# help? g35 wheel hop



## joerx (Mar 9, 2005)

This is my first post on this forum, I apologize if I make any errors.
Re: Infiniti G35 coupe 6 sp manual, Borla exhaust, Greddy turbo.
I have a 2003 g35 coupe with the Greddy twin turbo and intercooler setup 
installed. From a roll, the car runs like a rocket. I tried two passes at the dragstrip near Hattiesburg, Miss. and I could not get away cleanly from the 
start light. I experience violent wheel hop in 1st and 2nd, then the car settled down after about 100 feet, my 60 ft. times were terrible but my trap speed was 105 and 107 respectively. I turned 14 flat, which is a stock time with a faster trap speed. Here is the question, there is an on off swith called vehicle dynamics control, this is always on as default, it must be switched off by the dash off button. I think this is for slippery roads and not only switches power to the opposite wheel, it also applies the brake on the slipping wheel. I have not had time to confirm this. My main question, and I have not tried yet. Does this off switch turn off positraction ? Would you 
believe the mechanics at the Infiniti dealership nearby do not have a clue ?
I would appreciate any advice. joerx [email protected]


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## JAMESZ (Mar 12, 2004)

Wait so you do not turn VDC off when you go down the track? It is a traction control system plus; not only does it control the throttle, but it controls the brakes. It is made to keep drivers from killing themselves on the streets. It doesn't turn off "positraction" you have an LSD the computer does not control that. If your trying to race with it that is one of your problems (though you wouldn't be suffering from wheel hop). How wide are your tires? You have IRS welcome to the world of wheel hop. Do you want the car to be a drag car that launches well, a car that is well balanced, or a car just set-up for handling? Because your suspension set-up needs to be built along one of those lines. One thing is invest in some lightweight 16s or 17s that are wide enough to fit some decent size DRs on (265 or 275 or so).


I would recommend before doing anything to a car know more about it. Your lucky you haven't destroyed your G35C yet. Take time and research; get to know your car before you modify it or attempt to race it.


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## Zen31ZR (Mar 24, 2004)

One thing that maybe cure the wheel hop is to install urethane bushings on the main rear subframe attachment points. It helps on the Z32, so it may help here as well. Coilovers may help, as well as stiffer rear shocks.


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## joerx (Mar 9, 2005)

*I think you are correct on shocks and coilovers but*



♣Zen31ZR♣ said:


> One thing that maybe cure the wheel hop is to install urethane bushings on the main rear subframe attachment points. It helps on the Z32, so it may help here as well. Coilovers may help, as well as stiffer rear shocks.


What I did not realize before I tried the car at the strip, is both on Z cars and G35s is an electronic computerized device that must be shut off to race. It is called Vehicle dynamic control. It is on by default and a dash button shuts it off. Another member of this group, and I hope he is correct, posted me that the positraction stays active. The VDC, when on, not only transfers power to the other wheel, but applies the brake to the slipping wheel. I hopped down the track like a rabbit for all of 1st gear and part of 2nd till it settled and the final trap speed was 105 and 107 respectively. That should be good for low 13 s. I turned 14 flat. But, I was ignorant at the time, and think I have it solved, and thanks for the advice on suspension. I also need wider tires, I have 235s and probably need 275 or 285.

joerx


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## JAMESZ (Mar 12, 2004)

If you want to run at the track you need DRs. 235s are not wide enough to launch on. The VDC will basically shut the car off and modulate the throttle when the tires break loose. If you are not experiencing wheel hop if VDC is active you are experiencing throttle modulation by the computer. Also learn to drive; your biggest problem is your driving ability at this point. Even though I don't personally know you I can tell that if you are having problems in 1st and 2nd you need to work on your launching and driving techniques.


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## joerx (Mar 9, 2005)

*driving techniques--you are correct but*



JAMESZ said:


> If you want to run at the track you need DRs. 235s are not wide enough to launch on. The VDC will basically shut the car off and modulate the throttle when the tires break loose. If you are not experiencing wheel hop if VDC is active you are experiencing throttle modulation by the computer. Also learn to drive; your biggest problem is your driving ability at this point. Even though I don't personally know you I can tell that if you are having problems in 1st and 2nd you need to work on your launching and driving techniques.


