Real bad vibration question

[5.0literriceeater]

After a killer weekend at the wfc I started on the long ride home. As I was driving I noticed a vibration coming from the rear. At about 75 mph the car vibrated bad. Bad enough that the shifter was vibrating. I couldnt do anything about it on the road, so I kept going. Well, about 50 miles from home it got worse. Got so bad that it vibrated terribly at any speed. It seems to stop completely when I let off the gas. Clutch operation dosent effect the vibration. The harmonic balancer seems to look good also.

Anyone ever have this happen to them? I am leaning towards the tranny or the rear. I dont have any knowledge to base this off of because I have never had a vibration like this happen before. I just know I NEED HELP!!!!!!!

[blown93feature]

I would for the sake of argument check your tires to rule out the fact you didn't have a belt let go in the tire and also to make sure your balance is good. The next thing would be to see that you didn't blow a seal on the shock.
If those things pan out ok then check the tranny mount, if you do alot of pounding on her and you tear that rubber block, than you have taken it's ability to keep the tranny from bouncing every time the tires react to road surface.
I have seen times when the throwout bearing was almost on it's way out and will cause a bad vibration feeling through the drivetrain.
When your driving down the road, does the feeling come from the seat of your pants like a constant rubble strip feeling or does it seem like it's in your feet and hands "streering wheel and peddles"?

[5.0literriceeater]

I just replaced the clutch, pilot, and t o bearing about 3 weeks prior. Tranny mount then was in good shape. I dont think its the tires, but I will check them on a balancer just to make sure. Trust me, this vibration is not from a bad shock!! It does feel like a constant rumble strip coming from the bottom of the seat. The front suspension feels fine. Im thinking maybe a bearing in the input shaft might be out, or in the rear end. Its just too strong to be anything else.

[storm7127]

I don't think my problem is near as bad as yours but I have noticed when in higher gears...3rd,4th, or 5th that when at low rpms I get a lot of vibration up front and from the shifter. is this normal?

[5.0literriceeater]

If its at the beginning of the upshift its probably the clutch slipping a bit. If you mash it does it jump and rev?

[storm7127]

Yeah when I down shift and take off the vibrationis gone.

[Acedogg]

I have the same problem i just replaced both inner tie rods thinks it might be a bent tie rod or something mine happens about 2000 rpm when i let off the gas it just starts to vibrate real bad im leaning toward a bad tire or bearing any help ??????????

[Leo]

this might be a long shot but check ur drive shaft bolts they may be lose. and nothing in the world is scarier than having your drive shaft come lose on the road, especially the highway (trust me i know)

[Mrpeeps80]

you might want to check your u joints on your driveshaft. possible that there starting to go and that might be causing your vibration.

[greedy]

No one has mentioned this but it could be your rear end,
the bearing could be warn or the shims causing alot of play. this would of course get worse with higher speeds and would not show up to much during acceleration or deceleration due to drag, but cruising speeds it would show up most

[nufc1]

I just had my wheels balanced after a hard day at autox ,they were way out but not as bad as whats been said about shaking . hope it gets sorted out


storm if it aint there when you go fast THEN DONT SLOW DOWN LMAO C U M8

[Lawman]

this might be a long shot but check ur drive shaft bolts they may be lose. and nothing in the world is scarier than having your drive shaft come lose on the road, especially the highway (trust me i know)
Ding, Ding, Ding!!! We have a winner. It's the driveshaft.
My car was doing the same thing between 65-75 MPH. Supposedly they corrected the problem on the '04 Cobra.
I brought my car in, and they swapped out my '03 driveshaft for an '04.
So far, no more vibration.
There is a TSB on this problem. Bring your car into the dealership, and they will take care of it at no charge.

[5.0literriceeater]

Thanks for the ideas everyone posted. It turns out that it was a bad front u joint. Replaced them both, and the vibration went away! Now I have a new vibration. Its smooth at all speeds, but when I put it into neutral, like when I come to a red light on the highway, it vibrates slightly. It will also vibrate when the clutch pedal is pushed down. New king cobra clutch kit (t/o, pilot, clutch, and pressure plate) was installed about 1000 miles ago. Im thinking it has something to do with this clutch kit. I didnt like it when i put it on, and now I think I will never buy another king cobra!