r380 noise in 5th gear

hi does anyone here know what this noise in fifth gear is coming from. I suspect worn rear bearings in the gearbox, but it could also be something else. Has anyone experienced the same sound?
The sound only appear when going in 5th gear. Uphill its this on and off sound, but in flat or downhill its constent. If I am off the gas, or with the clutch in, there is no noise, and all other gears are fine.

Defender 110 td5 2000 (242 000km)
Stock R380 and LT230

Hi new member, common issue with high miles R380. Check Ashcroft transmissions for more info and fix.

Ashcroft's say that the bearings wear out on 5th gear, hence the noise. They offer an option of a stronger bearing on their reconditioned units (which you have to pay more for, of course!). I bought one off them with this option around three years ago. I'll be interested to see what it sounds like after another 150,000 miles.

Brown said:

Ashcroft's say that the bearings wear out on 5th gear, hence the noise. They offer an option of a stronger bearing on their reconditioned units (which you have to pay more for, of course!). I bought one off them with this option around three years ago. I'll be interested to see what it sounds like after another 150,000 miles.

Click to expand...

Best of luck to you with that I hope the r380 is actually significantly better than the lt77. Although I am running an LT77 not an r380 I am on I believe my 4th recon of it from ashcroft. I will categorically state here now that this is through no fault of Ashcroft what so ever, I cannot fault their workman ship or service. But I tend to only get about 75k out of a gearbox before the bearings start to complain, and on advice of @jamesmartin that is about right for the unit based on the design and age of the lt77. I am coming up on 400k on the vehicle and probably have about another 25k left on this box before it will be off for another rebuild.

dag019 said:

Best of luck to you with that I hope the r380 is actually significantly better than the lt77. Although I am running an LT77 not an r380 I am on I believe my 4th recon of it from ashcroft. I will categorically state here now that this is through no fault of Ashcroft what so ever, I cannot fault their workman ship or service. But I tend to only get about 75k out of a gearbox before the bearings start to complain, and on advice of @jamesmartin that is about right for the unit based on the design and age of the lt77. I am coming up on 400k on the vehicle and probably have about another 25k left on this box before it will be off for another rebuild.

Click to expand...

I can't remember what the mileage was when I swapped the gearbox, but it was probably around 120,000, in February 2021. The old one was just getting so noisy that it was hard to trust it, and in the last couple of longish drives I did with it I was expecting it to fail. The new one has a tiny song in its heart, but doesn't seem to have got any louder over the past three years.

When we were young, cars weren't built to last more than about 100,000 miles at the most. My early experience with cars was with Morris Oxfords, Triumph Heralds and Spitfires, Vauxhall Vivas and the like which were coming to the end of their lives and could be kept limping along with parts from scrapyards. Most of the cars we took parts from had between 70 and 100 thousand miles on the clocks (presumably the first time round, too) and were simply abandoned because it wasn't worth mending them.

How often do folk change their gearbox oil? I do mine 20 to 25k.
Did my car the other day as I was renewing a drive shaft. Oil from box looked pretty good for 100k ish
So question, is it worth it? Answer, not sure but can't harm.

tottot said:

How often do folk change their gearbox oil? I do mine 20 to 25k.
Did my car the other day as I was renewing a drive shaft. Oil from box looked pretty good for 100k ish
So question, is it worth it? Answer, not sure but can't harm.

Click to expand...

25k for me. I know the interval is 24k but 25k lines up nicely with a timing belt every 50k (early but I had one snap at 60k so am a little paranoid) and means everything resets every 100k to keep the maths easy.

It's just that a lot of things these days say "filled for life" but they do not give any idea what the machine's life should be.

Thanks for the replays.
I contacted Ashcroft and they thought it sounded like worn rear support bearings. Have ordered some new parts, but does anyone know how to put the collar bearing back on again. Is there any simple or cheap tool to get it back on without spending big bucks buying the Land Rover tool (LRT-37-015)? Also i will try to change the bearings without dropping the gearbox, does someone have experience with doing that?

Yep, turned out to be the rear mainshaft bearing. Nice driving in 5th gear now, i think the haul gearbox become less noisy. Had to buy land rover special tool after lots of failed testing with other tools haha. And yes, you can change the bearing without dropping the gearbox.

Good info, ta for comeback.