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Discussion Starter #1
I own a 2006 Cobalt LS, coupe, 5 speed manual, with 75,000 miles. Recently I have been experiencing what I believe to be a transmission/clutch issue. I am a mature adult driver (no hot rodding), however I am the second owner of this vehicle. I am very competent mechanically and have owned many manual trans vehicles, including multiple GM 5 speeds. The following is the issue I am currently experiencing:

When accelerating from a complete stop, the car starts jerking/shaking from 1st to 2nd. I have noticed that it does more so when there is additional weight in the vehicle (i.e. 3 average size adults, rater than just the driver only).

When this happens the whole car shakes and rattles. It doesn't seem to matter what speed the clutch is released/feathered. I have also experimented with different shift patterns and RPM ranges, only minor changes if any? It feels as though the clutch is being 'dumped' in a low RPM, but just enough to keep the car from dying. From a bystander's view it looks as though the driver is first learning to drive.

I am not aware of any other mechanical issues. Also, just to note this doesn't occur when the car is accelerating from a rolling start. Only when there is the initial force to overcome. As I stated it is amplified by extra weight. I do not experience this in any other gears.

I have searched this forum and have not been able to locate a similar thread. Thank you in advanced for your help and I pray (literally) that this doesn't mean I need a new clutch or transmission.
 

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I have the same Exact issue with mine!! Just have not had a chance to post a thread. Don't worry, the crew here is amazing! It's only a matter of time before we get some trouble shooting and explanations.

I'm driving a 2006 SS/SC 5spd
 

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if you drop it from 5th to 3rd for a hard pull on an incline will it slip?
 

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if you drop it from 5th to 3rd for a hard pull on an incline will it slip?

Humm... with my issue...I'm not quite sure..Have not hit or found a big hill yet. Though I know of one in a city I am going to today. I'll find out.

Thanks!
 

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Levee
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Ok, for both guys having this issue, do this for me and you can actually do this in your driveway. At a dead stop with the car idling, put the car in 3rd gear. Without hitting the gas, dump the clutch as if you were trying to do a burnout without hitting the gas lol. If the car dies immediately, your clutch is fine, if it bucks and jumps and trys to stay running, your clutch is underspec and needs replaced.

Now for another question for you. Do your cars have a hard time going in and out of gears? And where is the clutch engagement point at? Is it pretty high like around the brake pedal or higher? Or is is close to the floor? Let me know.
 

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Ok, for both guys having this issue, do this for me and you can actually do this in your driveway. At a dead stop with the car idling, put the car in 3rd gear. Without hitting the gas, dump the clutch as if you were trying to do a burnout without hitting the gas lol. If the car dies immediately, your clutch is fine, if it bucks and jumps and trys to stay running, your clutch is underspec and needs replaced.

Now for another question for you. Do your cars have a hard time going in and out of gears? And where is the clutch engagement point at? Is it pretty high like around the brake pedal or higher? Or is is close to the floor? Let me know.
Levi to the rescue!! Sweet.

For me switching gears is nice and smooth. Catch point is pretty close to the floor board. Not high up.

Question, before I go dumping the clutch to test there is a car litteraly 2 inches in front of my car...never done this on purpose, so should I move just in case? Or am I s....I''m gonna move over. Sounds like the right thing to do. lol

Stay tuned!
 

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Levee
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Yes please move the car if you have something in front of you, and have the e-brake on just in case. You never know lol
 

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Yes please move the car if you have something in front of you, and have the e-brake on just in case. You never know lol
Yay! Clutch is good! Stopped dead.

The other symptom I have is that the engine doesn't settle down when i come to a stop. It ..... bounces the tach.... Weird right?
 

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Levee
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Yay! Clutch is good! Stopped dead.

The other symptom I have is that the engine doesn't settle down when i come to a stop. It ..... bounces the tach.... Weird right?
If your car is still shaking and the clutch is good, it could be a slighly warped flywheel, and would need resurfacing.

Now as far as the idle at a stop, that is your IAC motor. Simple fix on that, just replace it.:cheesy:
 

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Nice! Thanks! I'll try and find a motor now and call my mechanic on the resurfacing. :cheers:
 

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Levee
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Nice! Thanks! I'll try and find a motor now and call my mechanic on the resurfacing. :cheers:
Resurfacing is going to need to be done by a Machine shop, not a regular mechanic so you know.
 

