TD5 Manual Transmission failure diagnosis - LT230?

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Si Click

Si Click

Well-Known Member
Posts
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Location
Lincolnshire
Seeking a bit a diagnosis confirmation. My son's 1999 D90 TD5 suffered a transmission failure coming off a roundabout onto the A303 in the middle of the night. A severe juddering suddenly developed, so he dipped the clutch and pulled into the side. There was no loss of drive, so that ruled out halfshafts.

The Police were excellent and towed him off the slip road to a services, where eventually at 3am the RAC picked him up. The D90 is now parked next to the Car Club at MoD Boscombe Down, so we should have access to a 4 post lift and somewhere dry and out of the wind to work on it. :)

He thought the noise was from the rear so to rule out the rear diff we disconnected the rear prop shaft, selected CDL and tried to drive. Juddering in forward and reverse very visible at the front diff.
So that ruled our rear diff. We also jacked up one wheel and checked that the rear diff spun freely.

We replaced the rear prop shaft, removed the front one, engaged CDL and tried to move. Juddering as before, now visible at the rear diff. So that ruled out the front diff. We tried in both Hi and Low ratios with the same result.

With the transfer box in neutral and the engine running we selected each gear and released the clutch - obviously no movement, but no sounds of problems either, the box switched gears smoothly. I am thinking that this rules out the R380 gearbox itself and that the culprit is the T'box.

So my questions:

Do you agree that the culprit is the T'box or could it still be the manual box?
What is the likely point of failure? I am thinking centre diff.
Lack the skill/tools/time to reconditon the box ourselves, so looking at an Ashcroft recon LT230 with a 1.22 ratio, any other upgrades worth having - cross drilled input shaft or is that a pre-TD5 issue?
Any other recommendations as to where to get the box repaired or swap for a recon box - south UK up to Midlands?

Thanks for your wisdom.
 
Juddering could well be the hand brake. Dissassemble , clean and reassemble. Or try backing it off.
 
Thanks for the response. Drive is still there, but you would not want to move more than a couple of feet under power. Judder is probably the wrong word; violent shaking is probably an overstatement, but you get the picture. Nothing to do with the handbrake, coasts just fine with the clutch in and we had no problems pushing it into a parking slot.
 
Cross drilled gear is what the box will have as standard, you could pull the cover off and look to see what is going on inside, one on the bottom and a PTO cover on the rear, used boxes are cheap enough and it's a fairly easy job to replace one.
 
I'd agree that the TB is the most likely suspect based on the info provided... It's worth taking the cover off the bottom of it to look for damage .....

I've never had a centre diff fail in over 400K miles in LR's but apparently, they are a known weakness o_O

I'll PM you regarding another repair guy.... :)
 
nobber said:
Cross drilled gear is what the box will have as standard, you could pull the cover off and look to see what is going on inside, one on the bottom and a PTO cover on the rear, used boxes are cheap enough and it's a fairly easy job to replace one.
Click to expand...

Thanks, I'll drop the bottom cover and see if there is obvious damage.
Can I ask how difficult it is to support? We will have access to a standard gearbox jack, but RAVE talks about attaching a specific tool and bolting that to the jack. Is this really necessary? It also talks about separately supporting the main gearbox. I had assumed that the t'box could be taken out without affecting the security of the main gearbox, allowing us to remove the old one, push the D90 off the lift and fit the new one a week later. If the gearbox has to be supported we may have to do it in one go.
 
Si Click said:
Thanks, I'll drop the bottom cover and see if there is obvious damage.
Can I ask how difficult it is to support? We will have access to a standard gearbox jack, but RAVE talks about attaching a specific tool and bolting that to the jack. Is this really necessary? It also talks about separately supporting the main gearbox. I had assumed that the t'box could be taken out without affecting the security of the main gearbox, allowing us to remove the old one, push the D90 off the lift and fit the new one a week later. If the gearbox has to be supported we may have to do it in one go.
Click to expand...

The whole transmission is mounted via the TB - so the GB "alone", (I.E. transmission less TB will be in free air), so to speak... The bracket in RAVE is, IMO garbage - even some of the dimensions are wrong FFS...., and IIRC, you have to take the crossmember out to fit said bracket :rolleyes: which means supporting the trans on the GB whilst you do that :rolleyes::rolleyes: :confused:o_O - I designed and made my own - can post a pic up if it helps ...

I'm pretty sure you could make something quite easily, even out of timber and ratchet straps to support the GB - word of caution/warning - make sure the fan can't trash the radiator when you are moving the transmission...:eek: - actually, as this is a deafener - you could support the GB quite easily from above using timber and straps or box section steel and straps .....
 
