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Car "rocks back and fourth" during 1-2 shift

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Old May 23, 2007 | 09:49 AM
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Car "rocks back and fourth" during 1-2 shift

You know, you're cruising hard in first... you switch gears to second full throttle...

You're supposed to feel that whole thing called "acceleration", but instead your car rocks back and fourth once or twice (slightly noticible), and THEN accelerates.

I dont know how to describe it really, its kinda just 'hesitation' between 1/2 shifts at full throttle. Any idea what this is?

Is it lack of torque, and all of our 8's do it? Is my engine lose in the engine bay and rocking back and fourth, causing my car to do it too? Its annoying.
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Old May 23, 2007 | 09:57 AM
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I've never had that happen. I don't think you're timing your clutch/gas well enough.
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Old May 23, 2007 | 10:57 AM
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Originally Posted by RazzyBRX-8
I've never had that happen. I don't think you're timing your clutch/gas well enough.
Floored through first.
Approaching 8.5k.
Push in clutch 100% & Release Gas to 0%.
Pull down to second.
Release clutch back to 0% & Press gas to 100% simultaneously.

Not quite sure how else to do it

No matter how different I time it, i get the same results. Its a different rocking back and fourth than if you were a noobster driver, it's sorta like a hesitation.
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Old May 23, 2007 | 11:03 AM
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It sounds like you are giving it to much gas when you shift to 2nd. If it is doing what I think it is doing I have had it happen many times, but if I adjust how much gas I give it as I am releasing the clutch (not 100%) it seems to be smoother.

Curiousity....traction control on or off? if it is on, try it with it off. I always seem to have better luck that way, but it could just be in my head.
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Old May 23, 2007 | 11:16 AM
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Try keeping it floored when you shift gears....just do it really, really quick. It's called speed shifting. Very hard on your drivetrain so don't do it often.
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Old May 23, 2007 | 12:28 PM
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Originally Posted by HCTR154
Try keeping it floored when you shift gears....just do it really, really quick. It's called speed shifting. Very hard on your drivetrain so don't do it often.
Uggh, I dont trust this advice :P I've been driving a stick for... at least 7 years now, and I dunno about that!

BTW, it happens with DSC/TCS on and off. I did the whole hold the button down thinger to turn them both off, and it did the same thing.
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Old May 23, 2007 | 03:47 PM
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I think I know what you mean- mine does this too. It didn't always do it. It's kind of a hesitation on the shift and then it suddenly gains power. My motor mounts are bad. I've got it at the dealer this afternoon getting them replaced. I'll let you know if that fixed it.

What I think is happening is that the engine is moving around too much as you shift. This trips the knock sensor and the ECU retards timing for a bit until the sensor clears, and then you get the power back. Does your car idle a bit rough?
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Old May 23, 2007 | 10:19 PM
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Well, I'm going to have to wait a few days to find out if that fixed it- the motor mounts have to be shipped from Irvine to my dealer. At least they didn't take the car apart before ordering them.
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Old May 23, 2007 | 10:35 PM
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From: Alice, Texas
Originally Posted by Imidazole
You know, you're cruising hard in first... you switch gears to second full throttle...

You're supposed to feel that whole thing called "acceleration", but instead your car rocks back and fourth once or twice (slightly noticible), and THEN accelerates.
It's the 8's lsd yo!
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Old May 24, 2007 | 05:53 AM
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Originally Posted by abbid
i vote bad motor mounts
I just had the mounts replaced due to vibration... two weeks ago!
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Old May 24, 2007 | 06:03 AM
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You are supposed to get a bit of shaking when shifting from first to second. Difference is that it should be sideways fishtailing as your rear wheels try to tear the asphalt apart.

Thats at least what happens to me every time i make an agressive shift from1 to 2, 2 to 3 and even 3 to 4 i have once had a fishtail on dry asphalt at full throttle.
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Old May 24, 2007 | 06:31 AM
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Originally Posted by PerSmitt
You are supposed to get a bit of shaking when shifting from first to second. Difference is that it should be sideways fishtailing as your rear wheels try to tear the asphalt apart.

Thats at least what happens to me every time i make an agressive shift from1 to 2, 2 to 3 and even 3 to 4 i have once had a fishtail on dry asphalt at full throttle.
I wish! I cant even get the sucker to chirp. Granted, I never hold the throttle in DURING my shifts (I like my car in one piece?) - but nope, no luck here.
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Old May 24, 2007 | 07:25 AM
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diable your DSC & TSC. Then you should be able to chirp
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Old May 24, 2007 | 08:05 AM
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Originally Posted by peterlemonjello
diable your DSC & TSC. Then you should be able to chirp
Thats also a misconception. You only have to press the button quickly once so the light DSC OFF lights up. TSC has nothing to do with chirping. It kicks in under hard breaking while turning. There is a demo video from best motoring on this site somewhere.

So all in all, there is no need to hold the button 7 seconds to chirp tires. I have stood still for 3 seconds + with white smoke around my rear tires by just pressing it quickly and then flooring it in a start.

Probably the suckiest start i ever did....
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Old May 24, 2007 | 05:29 PM
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Originally Posted by HCTR154
Try keeping it floored when you shift gears....just do it really, really quick. It's called speed shifting. Very hard on your drivetrain so don't do it often.
Thats funny, I thought that was called ruining your gearbox. Its a street car with synchronized helical cut gears. You can't shift like that without inflicting some major hurt on your car.
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Old May 24, 2007 | 07:09 PM
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maybe its detonation
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Old May 25, 2007 | 12:38 AM
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Originally Posted by eforer
Thats funny, I thought that was called ruining your gearbox. Its a street car with synchronized helical cut gears. You can't shift like that without inflicting some major hurt on your car.
If you fully press the clutch it should work, no? I dont know what he originally meant with speed shifting, but it sounds to me he only wants to keep the rev up on the engine. Same thing would be achieved by pressing clutch, changing gear, reving up, releasing clutch. I wears a bit more on the clutch but why would it hurt the car otherwise?
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Old May 25, 2007 | 05:57 PM
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Its not DSC/TCS, and since I replaced the mounts at the dealership 2 weeks ago, I sure hope it isnt that.

It sucks. Makes the whole 'going fast' thing a real drag when your front end kinda goes up down up down after the 2nd shift.
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Old May 29, 2007 | 03:28 PM
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From: A swirling eddy of electronic mayhem
You may have some other suspension problem. How are your shocks?
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