vibration at high rpm
 

my car drives fine normally, but at wot when the car reaches the higher rpm i feel a strong vibration from under the car like its coming from the trans or driveshaft along with a burnt kind of smell, is this a trans prob?

out of balance driveshaft? wheel weight might have come off. do you have a poly trans mount?

yes i have poly trans mount and it still looks good, i haven't checked the wheel weight

poly trans mount shook my car like crazy at highway speeds. worst mod ever. try and get a oem rubber mount and see if that is your problem

Does it do it at a certian speed also?

no, just at the top of 2nd or 3rd, i don't go to the top of 4th too often.

I just got my car back got a new 6.0 370 in it. I have a polly mount on it. About 55 I get a vibration coming around my tranny / drive shaft area. I have no clue. Looks like the shaft might be moving around. But that sounds kinda crazy

if it is at a certain point during gear shifting could be a u joint. if its at higher speeds, its probably a driveshaft out of balance.

As you said, its with engine speed and not vehicle speed, correct? Many people are getting confused with both perspectives. Wheel speed will be constant with vehicle speed, not engine speed. Same goes for the everything behind the trans tail shaft that rotates to make the car move. Their relationship with respect to speed is linear when talking about vehicle speed no matter what rpm the engine is at. This might be redundant, but trying to help. I'd put my money on the poly trans mount. Many people on this board say that GM made them rubber for a reason. All of your vibrations from the engine/trans are now being transferred to the chassis.

Good Vibrations @ high RPMs huh, sounds like a good time to me?! LOL! j/k, since you'll be checking your wheel weights, might just double check your wheels while you're already there. if one has been bent even ever so slightly, it'll feel like hell on the road.

My car has been doing the same thing since I had my LS6 installed a couple months ago, smooth at speed but under high rpm load like say a 70 punch the floorboard starts vibrating at higher speeds. I can bring it up from a dead stop to first to like 5k rpm and no vibration but at high speeds it will and yes mine is auto with a prothane poly mount is that the culprit?

Poly trans mounts are THE DEVIL. I have tried them in my various six speed and auto cars and every time they make horrible vibrations.I have done the various mods to them left out plate ,shaved the humps,tried prothane and the energy suspension one.
They all make huge noise in my cars. Put stock in and much much better. But of course not too hard to break the stock one. I have relocated my torque arm off the back of the trans so not too worried now.

i had this problem and i changed my tranny fluid and it went away.