Thread: 5 speed manual or LT77S ?

C'mon boys and girls there must be somebody out there that knows the ins and outs of this gearbox, the w/shop manual shows a "5 Speed" and an "LT77S", I've never seen a gearbox that needs so many "Specialist Tools and pullers" to dismantle, any tips or help will be appreciated, Regards Frank.

Originally Posted by Tank

My Land Rover Discovery (up to 1994MY) Workshop Manual shows and describes a 5 speed manual gearbox and also an LT77S 5 speed manual gearbox, they look identical, are there 2x 5 speed gearboxes? ...

...Regards Frank.

Frank You are correct about the specialist tools.

In fact there are variants of 2 main types of 5 speed in the Disco 1 and 2

The Range Rover had the first version of the LT77 starting in 1982 this was modified as below and later Discos received the R380 5 speed. The LT77S is actually the H suffix (version) of the LT77 gearbox.

"The gearbox number will be stamped or dot punched on the oval machined flat directly below the filler level plug, on the right hand side of the gearbox main casing. The relevant numbers we require are the first two and the last letter, i.e. the number may be 56A1234567G, we would call this a 56G."

From the Ashcroft Transmissions UK site

LT 77 Development

The LT 77 was introduced to the Landrover range in approx 1983 with the

suffix D box and was developed over the years to the suffix H which was last used in 1994.

The D and E are very similar the only difference being the reverse gear was a little fatter in the E,

When they went from E to F larger layshaft bearings were used.

The G was further improved by all the gear teeth including the pinion getting approx 20% thicker. Also a much wider pump was used to increase the lubrication and cope with the fact that some of the LT 77"s were now being supplied oil cooled, ie V8 NAS 90, 3.9 RR Classic and the 3.5 EFI Discos.

The H (termed the LT 77S) was the same as the G in terms of strength but used a different syncro set up called the "Double Syncro", In reality it didn"t work much better.

Originally Posted by Tank

Anyone got a special tool to remove the Seal Collar on the rear of the output shaft

Frank,
When I rebuilt my LT77, I used a 2 arm puller to pull the 5th gear housing off, as doing this pulled the seal collar off at the same time.

Thanks for that info, I'm still stumped by this "Ferrobestos" bush which is behind the rear seal collar, which I have spent the last 2 days unsucessfully trying to remove, I've busted 2 pullers, one a hydraulic, have frozen it, have heated it and it wont budge.
Reason I was asking about the oil pump gears is because of the heat applied to the seal collar would have damagged them if they were plastic, I have no reason to believe they are plastic, but I read somewhere that oil viscosity (too heavy) could break the plastic shaft, but I dont think that's the case here, any tips on how to get this seal collar off, Regards Frank.

Originally Posted by cmurray

Frank,
When I rebuilt my LT77, I used a 2 arm puller to pull the 5th gear housing off, as doing this pulled the seal collar off at the same time.

As you can see from my latest (posted after yours) this collar is well and truly stuck, I believe if I did it your way, with this collar as tight as it is I would probably damage the fith gear housing, as you can see in my post above it may come to having to cut the bugger off, any idea what this "Ferrobestos" bush behind the collar does??, Regards Frank.

Originally Posted by Tank

As you can see from my latest (posted after yours) this collar is well and truly stuck, I believe if I did it your way, with this collar as tight as it is I would probably damage the fith gear housing, as you can see in my post above it may come to having to cut the bugger off, any idea what this "Ferrobestos" bush behind the collar does??, Regards Frank.

Frank,
This bush is used as a seal between the oil pump and the main shaft, as the oil pump pumps oil through the mainshaft and into the bearings that support the gears on it.

rear seal collar, which I have spent the last 2 days unsucessfully trying to remove, I've busted 2 pullers, one a hydraulic, have frozen it, have heated it and it wont budge.

I'm mid way through dismantling a D suffix LT77, and that collar was a b@stard of a thing. I had to weaken it and cut slots in it with a grinder in order to get it to budge.

You wait until you get to pull the 5th gear. That's a real bugger because you can't afford to damage it.

MacMan, I'm really looking forward to getting to 5th gear, I can't understand why L/R make it sooo hard, can pull most gearboxes down and rebuild in hours, no special tools, except a dummy cluster gear shaft, can you tell me if the oil pump gears are steel or plastic, Thanks, Regards Frank.