There's numerous posts about guys having vibrations problems on their cars and they fixed it by replacing the u-joints. I have a vibration problem at around 60mph and I;ve covered all the obvious stuff: balance wheels, new suspension parts, front bearings, etc so I went to a suspension place and had them look underneath the car. The mechanic put his hands on the driveshaft, shook it, and said the u-joints were fine. Is this a good test for U-joints? DOes that check eliminate them as the cause of the problem or might it still be worthwhile to replace them? Thanks.

I am definitely no mechanic but it seems there would be more to checking u-joints than just that. Have heard an out of balance driveshaft can also cause vibration and I would believe that would require some kind of special equipment to test and balance.

Look for rust stains around the u-joint caps. That's one indicator that the the joints are worn and dried out. I don't think a shake of the driveshaft is sufficient for a diagnosis.
Check for a dent in the shaft. That will knock the balance of the shaft off. If it is dented, take it to a specialty place to have it rebalanced, or if the dent is bad, get a replacement.
Sometimes the bushing inside the back of the trans wears out and allows the driveshaft yolk to wobble and feel like a shake at speed.

Don't overlook the pinion yoke. Had a nasty vibration at 55mph on my 72 that would not respond to any of the usual treatments. The car had it from the day I bought it. Turned out that the yoke was sufficiently chewed up so that the rear U-joint would not center properly in there. Even a little misalignment can make a real big difference. Ordered a replacement yoke and she's smooth as silk at all speeds now. Pull the drive shaft and examine the yoke with a good light and see if there is any obvious damage or wear. Mine had a broken centering "ear" along with general uneven wear to the surfaces where the u-joint fits into. Plus I noticed some slightly elongated or egg shaped strap bolt holes. There were actually a couple of tiny hairline cracks radiating from those holes. I got real lucky to have found that problem when I did.

Hope this helps

Dave

When I check u-joints I like to remove the drive shaft and move both ends of the shaft to check for any type of binding. If they at all feel "sticky" or like they are binding then they need to be replaced....

Vibration from bad U-joints will almost always be noticed only under load... when accelerating it will vibrate, and when coasting you won't feel it.

You must remove the drive shaft to properly inspect the u-joints.

If you even question the u-joint replace it, they are extremely inexpensive and this is certainly a job that you can do yourself especially if you have someone show you one time.

I had a vibration last summer, I checked everything and couldn't find it. I found it alright at 75mph on the PA turnpike at 11:00am, the vibration was the rear u-joint.

I'll not make that mistake twice.

I really agree with the posts above.... I had a vibration @ 50+ mph
shook the shaft (the car's) & it seemed fine.

took the u-join apart after a hell of a fight & found that it was seized.

changed it & no vibes to 100+...........I assume, not that I've gone that fast!:D

I priced them and they are pretty cheap. Autozone has a heavy duty one for $16, but how hard is it to do yourself? I thought I heard you need a press to get those in and out.

Here is a good write up of the procedure - http://www.chevelles.com/forums/showthread.php?t=139074&highlight=bad+u-joint

Read Charbilly's reply

I priced them and they are pretty cheap. Autozone has a heavy duty one for $16, but how hard is it to do yourself? I thought I heard you need a press to get those in and out.
for something that takes that much abuse......don't skimp, Get the HD's from NAPA or another quality source. The HD Napa's are really nice for 25 bucks each!

did mine with a torch & a hammer!

I don't know about using a torch.... but I've installed my own with a hammer and a vice.

A good parts store (NAPA etc) will probably install them for you. Last set I bought, they installed for $4 ea.

I priced them and they are pretty cheap. Autozone has a heavy duty one for $16, but how hard is it to do yourself? I thought I heard you need a press to get those in and out.

I have pressed many U-joints in the bench vise and I'm sure this is what 99% of us DIY mechanics do. It's not difficult at all, you just have to be careful so you don't get one of those pesky little needle rollers stuck sideways when you install the cups.

I don't know about using a torch.... but I've installed my own with a hammer and a vice.

A good parts store (NAPA etc) will probably install them for you. Last set I bought, they installed for $4 ea.
the torch was to get the injected plastic out.

Ditto on NAPA

I had a vibration last summer, I checked everything and couldn't find it. I found it alright at 75mph on the PA turnpike at 11:00am, the vibration was the rear u-joint.