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Okay cool! Thanks. And this may sound amateur, cuz i am, but where exactly can I find the IAC? lol I am trying to get the part number off of it and I can not locate it in the Service Manual.
 

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Levee
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Discussion Starter #14 (Edited)
if you drop it from 5th to 3rd for a hard pull on an incline will it slip?
I will try this within a few hours.

Also, do you mean to shift from 5th directly to 3rd? Or 5-4-3rd?
 

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fifth to 3rd directly, its normally what my shop does if its not super obvious. What levi said sounds like an excellent idea as well
 

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Discussion Starter #16 (Edited)
Ok, for both guys having this issue, do this for me and you can actually do this in your driveway. At a dead stop with the car idling, put the car in 3rd gear. Without hitting the gas, dump the clutch as if you were trying to do a burnout without hitting the gas lol. If the car dies immediately, your clutch is fine, if it bucks and jumps and trys to stay running, your clutch is underspec and needs replaced.

Now for another question for you. Do your cars have a hard time going in and out of gears? And where is the clutch engagement point at? Is it pretty high like around the brake pedal or higher? Or is is close to the floor? Let me know.
I will try the dump from 3rd within a few hours and report back ASAP!

With mine I have no problems shifting through the gears, nice and firm.

I'll check the engagement point here soon too. But, I believe that it is below the brake pedal point. But let me make sure.


---------- Post added at 02:17 PM ---------- Previous post was at 02:07 PM ----------

:thanks
Thank you all for the help! I was not expecting this, so I haven't checked on replies until now. Shows me how wrong I am! I am so grateful for these forums! Especially for those who do not have the money to go to an auto shop every time something needs checked!
 

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Levi will voice his opinion on this but from what ive understood of the hydraulic systems is that the fluid is there so the pedal basically stays in the same spot until the clutch is done. I would assume if it was noticeably higher that you would have problems with slippage in normal driving (i.e clutch rivets rubbing on the flywheel)
 

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Discussion Starter #18
So as far the dump in 3rd:
-I tried this a few times and w/out the park brake on the car dies rather quickly.
-It does try to keep running but only for a second.

-Then I tried with the park brake and it dies as soon as clutch is released.

The clutch starts engaging less than half-way to the brake. So fairly close to the floor.

Also I did my best attempt of the 5th to 3rd on incline. Was not really up to correct speed for 5th. But, down shifted to 3rd No problems.

So, now I need help interpreting all this.
 

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Levee
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Levi will voice his opinion on this but from what ive understood of the hydraulic systems is that the fluid is there so the pedal basically stays in the same spot until the clutch is done. I would assume if it was noticeably higher that you would have problems with slippage in normal driving (i.e clutch rivets rubbing on the flywheel)
Kind of but not really. Your clutch works just like your brakes but backwards. The better the clutch, the lower the engagement, the worse, the higher. Thats why when people replace clutches will stall a bit because of the new engagement point.

---------- Post added at 10:01 PM ---------- Previous post was at 09:56 PM ----------

So as far the dump in 3rd:
-I tried this a few times and w/out the park brake on the car dies rather quickly.
-It does try to keep running but only for a second.

-Then I tried with the park brake and it dies as soon as clutch is released.

The clutch starts engaging less than half-way to the brake. So fairly close to the floor.

Also I did my best attempt of the 5th to 3rd on incline. Was not really up to correct speed for 5th. But, down shifted to 3rd No problems.

So, now I need help interpreting all this.
Ok, so by the engagement point, the stalling/hesitating to stall, clean gear changes and no slip, that all tells me the same as Ryan. Sounds to me like your flywheel is warped or under spec and your clutch is worn to the point where it may start slipping soon under harder acceloration (simple wear and tear for a clutch). I suggest new clutch, throw out bearing (clutch release bearing), and a flywheel resurface/replacement.
 

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The other symptom I have is that the engine doesn't settle down when i come to a stop. It ..... bounces the tach.... Weird right?
Interesting, I have the same problem. Usually happens when I depress the clutch coming to a stop at ~1000 RPM. Tach falls to about 500, lights go dim and the car shudders for a split second, bounces back up to 1200, and settles back to a normal idle. Happens more often when cold. IAC motor you say? Will have to look into that, thanks.
 
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