JAMEZ
You are correct, with only two passes, I need to work on launching, I have
not been to the drags in years, and practice is important. Remember you are the first person that had the real knowledge of how the VDC works, everyone else I have contacted were not sure or didn't know. But I assure you once this is solved, after 3 or 4 good runs I will have it down. In 1987 I had a Buick T type (white color version of black Grand National) With the V6 turbo and extensive engine mods this car ran in mid 12s and still was streetable with working Air Cond. Only down side had to use leaded fuel and buy O2 sensors by the doz. At any rate, I am an older guy and was a Jet Mechanic in Air Force, and we messed with our cars when off duty. I am rusty at the drags, but I got the urge to try this recently. I plan to get the tires you recommend and also Eheim makes a performance set of shocks I plan to look at. If it runs in low 13s I am happy, and the car is very streetable, with a somewhat rough ride. I live in suburb of New Orleans, and I promise you cannot find a city with worse streets. Fuel economy is bad, as injectors with kit are quite large.
Again, thanks for the information. Any other thoughts, I am looking for advice.
Thanks, joerx


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## asleepz (Feb 24, 2004)

joerx said:


> JAMEZ
> You are correct, with only two passes, I need to work on launching, I have
> not been to the drags in years, and practice is important. Remember you are the first person that had the real knowledge of how the VDC works, everyone else I have contacted were not sure or didn't know. But I assure you once this is solved, after 3 or 4 good runs I will have it down. In 1987 I had a Buick T type (white color version of black Grand National) With the V6 turbo and extensive engine mods this car ran in mid 12s and still was streetable with working Air Cond. Only down side had to use leaded fuel and buy O2 sensors by the doz. At any rate, I am an older guy and was a Jet Mechanic in Air Force, and we messed with our cars when off duty. I am rusty at the drags, but I got the urge to try this recently. I plan to get the tires you recommend and also Eheim makes a performance set of shocks I plan to look at. If it runs in low 13s I am happy, and the car is very streetable, with a somewhat rough ride. I live in suburb of New Orleans, and I promise you cannot find a city with worse streets. Fuel economy is bad, as injectors with kit are quite large.
> Again, thanks for the information. Any other thoughts, I am looking for advice.
> Thanks, joerx



WHOA WHOA WHOA NOW!

I live in Luling roughly 15 minutes west of you!

Where did you take it? Donaldsonville?

Hit me up on AIM or MSN

AIM : skddestroyer

MSN : [email protected]


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## joerx (Mar 9, 2005)

♣AsleepZ♣ said:


> WHOA WHOA WHOA NOW!
> 
> I live in Luling roughly 15 minutes west of you!
> 
> Where did you take it? Donaldsonville?


No I went to the track near Hattiesburg MS. I plan to go to Donaldsonville when I get some decent tires. I live in Metairie. I know Luling well, a cousin lived there years ago before it was hardly built up.

I would like to keep in touch, since you seem to know more than all of the contacts I have made concerning this problem.

I notice you rather not receive private emails, but would like to keep in touch through this forum. If you want to email me, my email is [email protected].
thanks joerx


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## asleepz (Feb 24, 2004)

check my last post

do you have aim or MSN?

After you have had your account for 2 days you can private message me through the forums.


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## joerx (Mar 9, 2005)

♣AsleepZ♣ said:


> WHOA WHOA WHOA NOW!
> 
> I live in Luling roughly 15 minutes west of you!
> 
> ...


I sent error on Buick, it ran mid 10s.
This Saturday is a big I think Chevy shoot out at the Hattisberg track, I cannot go need to work. I am not sure if is Chevy, but the track is closed and only for spectators. I forgot the name of the track, but well run, good surface, and well operated.
joerx


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## asleepz (Feb 24, 2004)

joerx said:


> I sent error on Buick, it ran mid 10s.
> This Saturday is a big I think Chevy shoot out at the Hattisberg track, I cannot go need to work. I am not sure if is Chevy, but the track is closed and only for spectators. I forgot the name of the track, but well run, good surface, and well operated.
> joerx



Still haven't said if you have MSN or AIM. But either way I have to get off for the night. But I sent you an e-mail hit me up again tonight or tomorrow.


