PROBLEM SOLVING
Stiffer steering: The steering feels tighter, with more ground effect and feedback.
This is a normal effect of driving with diff lock engaged, especially when reaching firmer ground where the tyres are less able to slip to release transmission wind-up. If so, it may be appropriate to come out of diff lock, to reduce the stress on the transmission.
Cannot select diff lock: The lever moves to select diff lock, but diff lock does not engage and the light does not come on.
The linkages may be stiff or seized due to lack of use. If so, it is possible, though fiddly, to clean and lubricate some of the linkage underneath the vehicle and to work the lever for a while to free it off. Otherwise, with the transmission floor cover removed for access, check the lock nut holding the operating arm to the pivot shaft is tight, and that the arm is correctly located on the shaft.
Difficult to disengage diff-lock: You can feel the steering pull associated with diff lock, and the warning lamp is on, even though the lever has been moved.
When disengaging the diff lock it’s often necessary to reverse a short distance.
Oil leaks from the front face suggests the intermediate pin, here, has worn the bore in the casing. Ashcroft Transmissions can re-bush the casing. Oil seeping from the transmission brake drum is a sure sign of a failed rear output shaft oil seal. This is a normal feature of the four-wheel drive system. Otherwise, the internal linkage will need to be checked by lifting the transmission cowl to gain access. The switch for the difflock warning lamp, on top of the transfer box front housing, may be incorrectly adjusted, and need screwing out slightly.
Front output flange movement: The transfer box flange to the front propshaft can be moved up and down slightly.
Slight movement can be expected here because there is always slight clearance in the parallel roller bearings supporting this flange, so it is unlikely to need attention. If movement is excessive, or there is an obvious problem, the bearing will need replacement.
Whining noise: Heard generally from the transmission area.
Whining is usually bearing noise, and it’s most commonly caused by the axle or final drive (differential) bearings which can transmit along the chassis. So it’s necessary to be sure before blaming the transfer box. The simplest way is to ask a garage to run the transmission on a wheels-free lift while listening underneath for the source of the noise. If the transfer box is the culprit, the wear is likely to be in the front or rear output bearings, or both. Diff lock warning switch is positioned on top of the unit, seen here from the side with cover plate removed, exposing selector mechanism. If an output flange is grooved here from oil seal contact, fit a new flange, or the grooving will damage the new oil seal. No traction unless diff lock is selected. Expect an axle problem such as a broken halfshaft. If so, with diff-lock disengaged, the propshaft for the defective axle will spin when you let the clutch out.
Oil leaks from front or rear output flange: Leakage from the rear flange might also contaminate the transmission brake shoes with oil.
It’s possible to disconnect the relevant propshaft, remove the flange and replace the seal in situ. When the flange is removed, check the condition of the plain surface of the flange stub where the oil seal touches. The seal can wear a groove, and that damage will quickly destroy a new seal as it rubs against it. If that is the case, fit a new flange with the new seal.
Oil leaking from centre of front face. Oil can leak from the intermediate gear pin which passes through the front of the casing between the front housing and the gearbox. It has an O-seal, but the pin has likely worn the hole in the casing.