For many Series Land Rover drivers, the transfer gearbox is seldom used, compared with the main gearbox. But the transfer gearbox must not be in neutral for the transmission to be able to drive the wheels. So the problem of the transfer gearbox slipping into neutral can have serious consequences, since it is necessary to stop the vehicle before the transfer box can be re-engaged. Slipping into neutral whilst offroading can cause the Land Rover to become stuck in soft ground or require a difficult reverse down a steep slope. Slipping into neutral whilst on the road can cause a dangerous situation in busy traffic e.g. you would not want to lose power suddenly and have to stop whilst negotiating a roundabout.
Those Series Land Rover owners who have experienced this problem will know that it is most likely to occur offroad when the vehicle experiences a sudden jolt. On the other hand, when driving on normal roads it is most likely to occur upon sudden deceleration.
The temporary fixes that drivers resort to are varied; some
will construct some kind of hook or strap to hold the transfer gear lever against the gearbox diaphragm cover, whilst others may cut and shape a wooden wedge to force the lever up against the cover. But temporary fixes are not the solution, as they become a nuisance when you wish to change from high to low ratio. So we need to look at the possible causes.
Whatever the cause is, the underlying problem is that the transfer selector shaft is not being held securely enough to prevent the selector shaft from moving independently of its red knob control lever. The transfer selector shaft, has 3 oval-shaped depressions scooped out of it and these relate to HIGH, NEUTRAL and LOW transfer selection. A vertical plunger (part No. 235416) should be located properly in one of these depressions and held there firmly by the plunger's spring (part No. 56102). If the plunger's spring is weak, then the plunger may bounce out of the depression, allowing the shaft to move; this is an unlikely cause though if the plunger is correctly located in the depression.
The main possible causes for the transfer box slipping into neutral on Series Land Rovers are now considered:
1. External obstruction to the lever movement
There is very little clearance between the transfer lever and the gearbox diaphragm cover, once HIGH transfer is selected. The rubber boot (part No. 338871 - from 1953-84) needs to be carefully fitted to allow full movement of the lever. It is also important to bear this lack of clearance in mind if planning to carpet the diaphragm cover.
2. Fault with the selector mechanism
The transfer lever has a ball incorporated into the shaft and this ball locates into a hole in
a detachable link at the end of the selector shaft. The relationship between this ball and the link is critical to the maximum movement of the selector shaft. If the link is secured at the wrong angle then movement will be restricted. Furthermore, there is a small locating spring (part No. 243714) that fits into a groove in the ball and is designed to retain this important relationship between ball and link. The spring is frequently either missing or damaged.
Arrow shows the inspection hole to view the depression (with plunger and spring removed).
The transfer gear lever is mounted, via a bracket, to a flange at the bottom of the bell housing casing and is the same for all Series I (1954-58) II, IIA & III Land Rover gearboxes. The bracket should be mounted such that the actual flange that it is bolted to is sandwiched between the bracket and the transfer lever rod i.e. mounted to the front of the flange and not the rear (I am grateful to Charlie Pendleton for pointing out this possible error). If the bracket is mounted incrorrectly the transfer lever will function but the lever will be very close to the gearbox diaphragm.
Transfer lever bracket sandwiching the flange it is mounted on.
Spacers fit betwen the bracket and the flange.
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