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Discussion Starter #1
I about to swap out the regular steel shaft in my 95 Thunderbird(4.6) for the 93 MKVIII aluminum one. Consequently, i have a vibration on the highway accompanied by an obnoxious noise. My goal is to hopefully eliminate the driveshaft and everything behind it by running the car up to the speed where the noise/vibration happens and see if its still there. If it is then i would be able to say without a doubt that its not anything in the rear of the car.

Can this be done? Is there any damage that will occur if i do this. I wasn't sure if maybe the rear seal on the transmission may require the slip yoke to not leak or any number of other things.

Thanks alot.

Willum
 

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i guess i dont exactly know what you mean...so you want to drive the car on the highway without the driveshaft...you gonna have someone push-pull you on the highway? Are you also removing the pumpkin and half-shafts? I guess I just don't get it.

If I am correct...yeah you'll need to put a slip-yoke in the rear of the trans, or it'll probably leak. Plus, you don't wanna get road debris up in the trans or around the seal. Put a slip yoke in and find a way to secure it in there (bunjee cord) without damaging the rear seal.

Have fun...heheheh

-danimal

P.S. does anyone else have trouble typing with those damn smileys dancing around and crap??? jeeeez

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Discussion Starter #3
no, thats not what i meant

I meant, the car up on ramps with no drive shaft. Just sitting there still and not moving.

So what i'm saying is, that the car will be sitting at 0mph in the parking spot but for all the car knows its doing 70-80 miles per hour. No shaft so no movement but if the vibration and noise is still there then i know where its coming from. If its not there then i still have localized it somewhat. This is a pretty persistent problem and no one that i've talked to yet can figure it out so i'm resorting to any means necesary to figure it out.

One more question now though; While the shaft is out of the car you can look at the end of the extension housing and see the splined end where the slip yoke slips over. Is that splined thing supposed to move any up/down/left/right? I'll probably take a picture with my digital camera to show what i mean, but maybe this explanation is sufficient.

Thanks alot, i appreciate you tryin to help. Any more help will also be appreciated.

Willum
 

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that is the output shaft...and it really shouldn't move other than rotating.

The idea of taking out the driveshaft and running the motor and trans up isn't possible. If you have the trans in gear (which you are saying you want to do) the output shaft will be spinning...so the slip yoke will spin...and probably come flying out. Trans fluid is pumped to those rear bearings, so it will then shoot out everywhere... I don't reccomend that at all...

-danimal
 

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Yes, why not...

With the car level and on jack stands, you can do it. What you expect to accomplish, I'm not sure. A MMC shaft will eliminate shaft vibration. Most MN12 vibrations comed from out-of-round tires and/or brake rotor run-out. Other problems come from worn suspension parts or bushings.

A-Train
 

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Discussion Starter #6
noises/vibrations i have

I have a vibration that occurs anywhere above 55mph and gets quite loud/strong at around 70 mph. I know that the noise is not coming from my front suspension because i have run the car up to this speed on jackstands with the tires up off the ground and the noise is definitely still there and it seems to be coming from the transmission area. As for the vibration, it was there but i don't think it was quite as strong.

If it is the tires/wheels etc that will soon be solved because i bought a set of supercoupe wheels from a guy recently and will soon put new tires on them and have them on the car. So if its tire vibration, that will take care of that.

The thing that really bothers me is the noise. It is coming from the middle to front section of the car because you can lean the seat back to where you head is essentially in the back seat area and its quiet as can be back there. But then you lean back forward again and theres my low pitch resonating throbbing noise again.

I just don't get it to be honest, i've had three dealerships try to figure it out and a driveshaft shop in the area was sure it was my u-joints and that turned out to not be the case. So now i'm putting in the mkVIII shaft(having the joints transferred over) and maybe that will help a smidget.

I have considered that internal bearings in the trans, the output shaft bushing(what this thread was supposed to be about to begin with) and the torque converter, but don't have thousands of dollars to pour into finding the problem so i need to know what it is, buy it and fix it rather than buy this, that didn't fix it, so now buy that... welp, that didn't do it either.... etc

Any suggestions would be greatly appreciated.

Thanks
Willum
 

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Greetings,

I had a similiar problem, I believe. Vibration started getting bad around 60ish and was downright frightening around 75ish. Turns out, one of my rear wheels either wasn't torqued down properly or was off-center. By off-center, on both of my rear hubs there's a small dot of paint on the hub. I don't know if this is common or not, but I have them. By lining the valve stem up with that dot, my vibrations went completely away. Another free thing to test out before you drop cash on a new driveshaft. :) Good luck!

HTH,
-joe
 

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It's the driveshaft,or the extension housing bushing...one of the two.
Don't waste your time looking at other things..as they do not make a resonating vibration as you describe.
JL
 

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Discussion Starter #9
Now my next question is:

Can anyone tell me what all is involved in taking off the extension shaft housing and then what is involved in changing that bushing. I imagine that the bushing is pressed in so it may be necesary to have it done professionally, if thats the case, what kind of shop would be a good place to take it.

Will i lose all of the trans fluid when i do this? or will it be an exxon style trans fluid spill but not all of it will come out... etc I'm planning to change the fluid and filter and go with the new pan design soon so it really doesn't matter to me at all if i lose the fluid. It just means more stuff gets done before my car comes off the ramps it currently sitting on and that it may be there a little longer than i had expected.

Fortunately for me, we have another car so theres no problem, just an inconvenience.

Thanks for the know how in advance,

Willum
 

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You can't buy the extension housing bushing from Ford...only the complete housijg with bushing already installed.You'll have to buy it seperate from a trans shop,etc..,and the special tool tool install it.
JL
 

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Discussion Starter #11
any other hints on removing the housing etc?

Curious what all i need to know to get it off of there and then get it back on.

Also wondering if i need to be ready to wear trans fluid.

Thanks, i'll stop by a trans shop on the way home today and ask about it

Willum
 
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