Really, really strange problem this. My 16v cinq was driven into my lockup a few months back after it had failed it's mot (emissions mostly). It had been driven in and out a few times afterwards and has stood over winter. When it was last driving, it was perfect transmission wise, no weird noises, graunches, whirrs etc, all silent. No notchieness, difficulty engaging any gears, clutch all good (and new).

Skip forward 3 months (and with the engine in bits at present) and it has seemingly randomly decided to break. I now either seem to have no gears or it is just not engaging anything down to the diff... or the clutch is no longer activating even though the pedal is still fine, light, smooth etc.... and all was perfect in that area when parked up and nothing has been touched since, i'm totally confused.

All the gears "feel" there, in that if you move the gearknob, 1,2,3,4,5 and reverse are all selectable... hell, it even makes that normal noise when selecting reverse like it is selecting "something" but it has no impact at all on moving the wheels, both are spinnable by hand in any "gear", either way. with absolutely no impact or rotation put on the engine, as if the 2 are no longer connected/somebody has their foot on the clutch?

All things like the driveshafts etc are intact, and it seems like both the wheels (car is on axle stands at present) spin together by hand but freely, either way regardless of gear selected. there is just no "drive"/resistance, Almost like the top part of the gearbox with all the gears is still there but no longer connected to the driveshafts....

Any ideas? i'm bamboozled.... hoping i'm missing something obvious tbh and my gearbox hasn't dissolved itself!

I had a similar thing. With me the crown wheel had detached from the diff. They are only an interference fit, there are no bolts.

Other than that, clutch friction plate material has come adrift, that's not unheard of.
Or the obvious is something has snapped inside. I've even heard of crankshafts snapping, leaving the flywheel spinning but no drive.

I would take the top cover off the gearbox, and rock it back and forth in gear to see what is turning and what isn't. That is reasonably non invasive and quick to remove and replace. Also physically put it in gear from under the bonnet, by moving the most rearward lever to the left or right. That will put you in 3rd or 4th. That should rule out cables etc.

If you jack it up and start it, do the wheels turn at all? When it's cold the wheels will turn even in neutral, just with oil resistance.

Huwbishop said:

I had a similar thing. With me the crown wheel had detached from the diff. They are only an interference fit, there are no bolts.

Other than that, clutch friction plate material has come adrift, that's not unheard of.
Or the obvious is something has snapped inside. I've even heard of crankshafts snapping, leaving the flywheel spinning but no drive.

I would take the top cover off the gearbox, and rock it back and forth in gear to see what is turning and what isn't. That is reasonably non invasive and quick to remove and replace. Also physically put it in gear from under the bonnet, by moving the most rearward lever to the left or right. That will put you in 3rd or 4th. That should rule out cables etc.

If you jack it up and start it, do the wheels turn at all? When it's cold the wheels will turn even in neutral, just with oil resistance.

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Thanks

I'm pretty sure it's not anything on the engine side thankfully, i had it running a few weeks back before taking half the engine apart, currently re-assembling the top end.

I know it's not cables etc as the lever is moving fine into where all the gears are and you can hear the selector click into gears etc, both ball joints are attached on the mechanism etc.

Clutch is brand new and was fine when it drove into the garage.... if it was going to fail i would have thought it would have done so under some kind of load rather than just on it's own, sitting idle for 3 months?

It "feels" like the crown wheel has come unbonded or something. Everything feels slick and moving as it should, it's just not loading up the wheels.

Come to think of it, i half remember a very light "pop" or groan when i jacked the car up on the drivers side, sounded like it came from the passengers side front but just assumed it was from the rear and from the handbrake as one side became unloaded... was hard to tell in the tiny lock up it is in. starting to think it might have been something more sinister now I really don't want to take the gearbox off again, hateful job and with no room and no peace to work, it took me days last time

How odd, as you say strange it should go when laid up. Pop the top cover off for a look before assuming the worse, that is the easiest job to do without risking dirt ingress, probably best place to start if you don't have much room. Diff casing would be my next port of call. If the diff has come unstuck you will be able to gently tap it off with a soft hammer. I could turn mine by hand.

Once oil gets between the two it is game over for the diff, unless an engineering company can sort you out. Don't try welding it, it doesn't work. Two dissimilar metals, trust me I tried that and buggered a diff casing.

I'm back at it tomorrow, i've to take off the 2 front struts anyway so i'll get a good poke around at the driveshafts, cups, look for anything weird/broken/loose/disconnected around the diff casing etc while i'm in there. and if all is fine, i'll pop off the cover and have a look and see what is moving.

The strangest thing is, although the engine isn't running right now (though i could get it running easily pretty quickly from where it is now), when i spin one wheel by hand, the other rotates too so the bottom part of the diff, all connections via the driveshafts etc are seemingly all intact and fine and from what i can tell up to now without really looking in depth, just by feel, the upper part of the box feels fine too in that everything feels accessible and can be heard clicking into every gear with a slightly different sound for reverse, it's just that there is no connection between the bottom part of the diff and the top part with the actual gears anymore, as said, like the crown wheel has just vanished/disintegrated whilst it has been sitting. An absolutely bizarre problem!

Definitely sounds diffish. Before removing anythiñg, put a block under one wheel and try to spin the other. With it in gear you shouldn't be able to turn it, well apart from backlash in the box. You will also get an indication if you spin one wheel and stop it suddenly. Any slippage should be felt through the wheel.

