Loud clunks when reversing with new tyres
 

I’ve just put my summer wheels back on with a new set of Michelin PSS (same size as stock) and when reversing slowly with more than about 75% lock it now makes a horrible loud clunking noise every metre or so, sounds like it’s coming from the front passenger wheel (when steering right). It feels and sounds like the wheel is dropping off a small kerb each time :-O It doesn’t do it when going forwards.

At first I thought it was just the suspension settling down after I had it jacked up, but it’s done it every time now. Normal driving is absolutely fine, no vibrations or noises or anything unusual, wheel nuts are all torqued up properly etc. Searching around people seem to blame the CV joint, but it would be a bit too much of a coincidence to suddenly start doing this after I put a new set of tyres on…

from the subject title my first thought was https://www.scoobynet.com/scoobynet-...-clicking.html

but having read your description perhaps it's something suspension, cv, shaft related

It certainly sounds like something suspension/shaft related, but I don't understand why it suddenly started just because I switched back to my summer wheels. It never did anything like this up until yesterday. I guess I could switch back to the winter wheels and see if it goes away again - but that's not really a solution!

What car is it mate?
The Imprezas are known for clunking a little on lock in reverse - it's just the diff unwinding is what many people usually say (my dealership said the same thing a while back when I noticed the same on mine).
If you're getting bad judder etc then yes it's probably something to worry about, otherwise it may just be your new tyres gripping more and causing you to notice it more?
That's a guess I'm afraid I can't offer a more technical response.

My last 2 have both done it a little and they're VERY well looked after. I have mates who's cars do it too, potentially nothing to worry about I'd have thought.
You can always ask the dealer

It's an 08 STi (hatch).

OK so I think it is DCCD/grip related. Firstly I cannot replicate the problem once the car has "warmed up", even on full lock on dry tarmac reversing in either direction it's completely smooth. And then this morning with a cold car on wet tarmac it wasn't as bad but still there, so I switched the DCCD to fully open (it's usually on auto) and the problem almost disappeared, it was just there very slightly.

It's in at the dealer next month for its 40k service so I'll mention it to them, I'll have a look in the service book to see if any diff oils or whatnot get changed at 40k.

Edit: BTW the Michelin PSS's have amazing grip in the wet :-)