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SLATZ said:
U Joints should have zero play. No exceptions. It's the most common cause of propshaft problems.
I had one that the customer complained of "brake vibration". That was the only time it vibrated (brakes applied) It was a bad U Joint.
I have been trying to track down a "thumping" similarly described in many threads. The difference I note from most is that it doesn't happen under acceleration. At first, I thought it was brake related because I only felt it at the very end of braking (ie under 5mph). After reading a few threads, and poking around, I tested out exhaust vibrations but found no rubbing, still felt it might be brake related. Took it back out for a spin, just down the street, I had the door opened as the car jjust rolled slowly when... BINGO vibration. I asked the wife again, and she says "oh yeah, it happens even when you are just slowly rolling!". Coming back to the threads, rereading a bit I found this comment. My experience with bad U-Joints has always been that you notice it under ACCELeration, not DEcceleration. Anyway, my question is this:
The comment quoted says there should be absolutely no play in the U-Joints, can this be determined by simply hand turning the prop shaft back and forth to check for sloppiness? or is this not enough to tell?
 

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Put her up on jackstands and had a look-see. I can twist the driveshaft about 3-4 degrees before I get movement out of the wheels, but as best I can tell, the slop is not in the U-Joints, but in the rear axle. I am under the impression that this is to be expected, don't know for sure, it just feels right. This vibration feels as if it's right under the driver side seat, or possible down the centerline of the car. I get it under acceleration in reverse, but not forward, but i do get it going forward with the car in neutral between 2-5mph (maybe slightly higher, the speedo isn't terribly accurate). It's hard to tell if it's there in gear going forward that slow as the car is near stalling even in first. Vibration is pretty serious, but again, this is the only time I feel it. Once the car is under way (above 10mph) I cant feel it at all, accelerating, coasting or braking. Does this still sound like a U-joint issue? I am in search of an Alfa repair shop here in South Florida if anyone might have a suggestion.
 

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Discussion Starter #24
Ricklandia,

My problem ended up being the drive shaft support bolts. They looked tight and felt tight. I crawled underneath and shook everything. My problem was a thump I could feel and hear from under the seats and in the middle. I could even feel the thumping with my hand near the emergency brake. I would suggest tightening everything you can.
 

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there is also an extension joint in the shaft itself, a spline that lets it lengthen and shorten. there is a grease fitting on the shaft that if is not greased occasionaly and the spline wears, it can bind and vibrate.
cliff
 

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Thanks for all the advice, guys. Unfortunately, I failed the "48 Hour" rule. You see, it's my wife's daily driver, and her rule is "if you can't figure it out in 48 hours, it's going into the shop!"

What can I say, it's her car.

As it turns out, she was out running errands today and saw a man with a beautiful Red '86 spider going into the same store she was. She struck up a conversation and asked if he could recommend anyone in town. He gave us the name of a place locally and highly recommended him. I'll hold off giving out a name until we've had it in the shop, but I will say I spoke to the man over the phone and we chatted Alfa's for a bit. Right off the top he mentioned quite a few "Alfa-centric" terms so I think he's at least knowledgable, more than I can say for most mechanics around here when you pull up in one! ;)

I'll post an update for any other S. Florida locals after we visit the shop. ;)
 
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