I've got some questions about VDC. I've done a search. For every 'fact' about VDC there is another 'fact' that totally contradicts it. But, my primary question has less to do with the technology and more to do with other people's experience.

Here is the issue. I took my 06 6MT coupe to the track. I never thought about turning VDC off. And since it took me most of the first and second day to really figure out what I was doing out there the VDC never came into play.

But the last two sessions I was getting better and more aggressive and was driving harder and VDC was going nuts and messing things up. My instructor had signed me off to drive solo and without him in the car I decided to leave VDC on and back off a little.

When I would come to a tight turn I'd brake hard, downshift to 3rd. No problem. Then off the brakes, clutch out and turn in. No problem. Then hard on the throttle at the apex. This is when the problems start. Of course the inside tire gets light and the viscous diff does not sufficiently control wheel spin. This is when the VDC starts playing games. I can feel it adding brake to the inside rear and kill the throttle input. Trying the same turn in 2nd gear just makes things worse.

The manual says with VDC off, traction control is off as well. However, it says that ABS and ABLS stay on. ABLS applies braking to the slipping tire. And this cannot be disabled.

My next track day is probably several months away and I'll find all this out on my own. But now I'm curious, has anyone had any track time with VDC off? Is the ABLS by itself intrusive? Does it slow you down? Do serious track guys completely disable VDC and ABLS? Can you disable ABLS without disabling ABS?

It seems to me that ABLS by itself would not be so bad since it is only affecting the slipping tire (in most cases the inside tire in a turn) and so the outside tire would still be getting traction.

 

ABLS, is just extra help to brake that one tired need be,

it will not work with VDC OFF,
You still have it but it will not brake for you
you still need to manually push the breakes for it work, and at that point all 4 will still brake but that one having trouble will be accounted for accordingly do to the ABLS.

 

Direct quote from the manual:

"The ABLS system and ABS will still operate with
the VDC system off."

ABS and ABLS are different things. ABLS is Active Brake Limited Slip.

Here is a longer quote from the manual:

The VDC system uses an Active Brake Lim-
ited Slip (ABLS) system to improve vehicle
traction. The ABLS system works when one
of the driving wheels is spinning on a slip-
pery surface. The ABLS system brakes the
spinning wheel which distributes the
driving power to the other driving wheel. If
the vehicle is operated with the VDC
system turned off, all VDC system functions
and TCS functions will be turned off. The
ABLS system and ABS will still operate with
the VDC system off.

 

Try pulling the Fuses, that should turn it off. Its behind the battery.

 

I may not need or want to turn the ABLS off. I'll just have to see how it responds on the track next time. I'm just curious about what others have experienced as far as performance, particularly cornering, with VDC off. (Not interested in burn outs or drifting since on a road course you're pretty much trying to avoid both of those )

 

I believe installing the yaw control sensor break switch will disable the ABLS. Before installing, I could feel it braking the rear at slides over 35 or 40 even with the VDC off. I haven't felt it ever grab since installing the kill switch. I do have some concern that timing, fuel or throttle may be pulled when the VDC disabled mod is active but have not been able to confirm with any tuners. If anyone can confirm, please let me know.
Here's a link to the disable mod, I've thoroughly enjoyed it.

https://g35driver.com/forums/drivetr...-vdc-real.html

 

Edit:

I think its only some cars, I have both a auto and 6mt g.




in the 6mt with vdc off I have no problem,
but with the auto I do see what everyone is talking about in that other thread. it cuts down the speed.

 

I read over that thread. There is a lot of misinformation there, even by the OP. I am not planning on interrupting the yaw sensor circuit on my own. I might consider a plug-and-play aftermarket product if I can feel problems on the track from the ABLS.

On a road course I do not want the tail kicking out. If ABLS can help prevent that then it will be okay.

My concern with ABLS is this: If I am accelerating out of a corner and the inside wheel starts to spin, despite the viscous limited slip diff and ABLS hits the brake on that wheel only then I'm fine with that. But, if it brakes the inside wheel and then traction goes to the outside wheel which then slips a little I'm afraid the ABLS will add brake to it too. To me that seems worse than a little wheel spin and if it does this then I will want to disable everything but the ABS.

