Delphi TC4478 front left lower control arm with ball joint for the 2014-2021 BMW i3 and other vehicles joins the wheel to the chassis. Because the ball joint comes attached, this control arm and ball joint assembly replaces both in one piece.
- Robot welding for consistent performance and quality
- 100% crack detection and ultrasonic flaw detection on the control arm
- Ball studs machined to micron tolerances for smooth joint operation
- Anti-corrosion protection applied to each part
- Withstands temperatures below -40 °C and over 120 °C, and is exposed to 720 hours of salt spray
Quick facts
- Part: Delphi TC4478 control arm with ball joint
- Also called: control arm and ball joint assembly
- Fits: 2014-2021 BMW i3 and other vehicles
- Position: Front Left Lower
- Condition: New
A clunk over bumps, uneven front tire wear or loose steering can mean the ball joint or arm is worn. A worn sway bar link, tie rod end or wheel bearing can sit behind those signs too, so find the cause before buying.
Fits
This arm fits the 2014-2021 BMW i3 and the 2018-2021 BMW i3s, and each of them takes one on the front left. The listing is one arm for the front left of that axle; the front right is a separate part, and the pair is normally replaced together.
Specifications
Fit and size
- Position: front left, lower
- Quantity per application: 1
- Sold individually
Build and materials
- Construction: control arm with ball joint, robot welded
- Finish: anti-corrosion protection
- Condition: New
Interchange: 31 10 6 863 733 · 31 10 6 863 739 · 526-687
KSC4471 · CMS101608 · X05CJ7359
This part cross-references / interchanges with the following part numbers:
31 10 6 863 733, 31 10 6 863 739, 526-687, KSC4471, CMS101608, X05CJ7359
Frequently Asked Questions
Does this Delphi control arm fit the 2018-2021 BMW i3s?
Yes. Delphi TC4478 fits the 2018-2021 BMW i3s as well as the 2014-2021 BMW i3. It is the front left lower position, so the right side needs its own arm.
What inspection does the Delphi TC4478 control arm get?
Delphi TC4478 control arms undergo 100% crack detection and ultrasonic flaw detection to confirm the materials match OE specifications. They are also robot welded.
Does this front left lower arm have corrosion protection?
Yes. Anti-corrosion protection is applied to each part, and the parts are exposed to 720 hours of salt spray.
Can I keep driving with a worn ball joint on a control arm?
No. A worn ball joint can affect steering and suspension control, so have it checked and replaced promptly rather than driving on it.
Does the Delphi TC4478 interchange with 526-687?
Yes. 526-687 is listed as an interchange number for Delphi TC4478, along with 31 10 6 863 733 and 31 10 6 863 739.
