Transfer Gearbox - Backlash/Clonk

Issue 2

24/05/96

37/02/96/US

SUBJECT:
Gearbox Mainshaft Spline Wear

MODEL:
Discovery
Discovery
Defender 90

AFFECTED VEHICLES:
LP
LJ 178205 Onwards
LJ 506525 Onwards
LD 976480 Onwards

DETAIL

Some customers may complain of clonks and backlash in the transmission system. This may be due to gearbox/mainshaft spline wear. The clonk/backlash will be most apparent in stop/go traffic under overrun conditions or when maneuvering the vehicle during parking, etc. From transfer box numbers 28D 460996 F (Discovery) and 22D 461124 F (Defender) all factory built LT230 transfer boxes have a revised design of input gear, featuring lengthened splines and cross drilled oil feed holes. This modification eliminates the requirement for an oil feed disc (bulletin H415) and eliminates input gear/mainshaft spline fretting/wear. Coincident with this change, the transfer box identification number has been changed to Suffix "F".

Information only:
The new parts supercede all old parts and should be used in ALL LT230 applications during repairs.

NOTE:
Do not use in conjunction with an oil feed disc, Bulletin "H415 Mainshaft Spline Wear Prevention." If a complaint of transmission clonk/backlash is made, it is likely mainshaft spline wear has occurred. The transfer box mainshaft input gear and gearbox mainshaft must be replaced together as a pair.

ACTION REQUIRED

If a customer complains of transmission backlash/clonk refer to the procedure below.

PARTS INFORMATION

Mainshaft/Input Gear replacement part numbers
Manual R380
FTC5087 replaces FTC4188, ratio 1:1.214,28 teeth
(Defender and Discovery)
FTC3703 - Gearbox Mainshaft (Defender and Discovery)

ZF Automatic
FTC5087 replaces FTC4188, ratio 1:1.214, 28 teeth
(Defender and Discovery)
FTC5090 replaces FTC3981 - Coupling Shaft (Defender and Discovery)

PROCEDURE





Follow procedure outlined in Workshop Manual Section 37 "Manual Gearbox", Section 41 "Transfer Box", and Section 44 "Auto Gearbox."

For ZF Automatics: When coupled to a ZF Automatic gearbox a new coupling shaft is required with extended splines. This is a factory fix for all Discovery Automatics and LT230 transfer boxes.

NOTE:
If the clonk/backlash is thought to be coming from the transfer box, remove the power take off cover and bearing housing from the rear of the transfer box to inspect the input gear. Visually inspect the transfer box input gear and the gearbox output shaft if visible wear is evident, the gearbox output shaft and the transfer box input gear will need to be replaced as a pair.

WARRANTY:

Normal warranty policy and procedures apply.

COMP.CODE:

3L9J

SRO:

37.20.88/26 - Input gear and mainshaft (manual) renew 10.50 hr.

44.20.88/26 - Input gear and coupling shaft (automatic) 7.00 hr.