If it does not do this then I'm fine with the ABLS.

 

It's been a while since I've driven without doing the VDC deactivaion, but from what I remember, it only affected me when breaking loose at higher speeds. I deactivate it during daily driving just because I'd rather not have any more electronic interference between my foot and the pavement than I have to.

Traction is only going to be gained on the driver side wheel when the VLSD heats up enough to clamp together. If the ABSL activates and the VLSD is active then its not going to apply more power to the other wheel. VLSD is basically turning into a solid axle where both wheels rotate at the same speed, so if one slow, the other will slow as well. If you have a helical type (which does not come with a stock G35) then it would apply more power to the opposite wheel. Helical in my opinion is the best way to go as its more predicatble and always on whereas the VLSD has to be heated first and is not immediately available.

 

I have a two way Nismo LSD and I have to run VDC off or else it goes nuts.

 

I wonder how well my VLSD is working. I'm pretty sure I could feel the inside tire spin more than the outside tire in tight turns and it should have been very,very warm. And being a viscous diff there has to be some slippage. But, it is hard to sort all that out with the VDC freaking out. I have heard that the VLSD is prone to boiling with hard track use.

I have a true LSD on my long term wish list (a few years down the road). Have looked at Quaife, Nismo and OS Giken. But, it is waaaay down the wish list.

I'm really curious about how the car is going to work on the track with VDC off. Better I'm sure, but its probably going to be February. I don't think there is any way on earth to duplicate a racing or school line on public streets. Anyway, I'll report back when once I've been back to the track. (I'm fortunate to have a great track about 1 hour away:

http://www.carolinamotorsportspark.com

 

Cool, must be great to have a track nearby. I'm not entirely sure which wheel is driven primary, I was under the impression that is usually the passenger side on RWD and driver side on FWD, but I may have that backwards.

Back when I had a 240sx, I installed a helical type diff and I swear it was the best mod I've ever done to any car for cornering. I'd love to do it to my G as well, but I totally understand it being down the list, particularly due to the large investment for a quality piece. Keep us updated!

 

I've done two track days in the G, and I'm a fairly advanced track driver. In my 2003 6MT sedan with no LSD, the ABLS doesn't kick in with VDC off, I can spin the inside wheel to my heart's content. When VDC is on, ABLS does work for some small slippage, but once the slippage is large, it throttles back and gets very intrusive. I would LOVE to have just the ABLS system active, but alas, this doesn't seem possible, so I've been running with VDC off and just having to practice precise throttle management to avoid breaking loose a wheel at the apex. ABS works fine with VDC on or off.

If I cared at all about tracking this car, I'd put in a clutch-type LSD and leave the VDC and ABLS completely disabled.

 

The only time I've been able to get the ABLS system to activate with the VDC off is wheel I spun the tires horribly threw 1st and some of second when leaving from a stop at a very slippery intersection. I think the ABLS saw way too much rotation on the back axle vs the front and engaged the brakes. It was far less intrusive that VDC.

I've always autocrossed with the VDC off and never had any sort of other electronic interaction. Even with an open diff, power oversteer can be easily induced. Luckily, oversteer is very easy to manage in this car. Now that I have a 3.54 gear with VLSD in my 5AT, the car is far more stable and controllable.

With that said, if you're getting a lot of spin, you really should look into the tires. They're key especially if you're doing longer road course stuff where keeping the VDC one is probably more ideal. If you have grippy rubber, VDC interaction should be mostly a non-issue because the tires are going to stick hard.

 

I'm still on average street tires (Hankook v12 Evo). They're grippy compared to all season tires but obviously not compared to track tires. I'll keeping tracking them a few more times. They won't last long. It is shocking what a weekend at the track will do to a set of new tires. If I keep tracking the car I'll pick up some track rubber and a set of track rims.

From what I'm reading it sounds like things will be fine with VDC off. If I get to the point where the VLSD is not sufficient and I'm going to be on the track a lot I'll look into a Quaife or something similar.