An Annoying Problem..
 

So, I have noticed that since it has gotten much colder here (I'm in Chicago), that when I first turn on my car (2011 Shelby GT-500), and especially when I am reversing, if I turn the wheel all the way to the right or the left, and then start moving slowly, I hear a clunking noise from the front tires. Is this just the front tire(s) slipping? Or is this something I should get checked out? Just trying to find out if this is normal or not. Once the car has been running for a little bit, I can make full turns to both sides with no noise or issues.

Thoughts?

John

Front suspension on the S197 Chassis is a common area of upgrade after a few years, even on the GT-500. I'd check your stabilizer bar end links and the stabilizer bar bushings under the radiator first. Also check out your control arms for cracked or broken bushings. Cold weather makes things shrink so it creates larger clearances.

I will take a look at the end links and bar bushings...but I have seen many other posters say they have the same issue when it's cold outside and the car has been sitting for 8 hours or so. Again, within 60 seconds of starting up, or just driving, this goes away completely. It is only when doing full-lock turns immediately after starting the car when cold.

Full "lock" turns then it could be the rack. When it reaches the internal stop,
then it thumps when you release the wheel and turn back the other way. IT
could also be pulling one of the lower control arms, and the thump is when
it releases, but the bushings would have to be broken.

End links, sway bar bushings; you hear those rattle on bumps. Every front end
knock on a bump, was the end link. Every rattle on bumps I got, was the
sway bar bushings or end links. With my VWs, it's always been the end
links. VW uses roller bushings... My Charger, was the sway bar bushings.

I've never had a thump when reaching the internal stop steering, then going back
without at least one side of the rack being bad, or a tie rod end; the ball joint pulling
up, then seating when steering back.

Are you holding the steering wheel firmly against the stops when this happens or just coming up lightly against them?

What tires are you running (make, model, and size)? How wide are the wheels they're mounted on? Summer tires and at least some all-season tires don't grip so well at colder temperatures and need to warm up a bit (by easy driving) first.

It's at least possible that the limited-slip differential is playing a part here - it much prefers both rear wheels to be rotating at the same speed, implying that it prefers to be going straight over turning.


Norm

Ah, boy, the memories! You know where Berwyn is? I had an old oil-fired heating stove in my garage, recall "swinging" my 430 Lincoln when it was -20F outside. EVERYTHING froze up on the cars, didn't dare leave parking brakes ON, could not move car when you got back. Power Steering was so stiff it was then Power by Armstrong! Guess the cars are better now. One of my first, '55 Merc., still had 6 volts. I put a 352 FE big block in it, had to buy a fancy battery which had a special solenoid mounted on it: 12 volt battery which fed 12 volts only when cranking to the starter only, switched 3 cells into parallel with the 3 others, charged with 6 volts! Can you believe it?

You missed my point. A limited slip diff will even fight the front tires wanting to turn because for that to happen something needs to 'slip' that doesn't have to with an open diff. Once the tires are warm enough, it'll be between the clutch plates or cone in the diff. When the tires are cold to where they don't have so much grip, all four contact patches will slip at least a little more than they normally would and you get into a stick-slip-stick-slip condition (the clunking). Up front, this would add to toe + Ackermann + compliance steer effects not being what they need to be either (which could be the bigger effect here).


Norm.

So amazingly I found the issue: my tires! The other day I bought some new Michelin Alpins and put them on the car (P265 40ZR19 front and P285 35ZR20 rear) and lo and behold, the clunking went away! I am absolutely stunned - it just doesn't make sense to me how this fixed the issue. To clarify, I am using the exact same wheels, only I swapped the tires.

My best guess is that they were slipping on the snow or rotating at different speeds when the wheel was turned heavily to one side, and that was imparting a clunking noise to the front end. Honestly, it also could've been the fact the tires were rock hard (Goodyear F1 G2s) in the sub freezing weather and thats why the slipping made a clunking. Who knows. The good news is it is fixed!

Crazy...

PS - the Michelin Alpin's are AMAZING tires - the grip in cold weather is phenomenal - feels like I'm driving on summer tires that have been warmed up and that I'm driving on a track - that's how good traction is. I am dump the clutch from a few K RPM and the tires hook - totally insane. And on corners, wow...these are amazing. Can't recommend them enough!

-John

Keep in mind that winter tires are primarily designed for use during winter conditions. They may not be as good in summer heat, and may wear rapidly.


Norm