Well the big day arrived! Truth be told, Red Ken with his 18" rims, has only ever suffered from the mildest of crabbing which, TBH, most people would probably find perfectly acceptable. But if there's a bandwagon to be jumped on, old Toobad will always arrive early to bag one of the best seats
Tactically I purposely delayed requesting the fix to allow the weather to warm up a bit as justification for Red Ken not exhibiting the tyre skipping characteristic should the technician want to verify it. On the day of the appointment the weather was just perfect, wet and mild. To my great surprise no checks were required and the car was simply booked in to the workshop. Perhaps, because their records showed they had already previously fitted all-season tyres, further evaluation was waived. When initially requesting the modification, I had told them "the clonking has returned because my tyres have worn down and now the tread blocks are no longer flexible enough to mask the lateral forces being exerted by the incorrect steering geometry"
And then there was the "snatching defeat from the jaws of victory" moment! The steering knuckle kit was still on back-order at the time of my arrival so they would just be doing my Euro 6b emissions software upgrade and replacing two door handle puddle lights which had failed (that's now 5 replaced on a 4 door car!!!) Realising additional leverage would not be a bad thing, I deployed my "fetch me somebody who is paid enough to get shouted at" instruction. This led to them scrounging the kit from another Dealer for the following morning and me leaving in a poverty-spec C220d Wagon. The silver lining was that the Wagon reminded me just how so much better a driving experience Red Ken provided with his Premium Plus, Driver Assists, Air Suspension etc.
So Ken is now back home and all is well with the world. It occurs to me members following this thread may appreciate some more detailed information regarding exactly what this anti-clonking fix involves. I requested a copy of the printout from the Dealer's Hunter Hawkeye alignment rig. Comparing it to the alignment figures I got when I had the all-season tyres fitted, it seems the revised geometry achieved by fitting the modified steering knuckles initially moves the Toe In/Out setting outside of its accepted range. This is then adjusted back to within its original tolerances. This means there is still only one set of correct alignment readings whether you have the modification done or not. It's good to know special readings don't have to be dialled in for modified knuckles, especially if alignment needs doing away from your Dealer.
For completeness and with grateful thanks to the legend that is
, here again is the parts list which comprises the steering knuckle kit:
PLEASE NOTE THIS MODIFICATION IS ONLY APPLICABLE TO RHD CARS AND CURRENTLY EXCLUDES 43/63 VARIANTS.
1 x Steering Knuckle MA253 332 33 00
1 x Steering Knuckle MA253 332 34 00
2 x Brake Cover Plate MA000 421 79 00
2 x Nut/Washer Assembly MA005 990 47 50
4 x Nut/Washer Assembly MA005 990 24 50/64
2 x Nut MA002 990 68 54
8 x Screw MA002 990 65 03
2 x Screw MA000 990 75 03
The parts alone total £962.64. The job takes about 4 hours so the labour charges will come close to £500 and I know a session on the Hunter Hawkeye alignment machine costs £100 alone. I would urge all owners to push for this fix under warranty asap as there is no guarantee it won't get withdrawn at some point in the future.
If selling your car privately there's a good chance a savvy buyer will try to bid you £2k less to cover the cost of this modification so why start negotiations from a disadvantaged position.
And finally, for anybody who doesn't know what the knuckle looks like or where to find it, here's some photos of the installed modified version:
You can see in the photo below how much they had to wind out the trackrod end to reinstate the original Toe In/Out setting:
Thanks for reading, now go and get your car booked in. It really was a simple "ask and you shall receive" experience for me