03 330 xi wobble under braking

I have a 330 xi w/ 62k miles; when light to medium braking from 50 or above the steering wheel wobbles at only around 40 miles per hour. This does not happen under hard braking. Mechanic says ball joint-any other thoughts?

Ball joints, control arm bushings, brake rotor run out, brake pads, improperly tightened lug bolts, etc can all cause this issue.

I'd believe the ball joint diagnosis but it's hard to confirm without being there.

Thanks for the reply. What is brake rotor runout?

Originally Posted by Bdallas

Thanks for the reply. What is brake rotor runout?

Brake rotors not spinning true. They wobble from side to side as they spin, kinda like out of balance bike tires.

Thanks. Would the rotors or pads show signs of this?

Usually warped rotors vibrate more under heavy braking.

I'd guess FCABs in this case. Did the mechanic actually look at the car?

The mechanic had the car on a hoist and checked the ball joint with a pry bar. Is the Front Control Arm and Bushing different from the ball joint

Originally Posted by Bdallas

The mechanic had the car on a hoist and checked the ball joint with a pry bar. Is the Front Control Arm and Bushing different from the ball joint

Yes.

Originally Posted by Bdallas

The mechanic had the car on a hoist and checked the ball joint with a pry bar. Is the Front Control Arm and Bushing different from the ball joint

If the outer ball joint is bad, you will need to replace the FCAB too to swap out the control arm (which has the outer ball joint attached).

Originally Posted by Kubica

If the outer ball joint is bad, you will need to replace the FCAB too to swap out the control arm (which has the outer ball joint attached).

How often do the inners go bad or just as often? My outers and CABs are for sure shot at this point, how do you diagnose the inner?

As stated previously, there are a number of things that can cause your "steering wheel to wobble" under light or heavy braking. Warped rotors (rotors that have excessive run-out due to incorrectly tightened lugs), a caliper that is sticking so that pads do not release (in case of warped rotors, you probably will not see brake pad wear, however, with a caliper that is sticking, you will see excessive pad wear on the side that is hanging up and in extreme cases, heat marks on the rotor surface and on the caliper. Also, worn out Front lower control arm inner and/or outer ball joints (basically you check the inners the same way as the outers), worn out/torn front lower control arm bushings, worn out tie rod ends. Any or all these suspension parts can give you the "wobble", but you should also have a "vague" feeling in your steering (a tendency to sort of go where it wants to going straight or turning).
If the outer ball joints are bad, you need to replace the front lower control arm because it has the outer ball joint pressed into it and unlike some of the 2 wheel drive models, there is not a replacement control arm made for the XIs that has replaceable outer ball joints. At the same time you replace the lower control arm, you will also have to replace the front lower control arm bushings. Here, opt for the PowerFlex Urethane Bushings, they last a lot longer than the rubber bushings, are re-useable and the cost is the same as the rubber bushings. Make sure if you opt for the PowerFlex Urethane Bushings that you get the offset ones which are the correct ones for an XI and then care must be taken to install them correctly (with the offset at the right location), the centered ones ARE NOT for an XI.
If one outer ball joint is bad, so that you need to replace the control arm, save yourself the grief and do the other side at the same time because that outer ball joint has the same mileage and wear and tear on it and will fail shortly if it hasn't already (plus if you use the PowerFlex Urethane Bushings, you will be installing them on both sides, not good to run one on one side and a rubber one on the other side).
To check rotor run-out/warped or not, you can use a dial indicator or you can make a make-shift indicator, the make-shift one will not tell you how many 1000s of an inch it is runout, but it will tell you that it is warped.

Originally Posted by SamDoe1

How often do the inners go bad or just as often? My outers and CABs are for sure shot at this point, how do you diagnose the inner?

I'm on my 4th or 5th set of arms, but only second set of inner ball joints.

I use a pry bar to see if there is play in the ball joint. Squeezing the ball joint wih channel-lock pliers is supposedly another way to do it.

Checking the inner ball joint with a pry bar like checking the outers is the best way, though I agree and have used a large pair of channel lock/water pump, as they are also known as, pliers. I also agree with you Kubica, you will go thru 3 to 5 outer ball joints/control arms before needing to replace the inner ball joints (there isn't as much stress and movement on the inners as there is on the outers).

Originally Posted by tomoyer

Checking the inner ball joint with a pry bar like checking the outers is the best way, though I agree and have used a large pair of channel lock/water pump, as they are also known as, pliers. I also agree with you Kubica, you will go thru 3 to 5 outer ball joints/control arms before needing to replace the inner ball joints (there isn't as much stress and movement on the inners as there is on the outers).

I have 111k on my factory inners (and outers for that matter ), time to replace? The outers are for sure gone and will get replaced.

Worst case, I swap the outers and then do the inners again later if needed...

My '03 325xi has 125,00 on the clock and still has the original inner ball joints, with little to no play, but I'm on my 2nd set of control arms/outer ball joints and 2nd set of lower control arm bushings (they were replaced when I replaced the control arms with PowerFlex Urethane Bushings). I would say that its time to replace the outers/control arms and control arm bushings. The inner ball joints are easy to do at any time with out disturbing the control arm/outer ball joint or control arm bushings. Just a note, the said 325xi got the control arms replaced at 105,000 miles for the first time. Tie rods and sway bar links were done at the same time.

RE; replacing both ball joints; mechanic's opinion was the other ball joint was good-the car has only 62K miles.

Bdallas, if he is talking about the outer ball joint, it is pressed into the lower control arm and the entire lower control arm needs to be replaced and along with that, so does the lower control arm bushing. At 62,000 miles, something made that ball joint fail, and more than likely the other side got the same stress even though right now it seems fine. In my book, best to do both sides at the same time.

Don't forget wheel balance/bends as well. I've replaced everything up front, shocks, brakes, ball joints/FCABS/control arms and i still have a shimmy under high speed braking. I have style 73s so they catch dents and lose balance like it is going out of style. Hopefully i can get them re-balanced soon. If not my steelies with snows are bang perfect for balance.

Originally Posted by Bdallas

RE; replacing both ball joints; mechanic's opinion was the other ball joint was good-the car has only 62K miles.

I would do one control arm and a set of powerflex fcabs if money is tight. Buying a second arm wouldn't be a waste of money though- labor will be about the same since you need to do both fcabs.

If you don't really drive quick, the ball joint was probably destroyed by a pothole and in that case I wouldn't replace both arms.

Kubica, you do make a good point there if money is tight for Bdallas, however, if the mechanic isn't careful when he goes to replace the Bushing on the side that the control arm isn't being replaced on, he can damage the ball joint, then another control arm will be needed any way. Your idea makes more sense if Bdallas is going to stay with the rubber OE/OEM Bushings, that way nothing is disturbed on the "good side", and the bushings will be the same type.