TVetteT

I own the C6 2006 model auto. Everyday in the morning or when car is stopped for long time, when I turn the car right or left there is a cranking sounds like "crank crank crank" when I turn the steering wheel left or right, I feel it is from the back. What could be the problem and what's resolution?

Jimmy W1

That could be a lot of things. I'd get it to a dealer.

C-INRED

There was a TSB issued on the differential. It involved changing out the fluid and doing a bunch of low-speed figure eights. The symptom was usually more of a grinding noise when doing low speed sharp turns, especially in reverse but it may very well be your problem.

Do a search here on 'differential TSB' and you should be able to find the TSB date, number and full text.

Edit: Here it is..... http://forums.corvetteforum.com/1563786073-post4.html

TVetteT

Yes I was advised it is the differential. The question is, does it go completely after the oil change or temporairly like 6 months to a year? I had that done, and the grinding sound disappeared and now it is back again.

Furthermore, what about car jerking at some gears at sometime, is it because the engine is carbon filled and needs speeding to remove it?

TVetteT

How do I do the "figure 8" pattern once the differential oil is changed? I dont understand it doing the 8 turns.

Knob Jockey

After you've had the TSB addressed and you have new diff. fluid, you just steer the car in tight turns left then right, repeat, etc., forward and/or reverse.

The process has to be repeated sometimes after the car has been sitting for a long time (winter) to redistribute the oil/friction modifier in the rear end.

I usually have to do this in the spring with my '06.

It also doesn't hurt to have the axle nuts checked/torqued while you're at it.

The A6 tranny, in auto mode, hunts some times finding the right gear/speed match. Unfortunately it's 'normal'.

bolivar

GM has had problems with the 'positraction' differential ever since it was developed in the mid 1960's.

And the 'figure 8' has been a help for this problem since then. With normal driving, the lub is pushed out of the diff clutch plates. When these plates become dry, popping, crunching, snaps, etc can all come out of the differential. Find an empty parking lot. Hope no police or security patrol comes along and want to talk to you during the procedure. Just start driving the car in a tight circle. Doesn't have to be full 'lock', full lock on a turn isn't good for the PS usually. Just a very tight turn. When you complete a circle, turn back the opposite way and complete another circle. Do this several times, 6 - 8 or so, and then drive off.

Do some figure 8's. If it still makes noises, have the diff fluid changed to the very latest part number. If it still makes noise, see if GM will put a new differential in the car under 6/100000 warranty, or pay for it yourself.

Driving the car thru the sharp turns forces the plates open and allows lub into them. Many, many times this procedure will make the car 'good' for months and months, and then can be repeated.

Of course, GM (Or probably lube refiners) has developed better and better diff lubs thru the years. Orginially, positractions had lube plus as additive. The additive supposed was made from whale oil. And in the mid70's or 80's this became unavailable, or environmentalist made the manufactors stop making it. So, a non-whale impact additive was developed. Which was probably re-formulated several times thru the years. A few years ago, the additive was dropped, and the lube was all that was specifiecd This posi diff lube was changed, at least once, because the part number was changed and GM TSB specified using the new lube to stop complaints such as yours.

But, 'figure 8's' will help many cars. For my 2007, with low miles, I've done this a couple of times. I have had some minor pops/snaps when backing out of the garage and turning (in reverse) 90 degress into the street. Even before figure 8's, it was never enough to concern me.

Don-Vette

Did you check you power steering fluid?