89 Mustang 5.0 Vibrates after hitting 60MPH

[mixael-17]

Hi, there

I have a 1989 Ford Mustang 5.0 that vibrates when just after I pass the 60 MPH mark, the tires are brand new and are balanced. I have replaced the rear horizontal shocks. I don't know what could be causing the problem. Could it be the differential or the rear axle? The car runs good and smooth before hitting 60 MPH once I do that the rear part of the vehicle and the center console just starts vibrating alot and it stops after it falls below 60 MPH. Any suggestions would help!

Mixael

 

[Roland69]

have you had the drive shaft out

 

[Sicarius428]

Check your U joints too.
Kevin

 

[Darkwriter77]

You don't have any upgraded rear gears, do you? A lot of cars with 4.10's and sometimes even 3.73's will experience rear-end vibration at highway or high speeds. Mine tends to get a weird sort of buzz at around 85 MPH, but it's not a terribly serious vibration. If it's affecting you at speeds as low as 60 MPH, though, I'd lean more toward it being something relating to the driveshaft - either it's out of balance, one (or more) of the four mounting bolts is loose, or your U-joints are getting wallowed out and sloppy.

Get under there and wiggle around on it. Look to actually SEE if there's any play at either the front or rear of the driveshaft U-joints - the whole shaft can usually be moved up and down a tad, but if the looseness is in the joints and not between the shaft and the rear of the transmission, you've got a problem.

 

[5ive.oh]

There is a bushing in the back of the transmission behind the flange that could be worn. I had an 89 that was vibrating badly, I replaced the whole rearend and it still did it but not as bad. I sold the car before I could get to the bottom of it though. However that bushing did need replacing, it's a bitch to do though.

 

[black89hb]

I'd check the DS. Mine did the same thing. I would feel the vibration through the shifter.

 

[jrichker]

Have the tire balance checked at another shop. I recently has Sam's Club try to balance tires 3 different times before they gave up & gave me a refund.

 

[68keyblr]

Yep, check tire balance again. More than once I've had new tires that were "supposedly balanced" cause a vibration right out of the tire shop.

 

[GreatWhite]

If it's not the tires, definately get an aluminum D/S

 

[Ellis Fox]

have a recommended shop do a road stress test on your tires, standard balance may not detect an issue... happened on my wifes 4runner

if that passes, go through your driveline back to front, check your bolts, check ujoints, check for dings in your driveshaft, check your transmission mounts.

also make sure to wiggle the heck out of your exhaust back to front, any contact may be your problem... drove myself crazy one weekend until I found that.

good luck man

 

[wht93gtEd]

a lot of people are mentioning the drive shaft, but if this has happened right after getting new tires, and nothing else was touched, then it's more than likely from the tires.

have them re-balanced...usually the place you got them from will do it for free. Just pop all the weights off and tell them they fell off right during yor drive home.

 

[fidstang]

We need a sticky with a check list for the "vibration" questions as much as they come up. It would be much easier then looking through all of the old post. Then posting a new thread because your tired of reading and skipped the one that actually had the answer.

 

[Aliate X]

Probably a driveshaft problem, if the rear wheels are out of balance you usually dont feel it that bad. Unless the steering wheel is vibrating too.

 

[fidstang]

Axle bearings will shake the whole car at 60-70mph.

 

[Pokageek]

I had this problem on my car and it turned out to be DS. Mustangs are known for this problem. My FRPP DS solved this issue. Try re-balancing first though. Was it a new guy that did your balancing? That's frustrating. it is a pain to have to do things twice.

 

[87Mustang351]

i have this problem i put other drive shaft in new u-joints on my DS new tranny moutn new tires and balancing a line up tie rod end, the vib is in the back and is runnoing from there to the consol right to my shifter handle,like i said b4 i could get a girl off on my shift handle i need toget this fixed

 

[rigamaroles]

I have the same problem, but its not until I hit about 160+ (km/h)...the thing is, if it was the driveshaft it would be based on revolutions, not speed. Therefore it would do it in all gears when it hits that certain rpm. If you're talking 60 mph, and lets assume you have 2:73 gears, then you're probably sitting in and around 2000 rpm, if you're in fifth. If the vibration doesnt occur at similar rpms in lower gears then it really shouldnt be the driveshaft... I would get your wheels re-balanced, I've seen and felt what unbalanced tires feel like, its probably quite similar to what you are experiencing.

 

[87Mustang351]

i dont know but im selling my five oh anyways

 

[87Mustang351]

hey man do you have any pics of the bushing or where it is? i am going to try this, did you talk to the guy and make sure thats what he did to fix it?

 

[Darkwriter77]

Wait, wait ... driveshaft is based on revolutions and NOT speed? How do you figure that? If you're sitting at a stoplight and you rev the engine, the driveshaft isn't turning at all - it only spins as fast as the rear end gears are going. It's merely transferring power from the output end of the transmission to the rear gears which, in turn, divide (or would that be multiply? I suck at math...) the number of the driveshaft's revolutions that the wheels, themselves, shall spin.

In short, the faster you go on the highway, the faster your driveshaft spins, and the more likely any imperfections in its balancing and/or connections are going to reveal themselves. There's a more steep ratio between the number of revolutions a driveshaft spins versus the rear wheels on, say, a car with 4.10's versus one with 3.08's, so a driveshaft that's got a slightly wobbled-out set of U-joints or an unbalanced shaft is going to rear its ugly head a lot sooner (at a lower speed) if you're running steeper gears.

But heck, why am I bothering to explain all this if you're selling the car, anyway...?