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Symptoms of Bad U-Joints?

Started by RobW, July 12, 2012, 08:53:23 PM

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RobW

My 73 CDV still has that shake up around 60 mph. A transmission guy said it might be the u-joints and the ball assembly in the CV assemblies of the drive shaft. Pulling and twisting on the shaft I don't feel any slop or play in the joints. He says they could be dry and very stiff and pulling on the shaft really isn't a good way to test.
So what do you guys think?
Rob Wirsing

dplotkin

Have you already ruled out the front end & are now looking at the driveline? Where is it shaking, steering wheel/column? Seat? Whole car? Bad control arm bushings among other bushings can certainly cause this, and far more likely than the driveshaft in my opinion.

Dan
56 Fleetwood Sixty Special (Starlight silver over Dawn Grey)
60 Buick Electra six window
60 Chrysler 300 F Coupe
61 Plymouth Savoy Ram Inducted 413 Superstock
62 Pontiac Bonneville Vista
63 Chevy Impala convertable
63 Ford Galaxie XL fastback
65 Corvette convertable 396
68 Chrysler New Yorker

RobW

Front end seems Ok. New upper control arm bushings, new strut bar bushings. Swapping out the tires doesn't change things. New motor and trans mounts, new timing chain, heads rebuilt, new complete exhaust.
Just when you get around 30-35 mph you feel a little unevenness? But at about 60 mph it feels like the car is about to fall apart. I was thinking the trans or torque convertor but the trans shop said could be a dried up driveshaft causing it. Looking in the caddy service manual it does mention these symptoms under driveshaft unbalance.
It's just that any other car I've ever had to replace u-joints on the drive shaft was sloppy and loose. This one seems tight, maybe too tight.
Rob Wirsing

TJ Hopland

How about tires?   I had a similar vibration on my 78 and was laying on the ground looking at the drive shaft when I noticed steel cords coming out of the tire tread. 

It does not take a lot of wear in those type of CV's to cause vibration.  The U joints being tight can also cause a nasty vibration.  If you take it off and feel em you will likely know if that is your problem.  I have had em that you cant even move by hand.
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

wrench

Look to see if the u-joints have grease fittings...it may be that simple.

Pull the drive shaft and check the joints with it out, if they are stiff, that could be your problem.

Don't forget to apply some sort of alignment marks before you pull it, or even re-clock it to a different position and see if that affects it.



1951 Series 62 Sedan
1969 Eldorado
1970 Eldorado (Triple Black w/power roof)
1958 Apache 3/4 ton 4x4
2005 F250
2014 FLHP
2014 SRX

RobW

Tried 2 different sets of tires with no difference in vibration. That's what the trans shop said, they may be too tight from lack of lubrication.
Maybe I should have a machine shop change the joints and centering ball assemblies and balance the shaft. I'm thinking if I do it the backyard way with a BFH, it won't be balanced and even with new parts may still vibrate.
Rob Wirsing

mgbeda

Try jacking up the back end and then running it up to 60 and see if the problem is still there.  If it is that eliminates anything in the front.  You can also jack up one wheel at a time (if you don't have a limited slip diff).  If it's in the wheel you'll feel it at 30 instead of 60 (one wheel by itself spins twice as fast as two together).

Of course be sure that the front wheels are chocked and there's nothing close in front of the car and be ready to hit the brake in case it slips and trys to go forward quickly.

I've had vibration problems in the torque convertor too, but not nearly as bad as you describe.  Brake drums sometimes come with balance weights on them which can fall off, but there too I doubt you'd feel it that bad.  My gut feeling is you're on the right track with the driveshaft.

I'd recommend you having a shop change those U joints (if that's the problem).  They aren't like normal U joints.  Also I think there's a rubber part between the U joints that can wear or crack.

-mB
-Mike Beda
CLC #24610
1976 Sedan DeVille (Bessie)

cadillactim

The centering ball/spring on the C/V joint may have fallen out. The joint may feel tight by hand, but still may be bad. Really need to remove the driveshaft to see. Did the problem start all at once, or did it gradually get worse?

Tim
Tim Groves

RobW

Yeah I've had the car jacked up in the rear and suported on jack stands and I feel it up around 60. Bought the car in 2008. Did it a little but nothing bad. felt like maybe a wheel balance issue. Planned on getting new tires so didn't worry too much about.
I really noticed it after it sat over the winter from October to March.
But funny you mention brake drums. I did the rear brakes and installed new brake drums. Chinese brake drums. Maybe they're part of the problem or a t least a part of it. I should try putting the OEM ones back on and see if it changes anything.
Rob Wirsing

wrench

Quote from: RobW on July 13, 2012, 04:35:42 PM
But funny you mention brake drums. I did the rear brakes and installed new brake drums. Chinese brake drums. Maybe they're part of the problem or a t least a part of it. I should try putting the OEM ones back on and see if it changes anything.

I had a bad brake booster cause a vibration on a different make of vehicle. Does the brake pedal move when you start the car? Mine actually sucked the pedal down to a slightly braked position, I didn't notice it at first, but then the car started to vibrate at highway speeds when I let off the gas, it was due to the booster dragging the brakes, and vibrating as the front disks overheated.
1951 Series 62 Sedan
1969 Eldorado
1970 Eldorado (Triple Black w/power roof)
1958 Apache 3/4 ton 4x4
2005 F250
2014 FLHP
2014 SRX

TJ Hopland

Since a brake drum is basically the same as a rim could a shop stick one on their spin balance machine? 

The other thing that is amazing that it does not cause problems is the wheel covers.  That late 70's era wire wheel covers weigh a ton.  When I first took them off my 78 I was amazed at the weight.  They redesign the motor to save 100 lbs and then put it all back on with the wheel covers....
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

RobW

I'm pretty sure it's not a wheel balance issue. I've tried 2 different sets of tires with and w/o the wheel covers, no difference.
Rob Wirsing

curly

Quote from: TJ Hopland on July 14, 2012, 08:54:27 AM
Since a brake drum is basically the same as a rim could a shop stick one on their spin balance machine? 

I had that done on my 59 Chevy truck.  I had some badly out of balance tires, the shop that balanced them used their machine to locate the heavy spots on the rim and the tire, and then rotated the tire on the rim to get the best balance.  They also pulled the drums off and stuck them on the balancer to check.  It was worth the $.

T Lewis

cadillactim

Did a balance weight come off the driveshaft, as it may be out of balance. You can look at the shaft and see a spot where the weight is missing if it fell off.

Tim
Tim Groves