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## JAMESZ (Mar 12, 2004)

joerx said:


> If it runs in low 13s I am happy, and the car is very streetable, with a somewhat rough ride.


It should be deep in the 12s with your mods. And maybe even high 11s with some DRs. How would it not be streetable? All the kits are made for street cars; I have never heard someone complain about the ride especially in a G35C. Just remember next time RTFM!


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## joerx (Mar 9, 2005)

♣Zen31ZR♣ said:


> One thing that maybe cure the wheel hop is to install urethane bushings on the main rear subframe attachment points. It helps on the Z32, so it may help here as well. Coilovers may help, as well as stiffer rear shocks.


I was advised to first try a set of eheim shocks, and if that does not solve the problem, it is thought they might do the job, then try other options, this car rides rather hard now, so I hate to make it uncomfortable to be street driveable. What do you think. Any knowledge about eheim shocks. By the way, I do not see Koni shocks mentioned anywhere, they used to be real popular.


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## joerx (Mar 9, 2005)

*DR questions Nitto or ??*



JAMESZ said:


> It should be deep in the 12s with your mods. And maybe even high 11s with some DRs. How would it not be streetable? All the kits are made for street cars; I have never heard someone complain about the ride especially in a G35C. Just remember next time RTFM!


Nitto makes a tire very close in size, maybe 1/2 inch taller, and that should not cause any problems, what other brands should I look at ?

Previously I only raced with slicks, but the cars I had could handle them, Slicks on this car, I am pretty sure, will certainly make other parts fail.

The stock clutch and pres. plate have not failed yet, but a lot of companies advertise heavy duty street and strip. Also any advice on brands.
thanks,
joerx


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## asleepz (Feb 24, 2004)

joerx said:


> Nitto makes a tire very close in size, maybe 1/2 inch taller, and that should not cause any problems, what other brands should I look at ?
> 
> Previously I only raced with slicks, but the cars I had could handle them, Slicks on this car, I am pretty sure, will certainly make other parts fail.
> 
> ...


Well a 1/2" taller wouldn't be a problem as in fitment but it's going to make your speedo be about 5-7MPH slow.. Which means if your going 70 your really going 75-77MPH..

How much boost are you running? Can't be too much if your stock clutch is still holding.


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## Zen31ZR (Mar 24, 2004)

joerx said:


> I was advised to first try a set of eheim shocks, and if that does not solve the problem, it is thought they might do the job, then try other options, this car rides rather hard now, so I hate to make it uncomfortable to be street driveable. What do you think. Any knowledge about eheim shocks. By the way, I do not see Koni shocks mentioned anywhere, they used to be real popular.


Koni still does coilovers, as I recall. At any rate, what you need to do is reduce the _play_ inherent in an IRS, by removing some of the weaker rubber subframe and suspension bushings and replacing themn with urethane. It won't necessarily make it ride harder, but it will reduce the bodies _isolation_, and you will hear more road noise. A somewhat harder ride is a small price to pay for better launchability, in my opinion. Gotta take the bad with good. Drag racing in particular is a sport where you cannot "_have it all_". Some things must be sacrificed in the name of performance.


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## asleepz (Feb 24, 2004)

joerx said:


> Nitto makes a tire very close in size, maybe 1/2 inch taller, and that should not cause any problems, what other brands should I look at ?
> 
> Previously I only raced with slicks, but the cars I had could handle them, Slicks on this car, I am pretty sure, will certainly make other parts fail.
> 
> ...



Haven't heard from you in a couple days, e-mail me back...


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## joerx (Mar 9, 2005)

♣AsleepZ♣ said:


> Well a 1/2" taller wouldn't be a problem as in fitment but it's going to make your speedo be about 5-7MPH slow.. Which means if your going 70 your really going 75-77MPH..
> 
> How much boost are you running? Can't be too much if your stock clutch is still holding.


