Strange LT77/LT230 issues?

[nobber]

I have an old TD with an LT77 , its the first ones built but I forget the suffix now, the one without the cross drilled transfer gear.

Anyhow, it lost drive in all gears when I changed gear so I coasted to a halt, it then got drive back but soon lost it again.

It has been gradually getting worse.

I took it to the local garage today, when I pulled away it pulled OK, then lost drive when I changed from 1st to 2nd.

So I pulled away in 2nd and it lost drive when I changed to 3rd.

So I pulled away in third and drove it a fair bit without changing gear however it lost drive when I slowed down for a corner (without changing gear).

Every time it loses drive I hear a chattering/rattling as if the release bearing on the clutch is bouncing around. It will not regain drive unless the vehicle is at a stand still, when the vehicle is moving if it loses drive the gear stick seems to select a gear but it is as if something isnt connecting and causing a chattering or rattling noise. When the vehicle is at a stand still it will usually go back into drive but sometimes when I let the clutch out all I get is a rattle.

It will still do this in diff lock.

The mechanic says it doesnt sound like a clutch problem but I cant see anything inside the gear box that it could be , but then again I know very little about gear boxes.

Any ideas?

[CwazyWabbit]

Take the pto cover off the transfer box and have a look to see if the shaft is turning or not in the centre of the transfer box input gear. It could have worn the splines on the output shaft and be jumping on them. I would expect you to have noticed a lot of transmission slack before it got to the stage of losing drive.

Or you could have ripped the centre out of the clutch. If you suspect the gearbox try 4th gear as it uses the least bits iirc.

[nobber]

The transfer gear was the first thing I looked at, I pulled it out and its all fine. The gears are all OK and it works smoothly in all gears.

The first time it happened I emailed Ashcrofts who told me to check the hi/low selector. I stripped it out , cleaned it and reassembled it however when I tried to test drive it I found the slave cylinder letting go and the clutch dragging.

So I put a new slave in and it drove along quite happily for 3 or 4 miles before the problem returned, although it did have a slight chattering when under load but I just put this down to me disturbing the transfer gear. The problem then returned during this drive and has remained ever since.

The thing about the clutch is surely if it had the centre ripped out it wouldnt drive at all?

[Bowie69]

Did you check the output shaft on the gearbox?

[nobber]

The one going through the transfer gear in the transfer box? Thats the first thing I checked. Surely if any splines were to shear off it would lose drive completely?

[CwazyWabbit]

I've heard of splines being worn on the gearbox output shaft but only slipping some of the time (Simon Smith had that happen IIRC), but you've checked that anyway.

I think the next time it loses drive I'd be inclined to remove the PTO cover to see if there is any drive from the gearbox, that way you can say for sure if it's transfer box or gearbox/clutch. If it's gearbox/clutch then it's gearbox out anyway and you'll see soon enough if it's a clutch problem.

Also you could try draining the gearbox oil and see if any large bits come out with the oil.

[jbs]

Have you by any chance got engine oil dripping from your wading plug hole on the base of your bell housing?, If so then you'll be looking at getting the rear main oil seal replaced.

Just a thought

John

[nobber]

Have you by any chance got engine oil dripping from your wading plug hole on the base of your bell housing?, If so then you'll be looking at getting the rear main oil seal replaced.

Just a thought

John

Hi John, Yes its been doing this for years now, I did plan to do it when the clutch eventually gave in. I had to top the engine oil up a few weeks ago and all I had was synthetic so that hasnt helped at all either. I cant see this causing the problem though, would it?

I just got off the phone to the garage and they are pretty sure it is either the gear or transfer box but wont know until later today when they get around to checking it. Looks like another big spend coming up.

Rob.

[jbs]

Rob, the oil contaminating the clutch plate-leaking from the rear main oil seal will cause you loss of drive with the clutch slipping by "lubricating" the surfaces of the pressure plate and clutch cover plate.

And now you've finally started to lose drive on the gearbox you may find that the seal is giving up the ghost-I had one on a TD I previously had and also 1 on my current 90 too.

John

[nobber]

Rob, the oil contaminating the clutch plate-leaking from the rear main oil seal will cause you loss of drive with the clutch slipping by "lubricating" the surfaces of the pressure plate and clutch cover plate.

And now you've finally started to lose drive on the gearbox you may find that the seal is giving up the ghost-I had one on a TD I previously had and also 1 on my current 90 too.

John

Thats the thing John, the clutch isnt slipping. It loses drive when I change gear so when there is no engine load but rotation of the drive train through coasting, this will even happen now without changing gear just by trying to engine brake. I'm still hopefull it is a clutch problem as LT77's are a bit thin on the ground at the moment. I can get an LT230 but the only LT77 I have found is way to expensive considering I can get an Ashcroft recon for a little extra.

I wonder if it is a broken selector fork causing it to slip out of drive?

[jbs]

Rob, Shame I'm not at home-I've got an LT77 in my shed as a spare, I changed my LT77 to a short R380 from Ashcrofts last time I was at home, heres a thought for you-is the T-box losing it's adjustment to be in either high or low-I had a T-box a few years ago that would come out of low ratio because the dog clutch was fubbarrd, Other than what I've put down here I can't think off the top of my head what else it could be to be honest

John

[nobber]

That does sound like the most likely suspect John, I did take the cover off the selector shaft and it all seemed to be working correctly but only in the sense that it would easily select HI or Low. When the thing loses drive the hi/low gear stick is still in gear and has not jumped out to the neuteral position.

There is nothing on the engine side apart from the clutch that would cause this is there?

I guess the only thing now really is to wait for the garage to get back to me with a proper diagnosis, fingers crossed its just a clutch problem.

[jbs]

What about driving the vehicle with the t-box lever restrained in high with say a ratchet strap and see how that reacts? As when i was driving the one with the fubarr'd dog clutch I had to hold it in low box for me to use it like that, then you'll have an idea if its that or not

John

[nobber]

What about driving the vehicle with the t-box lever restrained in high with say a ratchet strap and see how that reacts? As when i was driving the one with the fubarr'd dog clutch I had to hold it in low box for me to use it like that, then you'll have an idea if its that or not John

I just got a call from the garage and they say it is definitely the gear box, he is trying to source a second hand one but they are thin on the ground around these parts and the only one on EBay has a knackered main shaft, looks like I'll have to start saving.

[Bowie69]

Does he say what in the gearbox is stuffed?

[nobber]

No, I dont think he stripped it to find out, he just said the problem is with the gear box.

[nobber]

Well it looks like it is a problem with the gear box, the only thing I can think of is a problem with the input shaft connecting to the lay shaft, is it possible it may have sheared off splines somewhere preventing the lay shaft from being turned? Although the fault was intermittent to begin with the mechanic said that he took if for a test drive and it has now let go altogether.