Strange gearbox/clutch problem (V8/LT77)
Discussion
Yes the remote selector is solid - the "lift up the stick" method of diagnosing shows no play at all.
The box will stay in as it's still driveable - until it either fails or the Moly does its work. I have anpother box in reserve in case it fails.
I know what you mean regarding the layshaft bearings and usually another symptom of that is popping out of gear under power, but that hasnt happened, so far.
The box will stay in as it's still driveable - until it either fails or the Moly does its work. I have anpother box in reserve in case it fails.
I know what you mean regarding the layshaft bearings and usually another symptom of that is popping out of gear under power, but that hasnt happened, so far.
Well so far I still have excellent clutch action - the pedal is adlusted deliberately high to maximise the throw.
On the gearchange front I still had some crunching and occasional stuck gears so not completely solved, I think the flush'n'fill did help but so far the moly hasn't cured all.
I have a spare broken box (or two - yes I get through them!) to play with so I may take the end off and look inside to see what I can see through the oil fill hole - in case an endoscope style inspection would reveal any internal faults.
So it's keep driving it until it either improves or goes bang. Except I can't 'cos of the water pump (see other thread).
On the gearchange front I still had some crunching and occasional stuck gears so not completely solved, I think the flush'n'fill did help but so far the moly hasn't cured all.
I have a spare broken box (or two - yes I get through them!) to play with so I may take the end off and look inside to see what I can see through the oil fill hole - in case an endoscope style inspection would reveal any internal faults.
So it's keep driving it until it either improves or goes bang. Except I can't 'cos of the water pump (see other thread).
Well I put another hundred miles of so on it this week, but in all honesty, it feels like it's getting worse if anything, occasional vibrations coming from the gearbox (you can feel them through the gearstick under load at certain rpms), the stuck in gear phenomenon is just as bad, if not worse. I feel that it's on its way out so I will be preparing the replacement for an onslaught of 320 bhp...
Well it is getting slightly worse.
Latest symptoms are that occasionally it will refuse to go into any gear unless the engine is stopped. Also if doing > 3k rpm (say around 70 in 4th) then when you depress the clutch it still seems engaged.
So I think the fault is that the clutch is dragging when the revs are up - a strange one indeed. I have PM'ed Steve to borrow his endoscope.
Latest symptoms are that occasionally it will refuse to go into any gear unless the engine is stopped. Also if doing > 3k rpm (say around 70 in 4th) then when you depress the clutch it still seems engaged.
So I think the fault is that the clutch is dragging when the revs are up - a strange one indeed. I have PM'ed Steve to borrow his endoscope.
Well whatever has had it, it's gone now because I can't select any gear without the engine stopped.
The clutch bite point still seems quite reasonable but it must be dragging somewhere.
I shall try the new slave cylinder I have in stock as it's a simple changeover - nothing much to lose if it doesn't work out. And I'll have a look through the hole to see what I can see.
Clutch slave replaced - new stock would not fit (different thread) but I had an old one off my white Tiv hanging about (the one you saw Leigh) which cleaned up and went on fine. Good news is the master now bleeds properly and easily. Bad new is the problem is exactly the same. Nothing much could be seen through the slave hole but the pushrod/arm felt find and normal when pulled and pushed.
The clutch bite point still seems quite reasonable but it must be dragging somewhere.
I shall try the new slave cylinder I have in stock as it's a simple changeover - nothing much to lose if it doesn't work out. And I'll have a look through the hole to see what I can see.
Clutch slave replaced - new stock would not fit (different thread) but I had an old one off my white Tiv hanging about (the one you saw Leigh) which cleaned up and went on fine. Good news is the master now bleeds properly and easily. Bad new is the problem is exactly the same. Nothing much could be seen through the slave hole but the pushrod/arm felt find and normal when pulled and pushed.
Edited by adam quantrill on Wednesday 2nd May 12:27
Don't think so, but thanks for the ideas, keep them coming. What does work:
1. All gears will engage with the engine stopped. The car will drive too.
2. Clutch has a definite good bite point and loads of travel either side.
3. You can start it in gear with your foot on the clutch, then let foot off and the car will move.
4. No noises from release bearing.
1. All gears will engage with the engine stopped. The car will drive too.
2. Clutch has a definite good bite point and loads of travel either side.
3. You can start it in gear with your foot on the clutch, then let foot off and the car will move.
4. No noises from release bearing.
I'm still thinking (hoping?) some sort of clutch fault. What doesn't work:
1. Changing out of any gear above 2500 rpm
2. Changing down from 4th to 3rd, or lower gears, unless stopped.
3. Changing from Neutral to Reverse grates (even if you select another gear first)
4. (80% of the time now) selecting any gear with the engine running - sometimes works though.
5. When depressing the clutch above 2500 rpm the engine revs don't die as they should, but below 2000 rpm they seem to die away fine.
I'll take a look at the clutch first - my suspicion is that it's dragging and spinning up the input shaft thereby defeating the syncros. If that fails to show an obvious fault then the box will have to come out.
1. Changing out of any gear above 2500 rpm
2. Changing down from 4th to 3rd, or lower gears, unless stopped.
3. Changing from Neutral to Reverse grates (even if you select another gear first)
4. (80% of the time now) selecting any gear with the engine running - sometimes works though.
