Help Needed for shaking steering

[mmmusty]

Sup everyone,

My car has the steering wheel "shimmy" or slight shaking that happens similar to when the wheels are not balanced.

However, they are balanced. the wheels are brand new apex arc-8. the wheels were checked along with suspension when alignment was just done. the alignment shop said that if there were issues with the suspension (other than shocks) that alignment would show it. So, everything is aligned, suspension is seemingly all good, but I get the wheel shake and it gets progressively worse.

What do you guys think it could be? I

Im personally at a loss... my intuition says perhaps its the brake rotors?? perhaps they are warped or have uneven wear?

any suggestions or ideas?

[02Pilot]

If the shimmy occurs when not on the brakes, the thrust arm bushings are the traditional BMW culprit. An alignment would not show that the bushings are failing by itself. Get under the car, grab the thrust arm, and twist it while looking at the bushing end. If there's any visible movement, it's done.

[mmmusty]

Originally Posted by 02Pilot

If the shimmy occurs when not on the brakes, the thrust arm bushings are the traditional BMW culprit. An alignment would not show that the bushings are failing by itself. Get under the car, grab the thrust arm, and twist it while looking at the bushing end. If there's any visible movement, it's done.

Thrust arm bushings are same thing as Control arm bushings? If so, that would confirm my other suspicion... I noticed some time ago a small crack in the M3 control arms.

[02Pilot]

You have a CRACK in a suspension arm and are still driving the car?! If that is the case, stop driving it IMMEDIATELY and address the failed component.

There are two control arms on each side of the front suspension. BMW refers to these as the wishbone (the straighter arm perpendicular to the wheel) and the tension strut (the bent arm that runs diagonally from the hub assembly); look at Realoem for a full diagram. The tension strut is sometimes called the thrust arm, which I believe was BMW's earlier name for it.

The simple answer is that any bushing that's failed is going to reduce the control the suspension has over wheel movement. The tension strut/thrust arm is usually the first one to manifest the symptom you describe.

[mmmusty]

Originally Posted by 02Pilot

You have a CRACK in a suspension arm and are still driving the car?! If that is the case, stop driving it IMMEDIATELY and address the failed component.

There are two control arms on each side of the front suspension. BMW refers to these as the wishbone (the straighter arm perpendicular to the wheel) and the tension strut (the bent arm that runs diagonally from the hub assembly); look at Realoem for a full diagram. The tension strut is sometimes called the thrust arm, which I believe was BMW's earlier name for it.

The simple answer is that any bushing that's failed is going to reduce the control the suspension has over wheel movement. The tension strut/thrust arm is usually the first one to manifest the symptom you describe.

First, let me thank you for taking the time to help me out. The crack wasnt in the arm itself, but the bushing. Which makes sense as youd have more slack so to speak... it was in the Upper control arm, which I had replaced recently with the M3, I fucked up and didnt accept it when I saw it lol.

Can I change just the bushing? Do you have a recommendation on what route to go?

I also saw a kit that was the upper, and the lower control arm that is STRAIGHT that were all M3 bits for like 370. From my previous research it was the upper control arm that was the important piece to change so i never bothered with the lower control arm.

What do you think about the lower control arm upgrade?

From my take, you made it seem dangerous to drive on the cracked control arm bushing, is that correct its more of control and sloppiness?

[02Pilot]

A cracked bushing isn't as severe as a cracked arm to be sure, but it still isn't good. Think about all the uncontrolled movement allowed by that failed bushing. In normal driving, maybe it's an inconvenience or uncomfortable, but what happens when you need to maneuver suddenly to avoid an accident? The ability of the suspension to react predictably to your commands is impaired.

Generally speaking, I would advise changing all suspension arms at the same time. The rubber bushings and ball joints wear, so why replace some with new while others are old and worn? The old ones will compromise the effects of the new, as they all work together to control the movement of the wheels. At the least, I would do all the arms on a given axle.

