Front Lower Control Arms

[carbob]

Appreciate the feedback and the reassurance that this is a needed repair based on my thud test. I think I've heard some folks say the ball joint side is critical for torque while the wheel is in the weighted stance and other say the bushing side is critical. The bushing side travels in one direction, the ball joint in multiple directions, the explanation I've heard is by torquing in the unweighted position, there will be binding with movement in the weighted position, I guess that could apply to both sides of the control arm. And they are both accessible on the ground, so finish torquing both on the ground???

[andrewwynn]

The ball joint swivels it doesn't matter when it's torqued.

The rubber bushing doesn't swivel. The rubber twists. If you torque with the wheels floating you will twist the rubber when the wheels are loaded and then over-twist when you hit bumps. Keep that last bolt loose enough the bushing can swivel until the wheel is "loaded".

I do while the car is on stands by lifting the wheel hub until that side of the car floats just a bit off the stand. If I'm being pedantic that day I'll disconnect the sway bar link as that will slightly reduce how far the wheel hub will travel.

[80stech]

If you measure the distance from the center of wheel to the fender opening before you start, you will have reference to tighten the bushings at ride height.

[andrewwynn]

Thinking ahead?! That's like cheating!

(Great idea I will try to remember that next time)

[Fifty150hs]

Originally Posted by 80stech

If you measure the distance from the center of wheel to the fender opening before you start, you will have reference to tighten the bushings at ride height.

[carbob]

I have both control arms installed and I’m waiting for a new strap for the right side ride height sensor. Thanks for all the posts that helped, and I understand how placing the ride height bracket correctly on the busing side of the control arm ensures the lever is nearly vertical with the connecting lever nearly horizontal and there is a flat part on the arm for the strap, it’s made to all fit together correctly.

But I made a critical error that I’ve not seen on any of the posts so I thought I’d confess so no one else does this rather stupid thing. My ball joint was challenging to remove even with a ball joint tool, so I tried supporting the rotor with a Jack at various angles to see if it would help- the enemy of the good…. Well when the ball joint finally freed, the abrupt pop caused the rotor to fall off the Jack and the weight of the hub caused the axle to fall out of the transmission a few inches, probably held by other suspension components. After removing all the other connections to the hub and getting the axle back in place, all is well and anxious to see how it works once I get the wheel back on. If I do it again I would probably release the arm from the busing side then remove the ball joint side, I did that on the other side of the truck and the hub never moved a mm.

[Auto Parts Guy]

Thanks for the confession! We all do dumb things sometimes especially when you look back at it. As long at the seal didn't get damaged youre probably ok. Its just held in by a c-clip.

Another piece of advice, I take the nut loose then thread it back on hand tight before i bust the ball joint loose from the knuckle. Basically thread it back on until the locking feature. That keeps the control arm from falling somewhere unexpected.

For what it's worth, BMW still builds axles in what they call K0 Lage. It differs from model to model. All bushings are tightened at this position, even the axle is jounced before final tightening.

[carbob]

Yep, learned a lot about the “physics” of the front suspension, glad I ventured into an uncomfortable situation and will add your threading the nut loosely before busting it or other components loose to the list. It’s all back together and drives without any noises or fault codes, ride height is functioning. Appears just because it drives ok doesn’t mean I’m out of the woods, I will be looking for a leak from an undetected boot tear, but what should I look for with a broken seal? Transmission fluid leak? And not sure about your last sentence, was that reassurance that popping the axel out isn’t so bad because of the way they manufacture it on the line at the factory?

[andrewwynn]

Axle coming out of differential is a non issue. It's differential gear oil not xm fluid in there and when not moving no amount of consequence is near the seal. Sounds like it didn't even come all the way out.

You do need to confirm the c-clip is fully engaged by pulling on and make sure the inner shaft won't move outward.

[carbob]

Sorry to hijack this post from the OP.

Axel was all the way out an inch or so, and needed to be lifted up to slide back in, but it slid in easy, boot stayed attached at diff and axel side so I never saw the connection or the inner axel which didn’t seem to move relative to the outer axel because presumably the inner axel remained firmly attached to the hub. I’m guessing the seal you’re talking about is inner to outer axel holding grease inside. Tried to find some diagrams but appears the c clip you’re talking about holds the seal and inner shaft to the outer shaft. Its all back together, so I would have to take it apart to check it, anything I should watch out for with it all together either by driving or inspection of the components?