LT77 clicking loudly in 5th gear

On the drive into work today (30miles) 5th gear began to make a rhythmic clicking noise. It only happens when under load, so lift off the throttle and the noise disappears. Only happens in 5th no other gears are effected and all are quiet and normal. It does change slightly with speed and increases as speed does but not by a huge amount, seems to be roughly 120bpm. Clutch is functioning as normal. Assume it is not clutch, engine, transferbox, or axle as it only happens in 5th gear. Same speed in 4th gear and there is silence.



I am running an LT77 box behind a 200tdi. The gearbox was rebuilt by Ashcroft from memory about 45k ago. Everything seems to be working as normal driving as normal just have this noise.

I know on the r380 this is a fairly common sign that the rear bearing is beginning to fail, is this the same for an lt77?

Anyone any suggestions what it might be or other test to undertake on the drive home/tomorrow on the drive?

Noise got significantly worse on the way home. Plan to drop the oil tomorrow and have a look, but am really after if it is definitely the gearbox or not if so I will pull the box tomorrow as well and get onto Ashcroft to se how quick they can refurb it again.

Sound on:

Can not say specifically about Lt77 but that is the sort of noise a failed bearing can make.

tottot said:

Can not say specifically about Lt77 but that is the sort of noise a failed bearing can make.

Click to expand...

That was my concern. Assume I am correct in saying gearbox as is it doesn’t happen in any gear other than 5th. So unlikely to be another part of the drive train. Also a little Annoying it was such an instant failure rather than usual becoming a little Noisy and then slowly getting until actually howling giving time to plan the swap out.

The 5th gear is sort of an add on extra in the Lt77 and R380 box, some say it is just not that well designed.
TVR car owners often have issues with the same box

A quick post to show removing a gearbox is not a big job. But is a collection of lots of little jobs that people should not be scared of and does not require any special tools.

remove to foot well matting



remove the tunnel



remove the floor panels



remove the second part of the tunnel



remove gear lever



remove difflock lever



disconnect breathers (mine are a tow into 1 setup for my extended breathers so I disconnect at the pushfit, factory would be individuals where you unbolt the banjo fitting making sure not to loose the little brass washers!



remove reverse switch wiring



remove difflock switch wiring



remove speedo cable



remove all earth cables (I have about 4 as you can never have too many earths)





remove gearbox crossmember, do this by spreading the chassis legs not beating the cross member with a hammer like a monkey as someone has previously done to mine. I use a bottle jack and a couple of peices of wook one of which has been crudely shaped to fit the top of the bottle jack.







Remove prop shafts



remove the handbrake cable - I have a disc brake conversion and also remove this to save weight as it is very easy to remove



I ran out of time for the rest of it and completed the removal the following day int he rain so had no more pictures but I will add pictures of the final steps on reassembly. The remaining steps were:

support the transfer box with an engine crane through the passenger door and remove the transfer box chassis mount

remove the transfer box

remove the slave cylinder

support the gearbox with an engine crane through the passenger door and remove the gearbox chassis mount

remove the gearbox

In true Haynes manual fashion refitting is the reverse of removal!

The gearbox has been dropped off to Ashcroft's for its third rebuild by them, this not a reflection of their workmanship but more of the milage that I do, current speedo reading is 408k miles! There was a suggestion of swapping the lt77 for a stumpy r380 which is a lot more expensive. I have started a discussion on the pros/cons of that on a separate thread: LINK. This time around opted for another rebuild of what I have. Will hopefully receive the rebuilt box next week to refit before Friday ready for a nice gentle breaking in trip to Scotland and back over that weekend!

dag019 said:

A quick post to show removing a gearbox is not a big job. But is a collection of lots of little jobs that people should not be scared of and does not require any special tools.

remove to foot well matting

View attachment 321113

remove the tunnel

View attachment 321114

remove the floor panels

View attachment 321115

remove the second part of the tunnel

View attachment 321116

remove gear lever

View attachment 321118

remove difflock lever

View attachment 321119

disconnect breathers (mine are a tow into 1 setup for my extended breathers so I disconnect at the pushfit, factory would be individuals where you unbolt the banjo fitting making sure not to loose the little brass washers!

View attachment 321120

remove reverse switch wiring

View attachment 321121

remove difflock switch wiring

View attachment 321123

remove speedo cable

View attachment 321124

remove all earth cables (I have about 4 as you can never have too many earths)

View attachment 321126

View attachment 321125

remove gearbox crossmember, do this by spreading the chassis legs not beating the cross member with a hammer like a monkey as someone has previously done to mine. I use a bottle jack and a couple of peices of wook one of which has been crudely shaped to fit the top of the bottle jack.

View attachment 321127

View attachment 321129

View attachment 321128

Remove prop shafts

View attachment 321130

remove the handbrake cable - I have a disc brake conversion and also remove this to save weight as it is very easy to remove

View attachment 321131

I ran out of time for the rest of it and completed the removal the following day int he rain so had no more pictures but I will add pictures of the final steps on reassembly. The remaining steps were:

support the transfer box with an engine crane through the passenger door and remove the transfer box chassis mount

remove the transfer box

remove the slave cylinder

support the gearbox with an engine crane through the passenger door and remove the gearbox chassis mount

remove the gearbox

In true Haynes manual fashion refitting is the reverse of removal!

Click to expand...

Awesome post, thank you