Syncro looses all drive

[PetenAli]

Hi All,

Just had a great weekend on Dartmoor camping in the Syncro and walking (pics to follow when I can work out how to get them up here). Dropped my mate off and 10 mins from home when I changed into 2nd on a roundabout and lost all drive. There was no previous indication of any probs. Pulled over and no drive in any gear although sound of floating bits of metal from gear box when I did engage gear and lift foot off clutch. No point in doing other than getting relayed home.

Is this a broken diff? Any ideas about alternative explanations?

Other info that may or may not be relevant:
- decoupler currently not working (probably vacuum leak)
- used the rear diff lock today to get up a slippery grass slope. Then disconnected it as soon as no longer needed.

I'd be grateful for any ideas about how to work out whats happened.

Thanks,

Pete

[Simon Baxter]

Sounds like the clutch has expolded.
Probably best thing to go pop, it's the cheapest and easiest.

[PetenAli]

Thanks very much for getting back so quick Simon - that's hopefully a huge relief. Will pull the engine later in the week and then get on to Brickwerks for the bits if thats what it is.

Thanks again,

Pete

[syncrosimon]

I had the same thing happen to me on the motorway just coming into Nice. It was a drive shaft come loose. I was in 2wd at the time, and she pulled off the carriageway fine in 4wd. I had only done the CV bolts up hand tight, and never gone back to tighten them up fully . Bent one bolt. Hope it is an easy fix like that. If you put the diff lock on, you should get drive on the good one. If no drive with diff lock engaged then its something else. People have driven hundreds of miles on one drive shaft with diff lock on.

[PetenAli]

Thanks Syncrosimon - will try that tomorrow before pulling engine to check clutch.

This forum is just so helpful - really appreciate both these replies.

Pete

[Simon Baxter]

But if it's 4wd then he should still get some drive.... so long as VC it's failed open.

[syncrosimon]

- decoupler currently not working (probably vacuum leak)
Pete

[PetenAli]

But if it's 4wd then he should still get some drive.... so long as VC it's failed open.

That was my next question - does "failed open" mean that the decoupler is currently engaging or disengaging the propshaft? What is happening to me is that the propshaft is not being engaged and therefore no 4wd.

Anyway I've got two options to check when it gets light.

Thanks again both,

Pete

[PetenAli]

Whoo hoo! It was a drive shaft problem. Tried using the rear diff lock as Syncrosimon suggested and had drive at once. Can move it onto my drive now and get onto finding out exactly whats gone later if it stays dry.

Thanks again to Syncrosimon and Simon Baxter for such rapid replies last night.

[PetenAli]

The drive had gone on o/s outer. When I took drive shaft off (that's a bit of a game on a Syncro - had to undo the bash plate to get enough room) I could see that four of the six bolts on the outer CV had come loose (? or had not been tightened properly?) and the two remaining ones had sheared off.

That will make it a bit more complicated to fix as I'll have to strip the hub (I think) to drill out the two sheared bolt ends. Still its about a million times better than having to have the gearbox stripped!

Do people think that I should replace the outer CV now as a matter of course - just because it must have had some unusual stresses while all this was happening?

Thanks again,

Pete

[syncropaddy]

You make it sound easy! If you are lucky all you will need to replace is 6 bolts. If you are unlucky you might have to replace Drive Flange, CV Joint and bolts. I would take the CV apart and clean it thoroughly and check for damage. If its ok then repack it with fresh CV grease and replace all bolts having first checked the flange for damage. Those bolts do come loose if the job isnt done right.

[jebiga41]

just wrote a reply but it didn't post WHS the CV's are quite tough but worth checking. You can usually get a vice grips on the sheared ones they come out easily with no load on them, if you can't get the grips on them you can tap them around with a small punch or even a screwdriver. If you really need to take off the outer drive flange undo the 46mm nut and a few taps with a mallet will help it slide throught the bearings to the other side. Good luck with it

[PetenAli]

If you really need to take off the outer drive flange undo the 46mm nut and a few taps with a mallet will help it slide throught the bearings to the other side. Good luck with it

Thanks for that. I wasn't sure if it was OK to tap the drive flange out without disturbing the bearings. Once its out I should be able to turn the broken bolt ends out without too much bother. I'll give the CV a good going over.

Pete

[v-lux]

Be very careful with the threads on the end of that drive flange if you're going to give it a tap to remove it. It's very easy to squash them which makes a happy job a very grumpy one!

[PetenAli]

Be very careful with the threads on the end of that drive flange if you're going to give it a tap to remove it. It's very easy to squash them which makes a happy job a very grumpy one!

Thanks Al - it will be a rubber mallet hitting a block of wood onto the threaded end with the 46mm nut on 3 threads for as long as possible! I seem to remember from my IRS Beetle that once the shaft is started it should go quite easily.