LT1-LT4 Modifications 1993-97 Gen II Small Block V8

Bad Vibration in 1st and reverse PLEASE HELP

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Old Sep 13, 2012 | 12:44 PM
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Default Bad Vibration in 1st and reverse PLEASE HELP

Ok so i just had low mileage LT1 engine put in my Z28 (40K miles) and a new clutch. problem is whenever i try so start in 1st gear and in reverse its shaking real bad (the whole car- makes me look like i cant drive stick)!!!! for me to get a little less vibration that i can manage to get the car moving is like at 2500 rpms or more...imma burn the clutch out but i have no idea what the problem is..also if i down shift the transmission will vibrate/shake a bit...to me this is not good . I really dont know. also my clutch petal shakes and vibrates engaged or not its shaking...never done that before so any insight or questions ill greatly appreciate it. BTW when i first start the car in the morning it isnt bad..it shakes but not bad when starting off...as it warms up it gets worse....PLEASE HELP it bothers me soooo much,. thanks guys
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Old Sep 13, 2012 | 01:23 PM
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Why did you "have a low mileage engine swapped in?
Was the donor a T56 car, if it was was the pilot bushing inspected? If not was a pilot bushing put in?

No vibration in neutral?
Is the flywheel balanced stock or did you happen to get a neutral balance?

You have checked all the ignition stuff right? Plug wires in good shape to the right plugs etc?
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Old Sep 13, 2012 | 02:04 PM
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Originally Posted by 96capricemgr
Why did you "have a low mileage engine swapped in?
Was the donor a T56 car, if it was was the pilot bushing inspected? If not was a pilot bushing put in?

No vibration in neutral?
Is the flywheel balanced stock or did you happen to get a neutral balance?

You have checked all the ignition stuff right? Plug wires in good shape to the right plugs etc?


the original engine had a 200K and blew so we jjust had another LT1 put in it...a shop did it..just until i build my LT1 but will take about a year or two...idk if the engine was from anothr t56 car, i doubt the pilot bushing would have been changed but not sure (is that a must?) IDK about the flywheel either....no shaking in neutral
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Old Sep 13, 2012 | 02:24 PM
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I never had any experience with what happens if you leave the pilot bushing out but what you are describing seems plausible for what could happen if it were.

The pilot bushing goes into the back of the crank and supports the tranny input shaft. Without it the clutch disc is out on a limb unsupported at the engine end. Can't imagine it would take much tranny input shaft deflection to cause a violent shaking.

I can't say for certain that is what it is, but if the donor car was an A4 that bushing would not have been there.
Check your receipts and see if a bushing is listed, consider calling the shop too.

To even check to see if that bushing is there the tranny has to come out and if it was forgotten they are at fault, this is very basic automotive knowledge, but also easily overlooked since there are so few manual tranny cars out there these days.
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Old Sep 13, 2012 | 03:52 PM
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Originally Posted by 96capricemgr
I never had any experience with what happens if you leave the pilot bushing out but what you are describing seems plausible for what could happen if it were.

The pilot bushing goes into the back of the crank and supports the tranny input shaft. Without it the clutch disc is out on a limb unsupported at the engine end. Can't imagine it would take much tranny input shaft deflection to cause a violent shaking.

I can't say for certain that is what it is, but if the donor car was an A4 that bushing would not have been there.
Check your receipts and see if a bushing is listed, consider calling the shop too.

To even check to see if that bushing is there the tranny has to come out and if it was forgotten they are at fault, this is very basic automotive knowledge, but also easily overlooked since there are so few manual tranny cars out there these days.

yeah ill definitely get that checked out....this isnt the first time they messed up. last time when i would down shift you would hear and feel a loud bang!! and i dont know why my clutch pedal is shaking i hate it lol i really dont even feel like driving it of how bothersome it is..but ill never go back to them again for sure..but for now they have to fix this problem
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Old Sep 13, 2012 | 04:13 PM
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Was the flywheel replaced?
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Old Sep 13, 2012 | 05:20 PM
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Originally Posted by 96capricemgr
Was the flywheel replaced?
i really dont know. i mean i would figure they would do that but probably not..thats what i kind of thought it would be or something off balance...but its smooth when shifting up...but earlier today if i shift at 2k 2100 2200 it will vibrate only a little bit and jump forward kinda...
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Old Sep 14, 2012 | 06:12 PM
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Missing any bell housing bolts?
I would deffinately go back to that place and raise hell!

And if negligence is the case and need be
Threaten them with a call to your lawyer
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Old Sep 14, 2012 | 06:30 PM
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Mine shakes pretty good to in first. Could it be a tranny mount?
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Old Sep 14, 2012 | 06:55 PM
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I suppose, and a tranny mount would be GREAT because that is simple. A tranny mount should be easy to spot as bad and resolve during the R&R, I jumped to the pilot bearing idea because it is easier to forget to install or fail to inspect
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Old Sep 17, 2012 | 06:55 PM
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well imma take it on a flat bed now...we took it on Friday and had them feel it and right away they said there was a problem and nice about it. anyways they told me to bring it Monday (today) but on Saturday i completely lost my clutch...Ive noticed that heat was coming through more than usual from the shifter area...anyways i was out Saturday night noticed my shifts were getting harder and stiffer to put in gear...after i parked and dropped my girl off i turned the car on and couldn't get in reverse at all so i pushed the car back...made it home but noticed i had no clutch at all....if i was in gear and pushed the clutch down the car would bog down and shake and sound like it was gonna die!!! so what you think now?? put the clutch in bad? hopefully i can get it there by Wednesday...before the clutch went out when driving it would feel like the brake was on lightly...i could feel that my car wouldn't throw me in my seat like usual, it was being held back..very lightly tho but i could sense the difference....appreciate the help tho guys...i wanna learn a lot more and get the tools so i can do my own work...im tired of this kinda stuff and paying these labor prices...lol
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