2003 G35 VDC Problem

[gnotaz]

Hi Folks,

New to this forum. My 2003 G35 6 Speed Coupe developed an unusual problem. After I wore out my second set of rear tires, I purchased new Bridgestone RE 670 Sports for the rear only. I still have the Bridgestone SO One Pole Position tires on the front. The first time I attempted to take a corner at the speeds I had previously used, the VDC came on! The new tires differ only in the tread pattern. All the specs are the same. I called Tirerack and discussed the problem with them. Let them break in was their suggestion. The VDC still comes on each time in the same turn. The dealer mech said there is no way to determine if there is a defect in the VDC. The ABS light may come on indicating a defective sensor but that it. Anyone had the same problem? Any suggestions?

g not a z

[RED_DET]

The VDC is designed to come on if it detects any type of wheel spin. Are you just taking the corner to fast? Have you tried it with VDC off?

[G_whizz]

Have you tried it with VDC off?

And welcome to NICO!

[gnotaz]

Thanks for the reply. I regularly take the turn in question in my Lotus Esprit at the same speed. Never had a problem before. The expressway exit is a decreasing radius to the right. I haven't tried the VDC off yet. Will try today. Strangely, I have not had the problem turning to the left! Had a four wheel alignment. Checked the tire pressures. Had the car re-inspected. Did a basic nut & bolt check. I rechecked the spec's at Bridgestone's website. Except for the tread design, the two tires are identical.

Yesterday, I intentionally hung the rear end out too far entering that turn. I corrected the steering angle and the VDC turned on then! Very disconcerting in the middle of a turn. Unlike previous attempts, the VDC turned on very late. Once in a while the VDC turns on again at the exit of the turn. Very, very strange.

[Slider4105]

The G35 isn't a Lotus? I don't think it can take the corner as fast as the Espirit.

[gnotaz]

Hi Folks,

Quick update. As hard as I try to get the rear end out to turn on the VDC, it won't do it. When I steer out of the slide and get the car straight, it turns on briefly. I'm confused. Incidentally, I can't get the VDC to turn on turning left, only right!

G Not a Z

[gnotaz]

The G35 isn't a Lotus? I don't think it can take the corner as fast as the Espirit.

Slider,

I think you underrate the G35 6 speed coupe. Yes, the Lotus Esprit does "handle" better. But the G is a 99% solution and far more reliable. If we were talking about an Elise or Exige you'd be correct. I also have a '08 Honda Civic Coupe EX for winter. Thats another story!

G Not a Z

[Slider4105]

I didn't say anything about reliability or anything of that sort, I was just saying it can't corner as fast as any Lotus....chalk it up to lower weight.

[Sentientbydesign]

Out of curiousity, what type of tires did the RE670s replace?

I'm thinking the new tires can't handle the speed and are letting loose which triggers the VDC. If not that, then the system is having some serious issues.

You did have the correct tire size installed, correct?

*EDIT*

I think you meant the RE760s. Those tires don't grip like the RE0XX line do. They are meant to be somewhat sporty but are much harder and less sticky than the RE0XX tires are.

Your VDC is coming on because the tires are losing traction and the VDC is trying to keep you from flying off the road.

UTQG for the OE RE040s are 140 AA A

UTQG for the RE760s are 340 A A

The RE760s are a harder compound ergo the higher treadwear rating of 340 vs 140. They also have lower traction A vs AA.

[gnotaz]

Thanks for the question. I had Bridgestone SO One Pole Position 245/45 - 18's on the rear. The replacements are identical in almost all pertinent specs. Unfortunely, the RE 760's are a slightly harder compound. Tire Rack no longer carries the original tires. My guess is they are discontinued. I tried to contact Bridgestone. No answers yet. I'll keep driving the car till November. When it comes out of storage in April, I may put RE 050's on the rear. Roughly the same price as replacing the fronts. Should have bought them this time. I cheaped out!

Incidentally, the slip light does go on during my problem. I noticed it out of the corner of my eye last night.

Does anyone know if disconnecting the negative terminal of the battery resets the VDC as well as other functions? Just a guess.

G Not a Z

[WESIDE]

Turn off the VDC and drift a little through the turn. Problem Solved.

[gnotaz]

Hi weside,

I'm with you. I tried turning the VDC off in turns I know quite well. The car behaves as it did before I changed the rear tires (worn out, wouldn't pass NYS inspection). I was more concerned about a mechanical problem being masked by the VDC. I can achieve the same slip angles I used to get at the same speeds. The car feels fine. Thanks to all for the input.

