cliffcoggin

Frankly I don't see what red lining the engine in that test achieves that can't be achieved at idle speed, but that's by the by. If it was my car I would now get the clutch out as the only way to be certain of its condition, and if the clutch proves to be OK I would at least be half way to getting at the gearbox.

Well halfway up is right, and if there is no problem at idle there must something else going on, though it's hard to imagine why clutch opening should be speed or load dependent. I wonder if the splines of the driven plate or the input shaft are damaged so that the driven plate can not slide when under load. That's pure speculation of course, and I've never heard of it happening, but I can't think of anything else at the moment. Perhaps Gareth will have an idea.

10:1 the clutch needs either adjustment or renewal. Your clutch may not be slipping, but neither is it opening. Where is the bite point of the clutch pedal when it starts to engage?

It would be a heck of a co-incidence if the airbag sensor failed just when you removed the door panel. It's more likely I suggest that you have dislodged a plug connector or broken a wire.

It's common in such situations for pins to be plated, sometimes even with gold, to resist corrosion. Once the plating is removed corrosion can return much faster, though a few weeks seems unusually rapid in this case. Are you sure water isn't getting in or condensing there?

Thanks for the update. That was remarkably cheap for Audi. Kudos to them. Very odd about the manual cable. I assumed its function was an alternate opening method in case of solenoid failure.

Mad. Your problem is simple: the clutch is clapped out. If you don't change it soon, your gearbox will be too.

In hindsight I didn't phrase my reply very clearly, so as Gareth said test for looseness with the wheel bolted on and let us know the outcome. Do the test with the wheel off the ground, rocking it left & right and top & bottom. Listen and feel for any movement as well as looking, your ears and hands can give valuable information.

Rob. Even if the single screw that holds the disc in place is loose, the wheel studs provide the main securing force, so the main question is whether the disc is moving independently of the hub or is the hub moving with the disc. If the hub is moving with the disc then the bearing is worn or loose.

Fair enough Gareth. It's been forty years since I used a sealant like that, and I have no doubt technology has moved on since then.

As a short term measure until you get a new radiator plain water is perfectly fine and will do not the slightest harm to your cooling system. The coloured coolant you refer to is a mixture of water, anti-freeze (ethylene glycol), dye, and a corrosion inhibitor. The anti-freeze component is in it for obvious reasons; the corrosion inhibitor is essential for long term use to prevent the electrolytic corrosion which occurs between the different metals in the cooling system, (aluminium, copper, steel, zinc.) Whether the repair will survive a 400 mile round trip is unknown. It really depends what sort of sealant was used, how big the hole was, and whether that part of the radiator is under enough stress to open up the repair. What concerns me equally is the thought of all that sealant circulating round the cooling system. I don't know if modern sealants are any better, but at one time there was a fear of it clogging up the narrower water passages in the system. In your position I would certainly not trust the car for anything more than a few miles at a time on non-essential journeys. Get the train instead.

It's remarkable how little corrosion is needed to spoil the operation of some electronic systems, and how much effort is needed to overcome it. I admire your perseverance David.

I reckon you have the culprit in the suspension changes, Maris. Naturally you'll have to put the springs the right way round and then get the toe-in (tracking) reset, but I'm not sure if that will be enough to stop the tyre wear. By that I mean that I don't know if spring changes also need track rods etc. to be different. That's a point you need more knowledgeable advice about than I can give.

Maris. To wear the shoulder of the tyre like that either the suspension geometry is wrong or the tyre is rubbing on the wheel arch. I would get the tracking tested again as a first step. If that proves to be OK look for slack in other suspension joints. PS. Do you have wheel stud extensions or non-standard wheels?

I give up. Without specific and exact explanation of the techniques you have tried I can be of no further assistance, so I am withdrawing from the discussion. Good luck in solving the problem.