The car is a '97 Volvo 850 T5 with 115,000 miles. I get a strong vibration upon initial brisk acceleration like when I pull into traffic from a side road or when I pull away from a red light. This is only at the lower / initial speeds. The vibration is so strong when the car is cold that it turns into a rattle and it sounds like some think mettallic under the car or in the engine bay is rattling against some other metal part. I thought it could be my motor mounts worn out and causing the exhaust pipe under the car to move down enough to hit the cross plate under it. The vibration reduces when the car warms up but is still there.

The right (passenger side) drive axle has been replaced. Driver side has not been. The solid rubber "transmission" mount on the passenger side has been replaced. The upper mount on the engine (not firewall) has been replaced with a Poly bushing.

Thanks
Jay

 

9 times out of 10, this is an issue with a CV joint. Take a look at the one on your drivers side and see if it has gone bad. If not that, check out the rest of your suspension.

 

Jay,

Did you ever find the problem? I'm experiencing something similar.... when I accelerate when the car is cold (from a parking spot or light) for a few seconds I'll get a hard rattle (near the passenger side... like it's coming from the glove box kick panel or something). I can't see anything under the car or on that side of the engine compartment that would be causing it.

It just started happening. I noticed that my top motor mount (the one from the engine to the firewall) has 1 bad bushing (the one that attaches to the engine is cracked and completely seperated)... so i'll replace that one and I might as well replace the one that attaches to the firewall (it's old and cracked).

No idea what this rattle is... pretty sure it's not related to this top mount (but since it's obvious that they need to be replaced, I might as well do it).