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Old Nov 3, 2013 | 11:31 AM
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Default Acceleration problem

Recently had a set of Pfadt Headers and a tune done on my Z. It was 540 RWHP & 504 TQ. It already had a mild Crane cam installed. Have a nice little straightaway here, rolled to about 20 MPH let here have it, grabbed second at about 6700 RPM and the back of the car started coming around like it wanted to pass the front of the car. Had to let off of it. Tried it again on the way back, same thing. Had it in competitive driving mode, air pressures were all at 30 PSI. Have Michelin PS 2's, not run flats. 335/30-19 Even had the old lady in the car screaming like a little kid. Anybody have an idea how I can make the front of the car go any faster?
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Old Nov 3, 2013 | 01:11 PM
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Joe

I have the same issue. Just installed the Pfadt's on my eforce GS. I'm running at 539/527. I love the new sound....
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Old Nov 3, 2013 | 03:07 PM
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So I guess at some point we need to figure out how to keep it in a straight line.
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Old Nov 3, 2013 | 03:14 PM
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why not just turn traction control off? comp mode is ok if you are a professional driver on a road course. With TC off it will still spin but not try to come around on you..
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Old Nov 3, 2013 | 06:19 PM
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Originally Posted by stanger383
why not just turn traction control off? comp mode is ok if you are a professional driver on a road course. With TC off it will still spin but not try to come around on you..
I understand what you are saying but I don't understand why competitive driving mode ON would want to put me in a ditch and plain traction control OFF will keep me in a straight line??
I guess I'll try it your way.
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Old Nov 4, 2013 | 02:14 PM
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Originally Posted by stanger383
why not just turn traction control off? comp mode is ok if you are a professional driver on a road course. With TC off it will still spin but not try to come around on you..
That doesn’t sound correct!!! Traction control keeps the rear wheel from spinning. It decreases throttle angle and pulls fuel to control wheel slip.

COMP MODE lets the rear wheels spin but uses information from the SWPS and yaw accelerometer to apply and release the brakes to HELP keep the car in a straight line or in a direction that the driver turns the steering wheel.

If your engine makes enough power, it will easily OVERCOME TC and AH My measly 450 RWHP 02 ZO6 does!

I had a weird pull to the right when I roasted the tires. It turned out to be a limited slip clutch issue. The Belleview spring in the differential was broken and the clutch pack on the right wheel did not lock up the same as the wheel on the left.

Put the trans in neutral, and jack up one rear wheel. Try to rotate the rear wheel and see how much force it takes. A new set of clutches in the differential is approx 110 ft/lbs. That decreases as the clutch pack wear.
Do the same to the other wheel. They should both be close to each other. My left wheel was 75 ft/lbs. the right wheel was 45 ft/lbs

Here is what caused the issue:






Compare the mark on the right to the mark on the left. It started out making weird marks and a slight pull .





Bill

Last edited by Bill Curlee; Nov 4, 2013 at 02:20 PM.
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Old Nov 4, 2013 | 02:39 PM
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Bill

I never thought about issues with the rear end. Car only has 7000 miles on it but you never know. Now I'm thinking I may have screwed up when I changed rear end fluid, it was making bad ratcheting sounds on sharp u turns so I drained and installed new Amsoil with recommended additive. No more noise but maybe the additive was too much? I'll jack it up and see what that test looks like.
Thanks for the suggestion Bill.
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Old Nov 4, 2013 | 02:45 PM
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^^^Here in Paradise, our biggest employer is DOD and we are surrounded with lots of young or immature Military personals.

See lots of stuff like that in neighborhoods close to the many bases back in the days but now, it is being done everywhere.

Doing show off burn outs in congested areas all without regards to life and property.

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Old Nov 4, 2013 | 03:01 PM
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Originally Posted by victorf
^^^Here in Paradise, our biggest employer is DOD and we are surrounded with lots of young or immature Military personals.

See lots of stuff like that in neighborhoods close to the many bases back in the days but now, it is being done everywhere.

Doing show off burn outs in congested areas all without regards to life and property.

