Here are some frequently asked questions regarding the R380 gearbox.

My gearbox rattles on idle, in neutral, with the clutch up

This is very common on Diesel engined vehicles. The clutch friction plate has a ring of springs, which are there to soften the knock of the diesel engine to stop it being transmitted to the driveline. Often especially with a new clutch these springs are quite tight and a lot of the engine knock goes through to the gearbox and makes the gears “chatter” together when the box is in neutral and the clutch up, it goes when the clutch is depressed. This can sound quite bad and does vary from car to car but is not detrimental to the life of the gearbox and we view it as an undesirable characteristic of the LT 77 and R 380 as opposed to a fault with either the gearbox or the clutch.

The R380 gearbox in my 300 tdi DefenderDiscovery has recently started ‘blocking’ when I shift from 5th to 4th, to get 4th gear I have to nudge 3rd then it will drop into 4th no problem. Why?

A common fault on the early R380 gearboxes was the 4th gear baulk ring. The slot locating the synchro slipper wears and allows the baulk ring to rotate too far. This blocks the synchro assembly. It will be necessary to rebuild the gearbox, and replacing the baulk ring with a later type will eliminate this fault.

I have a Tdi 90 and it “clunks” when I take up drive. Why?

The most common cause is worn mainshaft spline but other things to check the A frame ball joint and the halfshaft drive flanges, especially if you have a 300 tdi Defender. To check mainshaft spline wear remove the PTO cover and with the main box in first gear rock the car backwards and forwards whilst looking into the end of the input gear. If the spline is worn you will see movement of the shaft in relation to the gear. Replace the gearbox and transfer box input gear (use a cross drilled gear to prevent recurrence of the problem).

I have a 300tdi Disco /Defender with a 5 speed manual (R380) gearbox and have lost fifth and reverse gears. Why?

The layshaft extension has sheared off effectively disconnecting these two gears. You require a rebuilt or new gearbox.

I have just fitted a R 380 and I can’t get 2nd, 4th or Reverse. Why?

Some people put sealant on the front face of the gearbox before they fit the bellhousing, this sealant can cause a core plug on this front face to ‘hydraulic’ inwards which then stops the selector rail moving fully forward to select these gears. There is no need to put any sealant on this face.

I’ve just fitted a rebuilt gearbox to my Discovery, the third and fourth shifts are not very good. Why?

When you let go of the gearstick on either the LT77 or the R 380 Discovery boxes the stick will spring to the 3 / 4th gate. This gate position is set by the position of the bias plate. This gate position must be adjusted correctly to agree with the selectors in the gearbox to ensure a good gearshift. When we rebuild the boxes we set this position but sometimes it needs fine tuning when in the car.
If the shifts to 3rd and 4th are not clean you may want to adjust this plate, to do this first you must drive the vehicle but when shifting into 3 and 4 instead of letting the gearstick go where it wants to go try holding it a little to the left then a little to the right, one way or the other it will drop in nicer. When you have worked this out you can slacken the 4 screws holding the plate and move the plate left or right accordingly to improve the shifts.

I’ve just fitted a rebuilt gearbox to my Defender, the third and fourth shifts are not very good. Why?

Most rebuilt gearboxes, including ours, come without the “turret”. This the part that the gearstick bolts to. If you pull back the rubber boot on the turret you will reveal two large springs and two adjuster screws and locknuts. The role of these springs and screws is to set the rest position of the gearstick when you let go of it and is referred to as the 3/4 bias setting. When you fit a new gearbox this can sometimes need adjusting to agree with the selector shafts to ensure a clean gearshift. Firstly you need to work out which way to adjust it, to do this drive the vehicle but when shifting into 3 and 4 in stead of letting the gearstick go where it wants to go try holding it a little to the left then a little to the right, one way or the other it will drop in nicer. When you have worked this out you can adjust the screws the springs are resting on to lean the stick left or right until it shifts better.

What oil should I use in my R380 gearbox?

We recommend MTF94 in your R380 box.

I have a 300tdi Defender/Disco with a 5 speed manual (R380) gearbox and have lost all drive. Why?

There are three possible problems. 1) The mainshaft spline has worn away and is not engaging in the transfer case input gear, (most common) 2) the centre has torn out the clutch friction plate or 3) the mainshaft has sheared just inside the rear of the gearbox. 1) and 3) will require a rebuilt unit.

I have a LT95 4 speed manual and would like to replace this with a 5 speed manual,

To do this you will need :
LT77 or R 380 with bellhousing
LT230 with handbrake, with hi/lo and diff lock linkages
Clutch kit, mounts, shifter

The above frequently asked questions are courtesy of Ashcroft Transmissions.