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Squealing drive shaft (what could be the culprit?)

updated thought it was only from one side but it turned out to be from the driveshaft.

Just started today. When in motion I get a squeak or squeal from somewhere along the passenger side that sounds almost like a bad belt (it’s not) that raises in volume with speed and decreases when slowing to the point where if under 5 mph you won’t hear it. It’s not effected by braking, turning, or RPMs. My suspicion would be bearings but I’ve never heard bearings squeal, only roar. I’ll test it myself tomorrow, but is there a chance it’s E-brake related? I just did a clutch job and had to remove and reinstall the arm for the E-brake while I did it.

More info: 66 Mustang, 200 ci, Manual trans, 9in drum brakes, power nothing.

Check your work again…Maybe the e-brake adjustment is off and cause rubbing of the brake lining inside the drums.

I’ve got an update!

It’s not the E-brake, it’s the drive shaft!

I greased both the seal and the slip yoke before it in the seal. The singing sound, as I would now describe it, changes pitch seemingly on its own accord and it started about 20 seconds after I started moving.
Is this U-joints or something related to the slip yoke?

I get a squeal/chirp sound from my Ford truck’s driveshaft sometimes. Early 70’s in my case. It’s usually not continuous but more a chirp chirp chirp sound, with the frequency corresponding to the vehicle speed. I’ve always been able to get it to quiet down by thoroughly lubing the driveshaft. All u-joints, and especially like you mention, the splines where the two halves comes together. Sometimes I have to lube it, drive it for a week, and lube it again. Be sure to get all the lube fittings on the u-joints, its easy to miss one. I have to use a custom-made needle grease applicator b/c of access problems to the u-joint fittings.

Be sure to twist the drive shaft , testing for play in the u-joints, while you are working on it, you may have a bad u-joint. All the lube in the world won’t fix that.

BTW, are you noticing a sort of clunck noise when you accelerate from a stop? If so, lubing the drive shaft’s splined joint can help that problem too. There are synthetic greases especially made for that problem.

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It’s worth noting that the U-joints are completely shot on this car. The rear one fell apart when I went to put the shaft back on after the clutch job. If it’s U-joints, then everything is basically fine because it’s an easy fix. My concern is that its something screwed up with the seal on the output shaft housing or something with the output shaft itself.

Just a quick question, what should I slip yoke in a new output shaft seal look like? Should it just slide on with little effort or, like how mine was once I changed the seal, require a little squeezing and pushing to get it on?

Oh, and no clunks. . .yet.

I’m presuming you’re referring to the transmission output shaft, right? My truck is 4WD, so I’ve never dealt with that part, b/c there’s a transfer case in-between the transmission and the drive shaft. Maybe somebody else here knows.

If I had your symptom and with known problem w/the existing u-joints, I think I’d probably just remove the drive shaft , set it up on the work bench and replace all the u-joints and clean and lube the splined joint (assuming you have a two part drive shaft). Good opportunity to check the flanges on each end too for signs of problems.

I presume you are aware there’s a magazine that specializes in repair and restoration of Mustangs of this era. The advertisers in that magazine would be a good source of info for problems like this. I think it is called Mustang Monthly, something like that. They may sponsor a web site w/user forums too.