Supporting the gearbox from above is a great suggestion. I wondered why RAVE requires the fan to be removed, now it makes sense. Thanks guys.
The only other aspect that I did not find well explained was the use of the guide studs LT-41-009. It says that they need to be "fitted through t'box bolt holes to support it during removal." So what was there before the guide studs, or are the guide studs there now? The latter seems logical given the warning that if they are removed during the process they must be discarded and replaced. Happy to buy a set from Dingcroft, but not sure if I am doing this to use them as part of the process or in case the existing ones are inadvertently removed.
 
Lief Zpring said:
Have you drained the oil and checked it for shrapnel? When my centre diff failed there was significant pieces of gear teeth in the oil.
Click to expand...

Not yet. We were not able to gain access to the Car Club this weekend, but should have access on Thursday when we both have some time. We will drain the oil and remove the bottom plate to look for damage and confirm the culprit.
 
The transmission is heavy, but it is possible to support it and get it into position. If taking the transfer box off on its own you've got to waggle it a bit to get it past the exhaust pipe (assuming you have left it on). For removing and refitting the transmission with the car on the ground I have found a little scissor lift like this very useful Amazon product Or if you're putting the car up on a lift, a standard transmission jack should be fine.

Before splashing out on a whole new transfer box, don't forget the dual mass flywheel. It's full of springs and compensators and when worn these can adopt an eccentric position under load and yield some alarming vibrations. But it's much less obvious in neutral. A friend's TD5 was suffering major vibration under load which was cured after I'd helped him do his clutch and flywheel. There appeared to be something loose and rattling about inside the old one.

One nice thing about taking the gearboxes off the TD5 is that the engine mounts are more or less at the engine's centre of gravity, so it will sit there as good as gold on its own without trying to tilt. A jack under the front can be used to tilt the rear down slightly so you can get the gearbox back on without it fouling the seatbox, which makes life a little easier.
 
I had not considered the DMF, I guess that could indeed be a suspect. With the tbox in neutral the action of the clutch was smooth, with no vibration at all and I could feel it biting. Any idea how I could rule it out or in as a suspect?
 
I've had my transfer box off and on again several times and I've never bothered with special guide studs. On mine there are a couple of studs in the back of the primary gearbox, so I just offer it up, get the driveshaft into the relevant hole (there's a seal in the transfer casing that you want to avoid butchering) then a little more adjustment to get it onto the studs, and you're practically ready for a test drive!
 
Si Click said:
I had not considered the DMF, I guess that could indeed be a suspect. With the tbox in neutral the action of the clutch was smooth, with no vibration at all and I could feel it biting. Any idea how I could rule it out or in as a suspect?
Click to expand...

Well seeing as you're taking the transfer box off anyway, and the car is up in the air, there's not very many more bolts to undo before you've got the gearbox off to have a look. In our case there was something inside that was loose. If it's a long time since the clutch was done it might be worth changing anyway while you've got the use of the post lift.
 
Thanks, good to know that they are not essential. For the sake of £45 I think I will buy them anyway. If I understand this correctly they fit into the 3 existing bolt holes shown in RAVE, allow the two boxes to be mated smoothly and then when enough bolts are in place you can remove them and put the original bolts back in. Is this correct?
 
Brown said:
Well seeing as you're taking the transfer box off anyway, and the car is up in the air, there's not very many more bolts to undo before you've got the gearbox off to have a look. In our case there was something inside that was loose. If it's a long time since the clutch was done it might be worth changing anyway while you've got the use of the post lift.
Click to expand...

This is escalating rapidly. :eek: But that is good advice.
 
Si Click said:
Thanks, good to know that they are not essential. For the sake of £45 I think I will buy them anyway. If I understand this correctly they fit into the 3 existing bolt holes shown in RAVE, allow the two boxes to be mated smoothly and then when enough bolts are in place you can remove them and put the original bolts back in. Is this correct?
Click to expand...

I think so. If they're Dingocroft items they'll be nicely made. But two of the fixings are studs anyway so it's easy enough to get things lined up.

Oh, and one mistake I've made concerns the bolts holding the gearbox to the transfer box. They're slightly different lengths. For the hole that's between the main gearbox and the nose cone that contains the centre diff, you want to select the shortest one. I've put a longer one in by mistake, which fouls the centre gears of the transfer box and they won't go round at all. So hope that saves you a little time and frustration!
 
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