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Heaving / Jerking at low speed

Old 08-21-2012, 07:10 PM
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Default Heaving / Jerking at low speed

So I've been noticing in my '01 SS that when I'm at low speed (< 25mph) I occasionally get this heaving type forwards backwards movement (its most prevalent at constant throttle, maybe 1500rpm). The best way i can describe it is that it feels similar to letting the clutch out too fast and you get the forward/backward jerk real quickly as the energy from the flywheel gets put to the wheels, but over and over.

This occurs when im fully in gear, its most obvious in 3rd gear, around 1500 rpm, but I can get it to happen in 1st and 2nd less noticably. It might do it in 4th occasionally but I might just be tricking myself in to feeling it.

Does anyone have any idea what this is? It seems odd in a car that drives so smoothly most of the time.
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Old 08-21-2012, 07:16 PM
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is the car cammed???
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Old 08-22-2012, 06:22 AM
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Nope, this is completely stock except for a cat-back exhaust. That was one of my original thoughts, but it idles very smoothly and has not been modded.

My only other thought is that the car does need a wheel bearing somewhere, but I haven't had a chance to check any of them yet. But I'd be shocked if it was bad enough to cause the car to do heave forward backaward. Also the issue stops with the clutch in, so it must be engine caused?
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Old 08-22-2012, 10:35 AM
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My car did similar when it was new and stock. I think it is just last in the drive train and you sort of bounce back and forth on the lash.

I think it is likely normal. It is only at lower speeds and some what flat ground if I recall. It has been a long time since it was stock.
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Old 08-22-2012, 11:04 AM
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Do you recall what mod made it stop?
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Old 08-22-2012, 01:34 PM
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Originally Posted by IceHammer View Post
Do you recall what mod made it stop?
Yes I do, 700hp + stroker, all rod end suspension, grabby clutch. I am sure it still does it, but other things now are banging, rattling and bumping get your attention!

Sorry, I think it is just the way they are. All the rubber bushings and lash in the drive train. If you are slowing down, or driving at highway speeds or speeding up no issues. I think the reason you get nothing at higher speeds is that there is lots of wind and road drag to keep everything loaded up, but at low speeds there is a lot less load and it kind of bumps back and forth. Plus our cars have pretty good throttle response right from the factory.
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Old 08-22-2012, 02:40 PM
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Well, since I wont be doing those mods anytime soon , I guess i'll try and skip 3rd around town more often.
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Old 08-22-2012, 02:48 PM
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Could be the low rpm. My car hasn't been stock in forever (I know it doesn't like that rpm anymore). A high gear/low rpm/large throttle open situation will load things up.
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Old 04-01-2018, 10:34 PM
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Sorry to dig up an old thread but just wondering if you ever figured this out or fixed it?
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