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Thread: Driveshaft or U Joints?

  1. #1
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    Default Driveshaft or U Joints?

    I took a video but you canít hear the noise so Iíll try to describe it. On my 87 mgm thereís a vibration through the body pretty much at anything above 30 or so. Now when I get to about 60 it starts to vibrate worse and thereís a hum. Itís sort of like a week bearing hum but it comes on within 5 mph and increases with speed and instead of a steady hum itís like it oscillates. I know Iím not the best at describing noises but thatís the best I can do. I have u joints on standby as Iím sure the ones on it are original but could it be the driveshaft itself?


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    GMN Regular DerekTheGreat's Avatar
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    Oscillates. That sounds like a bad u-joint to me. They kind of pulse. If it was the driveshaft, the whole dash would shake and all that.
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    Iíll do the u joints maybe this weekend when I have more time off. Yeah itís like a pulse and it comes on quickly instead of a wheel bearing sound that starts off at low speeds and gradually gets louder. And I couldnít change the sound when I would steer the wheel either way so Iím sure youíre right.


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    GMN Regular WagonMan's Avatar
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    A good indication of bad U-joints is a major "clunk" when shifting from drive to reverse. Any noises then? WagonMan
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    Quote Originally Posted by WagonMan View Post
    A good indication of bad U-joints is a major "clunk" when shifting from drive to reverse. Any noises then? WagonMan
    I will +1 this but I will also note that U-joints can be bad, and still tight.
    I would also guess that most of these cars by this point have a little bit more lash in the diff than they originally did, which can contribute a clunk, so a clunk also does not guarantee the u-joints are bad.

    Specifically, when the bearings in the U-joint dry out and start to seize up, the joint can be tight, but it does not move smoothly on the bearings, so it vibrates as it fights changing angles through the dry bearings.
    If it gets like this, it can be totally silent from inside the car, but might make a slight squeak-squeak-squeak noise when just idling forward in gear as it rotates.

    U-joints kind of suck to change but they aren't super expensive, and if their history is unknown, I'd just change them if it were me.

    I still have a wicked vibration in the wagon, at much higher speed than you, which I believe is coming from somewhere in the rear end. Keep in mind there are several bearings back there which can and do wear and fail, so your problem could be back there.

    If you can safely support the car in the air and let the engine idle in 1, with wheels turning freely, you might be able to get a better feel for where the noise is coming from which will help tell you where the problem is. This is extremely dangerous though, the risk of the car dropping off whatever you put it on is higher with the wheels spinning, and the risk of damage or injury if it does fall is also higher with the wheels spinning.

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    I'm an air-conditioned gypsy gadget73's Avatar
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    Pulling the driveshaft and running the joints through their full range of motion will tell you right quick. If its notchy or stiff at all, its done. It should move smoothly through the full arc of motion with no sign of hangup.

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    Quote Originally Posted by phayzer5 View Post
    I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

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    Default Driveshaft or U Joints?

    I donít have anywhere to safely put the car up on stands but that would be a great idea. And good call on the rear suspension. Iím sure itís all original, is there anywhere that sells rear control arm bushings for these cars?

    Wagonman, no thereís no thud going into gear.

    Gadget, itís easy enough to pull the drive shaft and change the u joints so yeah I think Iíll do that and check for stiff bearings. That was my thought as you and Kishy pointed out. The car has unknown mileage and I know has a few periods of sitting so Iím sure thereís bound to be something stuck.


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    Last edited by 87GrandMarq; 10-12-2021 at 06:43 PM.

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    while it is out make sure the shaft is true.
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    I'm an air-conditioned gypsy gadget73's Avatar
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    and do not put the slip yoke in a vise. Someone did that on my car when the U joints were changed before I got it. Couldn't ever get the damn thing to not leak at the tailshaft until I actually inspected the yoke and found the vise teeth marks on it.

    86 Lincoln Town Car (Galactica).
    5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

    91 Lincoln Mark VII LSC SE, triple black (Timewarp) - poly front bushings, KYB struts and shocks, Holley SystemMax1 lower intake, SilverFox AOD valve body,

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    Quote Originally Posted by phayzer5 View Post
    I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

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    Quote Originally Posted by gadget73 View Post
    and do not put the slip yoke in a vise. Someone did that on my car when the U joints were changed before I got it. Couldn't ever get the damn thing to not leak at the tailshaft until I actually inspected the yoke and found the vise teeth marks on it.
    Wow
    ..

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    Some people just shouldnít work on carsÖ

    And yes Iíll definitely check to see if itís straight and the weight is still there.


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    Ashley's '89 did not clunk when put in gear. However, it had a pulsing vibration that started around 65mph and got pretty noticeable at 80. Front U-joint was bad.
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    Thatís pretty much how Iíd describe it. And has a humming sound too like those trucks with the big tires.


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    I'm an air-conditioned gypsy gadget73's Avatar
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    joints have to be really bad to have enough slop to bang. usually means the needle bearings have completely disintegrated. They get dry and start binding long before they turn completely to powder. Its one of those deals where if you ignore it long enough eventually it will start to bang but very unlikely it went from perfectly fine to making nasty noises with nothing in between.

    86 Lincoln Town Car (Galactica).
    5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

    91 Lincoln Mark VII LSC SE, triple black (Timewarp) - poly front bushings, KYB struts and shocks, Holley SystemMax1 lower intake, SilverFox AOD valve body,

    1984 Lincoln Continental TurboDiesel - rolls coal

    Quote Originally Posted by phayzer5 View Post
    I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

  15. #15
    GMN Regular DerekTheGreat's Avatar
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    Quote Originally Posted by gadget73 View Post
    U-joints have to be really bad to have enough slop to bang...
    This.
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    Might not hear it over the exhaust if its non-stock in the early stages. BTDT.

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    Also, if the u-joints are seizing up, they won't bang either.

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    Since I have you guys here I have another question but itís about brakes. My 85 ltd had awesome brakes, this car does not. Theres resistance but I have to press them Iíd say about 3/4 the way to the floor to stop. And they have locked up on me when braking moderately but I didnít feel like it should have been at that point if that makes sense. Itís like a light switch, itíll brake normally most of the time though. And the pedal is slow to return to the up position. I can take my foot off it when itís at the bottom of its travel and itíll take a few seconds to return to the top.


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  19. #19
    I'm an air-conditioned gypsy gadget73's Avatar
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    ever inspect the rear brakes? Most of them haven't been touched in decades. If they aren't working right the braking gets far worse than it should be.

    86 Lincoln Town Car (Galactica).
    5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

    91 Lincoln Mark VII LSC SE, triple black (Timewarp) - poly front bushings, KYB struts and shocks, Holley SystemMax1 lower intake, SilverFox AOD valve body,

    1984 Lincoln Continental TurboDiesel - rolls coal

    Quote Originally Posted by phayzer5 View Post
    I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

  20. #20
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    No I havenít, though Iím sure theyíre old like everything on this car.


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