I'll not make that mistake twice.

What happened at 75? I have noticed a vibration only at speeds above 60, really bad over 70. Cruising around town, no problem. Could it be the u-joints? What happens when they go bad and how do you know?

What happened at 75? I have noticed a vibration only at speeds above 60, really bad over 70. Cruising around town, no problem. Could it be the u-joints? What happens when they go bad and how do you know?

my guess is that the driveshaft decided to see what it was like rolling across the highway!

you will know when your driveshaft decides to rip your exhaust out before going for a spin.

not fun BTW

Dreis454 has it about right, here is a picture of what it did when it came apart on my El Camino, I just thank God that it wasn't the front u-joint.

http://prod.campuscruiser.com/cruiser/widener/bwshook/elcamino-ujointfailure.jpg

The damage was actually alot worse that it looks. The floor pans were dented, the exhaust was really dented and torn apart and the driveshaft was scrap metal it was bent so badly.

Please if you have any questions replace the u-joints!

I had a similar vibration between 60 and 70. I had the wheels balanced, slight improvement and then changed U-joints, slight improvement. I finally took it to a drive shaft shop where they cleaned and balanced the drive shaft and the vibration is gone.

I was going to suggest the same thing. The driveshaft may need to be balanced. You can in the very least check for any play in the u-joints by twisting the driveshaft and the rearend yoke and the transmission yokes and see if the joint has any play in it. At least then you know if they are tight still, but wont tell you if its starting to really rust inside the cups.

Well I pulled the driveshaft out the other day and took it to the local Napa. They have a machine shop right inside and I was going to have the u-joints replaced. The guy there inspected the draiveshaft and the u-joint and thought everything looked fine so I guess I'm back to square one. I'm going to try to run the car with the rear up on jackstands as recommended in other post in this forum. Anyone have any luck diagnosing a vibration by trying this? I hope to at least determine if the issue is coming from the front or the rear.

If you would rather use an actual u-joint press tool, go to Autozone and borrow theirs. I've done it several times in the past. Give them a deposit, take the tool, bring the tool back, get your full deposit back. It's that easy. Doesn't cost you a thing.

I hate to say it again, but REPLACE THE UJOINTS. You have a question as to whether or not they are okay just replace them. They will cost you no more than $15-$16 each and you can have them in and out in your driveway in less than 30 minutes.

If you have your doubts, I speak from experience, look at the above photos.

I don't know about using a torch.... but I've installed my own with a hammer and a vice.



Me too. Two ball peens and a vice. Use the ball peens to remove, vise to install.

I hate to say it again, but REPLACE THE UJOINTS. You have a question as to whether or not they are okay just replace them. They will cost you no more than $15-$16 each and you can have them in and out in your driveway in less than 30 minutes.

If you have your doubts, I speak from experience, look at the above photos.

X2,3 & 4!:D

Update: I took the whole driveshaft to a nearby place that specializes in high performance racing driveline components so that they could give it a full inspection. They found that it was bent! and the U-joints are bad too. They are straightening it, balancing it, and replacing the U-joints for $165 (no too bad). I think this may fix my vibration issue. We'll see. Goes to show you that on these old cars that have had previous owners you really don't know if the parts are original, had been in accidents, etc. I doubt the mild 350 in my car could have bent it.

Be sure to let us know if they fix the problem and what they did!

Well I picked up the driveshaft last week and they told me that it in fact was not bent. The U-joints were bad and the it just needed balancing. $165 and no difference in the ride! Thats a huge disappointment because I really thought I had this figured out. I'm running out of things to replace. All thats left is the engine mounts, the rearend, and the rear upper control arm bushings. I'm going to knock out those upper control arm bushings next.

Similar problem, I have a manual transmission. I had to replace both U joints and both the front and rear yoke on the driveshaft and also balanced the driveshaft. Then I replaced the bushing in the tailpiece of the transmission that the front yoke slides into when I had the transmission rebuilt, don't know if your automatic has a similar bushing. Finally I had to correct the pinion angle. Now everthing is fine from 0 -100. Oh Beside balancing the rim/ tires, I had the brake drums balanced. What is the condition of your rear axel assembly? Did you force balance your tires, check the run in/out of your rims, check for out of round rims?

