Shuddering Steering Problem

[Lachrymologist]

So I've got a 30th Anniv. BD. I'm pretty new to working with automotive mechanics and don't want to go pulling things apart without first having a fairly confident diagnosis of the problem. I know an internet forum where people are thousands of miles away from my car isn't a surefire way of figuring things out, but I figure if some of you have had the same problems in the past you can help me out.
There is a noticeable vibration in the steering wheel at speeds above ~45 mph, becoming very pronounced at ~70 mph. Though the vibration can be felt through the steering wheel it is more noticeable coming from underneath, I can feel the whole car shuddering and churning, its very rhythmic not chaotic. The car will sometimes pull in random directions. Braking at high speeds or with heavy force causes the steering wheel to shake violently like my rotors are warped (but I am doubtful about that, because the front rotors are nearly brand new and the rear rotors still appear to be in good shape). Sometimes coming to a stop the car rhythmically lurches, it'll be rolling fairly smooth and then kind of jump. I also tend to get shuddering under heavy acceleration.
Right now with my limited knowledge its seeming like I will probably be needing new drive axles. Anybody have any other ideas or things I should check?

[iampetro]

i had a VERY similar problem with my 99 LGT BD

i kept checking the tires and couldn't see anything wrong with them (toyo proxes all seasons)

driving on the highway i HAD to have 2 hands on the steering wheel
slow speeds sometimes it was ok sometimes it would pull randomly

one morning after not driving the car for a day or 2 i notice my front pass tire is flat.
I jacked it up to put on the dummy and there was a nasty hole that i couldn't believe i had missed

http://a.imageshack.us/img203/4939/tiretrouble003.jpg (http://img203.imageshack.us/i/tiretrouble003.jpg/)
http://a.imageshack.us/img203/4118/tiretrouble004.jpg (http://img203.imageshack.us/i/tiretrouble004.jpg/)
http://a.imageshack.us/img203/8169/tiretrouble005.jpg (http://img203.imageshack.us/i/tiretrouble005.jpg/)

Uploaded with ImageShack.us (http://imageshack.us)

so my advice is to jack up all 4 corners and turn all the tires around and make sure there nothin funny goin on

1999 SUBARU LEGACY LGT BD = #1

[ouch1011]

If you have the ability to do so, jack up all 4 corners and spin all 4 tires and watch for any bulges. What I do is I look at the tire from the side, look at a fixed point on the vehicle (like the bottom of the spring) and watch the distance between that fixed point and the tire as you spin it. Anything more than a very minimal change will cause a vibration. Also look for areas where the tire tread is worn more than other spots. This can indicate a lot of different problems, from a bent wheel, to unbalanced tire, to a blown strut.

actually dude, "an internet forum where people are thousands of miles away from (your) car" is a great way to find the problem, like you said, alot of the members here have alot of knowledge on this paricular car and some have had the same problem... plus we arent trying to make money off you like your local mechanics.. i dont know of a better place to diagnose a potential problem


:)

['Buru in the Burgh]

I'd take it to a mechanic and have them look at the bearings inside of the wheel, one of mine went bad and was basically a morphed block of junk instead of a sphere.

[Navi271]

If it is a bearing, there should be a very pronounced "whomping" sound coming from the hub and wheel while driving. And if you're car is shaking that much due to a bearing, I can't believe the whole thing hasn't come apart yet!

Steering wheels shaking always point me to either bent rims or unbalanced tires with my experience. BUT, Still really sounds like bent rotors when you're talking about the lurching when coming to a stop... I think you might have to either try replacing parts by trial and error, or take your car in to get it diagnosed, then see if you can fix it yourself.

[Lachrymologist]

actually dude, "an internet forum where people are thousands of miles away from (your) car" is a great way to find the problem, like you said, alot of the members here have alot of knowledge on this paricular car and some have had the same problem... plus we arent trying to make money off you like your local mechanics.. i dont know of a better place to diagnose a potential problem


:)
Oh yeah no doubt about that, just saying you can never be sure without actually working with the car in person.
After classes tomorrow I'll have to pop it up on the jackstands. Blown strut could definitely be the issue. I started having problems in the winter and it gradually got worse. Switched over to my summer tires, everything seemed to get a lot smoother, then gradually back to the roughness.
I still have fun with my car though, left some nice spinning ruts in a gravel lot on the way home today :)

[jey]

Check the front end for any excessive play while you have it on jack stands. Could also be a loose tie rod or something.

[Lachrymologist]

Tires look fine. Alignment and balance are good (at least as of a couple months ago, and the problem started before then). Took the pry bar to as many things as I could, everything seems reasonably tight. My swaybar bushings do look pretty shot, and one inner cv axle boot has some holes, but no other visible excessive wear.

[DarkPhoenix]

What about checking the carrier bearings and the driveshaft.

[jey]

I'd take care of that axle boot - if it's been like that for a while it's possible the grease has leaked out of it and your axle is starting to seize...