LT230 Input Gears

The LT230 Transfer Boxes on Land Rovers have had different types of input gears over the years. This is the gear that connects the output shaft of the gearbox and passes drive through the high/low ratios and centre differential. The gear is fairly easily accessible behind the PTO cover.

The input gear is an important aspect of a Transfer Box, as pre 300Tdi vehicles were prone to wear on the splines on the gearbox output shaft. This causes a massive slack in the transmission and in extreme cases the vehicle would lose drive if the splines were worn down. It was caused by a lack of lubrication to the splines, so later input gears were "cross-drilled" and can be fitted to fix this problem.

However, the LT230 was used in Defender, Discovery and Range Rover models over 30 years, with subtle changes and differences in ratio, so there are also a wide variety of input gears available as they are not necessarily interchangeable. The Transfer Box serial number suffix is particularly important when determining which variety of input gear you have.

Vehicle	Serial Number Suffix	No. of Teeth	Gear Length	Gear Width	Dog teeth	Drilled?	High Ratio	Part number	Notes
Defender	A	26	?	27mm	18		?	FRC5428	Cannot take a cross drilled gear, due to a different tooth pitch
Defender	B	26	?	27mm	18		?	FRC5428	Cannot take a cross drilled gear, due to a different tooth pitch
Defender	C - D	26	129mm	33mm	9		1.41	FRC8917
Defender	C	26	129mm	33mm	9		1.41	FTC5089
Defender	D	26	129mm	33mm	9		1.41	FTC5089
Defender	E	26	129mm	33mm	9		1.41	FTC5089
Defender	F	26	129mm	33mm	9		1.41	FTC5089
Disco	C	26	129mm	33mm	9		1.41	FTC5089
Disco	D	26	129mm	33mm	9		1.41	FTC5089
Disco	E to 308626E	26	129mm	33mm	9		1.41	FTC5089
Disco	E from 309143E	28	129mm	?	?		1.22	FTC5087	Defender V8 also. 32D309417E - 551441F. Supersedes FTC4188, which isn't drilled
Disco	F to 551442F	38	135mm	?	9		1.22	FTC4850
Defender to 7A	G	26	135mm	?	?		1.41	FTC4962
Defender from 7A	G	38	135mm	?	9		1.22	FTC4850 / IEH500010	IEH500010 has no dog teeth