Annoying Vibration and Rumble

[TitaniumTT]

Originally Posted by Max777

Well guys, Max chiming in on my own problem:

I had the car up on the lift at work (Volvo Dealer) and the little stub shafts that come out of the diff had a lot of play in them. At first I thought it was the axles, but now I'm questioning that it's the diff?

One REALLY strange thing is: as I accel to 4th gear on the highway, I get NO vibration in 4th... Then I up-shift into 5th and bam, brrrrrrrrrrrrrrrr, there it is.

Does anyone have a clue as to why the vibration would disappear in 4th at 65mph?

So at 65 in forth there's no vibs, but at 65 in 5th there is vibes? Could be harmonics, could be tranny

[Pete_89T2]

Originally Posted by TitaniumTT

So at 65 in forth there's no vibs, but at 65 in 5th there is vibes? Could be harmonics, could be tranny

Noise & vibes in every gear except 4th sounds like shot tranny bearings to me. When the trans in my '85 GSL-SE was on its way out, that's basically what it was doing. Fix was a tranny rebuild. 4th is a 1-to-1 ratio, which explains why the noise/vibes change dramatically. In my FB, it sounded like marbles rattling around in a coffee can in all gears except 4th, with a noticable change in driveline vibration that you could feel if you pay attention to it. Symptom was more noise than vibration though, however the FB didn't have an independent rear suspension like the FC does, so the noise/vibe characteristics would likely be different.