Can only safely use 7lbs boost with stock pistons and connec. rods. Have seen others have connec. rods fail at 10lbs boost. I do not think I will change connecting rods and pistons-too much work, and too much down time to pull engine. 

I still am asking if turbo car will show proper hp on dyno. I dont think since air does not pass thru intercooler. What do you think. Thunder racing in Baton Rouge charges $90.00 for two pulls. What do you think ?
joerx


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## joerx (Mar 9, 2005)

♣Zen31ZR♣ said:


> Koni still does coilovers, as I recall. At any rate, what you need to do is reduce the _play_ inherent in an IRS, by removing some of the weaker rubber subframe and suspension bushings and replacing themn with urethane. It won't necessarily make it ride harder, but it will reduce the bodies _isolation_, and you will hear more road noise. A somewhat harder ride is a small price to pay for better launchability, in my opinion. Gotta take the bad with good. Drag racing in particular is a sport where you cannot "_have it all_". Some things must be sacrificed in the name of performance.


Hard ride does not bother me, and I will talk to my mechanic about doing the shocks and replacing the bushings with urethane. 
I cannot give up my car now, I am moving to another home in about 2 or 3 months, and is consuming all my time.
I will try to make a couple of passes if I can get to Donaldsonville or Hattiesburg track in next month or so. I will get DRs first, and have located two stock wheels real cheap with only cosmetic damage. I will get them soon as possible. Will notify every one what happens. I noticed another Z person test drove a new Z and had wheel hop as I did. I forgot who it was, but if you see his post, have him contact me or let him know the vdc must be shut off.
joerx


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## asleepz (Feb 24, 2004)

joerx said:


> Can only safely use 7lbs boost with stock pistons and connec. rods. Have seen others have connec. rods fail at 10lbs boost. I do not think I will change connecting rods and pistons-too much work, and too much down time to pull engine.
> 
> I still am asking if turbo car will show proper hp on dyno. I dont think since air does not pass thru intercooler. What do you think. Thunder racing in Baton Rouge charges $90.00 for two pulls. What do you think ?
> joerx



Most places with dynos have high output fans they put in front of the car.


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## JAMESZ (Mar 12, 2004)

joerx said:


> I still am asking if turbo car will show proper hp on dyno. I dont think since air does not pass thru intercooler. What do you think. Thunder racing in Baton Rouge charges $90.00 for two pulls. What do you think ?
> joerx


Your not even producing anough boost to make that much of a difference with an intercooler. You will show "proper" hp. Maybe 1 or 2 less then what you would see on the street, but it will be accurate. They will have fans infront of the car pushing air throught the intercooler. 2 pulls is not enough. You will need more like 5 or six to hit peak numbers, and 90 bucks for 2 pulls is not very good.


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## joerx (Mar 9, 2005)

JAMESZ said:


> OMFG!!! Listen to me. If VDC is on YOU ARE NOT EXPERIENCING WHEEL HOP! You have IRS that is why you are experiencing wheel hop. With VDC on you are experiencing throttle modulation. Did you ever even read the manual that came with your car? You still have no clue what your talking about. I also highly doubt you have any experience drag racing, because you know absolutely nothing.


The manual that came with the car stinks, and gives no useful information, by the way did you ever see the manual for this car? As far as knowing nothing, get two equal cars, I will beat you 9 out of 10. If you want to throw around insults, talk to someone else, I just came here for some useful info which others were considerate enough to give without insults. I doubt if you ever drove in a real drag race.
DRs and some practice will solve 80% of my problems. I ran cars in the 10's in the years when that was good number and this toy will be in the 12s soon.
joerx


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## JAMESZ (Mar 12, 2004)

If you had read the manual you would know what VDC is and what it does. I showed this thread to several people that I know with 350Zs and that are in development of parts for your car, and they said you should read the manual also.. What do you define as a real drag race? Your car is capable of running 12s now on STREET tires. I'm sorry if I was harsh, but you don't know anything about your car, and you have modded it and even raced it. next time you go to Hattiesburg tell me and I will tell one of the guys who goes there on occassion to video tape it.


