Concerning Small Radius Arm Bushings

Ref prior discussion on control arm bushings:

I got the following helpful reply from a bushing manufacturer:

Fully bonded and semi-bonded rubber bushings are two types of bushings used in various mechanical applications to isolate vibrations and provide cushioning. The main difference between these two types lies in the way the rubber material is attached to the inner and outer metal components of the bushing.

1. Fully Bonded Rubber Bushings:
Fully bonded rubber bushings, as the name suggests, have the rubber material completely bonded or adhered to both the inner and outer metal components of the bushing. This bonding process typically involves vulcanization, where the rubber is chemically bonded to the metal surfaces. The complete bonding ensures a strong and secure attachment between the rubber and metal, resulting in enhanced stability and durability.

- Improved strength and durability due to complete bonding.
- Better resistance to axial and radial forces.
- Higher load-bearing capacity.
- Enhanced vibration isolation properties.

- More complex manufacturing process.
- Higher cost compared to semi-bonded bushings.

2. Semi-Bonded Rubber Bushings:
Semi-bonded rubber bushings, also known as partially bonded bushings, feature a partial bonding between the rubber material and the metal components. In this design, the rubber is bonded to only one of the metal components, typically the inner metal sleeve, while the outer metal casing remains unbonded. The rubber is molded or pressed into the bushing and may have mechanical interlocking features to provide some level of retention.

- Simplified manufacturing process compared to fully bonded bushings.
- Lower cost compared to fully bonded bushings.
- Easier replacement or repair since the rubber can be easily removed from the unbonded metal casing.

- Reduced overall strength and durability compared to fully bonded bushings.
- Lower load-bearing capacity due to the lack of complete bonding.
- Limited resistance to axial and radial forces.
- Potentially lower vibration isolation properties compared to fully bonded bushings.

The choice between fully bonded and semi-bonded rubber bushings depends on the specific application requirements, such as the magnitude of vibrations, load-bearing capacity, and cost considerations. Fully bonded bushings are generally preferred for applications where high strength, durability, and superior vibration isolation are critical, while semi-bonded bushings may be suitable for less demanding applications where cost and ease of replacement are important factors.

My thoughts from that:

  1. the standard LCA bushings would fall under the heading of semi-bonded
  2. I do want to try a fully bonded bushing in the LCA front position, for enhanced cornering stiffness. It might also increase stiffness in the braking mode, I don’t currently see a problem with that but will include it in the modelling after I’ve found a suitable bushing and rate tested it.
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