Really bad vibe
 

Ok I'll get right into it when i'm slowing down iI have this bad to really bad vibration it feels like the rear end then it transfers all theway up the drivetrain through the shifter. And it only dies it when i'm slowing down or coasting. It doesnt matter if the clutch is in or out ,or if its in gear or out and it gets worse the slower i go. I've had people say its the U-joints Diff And trans it better not be the trans because i just put in a T-5Z

Thanks
Jason

It's something between the output shaft of your tranny and the wheels. I would check the condition of the u-joints, and have the wheels balanced, and go from there.

Take care,
~Chris

Could be as simple as a loose pinion nut. Had my 3.73s 'professionally' installed so I never gave it any thought. After a new FMS aluminum shaft and a transmission rebuild it still vibrated. Got out the 250#dial indication torque wrench and turned that nut a 1/4 turn before it even moved the needle. Torqued it down to Ford spec of 140# and the vibration went away.

I was thinking an unbalanced wheel too but it gets worse as i slow down

other than changing the fluid which i did myself the diff cover has never been off it even still has the 3.08s. I was thinking a bad Trak-loc?

Does it vibrate at idle sitting still? Could be your harmonic balancer if it does. I've seen the centers spun before on factory balancers.

If you don't want to get the back tires balanced, try swapping the fronts with the backs. If the vibration moves to the steering wheel, it's a tire/rim out of balance.

Take care,
~Chris

it's not the balancer it doesn't do it when i'm sitting still

If your u-joints are good, drop the shaft and put a wrench on the pinion nut. Has the car always done this since you've owned it? or is this a recently developed problem? If the pinion's tight, I'd get a set of carrier bearings and axle bearings and replace the old ones. I wouldn't fool with the pinion bearings 'til I didn't have anything else left to check. Before you do bearings though, you might take your driveshaft to a machine shop and have them check the balance. Maybe a balance weight came off.


Bring the car to Ford Nationals at Atco next weekend. It's always easier to figure out problems by feel and listen than it is to guess at the keyboard.


Good luck.

I really started to notice it on tuesday night and i've had it since october. i'm going to check the shaft and u-joints tomorrow

Was asking around for you. Somebody said it could be warped rotors. Might want to check them out before you get too deep into the back end.

If you're experiencing vibration in the rear... and not depressing the brake pedal... then it's not a case of warped rotors :)

Otherwise, looks as though it's gonna be a process of elimination from the output shaft of the trans to the tires...

I was just wondering what your bad vibe turned out to be and how you fixed it.

If the problem occurs only when you slow down, then the "decelerate" face of the rear end gears could be damaged. Its worth it to take the cover of the rear end and take a peek.

FIXED
 

Loose Driveshaft