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## FSU_Z33 (Jan 12, 2005)

There are a lot of people that complain about having to change brake pads and even rotors on the Z after only 10-15K miles. From what I've heard and read online, I've come to the conclusion that they are almost all like you. They drag race their car with TC/VDC on and the harder they accellerate, the harder the brakes clamp closed...


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## joerx (Mar 9, 2005)

FSU_Z33 said:


> It's amazing that you've spent that much for a car, spent half of that again on modifying it; and you still don't even know how it works.
> 
> There are a lot of people that complain about having to change brake pads and even rotors on the Z after only 10-15K miles. From what I've heard and read online, I've come to the conclusion that they are almost all like you. They drag race their car with TC/VDC on and the harder they accellerate, the harder the brakes clamp closed...and the best you can come up with is the manual sucks?!?!?! You're lucky your engine hasn't crapped out on you.
> 
> ...


Remember after two tries I quit, the car is not crapped out, and the computer is piggybacked with the greddy control unit which has various adjustments as far as when the boost comes in, how much boost and 3 or 4 other options.
I would not call the only two passes I made drag racing, I quit on 2nd pass.
I wish I could turn the VDC off permanently, and I may be able to. I don't blame anyone but myself. At any rate, I am going to firm up the shocks with Eheims, they were recommended buy two different mechanics. I do not see Konis advertised lately, but they also make or made excellent performance shocks.. You know I joined this forum for some technical support, but several have only sent me " you can't do that" with no further info. I stand by my statement the manual stinks. Only 1 page mentions the VDC and not very clear. This is the car manual, not a shop manual. I usually order a shop manual any time I get a new car, but did not on this one. Unfortunately my ignorance of the VDC came back and bit me. My third question, on this issue, and I have two different anwsers so far.. When VDC is off, is positraction off or on. I think it is on, but have not tried it yet.
Thanks (By the way, my brakes are still in excellent shape.)
joerx
[email protected]


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## JAMESZ (Mar 12, 2004)

joerx said:


> When VDC is off, is positraction off or on.
> [email protected]


You have an LSD. 
WITH VDC OFF YOUR TRACTION CONTROL SYSTEM IS OFF, the LSD still works like the mechanical device it is. You can't turn it off.


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## joerx (Mar 9, 2005)

JAMESZ said:


> You have an LSD. Do you not have any reading comprehension? I mean seriously I told you it is still on. YOU HAVE AN LSD! You see this is why I highly doubt anything you have said. You may own a G35C that is equipped with a Greddy TT kit, but you know absolutely nothing about cars. Go read up on what a Limited Slip Differential is and then come back. If the manual didn't make it all clear enough from the beginning nothing will.
> 
> WITH VDC OFF YOUR TRACTION CONTROL SYSTEM IS OFF, the LSD still works like the mechanical device it is. You can't turn it off.


That is what I think all along, but the technician at Infiniti told me vdc off shuts off lsd, there fore I know we are correct and he is wrong. The greddy kit has a computer pack that piggybacks the main computer, allowing boost adjustment,also,can adjust when boost comes in,and several other paramaters. Calm down, I believe you, I just doubted the technician at infiniti and wanted to be sure I was correct. Last night I went on a dead end street and did a light burn, about 15 feet, and both stripes were almost the same with no wheel hop. Of course with the vdc off. I still recommend you get or borrow the manual and see how poorly it is written.


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## JAMESZ (Mar 12, 2004)

joerx said:


> That is what I think all along, but the technician at Infiniti told me vdc off shuts off lsd, there fore I know we are correct and he is wrong. The greddy kit has a computer pack that piggybacks the main computer, allowing boost adjustment,also,can adjust when boost comes in,and several other paramaters. Calm down, I believe you, I just doubted the technician at infiniti and wanted to be sure I was correct. Last night I went on a dead end street and did a light burn, about 15 feet, and both stripes were almost the same with no wheel hop. Of course with the vdc off. I still recommend you get or borrow the manual and see how poorly it is written.