Don't be too disheartened, gives you a chance to change the diff bearings while you swap the diff and the driveshaft seals while you're there.

I had mine all ready for mot, just fiddling with a few things. Decided to clean up a bit of underseal that looked past its best. Ended up chopping a load of floor out around the rear jacking points d'oh.

These little cars do like to try us.

Good luck, and keep us up to date with you're progress.

Oops, how did I miss that.

Huwbishop said:

Oops, how did I miss that.

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ouch!

Haven't had a chance to look at it yet after getting called into work, but hopefully will be able to run a few tests on it tomorrow, i'm running on the theory of it being diff related just now though.

Will try and get pics/vids of anything i find

Finally got back to this... mystery deepens.

Got the engine running (very nicely i may add ), so got the chance to test all the gearbox/clutch with the car on axle stands but with engine power going through it.

with the car in neutral and the engine running, the wheels do not spin.

If you put it in any forward gear without putting the clutch in, they is no graunching, almost like the clutch is in, however the wheels spin gently.... but you can put your foot on the spinning wheel and stop it fairly easily.

If you put it into reverse, exact same, except obviously the wheels spin backwards very gently, but can be stopped by foot.

There are absolutely no strange noises or clonks from the box.

So looks like it's a clutch issue?

Possible contamination? The lack of noises makes me suspect it's not a failure per-se, like friction material coming off.

Not sure how that's happened standing still all the same.....

Is the clutch mechanism allowing the clutch to engage correctly, eg is it seized off, rather than on? Disconnect the cable at the gearbox and physically pull the clutch arm back toward the exhaust. With it on axle stands keep it all running and engage gear, wedge the wheel with something that it will easily spit out if it goes. Leave it run for a bit to see if it improves.

If it is the clutch, it should get hot and smelly quite quickly. If not, I would lean more towards the diff.

I have a spare diff now, as that wasn't what was whining on my car. I think it's a 53 tooth one if you need it.

It's siezed off rather than on.

Running it showed the wheels turn gently forward in forward gears and backwards in reverse, also when in neutral the it is super easy to turn the wheels, when in gear it's still fairly easy but there's more resistance so it feels like the diff connection is intact.

With the little inspection plate off the gearbox and the car in gear, if you put your finger on the clutch cover and reach down to jiggle/rotate the wheel, you can feel that it is moving the gearbox right up to the clutch plate, so it's just like it is permanently disengaged.

The actual clutch lever is moving fine.

I'm wondering if it's a failed drive plate and the little ping/pop i heard when i jacked the car up was either spings on the drive plate or rivets snapping on the friction material.

My theory being that if the car was in gear when it was jacked up, the rotation of the front wheel when it was loaded up was when it let go.

In a strange way, i'll be pleased if that's "all" it was!, even though i'll be really annoyed that it was a brand new clutch, maybe just bad luck.

Guess it's gearbox off time for a proper inspection!

I'll be very interested to see the results of you're strip (oo er, not like that).

Strange that the clutch popped just jacking it up.

I bet if you could translate gearboxese language, the clutch would have said " put a Feckin 1368 on me will ya, let's see who's laughing now"

Will you do me a favour when it's off. Wrap some tape around the input shaft, clamp a pair of mole grips onto it. Two pairs of stilsons on the driveshaft cups and turn the mole grips. You can use the friction plate instead of mole grips.

Just to put my mind at ease, because it just sounds so similar to my problem 18 months back it's uncanny. I went and bought a clutch and everything, so convinced was I that was the problem.

Will do.

I've got a clutch kit on the way too, so i'm hoping i'm right with the hunch haha.

The fact i can run the engine and put it in any gear without any kind of crunches is mostly why i'm so sure this time though, even if the box had no diff on it at all i'd assume the top part of it wouldn't take too kindly to being banged into 1-2-3-4-5-R with the engine running and the clutch pedal not being touched!

Regardless, it's a strange problem, pretty sure all will become clear when the box is off, if the clutch is well, then i'll know it's box related and at least i'll have a spare clutch kit

Results are in (i think)

And it seems you're correct and it's a box/diff issue.

Clutch is all intact and in good condition.

Put the plate on the spline off the car, stood on the cups to give them some resistance and whilst it does try to spin the cups, it feels like there is "slip" and aren't 100% engaged with the rest of the box and don't seem to be putting up too much of a fight when the plate is spun by hand, so probably multiply that times a million when the torque of an engine is going through it = post 1 and post 9.

Defo the diff then. Nothing else in the gearbox that is an interference fit.

Pop the diff housing off, I bet a light tap on the crown wheel with a soft hammer will shift the two bits apart.

I'm really just looking to replace the box but i'll take the diff off and see what failed, but i expect it is something like the crown wheel splitting.

I know where i can get a new diff wheel for it, but i can't for the life of me work out how to get the cups out again from the old box, i know they just lever out (allegedly) with their clip and all, but i can see anywhere to really get in to get any decent purchase on the sides of them and my half hearted attempts today resulted in skinned knuckles x2, so it can wait haha.

Take the diff out and stick it in a vice, you can then drift the cups out from the back.
They are a bit of a sod, but it is possible to get them out in situe.

If you are swapping the box, leave the cups there until you are ready. Saves getting them damaged or covered in dust and dirt.

Any idea what box you're getting?