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Well I finally got around to dropping the drive shaft out of the 88 244 Auto w/177k on the odometer. The issue was that I've been hearing / slightly feeling a vibration when the car slows down. More prominent when the car hasn't hit OD, but is still there even then. Also a slight vibration around 52-55 that smooths at 60+.
Anyway I got the shaft out, brought it to the local machine shop, and paid 60 bucks for the installation of 3 new u joints and a new center support bearing. The old joints seemed smooth to me, but the old center support bearing was very noisy when spun by hand. Put everything back together tonight, in the dark I might add, and just got back from a test drive.
Everything, and I mean everything, is exactly the same. Same vibs when slowing, and same feeling around 50+. This has been getting worse over the last 6 months and I'm starting to wonder if my trans really does have something inside it going like the local Aamco told me back in June when I had the tailshaft bushing and seal replaced.
What do you guys think? I've already replaced the trans mount, u joints and center support assembly... Anything else you can think of that would cause this? I haven't peaked into my rear end, but I'm not getting any noise from back there. Also I'm sure I probably need engine mounts.
I'm at a loss and I really hope that the car gets us through the cold months and into Spring.
WB
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I've experienced drive shaft vibration after repair attempt due to two things:
1. The drive shaft was not properly "timed" upon reassembly. Essentially the U joint yoke from the front half of the drive shaft must line up on the same plane as the yoke on the center U joint. Take a look, you'll note that the opposite yoke for the center U joint does line up with the yoke on the rear drive shaft U joint. This misalignment can easily occur when reinstalling the rear half of the drive shaft into the slip joint at the center support and getting it off a spline or so.
2. I have "tweaked" one of the flanges that mount to either the pinion or trans output flange by applying excessive force when changing U joints. I could have sworn everything went properly, but after a trip to the local drive shaft shop for a balance I was instructed of the error of my ways.
Hope this helps.
No change after 3 new U joints and center support bearing...
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If you do not feel the vibration when you accelerate, but sense it at cruise or when coasting, you have to be suspicious of the relationship of the pinion shaft in the rear end to the output shaft of the transmission. Ideally the two shafts will be parallel with no movement under power or while coasting, but in real life the pinion shaft will rotate slightly up and down with throttle position. If suspension parts are worn, or even weak springs, the front of the center section may point down slightly at rest or while coasting, no longer parallel to the trans output shaft, which will cause a vibration while coasting, but the vibration will go away or lessen as power is supplied to raise the front of that pumpkin up and get the two shafts close to parallel again, lessening the vibration, until you lessen throttle input at cruise or get off the throttle completely and coast and the vibration returns. This scenario may have nothing to do with your problem, but I have a bit of experience with drive train alignment so I thought I should mention it as a possibility. Good luck, and if you solve the riddle, please let us know what was wrong.
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I'm thinking along the same lines - driveline misalignment.
One contributing source can be the trailing arm and torque rod bushings in the rear suspension. During an unplanned excursion to a Volvo dealer, they sensed a money pit and not only took care of the immediate need but put the car up on the lift as well. TAB's were completely toast, which allowed the entire axle + diff to rotate about 15-20 degrees about the rear wheel axis. If I recall correctly, there was more play in the pinion-down direction, creating a more extreme driveline angle on deceleration.
The car had a lot of other problems at the time so I never noticed the noise and vibration until that shop visit. Replacing all the rear bushings took care of things nicely.
--
In God We Trust. Everyone else, keep your hands where I can see them.
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Your description sounds very much like a tail shaft bushing that is worn and allowing output shaft to vibrate. Suggest you carefully check it even though it was replaced (????) once.
I do not trust those transmission shops at all. They love to haul out your tranny and sell a rebuild when it's too late to say no. If it is the bushing any mechanic can change it, do not go to a transmission shop for that.
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David Hunter
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The tailshaft bushing and a bad trans mount were going to be my top two ideas after the center bearing, but since you've already ruled them out, I'll venture a couple more guesses.
1. Driveshaft out of balance. Rare issue, but you might have thrown one of the small square weight pads that were welded on at the factory to balance it when new.
2. Low compression in one engine cylinder causing a non-even drag when slowing/engine-braking. It may be sucking air past the cylinder rings from the crank-case during deceleration, but isn't bad enough to notice a vibration when accelerating (under load). If you find one cylinder more than 35 psi or more below the rest, it's a chance you've found the culprit (I've seen B230 engines that sound perfect and accelerate pretty smooth with compression numbers of 185, 183, 187, 110.)
3. Engine mounts sagging and putting the engine & transmission in an odd relationship to the driveshaft and causing a binding issue at one of the universal joints (probably not visible to the naked eye, would need to test on a dyno to troubleshoot).
4. I've heard of an issue involving the rear pinion, but that was just before the differential ran dry and seized up. After having seen that on a friend's car, I keep my differential just a bit overfilled. A tiny bit of fluid leaks out of the pinion seal in it's overfilled state (yours might seal better), but I know it's not going to seize on me.
5. Found an issue on my wife's car 3 years ago similar to yours that involved a bad tire. It had no outward visible issues or problems noticeable and the tire was balanced properly. However, there was a small spot in the tire somewhere that was a bit harder or softer than the rest of the tire. Vibrations would occur only at speed (45+) and were VERY elusive to track down until I switched to the snow tires and the problem disappeared. When it reappeared in the spring, I troubleshot by swapping each tire one by one until I found the bad one. Not fun, but found the problem eventually.
I hope these help you in your quest. God bless,
Fitz Fitzgerald.
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I'm sure it could be the motor mounts or the mounts in the rear suspension. Next time I have spare time I'll jack up the rear end and look at those.
What am I looking for? Will they be noticeably bad, lots of play, or missing parts of the mounts?
As for the motor mounts they should not be oily, and be intact?
Thanks,
WB
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Take a look at Dave Shannon's writeup about mounts here: http://volvo2.homestead.com/240mount.html
They should not be bulged or deformed.
Support the back of your car by the frame rails - not by the axle - with wheels off the ground. Grab the front of the differential and push it up and down. If you get clunking or more than a small amount of motion, check the condition of the front bushings on the trailing arms. If they haven't been changed in a hound's age - or ever - they're probably due. Also, grab each torque rod and try to move it up and down, and twist it. Too much motion there means those bushings need to be replaced as well.
--
In God We Trust. Everyone else, keep your hands where I can see them.
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Where is the vibration? In the steering wheel? Balance the front tires lately?
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