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Details
| Specification | Value |
|---|---|
| Brand | SIDEM |
| Fitting Position | Bottom |
| Fitting Position | Front Left |
| Cone Size [mm] | 16.4 mm |
| only in connection with | Ball joint+HYDRO SB |
OE/OEM numbers (2)
Search by this OE number to find compatible parts
- BMW—31 12 1 141 721
- BMW—31 12 1 141 723
Where this part fits
Original-fit position for OE 31121141721. The red ring marks where this part installs on the vehicle.
About this product
The SIDEM Control Trailing Arm Wheel Suspension (21178) is a professional-grade replacement component engineered for long service life and reliable operation across all conditions your vehicle encounters. The part is built to the following specification: Fitting Position: U, Fitting Position: Front Left, Cone Size [mm]: Silicone, Copper mm, only in connection with: Ball joint+HYDRO SB, Material: Brass. Each dimension is checked against the OEM reference to ensure the component seats and functions correctly first time. Verified to fit BMW models. All compatibility data is cross-checked against the TecDoc database — select your vehicle to confirm the part matches your specific engine and year. This part supersedes original equipment references: 0391033, 0391044, 11819, 12.03.173 and 21 more. Matching these numbers confirms a like-for-like replacement with no loss of function. SIDEM is a recognised supplier of automotive suspension components to independent workshops and dealer networks across Europe. All parts are sourced from authorised distribution channels and carry full manufacturer traceability — you receive exactly the same component supplied to professional garages and dealer workshops. If fitment or specifications do not match your vehicle, our technical team can help identify the correct alternative — use the vehicle selector or contact us with your VIN for a guaranteed-fit recommendation. Replacing worn components on schedule preserves your vehicle's safety, reliability, and resale value — and aftermarket parts from established brands deliver OEM-equivalent performance at a fraction of the dealer price. Every part is dispatched from our UK warehouse with a 30-day money-back guarantee and free hassle-free returns.
Suitable cars
Equivalent products (23)
Show all 23 OE numbers
Control Trailing Arm Wheel Suspension SIDEM 21178 — compatible car models
| Car models | BMW: 7 (E38) |
|---|---|
| Engines | 725 tds |
| Year of manufacture | 1994-2001 |
| Manufacturer article number (MPN) | 21178 |
| OE part numbers | 31 12 1 141 721, 31 12 1 141 723 |
Compatibility check
Loading vehicle data…
Please wait while we load vehicle compatibility information.Description and what's included
SIDEM 21178 . Cone Size [mm]: 16,4 mm. Control/Trailing Arm Type: 2. Fitting Position: U. Fitting Position: VL. Material: 10. only in connection with: Ball joint+HYDRO SB. paired article number: 21179. Rod/Strut: 1
- 1x Control Trailing Arm Wheel Suspension
Shipping, returns, warranty
Free UK delivery on orders over £99.00. Express and standard shipping available.
- Standard delivery: 2-5 business days
- Express delivery: 1-2 business days
- Free returns within 14 days
- All parts backed by manufacturer warranty
Warranty: 12-month manufacturer warranty on all parts. 14-day money-back guarantee if the part doesn't fit your vehicle.
Frequently Asked Questions
Is this Control Trailing Arm Wheel Suspension compatible with my car?
This Control Trailing Arm Wheel Suspension fits BMW vehicles. Use the vehicle selector at the top of the page to check exact compatibility — enter your car's make, model, and engine for a confirmed fitment match. All fitment data is verified through TecDoc.
What specifications does this SIDEM Control Trailing Arm Wheel Suspension have?
This SIDEM Control Trailing Arm Wheel Suspension has the following specifications: Fitting Position: U; Fitting Position: VL; Cone Size [mm]: 16,4 mm; only in connection with: Ball joint+HYDRO SB; Material: 10; Control/Trailing Arm Type: 2. Check the full specifications table above for complete details.
What OE part numbers does this Control Trailing Arm Wheel Suspension replace?
This Control Trailing Arm Wheel Suspension replaces OE part numbers: 31 12 1 141 721, 31 12 1 141 723. Cross-reference these numbers with your vehicle's original part number to confirm compatibility.
How much does a Control Trailing Arm Wheel Suspension cost?
This SIDEM Control Trailing Arm Wheel Suspension is available for £46.99. Control Trailing Arm Wheel Suspension prices vary depending on brand, specifications, and vehicle compatibility. SIDEM parts offer a balance of quality and value, backed by our 14-day money-back guarantee.
How do I know when to replace my Control Trailing Arm Wheel Suspension?
Regular inspection of your Control Trailing Arm Wheel Suspension is recommended as part of routine vehicle maintenance. Watch for changes in performance, unusual noises, or visual signs of wear. Consult your vehicle's owner manual for manufacturer-recommended replacement intervals specific to your make and model.
What tools do I need to replace a Control Trailing Arm Wheel Suspension?
Tools required vary by vehicle make and model. Generally, a basic socket set, screwdrivers, and vehicle-specific tools may be needed. We recommend consulting a workshop manual for your specific vehicle, or having the Control Trailing Arm Wheel Suspension fitted by a professional mechanic.
Can I use this part as a replacement for OE 31 12 1 141 721?
Yes, this SIDEM Control Trailing Arm Wheel Suspension is a direct replacement for OE part number 31 12 1 141 721. It is manufactured to meet or exceed original equipment specifications, ensuring proper fitment and performance. All cross-reference data is verified through TecDoc.
Related categories
Common OE numbers for this part
Common original equipment numbers linked to stocked alternatives.