VDC is not causing the wheel hop. If VDC is on the throttle is being modulated you are NOT experiencing wheel hop.


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## FSU_Z33 (Jan 12, 2005)

I'm going to forego all of the negative things I want to say.

I would like to hear what you think "positraction" is, and how it relates to your G.

...anyway:

1. Traction control: This keeps the wheels from spinning by electronically modulating the throttle and the brakes.

2. VDC (or Vehicle Dynamic Control): Works mechanically similar to TC, but activates when any sideways motion or slipping of the car is detected. VDC can modulate the throttle and helps to stabilize the car by pulsing the brakes to the 4 wheels independantly.

3. "SLIP" light: This lights up on your dash when TC/VDC is on and any traction loss is detected. I don't know the specifics, but after a few seconds of traction loss (like dragging w/ boost and TC/VDC on) it will remain shining in your face until you shut the car off and restart it. This is to tell you (in the case of slippery/icy roads) that you may want to park the car or be more careful. In your case it's telling you to sell your car and buy a Civic.

4. TC/VDC: Some Z's (I don't know about the G) only have TC, others have TC and VDC. If you have VDC then you have TC; they work through the same system, and you cannot turn them on/off independantly.

My advice:
For everyday driving TC/VDC is good to have on. You never know when you'll have to make a sudden move and TC/VDC is there to keep you from spinning out of control (and it works, because I've tested it in a wet parking lot). If there's any chance that you will spin the tires (whether drag racing, autocrossing, tracking, or just being a typical ricer when you meet a V6 Mustang at red light) turn it off. All it takes is a touch on the button and it's back on again.


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## joerx (Mar 9, 2005)

*I agree*



FSU_Z33 said:


> I'm going to forego all of the negative things I want to say.
> 
> I would like to hear what you think "positraction" is, and how it relates to your G.
> 
> ...


GOOD ADVICE:
Since the VDC is on by default, I leave it on. And I appreciate the info you have listed. I did a test for myself on a dead end street the other night I turned the VDC off and just went about 100 feet. The wheels spun for about fifteen to 20 feet before grabbing, and no wheel hop. I did not really get into it, these tires are of no use for a launch, but another member made some recommendations, I like the Nitto brand but 1/2 inch too tall and have not decided yet. I was offered some "cosmetically" damaged wheels, which was ready to buy today, but some people don't tell the whole story. They had beed damaged beyond usage, apparently the guy hit something and one was quite out of shape. I am sure I can find something useful. 

Positraction, as I define is ,and I am not an engineer, a limited slip differential. There are several types, but in general if a wheel slips, torque is transfered to the other wheel, this is simply put, and there are several ways to achieve this, most, and this is real general, provide a controlled amount of resistance to the spinning wheel, so the other wheel, which has traction gets enough power to keep the car going. If I recall, a company "Eaton" makes lsd for muscle cars and some off road vehicles. Remember I have not raced in some time, and am sure that newer cars have a lot more involvement in traction control with computer involvement. I joined this group to get some up to date info, but seems every one is ragging me because I made a run with out proper info. This is my fault. But I think with the info you and others have provided I can move forward. I just hate to learn from mistakes as I did. As I had said earlier, another car with similar setup to mine, ran in low 13s, but I do not know his exact setup. My plans are, new tires as has been recommeded, and eheim shocks, and give it a try an go from there. I am open to any useful ideas and suggestions. My last car, and that has been some time ago ran in high 10s to mid 11s, and I ran it often. I am not green to racing but just to some of the computer hangups I was not aware of.
Your comments above show you have good knowledge of the mechanics and engineering, and this is the kind of info I need.
Thanks, joerx
If you wish to email I will supply my address.


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## Ruben (Oct 15, 2002)

I just went to the drags for the first time in my Z and forgot to turn off VDC in the burnout box... sputtered all to hell, and retarded the timing for a great 14.4 run.

VDC is great to save you for some unexpected wheel spin, but make sure its off for best launch.


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