Similar problem, I have a manual transmission. I had to replace both U joints and both the front and rear yoke on the driveshaft and also balanced the driveshaft. Then I replaced the bushing in the tailpiece of the transmission that the front yoke slides into when I had the transmission rebuilt, don't know if your automatic has a similar bushing. Finally I had to correct the pinion angle. Now everthing is fine from 0 -100. Oh Beside balancing the rim/ tires, I had the brake drums balanced. What is the condition of your rear axel assembly? Did you force balance your tires, check the run in/out of your rims, check for out of round rims?

Yep, I just replaced the trans mount bushing when I had the driveshaft out. That did help with some engine vibrations I had at idle, but didn't help my 60mph issue. The rear drums, front rotors, front bearings, all 4 rims and tires are all new. The rears I had Summit racing mount and the fronts I had mounted by the local Pep Boys. I'm pretty sure Summit road force balances, but I'm not sure about Pep boys. I might try getting all 4 rebalanced just to be sure thats not it. I am pretty sure my rear axle has some issues. I hear a scraping noise coming from back there when I'm moving slow. The frequency of the scraping changes when I acclerate and decelerate. The car has 108k miles on it so I wouldn't be surprised if the rear axles and/or the bearings need to be replaced. As for changing pinion angle, you need adjustable upper control arms correct?

Check all the bearings in the rear. There are 6 of them total (2 axle, 2 carrier, 2 pinion) I've seen bad pinion bearings cause vibrations, been there done that. I've been chasing a similar vibration in my 70 for the last couple years and I've gotten down to replacing the whole rear even though I've rebuilt it already. I have ruled out everything else.

autoengineer, are you talking about the rubber bushing on the crossmember that transmission mounts to or the brass bushing that is inside the tail piece of the transmission that the front yoke shaft slides into when you slide the yoke shaft on the output shaft? I would not rule out rebalancing the tires. Did they check the runin/runout, etc on the rims and were they within tolerances? Also sounds like a rear axel rebuild is not out of the question. But first make sure that summit and the pep boys didn't just do the best they could with your rim/tires.

autoengineer, are you talking about the rubber bushing on the crossmember that transmission mounts to or the brass bushing that is inside the tail piece of the transmission that the front yoke shaft slides into when you slide the yoke shaft on the output shaft? I would not rule out rebalancing the tires. Did they check the runin/runout, etc on the rims and were they within tolerances? Also sounds like a rear axel rebuild is not out of the question. But first make sure that summit and the pep boys didn't just do the best they could with your rim/tires.

I replaced the rubber bushing that connects the trans to the crossmember.

Update: Huge Breakthrough. I made a huge improvement in how my car drives and the shake its been having at speed and it didn't cost me a cent. I had my front control arm bushings and ball joints done at a local place awhile back. Since then, I've done some additional work to the front end such as new springs and shocks. I had an annoying squeak in the front end recently and I was kind of annoyed considering one of my reasons for going with rubber and not poly bushings was the squeaking problems I had heard about. Well a poster on this forum recommended "resetting" the bushing tension by loosening up all the control arm bolts, bounce the car up and down a few times, and then retorque with the car flat on it tires. I did all that and then took the car for a rest ride and THE Vibration is gone! I wouldn't be surprised if the place who did my bushings originally torqued them down with the car on a lift and the wheels hanging down. I had read nearly every vibration post in the forum and I hadn't heard of improperly set bushings causing such an issue so I thought I would post it. I'm going to do the same to my rear bushings this weekend.

Thanks for posting your solution Autoengineer! It will surely help someone else someday.

I'm not sure you want to do the same on the rear though. In the assembly manual it shows that the top of the rear axle housing should be a specific distance from the bottom of the frame hump when you tighten those arms. I don't remember the distance, I'd have to look it up again.

I know that I am rising an old thread from the dead, but is it possible that the tension in the rubber bushings was causing incorrect pinion angle?

From what I read when reinstalling the rear, you were suppose to tighten the bolts on the bushings (8 in all) with the weight sitting on the rear wheels. Do you have new/good rubber bushings? If you have new adjustable control arms (upper and lower) then you could adjust the pinion angle. Do you have a good original transmission cross member with the right bends, correct transmission bushing, and correct springs, correct rear if its a 64-67 car? Don is referring to "Ride Height" which should be correct with the correct springs and rear axel assembly. Ride Height could be changed with spacers or different springs.