So it had been decided that the grumbling noise from the rear of the car was either the differential or a noisy CV in a drive shaft. Many thanks to Ian Haynes, Ben Smith, and a chap called Simon who I’ve never met who clubbed together to deliver a spare drive shaft to me at work today.

This evening I drive up to Robin’s and we investigate further. Various tests with the rear wheels up suggest to us that it’s probably the differential rather than the drive shafts. As we’ve disconnected the drive shafts already to test, and Robin has a spare open differential, we decide that it’ll be just as quick to swap the differentials over as it would to change drive shafts.

Craig Smith, the man who lent me a spark plug tool in my hour of need wanders in to say hello as we’re just getting to work. There are some pictures of all this somewhere on Robin’s camera – I’ll update again as and when I receive them.

Once we’ve got my LSD off we get it on the bench for an inspection. There’s certainly a fair bit of play in the offside bearing. Due to various complications Robin’s open diff doesn’t have its back plate on. We drain away his old fluid for disposal, and whip the backing plate off the LSD.

We transfer the oil from the LSD to the open diff (we know it’s not the right specification – given the short term use of the open diff we decide it doesn’t matter – anyone who knows different please let me know!). Having taken the backing plate off my LSD we notice that the speed sensor is badly damaged – see below:

As far as we can deduce, the failing bearing (which probably failed due to the suspected oversteer kerbing by a previous owner) caused the metal spinner which passes through the speedo sensor to come out of alignment. It would have hit the sensor rather than passing through its two prongs, damaging it. Our theory is that under positive load the bearing moves into a position where the spinner passes neatly through the prongs, but on the overrun the negative load moves the bearing out of shape to the spinner’s blades hit the sensor.

As we stand, it’s rather ironic that the LSD’d car I hunted for so long currently has an open differential! Still, this is temporary. It is lovely to drive without a nagging “I’m broken” noise in the background, and the car seems more tractable – less resistance in the bearings possibly, or maybe just the different final drive ratio.

So I’m now left with an LSD without a backing plate that may as well have all its bearings replaced. I also need a new speed sensor – I notice the ETK reckons that part isn’t available separately.

I know Ian and Simon have ideas about getting the LSD sorted, so I’ll be looking into those shortly. If anyone has any other ideas, or knows of a source of speedo sensors, please let me know.

Finally, I’d like to re-iterate my thanks to those who’ve helped source this half shaft that I haven’t yet used. It is appreciated, and at the very least I plan on keeping it in stock – we all know it could well be required one day!