G Not a Z

[C-Kwik]

Its possible that if you only replaced the rear tires, and your fronts are somwhat worn, then the ratio of front tire to rear tire diameter may be close its limits. When taking a turn, it might sense even a slight mount of slip as beyond the threshold and turn the VDC on. I would of course, hope the engineers accounted for this, but who knows...

[Sentientbydesign]

IT'S THE TIRES!!!

[joe603]

I'd replace the fronts too...

[Beancooker]

I think that the front tires are grabbing the road, and the rears are sliding a bit. This is because the fronts have a better tread design, and a stickier composition. You are getting the classic symptoms of a mild case of oversteer.

]

[Sentientbydesign]

The SO Pole positions in the front are much stickier than the RE760s in the rear.

I feel like I'm speaking a different language

[gnotaz]

The SO Pole positions in the front are much stickier than the RE760s in the rear. I feel like I'm speaking a different language

I agreee with you! The most cost effective way for me to proceed is taking the RE 670's off and installing RE 050's. This will have to wait till next year as my Lotus Esprit has a drive train problem that need repair now. Only so many dollars for my toys. Regardless, thanks for the input. I really do appreciate the help.

G Not a Z

[gnotaz]

I'd replace the fronts too...

Thanks joe,

I wish I had the available funds to do it today. I cheaped out on the rears and it bit me. My fault completely!

G Not a Z

[joe603]

If you cant replace the fronts then you probably need to tone down your driving until you have the $$. Be careful!!

[SteveTheTech]

That's not as out there as you would believe the tires do in fact need need to be broken in, the tread pattern may also effect the wheel spin. How fast are you hitting the corner? I find it interesting that its worse in one direction more than the other, it makes sense its still a little odd. Whats the tread wear and traction rating on the old tires vs. the new ones?

[gnotaz]

Hi Steve,

My entry speeds very but never over 65 or less than 40 mph. The VDC has NEVER turned on turning left. Only right. I checked air pressures all around (35 psi). My dealer did a four wheel alignment (perfect). The tread pattern is wide open on the SO - One fronts. The RE 760 Sports are more closed. Bridgestone claimed the 760's should give me the same level of performance as the discontinued SO - Ones.

The VDC never gives me a chance to correct the steering angle. I attempt to throw the rear end out with power entering the corner. The VDC clamps the throttle and brakes. Strangely, once the VDC has turned off, I can throw the car nearly as sideways as I want without another interruption! It will turn back on only if I get the rear out way too much and try to steer out. It comes back on . Honestly, the rear appears to stick better than the front! Perhaps my perception is incorrect. My Lotus Esprit gives the same sensation without the electronic assists trying to correct my line. Incidentally, the car appears to work perfect with the VDC switched off.

Would worn brake pads add another parameter to this equation? My Brembo's are do for new pads (41K). Thanks for your interest in my problem.

G Not a Z

[TeflonG35]

I think that the front tires are grabbing the road, and the rears are sliding a bit. This is because the fronts have a better tread design, and a stickier composition. You are getting the classic symptoms of a mild case of oversteer.

]

Oversteer raped me.

[SteveTheTech]

The VDC never gives me a chance to correct the steering angle. I attempt to throw the rear end out with power entering the corner. The VDC clamps the throttle and brakes. Strangely, once the VDC has turned off, I can throw the car nearly as sideways as I want without another interruption! It will turn back on only if I get the rear out way too much and try to steer out. It comes back on . Honestly, the rear appears to stick better than the front! Perhaps my perception is incorrect. My Lotus Esprit gives the same sensation without the electronic assists trying to correct my line. Incidentally, the car appears to work perfect with the VDC switched off.

Yeah the tire companies will say that they don't want you to try something else. I read a good three hundred reviews, and did extensive research before I bought my last set of tires, and I'm not that impressed.

The VDC issue your describing is a programming flaw(I'm not saying a problem or anything that can be repaired)that incorporates the wheel speed sensors, steering angle, yaw, and G sensors, the earlier G's lacked a sport setting. It's one of the only things missing from it, definitely takes some of the fun out of driving them.

I really don't think worn pads would really cause that, not definitely but its not too likely. Depending on how much if any break pressure is applied, it should not significantly effect the quality of braking. It sounds more like the variance in composition of the tires, your old ones gripped slightly better keeping the VDC from activating.

A quick Google for any updated VDC control units or software reflash to fix that would change the engagement parameters showed nothing useful. Damn

BTW you cant really compare a daily driver for all age groups to a race ready toy. Although the Lotus is a great choice.

[G_whizz]

Way to help out Steve!!

Great to have you onboard!

[SteveTheTech]

I love the product and I know them inside and out, I really want to help the people here if I can.

[coolbratva]

Forget vdc, just drift your corners.