Need help - steering wheel wobble

[JoeFromPA]

Just trying to prevent a shimmy I've driven on for 5k miles (and is manageable by changing speeds) from developing into a $800 repair - my hope has been I can identify it before starting down the road of paying to identify it.

However, I do have a mechanic I trust.

[jhandy]

Before you run out and spend a lot of money...

the shaking.... left to right, does the speed of the shake increase with speed of the car?

If it does, it is not the bushings. It is something that is spinning.

On top of that. you can replace just the bushings if you want. You should replace the bushings on a 12 year old car anyway, but that is another topic for discussion.

you can buy them here:
store.powerflexusa.com/porsche-boxster-1997---2004-urethane-bushings-p80.aspx

If a mechanic can push or pull the bushings and it wobbles, then they are badly screwed up and would be knocking and shuddering all over the road.
You can not tell by this method. The tolerances are just too small.

[shlim8]

My car suffered a bad case of steering shake which took me months to sort out... While I can't tell u exact what your problem might be, I can share the following:

1. It is difficult to diagnose whether the control arm and control arm linkage bushings are bad while they are still installed on the car, unless they are really really gone... Mine was rock solid with no play when my mechanic tested them by lifting up the car and shaking on the wheels and knocking on arms. BUT when they were disconnected from each other, the control arms had a lot of lateral play. The control arm linkage had slight play on them.

2. My outer tie rods looked good too, with no play, but when the mechanic tried to remove them, the ball joint just dropped out of the mounting point on the hub (?) after the nut was removed... no need to press them out.. In my case, changing the outer tie rods had the biggest impact on the shimmy.

Not to scare you but in the end, what I found on my car was:
1. front shocks shaft badly shaking but no leaks
2. front control arms (end bushings) bad
3. front control arms linkage bushings slightly bad
4. tie rod end one side bad
5. front rims badly dented

I now have all new suspension components... I now still have very very slight movement from the steering, maybe my wheel balancing is off, or because I now have 7mm spacers...but very acceptable. I'll be doing the inner tie rods next - more of preventive maintenance and because the new parts have been sitting around for the past 6 months... it's the only relatively cheap and easily renewable part in the front suspension/steering component left my car !

These cars are very sensitive to slight imperfections in the suspension/steering components !

[Cloudsurfer]

Originally Posted by JoeFromPA

Just trying to prevent a shimmy I've driven on for 5k miles (and is manageable by changing speeds) from developing into a $800 repair - my hope has been I can identify it before starting down the road of paying to identify it.

However, I do have a mechanic I trust.

That's great that you've got new shocks, but I'd be willing to bet that you've got worn bushings in more than once place. You've got a 12 year old car, so plenty of rubber components are due to be replaced.

[JoeFromPA]

Yikes - looks like this is going to be my winter 2011 job. 2010 was spent tuning the car up, replacing all the fluids, and replacing the motor mount.

Now I've got a rattling heat shield (easy), squeaky rear brakes (easy), a horn that stopped working (we'll see how easy), and the front end shimmy (ugh).

I'm almost certain this is bushing related at this time. I took the car up to ~105mph yesterday on an extremely clear, flat section of (track) roadway in great road surface condition. The car actually felt great from 85-105 and had more shimmy at 70-80mph. It's not distinctly rotational in nature, though it tends to be harshest when it kicks in at the higher speeds. Bushing-related shimmy makes more sense considering sometimes there's no shimmy at a speed and other times it's more severe.

Further, I believe the reason the shimmy changed in nature when I switched from my winter to summer wheels/tires is because the winter rubber has different dimensions and absorbed more wiggle - whereas the michelin pilot sports are far stiffer and will twitch more by their stickiness.

I'm going to focus on the front end at this time since that is what will cause steering shimmy. I'm thinking I should tackle it like this:

1. Replace front track and control arm bushings (inner & outer)
2. Remove, inspect, and possibly replace outer tie rods
3. Remove, inspect, and possibly replace inner tie rods

Stop there and examine shimmy - if dramatically different, get the car re-aligned and call it a day.

If it called for replacing both tie rods, and I did all the work myself except I took the control arms to my mechanic to get the new bushings pressed in, I'd expect this all to come in under $500. Tie rods are around $100 for both inner and outer on pelican parts. The bushings are about $170 from powerflex (which is also sold at pelican parts as the only full rubber replacement bushing.

So that's $270 - figure $50 for pressing the bushings in, $100 for the alignment, and $80 for miscellaneous tools (like a tie rod end puller) and random parts.

Yep, $500 for a freshened up front suspension and steering. Yikes.

Might also be worthwhile to drop another $100 at that point and have the tires rotated laterally and re-balanced. One more area to get rid of shimmy, and might be worth $100 to extend the tire life that much....