5. When depressing the clutch above 2500 rpm the engine revs don't die as they should, but below 2000 rpm they seem to die away fine.
I'll take a look at the clutch first - my suspicion is that it's dragging and spinning up the input shaft thereby defeating the syncros. If that fails to show an obvious fault then the box will have to come out.
Thanks, good suggestions. Well I had a poke inside the bellhousing with the endoscope, the arm and release bearing look fine, move OK, but you can't see much else.
So I have started pulling it apart - having done it once before it's a known quantity, just hope I find a clutch problem and don't have to pull out the box too.
As an aside I pulled apart a spare LT77 box that was jumping out of gear all those years ago when it was in a car, and the fault turned out to be one little bearing in the middle. The rest of it looks good so I have a box of spares (literally) apart from the input shaft that I gave to a mate.
Today I made more progress after looking at the Jeep - needs a new UJ - and am now almost at the point of splitting g/b and engine. hopefully tomorrow I will have the clutch out to give it a once over.
So I have started pulling it apart - having done it once before it's a known quantity, just hope I find a clutch problem and don't have to pull out the box too.
As an aside I pulled apart a spare LT77 box that was jumping out of gear all those years ago when it was in a car, and the fault turned out to be one little bearing in the middle. The rest of it looks good so I have a box of spares (literally) apart from the input shaft that I gave to a mate.
Today I made more progress after looking at the Jeep - needs a new UJ - and am now almost at the point of splitting g/b and engine. hopefully tomorrow I will have the clutch out to give it a once over.
Edited by adam quantrill on Sunday 6th May 19:04
At last - I think I've found the problem! ;^)
Note that three of the springs in the friction plate are busted, plus these three steel parts fell out when I freed it off - they were obviously stuck between the friction plate and cover plate with nowhere to go, so were causing the clutch to drag. Quite why it didn't make a clanking noise I don't know.
Ift also fits the symptoms very well - at high rpm the metal fragments were being thrust outwards to wedge in the friction material - in fact you can see eroded parts of the friction meterial on the inside edge, where they were bedding in. So at high rpm the clutch dragged more!
I just shook out the cover plate and found two more bits of the same metal, but otherwise it looks in good nick so will be re-used.
So - not getting a National clutch plate again, only lasted 20k miles. If I can find the old one I took out at 25k I might put it back in - at least the parts in it seems strong and it had a lot of friction material left.
Or else any recommendations for good clutch plates at a reasonable price?
Note that three of the springs in the friction plate are busted, plus these three steel parts fell out when I freed it off - they were obviously stuck between the friction plate and cover plate with nowhere to go, so were causing the clutch to drag. Quite why it didn't make a clanking noise I don't know.
Ift also fits the symptoms very well - at high rpm the metal fragments were being thrust outwards to wedge in the friction material - in fact you can see eroded parts of the friction meterial on the inside edge, where they were bedding in. So at high rpm the clutch dragged more!
I just shook out the cover plate and found two more bits of the same metal, but otherwise it looks in good nick so will be re-used.
So - not getting a National clutch plate again, only lasted 20k miles. If I can find the old one I took out at 25k I might put it back in - at least the parts in it seems strong and it had a lot of friction material left.
Or else any recommendations for good clutch plates at a reasonable price?
Edited by adam quantrill on Monday 7th May 19:45
Yes it is good news - the box input shaft feels fine and hopefully it didn't take too much stress from the crunchy gearchanges. Time will tell.
Yes you can do the clutch without removing the engine, the procedure is here:
Clutch Progress
I'll see if I can get piccies to add to it as it is split open right now so it's the ideal time.
Yes you can do the clutch without removing the engine, the procedure is here:
Clutch Progress
I'll see if I can get piccies to add to it as it is split open right now so it's the ideal time.
Well it's finally going back together - wasted a day yesterday almost getting hte box back on and it wouldn't quite go, so pulled it apart again and finally got it on today. I also put the clutch slave on temporarily to check the action and it seems fine, so it's just a case of putting all the other bits back on and we'll be mobile again.
The Beast Breathes Again
Well finished it off tonight, sorted out an intake hose, and took it for a little spin.
1. No graunching in reverse any more!
2. I can change up - whatever the revs!
3. I can change down too - whoo hoo!
I did have a small scare when I put my foot on the clutch before I got it off the axle stands and it went to the floor - I musta been tired last night and trapped the release pin behind the clutch cover, then put the clutch slave in with no pin? Or maybe it slipped out? Anyhoo it was quickly sorted and back operational again.
Zig - only one bolt left over so my tray technique works pretty well!
BBWF here we come!
That nut's as loose as ever Alan!
For the record the clutch replacement has fixed one other symptom - there was a lot of driveline shunting which made low rev tickover cruising (e.g. 30mph at 1000 revs) somewhat jerky and uncomfortable. I now think this is because the clutch centre was so broken, thus allowing torsional vibration rather than coupling the engine to the gearbox properly.
Not it drives a lot smoother at low revs.
For the record the clutch replacement has fixed one other symptom - there was a lot of driveline shunting which made low rev tickover cruising (e.g. 30mph at 1000 revs) somewhat jerky and uncomfortable. I now think this is because the clutch centre was so broken, thus allowing torsional vibration rather than coupling the engine to the gearbox properly.
Not it drives a lot smoother at low revs.
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