Upgrade or not is up to you. As long as they are quality parts installed correctly, you'll be better off than you are now.

[juld0zer]

Get the wheels rebalanced at another shop but get them to do a balance check first, then get them to do it properly. That way you know if any were out of balance.

Also check for humps in the sidewall and any egg shaped tyres - should be visible on the balancer.

[mmmusty]

Originally Posted by juld0zer

Get the wheels rebalanced at another shop but get them to do a balance check first, then get them to do it properly. That way you know if any were out of balance.

Also check for humps in the sidewall and any egg shaped tyres - should be visible on the balancer.

I took the car to my alignment shop and we checked the suspension bits, bushings and wheels thoroughly and didnt find any issues! So they suggested balancing the wheels also.. even though I had done it literally two days before and immediately after, the wheel was still shaking.

So, I paid 20 fucking dollars at a crooks tires shop and they told me the accelera/ achiles tires I had were the issue. They required upwards of 3.5 oz on one section and .50 ounces on another section of just one wheel. also, as the wheel was rotating on the balance machine we observed the wobble in the tire... I had seen this before every time I took the car for balancing, but was under the impression that was "normal" and thats what counter weighting is for.

Took the tires back to the shop and my guy was very cool about it, he first offered and suggested to do a special balancing on the road force machine but I opted to upgrade to Hankook V12 evo2's since they had a $100 rebate for 4 tires. 235/40/18 all around just yesterday.

I have learned some valuable lessons recently regarding tires!

[MightyMouseTech]

Were the tires road force checked?

Edit: Just saw the above post. accelera/achiles tires? What even are those? No wonder you had a vibration. A roadforce balance would have shown that tire out of round.

Driving a $50k car and putting $50 tires on it. Sheesh. Cheap tires are cheap for a reason.

[mmmusty]

Originally Posted by MightyMouseTech

Were the tires road force checked?

Edit: Just saw the above post. accelera/achiles tires? What even are those? No wonder you had a vibration. A roadforce balance would have shown that tire out of round.

Driving a $50k car and putting $50 tires on it. Sheesh. Cheap tires are cheap for a reason.

I didnte even bother when given the chance to swap them out and pay the difference.

Back in the day, I was told by a very intelligent and knowledgable friend of mine, when it comes to tires on the street, get the best bang for the buck.

Back then, the cheapest, and most bang for the buck was actually the hankook v12 evo first gen... those were great in relation to cost compared to michellins and the like.

Nowadays much like everything else, there is a reeeeeeaaaaaaaaalllly cheap version that sucks all around.

Lesson learned... to be fair, those tires, actually had great dry grip performance and even descent in the rain... but none of them seem to balance well. Seems to be thats where the cost savings has gone.

I thank you all for your input!

[MightyMouseTech]

Originally Posted by mmmusty

I didnte even bother when given the chance to swap them out and pay the difference.

Back in the day, I was told by a very intelligent and knowledgable friend of mine, when it comes to tires on the street, get the best bang for the buck.

Back then, the cheapest, and most bang for the buck was actually the hankook v12 evo first gen... those were great in relation to cost compared to michellins and the like.

Nowadays much like everything else, there is a reeeeeeaaaaaaaaalllly cheap version that sucks all around.

Lesson learned... to be fair, those tires, actually had great dry grip performance and even descent in the rain... but none of them seem to balance well. Seems to be thats where the cost savings has gone.

I thank you all for your input!

Get the best tires. Period. Full Stop.

[juld0zer]

Glad to see you have finally resolved it!

It's not always the tyre's fault though. Sometimes during the initial inflation procedure which blasts the beads against the rim, the tyre doesn't sit perfectly even and that can create a similar effect. This effect is more common on rock hard runflats and stiff new tyres. Also happens if the fitter is stingy and didn't slather on enough lube.

Good to hear the tyre shop was cooperative