Please Help With Vibration Problem

erniet17 · May 16, 2008

Hey all. I recently swapped my tranny out for a T-5. Before my swap I had vibration at about 80-85 MPH and then it would settle a bit.The car starts to vibrate at about 80 MPH and dies down a bit after 85 or 90 MPH. Kind of the same thing as before. I replaced the driveshaft for a new aluminum Ford driveshaft, re-balanced the wheels, replaced the gears for 3.73 and replaced the harmonic balancer. The driveshaft tamed it down a bit. Any idea on what this could be? I don't know what else to change/check out. Thank you all in advance.

erniet17 · May 19, 2008

Wow! No replies???

S&B · May 19, 2008

have you changed suspension, is your pinion angle correct

erniet17 · May 19, 2008

The suspension is stock at this time. I am going to replace the shocks and struts soon. I would think that if it was the suspension that I would feel it throughout the whole car. There is some vibe throught the car but most is on the shifter. How do I go about checking the pinion angle?

skunk21 · May 19, 2008

Like S&B states you want check the angle. you want the angle of the drive shaft in relation to the rear end to be as straight has possible. when you look under the car the drive shaft should close to straight it won't be prefect. If the front of the shaft coming out of tranny pitches down and the rear pitches up the tail of tranny is up high(since the car is on stock suspenion the pumpking shouldn't have moved) I would check for worn motor mounts which will cause the motor to drop. you can look at your fan and see if has worn at the tips from rubbing on the fan shroud or is real close to the bottom of the shroud vs the top, also they will be dry rotted pretty bad and look collapsed. If it's the opposite the tranny mount maybe bad. most of the time it's worn motor mounts causing an issue. a bad pinion angle can cause binding and wear out the u-joints and I'm sure cause a vibration. that's a starting point anyways.

1987stangman · May 19, 2008

greensvt21 said:
Like S&B states you want check the angle. you want the angle of the drive shaft in relation to the rear end to be as straight has possible. when you look under the car the drive shaft should close to straight it won't be prefect. If the front of the shaft coming out of tranny pitches down and the rear pitches up the tail of tranny is up high(since the car is on stock suspenion the pumpking shouldn't have moved) I would check for worn motor mounts which will cause the motor to drop. you can look at your fan and see if has worn at the tips from rubbing on the fan shroud or is real close to the bottom of the shroud vs the top, also they will be dry rotted pretty bad and look collapsed. If it's the opposite the tranny mount maybe bad. most of the time it's worn motor mounts causing an issue. a bad pinion angle can cause binding and wear out the u-joints and I'm sure cause a vibration. that's a starting point anyways.

He did say that the car vibrated before the gear and tranny swap so pinion angle couldn't be it if he was running a stock rear and trans before unless he reused a drive shaft with bad U-joints. I had a vibration issue RIGHT after I installed my 3:55's. I did the install myself but was 100% sure of my work so I looked elsewhere. I had the tires balanced first but problem not solved and I already had an aluminum drive shaft. Vibration at the exact same speed and just when I started to doubt my work I noticed there was a odd deformaty in my right front tire. I had it check and sure enough it was bad. Once a new tire was installed vibration gone.

Front wheel bearings, bad suspension bushings, including rack bushings can all cause bad vibration including the previously mentioned motor & tranny mounts.

erniet17 · May 19, 2008

The motor mounts and transmission mount were replaced last month. I am going to take it to a guy that has been working on these cars for about 20 years. Maybe he can figure it out. The problem is that in Miami it is hard to maintain 80+ MPH due to all the traffic. Maybe he can look at the pinion angle and tell me what he thinks. I'll update the post when I find something out.

Please Help With Vibration Problem

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I hate my CT. :(

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Please Help With Vibration Problem

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