roser4888

I have a 05 cobalt s/c and it seems more noticed in 2nd and 3rd gear when I hit the gas and boost builds my whole car shakes violently. I know that the tires are not out of balance and I've never felt anything like this in any vehicle. It seems to be coming from the right front but its hard to tell with all the shaking. When I raised the vehicle on a lift and put it in gear and ran it the engine seemed to jump like a bad motor mount, but I replaced it. So far I have replaced:

R/f axle (boot split open)
R/f control ARM bushing
Top engine mount
Rear trans mount

Has anyone ever had this type of issue or know what it may be?

GRok25

are you throwing any codes?

roser4888

no, i wish i was though. i was thinking it was something in the suspension, but ruled that out when i took all the weight off of it. the only thing i can think is to replace the front trans mount but i dont even think thats gonna help.

GRok25

do you hear any metal on metal scraping, or squeeking like a bad bushing???

roser4888

no, theres no noises out of the norm. all i know is its not in the tires or the suspension. iit seems like a motor mount. none of them seem to be bad the 2 that i replaced had some looseness to them, i would expect that with 100k on the car. the only other thing i can think beside a mount is something internal going bad, but i only notice the bad shaking in 2nd or 3rd gear line the engine is rocking with the change in power.

GRok25

I would start by replacing the front tranny mount before going on to the motor because if it is the mount, you will save alot of trouble and money. trying to diagnose the motor that isnt throwing codes will be a bitch!

roser4888

thats what i was thinking but im tired of throwing parts at this car

chowell_09

You may wanna try replacing the other sides axel.

Not sure if your having the same problem I had but when I accelerated through 2-3.5k rpms you could literally see the columns on the dash shaking back and forth and feel it in your seat. We did the same thing you did putting the car on a lift and accelerating through the gears and we couldn't see or hear anything out of the usual. The only thing we could think of it being was a bad cv joint that got extended too far out causing the shaft to buckle back and forth. Not knowing which one to replace we went ahead and did both and that solve my cars issue.

roser4888

Might do that u did notice it after a Sharp turn.

roser4888

I did notice it after a Sharp turn.

chowell_09

I think I noticed it after I hit a bad pothole on the front right. I'm not too sure but my buddy who's a mechanic that's delt with bad fwd axles immediately said that's what was causing the shaking. I do recall him saying that taking corners hard can cause the joint to mess up, specially on the pos stock axles of ours.

Side story: before I took it to him I dropped it off at the dealer. They raised the car, saw that the springs were aftermarket and took it right on down. Wouldn't even look at the car lol.

roser4888

replaced both axles and problem went away. thanks