A Guide to Suspension Strut Mounts for the 2004-2005 BMW 645Ci
Understanding when to replace your strut mounts and which aftermarket options are best for your E63/E64 chassis.
- Listen for clunking over bumps or creaking when turning; these are the most common signs of failure.
- For best results, choose OEM-supplier brands like Sachs or Bilstein to maintain your BMW's intended ride quality.
- Always replace strut mounts in pairs and plan for a wheel alignment after the job is done to protect your tires.
- While cheaper brands like URO Parts are available, they are not recommended for critical suspension components by many BMW owners due to poor longevity.
Signs of a Failing Strut Mount
When a strut mount on your 645Ci begins to fail, the signs are often hard to ignore. Because this part is made of rubber and metal, it wears out over time from constant stress and exposure to the elements. Ignoring these symptoms can lead to more expensive repairs down the road.
Common symptoms include:
- Clunking or Knocking Noises: A distinct clunking or popping sound when you drive over bumps or potholes is a classic sign. This noise comes from the worn rubber allowing metal parts to hit each other.
- Steering Noise or Stiffness: You might hear a creaking, grinding, or squeaking sound when turning the steering wheel at low speeds, like when parking. This often points to a failure in the bearing within the front strut mount.
- Increased Vibration: If you feel more vibration through the steering wheel or the car's floor, the mount's ability to absorb road harshness may be compromised.
- Poor Handling and Alignment: A worn mount can alter the suspension geometry, making the car feel less stable, pull to one side, or cause uneven tire wear.
Choosing the Right Aftermarket Strut Mount
When replacing strut mounts on a performance luxury car like the 645Ci, the quality of the part matters. Aftermarket options range from OEM-supplier quality to budget-focused parts. Here’s how the available brands generally stack up based on owner experiences and brand reputation.
Tier 1: OEM Quality & High-Performance
These brands are known for making original parts for BMW or for providing equivalent or better performance. They are the safest bet for restoring the original ride and handling characteristics.
- Sachs: Often an original equipment manufacturer for BMW. Choosing Sachs is typically the closest you can get to the original part without the dealer price tag. They are designed to restore the factory ride.
- Bilstein: A highly respected German brand. Their B4 line is designed as a high-quality OE replacement, perfect for matching with stock springs. Many BMW enthusiasts trust Bilstein for durability and performance.
Tier 2: Standard Aftermarket
These brands are well-known in the aftermarket and offer a balance of price and quality. They can be a good choice for daily drivers where budget is a consideration.
- KYB: A major player in the suspension world, KYB is generally considered a decent mid-range option. However, some users have reported their strut mounts can be noisier or less durable than their struts.
- Monroe: A very common aftermarket brand offering a comfortable, non-sporty ride. While they are a cost-effective solution, many BMW owners feel they are a step down in performance and longevity compared to OEM suppliers.
- CRP (Rein): Rein is known to be a decent aftermarket supplier, but there is less specific feedback on their strut mounts for this particular BMW model.
Tier 3: Economy Brands
These brands compete primarily on price. While tempting, they are often not recommended for critical suspension components on a BMW, as premature failure is a common complaint in owner forums.
- URO Parts: Generally regarded as a budget brand. Many experienced owners advise against using URO for suspension parts, citing poor fitment and a short lifespan.
- Vaico: Marketed as a quality alternative, but with limited specific reviews for this application, it falls into the budget category for many buyers.
- DEA Strut: Limited information is available for this brand in relation to BMW applications, placing it in the economy tier.
Pro Tip: Replace in Pairs
It is always recommended to replace strut mounts in pairs (both front or both rear). If one has failed, the other is likely not far behind. Also, it's wise to replace the mounts whenever you are replacing the struts themselves to save on future labor costs.
Cost of Replacing Suspension Strut Mounts
The cost can vary based on your location and the parts you choose. The table below gives a general estimate for the 2004-2005 BMW 645Ci.
| Item | Estimated Cost |
|---|---|
| New Aftermarket Strut Mount (Single) | $34.19 - $97.37 |
| New OEM Strut Mount (Single) | $110 - $130 |
| Shop Labor (Pair) | $250 - $450 |
An alignment is almost always necessary after replacing front strut mounts to prevent uneven tire wear and ensure proper handling. Factor this into your total cost.
Frequently Asked Questions
Do I need to replace my struts and mounts at the same time?
It is highly recommended. The labor involved in accessing the strut mount is the same as replacing the entire strut assembly. Doing both at once saves you from paying for the same job twice. A new strut deserves a new mount for best performance and longevity.
Can I replace just one strut mount?
You can, but it's not advisable. Suspension components wear at similar rates. If the left mount has failed, the right one has endured the same mileage and road conditions. Replacing them in pairs ensures balanced performance and predictable handling.
What other parts should I inspect or replace at the same time?
When the strut assembly is out, it's a great time to inspect the strut bellows (dust boot), bump stop, and spring pads. These parts are inexpensive and protect the new strut and mount.
Are there any recalls for the 645Ci suspension?
As of late 2023, there are no specific NHTSA recalls for the suspension strut mounts on the 2004-2005 BMW 645Ci. Recalls for this vehicle have addressed other issues like the brake vacuum pump and battery cables.
Technical Specifications
OEM Part Numbers: 31336760943 31336752735 33526779611
The front strut mount for the 645Ci incorporates a bearing to allow for steering rotation, while the rear mount is a solid rubber design. Both serve to isolate noise and vibration. The 645Ci uses a double-pivot front suspension, making the mount's integrity crucial for proper kinematics.
We Have This Part in Stock
The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- BMW 645Ci: