G37 Sedan

VDC engaging in straight line accel

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Old Dec 31, 2013 | 04:55 PM
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skeener
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VDC engaging in straight line accel

Conditions:

RWD Journey. Half Throttle. Straight smooth road. Cold but dry conditions. Michelin Xice3's almost new.

As the RPM's build north of 3K, and the power begins to "surge" (come on cam - oldish expression), the VDC IP light flashes at somewhere around 50 MPH, indicating that one of the rear (drive) tires is slipping.

The concept is quite clear. What surprises me is the relatively high vehicle speed and part throttle still results in slip. I know conditions are far from ideal, but I hadn't considered the G to possess such grunt. The longitudinal G's are stout for sure.

Anyone else notice their VDC activate at higher vehicular speeds and part throttle? Maybe 6MT's mitigate with their LSD, raising the threshold?

In the spring I will research this tendency w/ the original OEM Goodyear RSA's.
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Old Dec 31, 2013 | 06:01 PM
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Yazovets
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From: Toronto, Canada
What you are describing is very strange - especially at 3K rpm.

The G is a very well endowed car but it doesn't have such brute force to spin its tires on a dry road at 50mph. You would need something like a C63 to pull that off. The only possibility is if the road was super salty - then it could feel like having sand on the surface.

Speaking of this scenario, just today I spun all 4 tires from a standstill with moderate throttle. The road was dry but heavily salted and the temperature was -9 Celsius.

Don't bother basing any of your research on the Goodyear RS-A tires in the spring. That model of tire is by far the worst I've ever driven. They provide mediocre dry traction and non-existent wet traction. Had them on a 3-series back in the day.

Can you check if your tires are mounted in the correct rotational direction? If they're mounted backwards, then you could indeed spin at higher speeds.
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Old Dec 31, 2013 | 06:38 PM
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Tire Rack did a good job on the orientations, etc. I did the same during installation. Some salt on the roads - yes, but not much as it rained heavily since the last snow. I too find this behavior out of character for a G, hence the post. Thinking back, it's actually happened several times under various conditions. Once I made it a point to monitor any RPM flash coincident w/ the flashing VDC light - and there was some audible evidence, though I couldn't view the tach due to safety concerns. Maybe the trigger threshold for VDC is quite low?
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Old Dec 31, 2013 | 11:07 PM
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It's going to engage when it detects slippage.
That's the point of ANY traction control, to intervene before it's to late.
It's also linked to abs , so it's intrusive unless you deactivate it.
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Old Jan 1, 2014 | 11:29 AM
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skeener
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Originally Posted by Yazovets
What you are describing is very strange - especially at 3K rpm.

The G is a very well endowed car but it doesn't have such brute force to spin its tires on a dry road at 50mph.
I'm going to lower my tire pressure a bit and see what happens. I do tend to overinflate for a variety of reasons.
Regardless, I am spinning one rear tire at speeds up to 60 MPH at part throttle. I've confirmed this today on various roads. Usually there is a corresponding RPM flare that's quite noticeable. All the while the VDC light is flashing and remains so until the RPM's drop and the guilty tire stops spinning.
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