Maybe you should go to the Drury Inn and apply for a job watching their parking lot? I'm thinking if you don't have anything positive to add to a thread you should most likely stay off of it.
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Old Nov 4, 2013 | 05:00 PM
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Yea,,, I suppose you have NEVER done anything wrong!!
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Old Nov 5, 2013 | 01:27 AM
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I guess here goes my thread into the gutter? I just hate when people think that they can just mouth off anytime they want with no regard to anybody else.
So anybody else have anything good to say?
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Old Nov 5, 2013 | 08:44 AM
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Originally Posted by Bill Curlee
That doesn’t sound correct!!! Traction control keeps the rear wheel from spinning. It decreases throttle angle and pulls fuel to control wheel slip.

COMP MODE lets the rear wheels spin but uses information from the SWPS and yaw accelerometer to apply and release the brakes to HELP keep the car in a straight line or in a direction that the driver turns the steering wheel.

If your engine makes enough power, it will easily OVERCOME TC and AH My measly 450 RWHP 02 ZO6 does!

I had a weird pull to the right when I roasted the tires. It turned out to be a limited slip clutch issue. The Belleview spring in the differential was broken and the clutch pack on the right wheel did not lock up the same as the wheel on the left.

Put the trans in neutral, and jack up one rear wheel. Try to rotate the rear wheel and see how much force it takes. A new set of clutches in the differential is approx 110 ft/lbs. That decreases as the clutch pack wear.
Do the same to the other wheel. They should both be close to each other. My left wheel was 75 ft/lbs. the right wheel was 45 ft/lbs

Here is what caused the issue:






Compare the mark on the right to the mark on the left. It started out making weird marks and a slight pull .





Bill
isn't that what I said? if you want to spin the tires turn tc off... if u want to fish tail turn comp mode on
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Old Nov 5, 2013 | 10:59 AM
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Hows your alignment? I know when I got my GS it was all sorts of squirrly under heavy acceleration. Had the car realigned to Pfadt's street tire aggressive specs, and its a whole new car when on the throttle..

Just a thought
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Old Nov 5, 2013 | 11:46 AM
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Originally Posted by UrbanKnight
Hows your alignment? I know when I got my GS it was all sorts of squirrly under heavy acceleration. Had the car realigned to Pfadt's street tire aggressive specs, and its a whole new car when on the throttle..

Just a thought
Next on my list. Where are these specs available?
Thanks
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Old Nov 5, 2013 | 12:17 PM
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This should be it
http://www.pfadtracing.com/pdfs/Corv...09.12.2011.pdf
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Old Nov 5, 2013 | 02:32 PM
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Be sure your alignment shop reads the fine print. With Pfadt's specs a negative number indicates toe in, whereas in the factory specs, and on most (all?) alignment machines, a positive number indicates toe in. This has resulted in some bad alignments due to the confusion. Toe out, especially in the rear, can make the car want to go anywhere but straight.
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Old Nov 5, 2013 | 03:40 PM
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Street tires @ 620/620!
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Old Nov 5, 2013 | 04:19 PM
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Originally Posted by Bill Curlee
Yea,,, I suppose you have NEVER done anything wrong!!
The difference between you and I:

I RESPECT LIFE AND PROPERTY OF OTHERS.

HOW WOULD YOU LIKE: DURING MY "WRONG" DOING IN THE PARKING LOT AND T-BONED YOUR CAR WITH YOUR FAMILY IN IT, WHILE YOU ARE BACKING OUT!

---

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Old Nov 5, 2013 | 04:48 PM
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Originally Posted by victorf
The difference between you and I:

I RESPECT LIFE AND PROPERTY OF OTHERS.

HOW WOULD YOU LIKE: DURING MY "WRONG" DOING IN THE PARKING LOT AND T-BONED YOUR CAR WITH YOUR FAMILY IN IT, WHILE YOU ARE BACKING OUT!

---



Thought everyone knew that Traction control off is the way to keep the rear from coming around.
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Old Nov 5, 2013 | 08:41 PM
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Originally Posted by victorf
The difference between you and I:

I RESPECT LIFE AND PROPERTY OF OTHERS.

HOW WOULD YOU LIKE: DURING MY "WRONG" DOING IN THE PARKING LOT AND T-BONED YOUR CAR WITH YOUR FAMILY IN IT, WHILE YOU ARE BACKING OUT!

---

Hey Victor
I just checked your profile and I see your retired. That means your probably kind of old and I always respect old people. However I would really appreciate it if you would leave my thread alone. I'm just trying to get some answers here and not stir up any kind of social debate. Thanks and I hope your enjoying your retirement.
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