Quote:
Originally Posted by wilkin250r
I've got a vibration around 55mph. It's rather high-frequency, much higher than a wheel imbalance, so it's got to be someplace else in the drivetrain.
But it's rhythmic. It's not constant, it comes and goes at a regular rhythm. A fast rhythm, like once a second. It's there, it's gone. Over and over. There, gone, there, gone, there, gone. Bruuup. Bruuup. Bruuup.
A driveshaft vibration wouldn't come and go. It would be constant. Plus, a local driveshaft shop pulled the driveshaft and told me that although the driveshaft is old, and could probably use some attention, they don't believe it's THIS bad.
What else is going to give me a vibration? Especially a vibration that comes and goes.?
|
I don't want to over-rule your statement, but what you indicate here is just not accurate.
When the rotational speed of the drive-shaft increases, it tends to allow oscillation due to inertial loading. Just like a tire that has a tread separation with a vibration that shows up once certain speeds are reached.
Did you replace the front and rear u-joints when the carrier bearing was replaced?
There is a possibility that you had a balance weight come off the drive-shaft, and the drive-shaft needs to be rebalanced.
I had a Fiat that developed a vibration very similar to what you are describing. I took it to a shop, and they separated the two-piece unit, balanced each part, then put it back together, which wasn't the problem, because I still had the same vibration when I got it back, only worse. They also, for some unknown reason, took it upon themselves to tighten the nut that the rear yoke secures to the differential. And then blue RTV'ed the seal at the differential yoke, Money down the toilet. It was the rubber donut that Fiat used (Like BMW) which is the equivalent to having a bad front u-joint. I then had to pay another shop to balance the drive-shaft because the first garage was too stupid to know that you have to balance an entire two piece shaft while the shafts are connected.
Maybe when you or whoever replaced the center bearing put the drive-shaft back together, the two halves were reconnected 180 degrees out.
Like already mentioned, you might want to check the tailshaft mount to make sure it isn't broken by trying to lift up the back end of the housing. If it's free to move, that is something else that could cause your problem you are indicating here.