I have a 79 T-Bird with a 9 inch in it. When I am going down the road I can hear a hmmmmm, well not sure how to describe it, but it almost sounds like I can hear something turning as far as either my driveshaft or something in my rear end. I also have a leaking seal. Fluid was ok. Is my driveshaft out of round? U-Joint? Do I have a bearing going bad on my axle?
Thanks in advance
Chirs Diedrick

Chris, is it a humming sound?

You have a 79 with a 9 inch?????

It is a humming/ vibrating sound. Yes my 79 has a nine inch and I believe most did.

Yeah, I think that's correct, too. It does have the removable carrier, right?
I think the other offering for that year was a 8.7" 'WER' axle that had a cover on the back.

The T-Birds had a body style change (much smaller) for 1980, and they would not have a 9".

Reading between the lines a bit ... if the pinion seal is leaking, it's possible that the rear pinion brg is getting sloppy. Those 9" were awesomely strong though ... they even use a pinion pilot bearing that really helps to keep that pinion shaft straight and true.

Don

Could be a few different things, first a couple of questions for you. Does the noise change with road speed or engine speed? Does it change with the road surface? Does it change when you let off the gas or accelerate?

Your answers will help to narrow it down.

Rick

Well, I will be taking my car on a cruise this weekend. I will listen carefully to how is sounds at different highway and engine speeds. All I know so far is its there and at highway is consistent.
Thanks guys
Chris

There were some 8.8s in the Bird and Cougar, and even in the leaf spring Granada/Monarch in 80, their last year.

This is kind of odd, but the noise was there when I got the car out. I only really noticed it at highway speeds, and as I sped up, the noise went with me. Then mysteriously it went away, then would come back, then go away. There really were no drastic changes in road conditions, so I am stumped. Bottom line, leak is still there no matter what.
Chris

I believe Ford didn't start using the 8.8 until 1983.

The 80 Monarch deluxe version, (interior like the Versailles but without the roof) wore the 8.8 on leaf springs with drum brakes 57 1/2 wide, 2.47 gear. I robbed the rear and replaced it with an 8 and sold the cars. I know where there is one sitting right now, and am trying to get it.

I stumbled into this when buying Versailles for their disc 9", and I was replacing them with 8 " from a Granada, and reselling the cars,,,,,,, so, if you see a Versailles with an 8 inch.... Ford didn't build it.

Again, does anyone have any ideas to this problem. Only noticable at highway speeds, does not seem to change with road conditions, it is more of a vibration vs a hum, and I go through pinion seals.
Thanks
Chirs

I think you'll have to take it apart and look for yourself, Chris. (Or is it really Chirs? You've typed it a couple of times that way.)

If it's a driveshaft imbalance, I doubt that it would fade in/out like that.

Are the U-joints tight and greased?

Is there any lateral movement (up/down or side-to-side) in the yoke or anywhere else on the drive line?

Does the sound or vibration change on accelleration / decelleration?

Are there any obvious reasons that might lead you to believe that the pinion shaft or yoke may be bent? Anyone been doing "gear drops"?

Is there a chance that anything (cord, wire, etc) could be wound up on the diff yoke?

Have you done anyhing other than change seals? And did you lube the seal before installing it on a dry pinion yoke?

(I'm trying to think of things that keep taking out the seal AND/OR causing vibration)

You're going to have to be more specific, and tell us what you have tried.

HTH,
Don

Chris, what I'm about to say is intended as discussion - not public humiliation, as I have no idea of your skill level ... OK?

Now somebody correct me if I'm wrong here ...

The only time that you need to replace the crush sleeve is if you do anything that changes the position of the pinion shaft or the length of the assembled pinion and bearings ... correct?

The crush sleeve is only there to maintain a specified preload on the bearings, right?

To my way of thinking, it seems to me that a lot of guys are replacing these when they really don't need to ... i.e. when doing a seal replacement only. IF you are also changing either of the bearing cup/cones then yes ... change the crush sleeve.

Following this scenario ... if the average DIY guy that doesn't know better does replace the crush sleeve and just "snugs" up the yoke without torquing it to specs ... I'm thinking that that would allow the outer pinion bearing cone to wander significantly, as it would not be seated in the cup. Like I said earlier, a properly assembled 9" pinion shaft should be rock steady.

The other thought was to check to make sure that all of the needle bearings are in that rear u-joint. It's quite easy to drop a few of them when removing the driveshaft from the yoke. One or two missing rollers would be enough to screw things up in there... and that would display "come and go" type symptoms.

Opinions on my theories, anyone?

You could be chasing tire hum. Some vary widely as per road surface texture.

Here's what I would do.
Jack it up supported under the rear housing,
check the ujoints
pull the driveshaft off rear
turn that pinion to see if it is smooth (bad bearings)
check those rear wheel bearings for smooth... lots of bad ones will feel ok
pull that yoke and replace that seal
torque that yoke against the parking brakes,---- what is it 175 ???

you might get by without replacing the crush sleeve..... once it is crushed it doesn't have the resiliency that it originally did and the pinion bearing preload will not be accurate. (Think of it sort of like the stretchy engine head bolts that are used today.) that's why solid spacers are so popular.

check for tire noise. I'd almost bet that is your problem.