle is split, and the arm lifted with a pry bar to separate it from the knuckle.
The top of the hub knuckle is now swung out (still attached to the lower suspension arm) and the driveshaft separated from it.
The driveshaft is now free to be withdrawn from the differential, taking care to avoid damaging the components and CV joints and gaiters.
On the other side of the vehicle, the process is repeated to remove the left hand side halfshaft, before returning to work at the right hand side.
Unbolting the differential: With the right hand side driveshaft removed, the outer retaining bolt can then be undone from the driveshaft support tube’s mounting bush.
The driveshaft support tube is also located to the front differential by four bolts as shown, which are removed as well.
The driveshaft support tube is tapped free from between the diff and the chassis using a soft mallet. O-ring seen at right of pic is discarded.
The plastic breather line, from the breather stub coming out from the top of the front diff assembly, is unclipped and removed.
The differential is still supported at the front and on one side. This is the front housing support bush and mounting bolt being removed.
The diff is also supported at the side to the chassis rail by three bolts. Once they are removed, the diff will be free from the vehicle.
Assistance is needed to safely remove and lower the heavy front differential down and out from the Discovery.
Fitting the new differential: This new diff is seen from the left side (propshaft flange to the right of pic, red protective cap on breather stub, cap on left axle hole).
It’s a two-man job to handle the weight of the replacement front differential when manoeuvring it into position under the Discovery.
The differential is filled with the Land Rover specification grade of oil and the filler plug refitted as the rebuild progresses.
With the axles, knuckles and calipers on, new axleshaft stake nuts are tightened to torque, before locking the nut to the axleshaft using a small punch.
After refitting the propshaft and checking all bolts for correct tightness, the engine undertray and wheels are refitted.
Lastly the top of front diff breather pipe is checked that is clear and clean, and that its secured into position in the engine bay.

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