Vibration on accel, mostly

shadetree_v70 · Post by **shadetree_v70** » 10 Feb 2011, 20:18

My ride is a 98 S70 GLT, FWD. Recently I've swapped in new outer and inner tie rod ends, ball joints, and the CV axles are a year old. the upper torque mount is good. I'm getting a vibration off and on that seems to come from the rear, but is most pronounced under acceleration, and shakes the whole car. When it's shaking, I can slide into neutral and the vibration stays. I checked the trailing arm link on the pass side and it seemed OK. Could the wheel bearing be the culprit? Could a front strut mount (needs to be replaced) be sending vibes through the body to the point of making it feel like it's coming from the rear?

Overall it still drives OK, and it's been so snowy and crappy in VT lately I'd like to have an idea before I go hunting.

Thanks in advance.....

Post by **mrreilly** » 10 Feb 2011, 20:45

Could be a wheel bearing. But from what I've heard there's usually some noise that goes along with a bad wheel bearing.
Possibly a wheel balance issue. I know my car had some really bad shakes until I got new tires and properly balanced.
Also did you get an alignment after doing those repairs?

Post by **vjaneczko** » 10 Feb 2011, 20:49

Is there any clanking noise? Check your shock mounts.

Might help to jack the car up and give the tire a 12to6 and 3to9 wiggle. If it moves at all, and it seems to be centered on the hub, that's probably it. If it does wiggle but doesn't pivot on the hub axis (hope that makes sense), it might be the arms.

I doubt anything in the front would feel like it's coming from the back.

Post by **BEJinFbk** » 10 Feb 2011, 21:10

shadetree_v70 wrote: It's been so snowy and crappy in VT lately

Hmmmm....
Snow packed in the rims?
Sounds like a few hours in a warm garage may be in order!

shadetree_v70 · Post by **shadetree_v70** » 11 Feb 2011, 09:02

All good suggestions!

vjaneczko: Would bad shock mounts cause intermittent vibrations? I don't hear clunking.....what's the best way to check these?

mrreilly: I've been listening for the strange sounds of wheel bearing failure, but so far have not heard any. I'll give the wheel a wiggle. I do need an alignment, but i got it REALLY close because I replaced inner and outer at the same time, and measured to the mm. That took care of all the wandering and front wobble. Tires are good, although the bead on one leaks a little.

BEJinFbk: Snow in rims probably isn't the problem since it comes and goes, and when it's present gets worse while accelerating, not necessarily worse at higher speeds like an unbalanced wheel would be. BUT, I'll get the car washed today and rule it out.

You guys are confirming what I suspected, but I'm not sure about other factors that might contribute.

Thanks for the input, and please keep it coming!

Post by **vjaneczko** » 11 Feb 2011, 09:14

shadetree_v70 wrote:vjaneczko: Would bad shock mounts cause intermittent vibrations? I don't hear clunking.....what's the best way to check these?

Would they cause vibration? Sure, I guess, depends on how healthy they are (reading between the lines? "I have no idea"

). When they're totally ripped apart, that's when they clunk around.

You can look at them by peeling back the carpet in your trunk. The video is from my wagon, so I have extra room to work on them but they're pretty much the same - unless you have Nivomats.

Here's what busted shock mounts look like in motion:

shadetree_v70 · Post by **shadetree_v70** » 11 Feb 2011, 09:30

Thanks I'll check it out