Improved Control Arms for Tesla 3 & Tesla Y

SH Auto Parts have designed, patented and manufactured an improved front upper control arm for the Tesla Model 3 and the Tesla Model Y. This is in response to issues arising with the OE front upper control arm, which was manufactured using composite materials and suffered from premature failures including the potential for ball joint separation, and the OE revised version, which was heavy and still suffered from ball joint failures.

Why did we need to improve the control arms for Tesla 3 & Tesla Y?

We needed to engineer an improved design for the Tesla Model 3 / Tesla Model Y composite control arms (example shown above with evidence of attempted repair) because of two serious issues identified after the vehicles were in production and widely available to the public. Both issues are related to premature failures; structural failures of the control arm around the ball joint, and failure of the ball joint itself. In extreme cases, this can lead to separation of the ball joint, which is potentially very hazardous.

Why did the Tesla control arms fail?

Tesla vehicles are modern, innovative, designs that include many novel features, materials and technologies in a complex package. The failure of the composite upper front Tesla control arms in the Tesla Model 3 appears to be the result of seeking to reduce weight as much as possible by using lightweight materials. The strength to weight ratio of composites is good compared to most metals, which is why they are seen as a sensible option for modern auto manufacturing.

Composite control arms failed from flexing and environmental factors

Composite control arms achieve weight reduction for performance gains, but the composite Tesla 3 control arm shown above lacked the resistance to repeated flexing, temperature and humidity changes that is achieved with steel control arm manufacturing processes. It is often difficult to predict the mode of failure of a novel suspension component, and although a composite arm might pass standard tests of flexibility and strength it is harder to identify the potential for failure due to longer term environmental stresses.

Ball joint seals leaked causing corrosion and increased wear

An additional problem that arose with the Tesla 3 upper front control arm is that the ball joints were subject to early failure. This was because the seals tended to leak, which allowed moisture to enter the ball joint, causing corrosion and increased wear. When this was combined with the tendency of the composite control arms to fracture, the increased and erratic forces from the compromised ball joint could lead to ball joint separation, which is a significant safety issue in critical suspension components.

Did Tesla correct the problem with their Tesla 3 control arms?

Tesla addressed the flexibility and cracking issues of the composite control arm for the Tesla 3 by designing an OE replacement made out of steel, shown above. The revised version had a similar configuration to the original, which did not address an additional problem of seal failures leading to premature failure of the ball joint.

The risk of fracture and control arm separation was reduced, but the problem of ball joint failure was still an issue and the revised control arm was significantly heavier than the composite original, weighing 3kg compared to the 2.43kg of the original composite control arm. The revised design lost the weight performance of the original and still suffered from problems with the ball joint seals.

SH Auto Parts improved upper front control arms for Tesla 3 & Tesla Y

At SH Auto Parts we evaluated the engineering and material design of the original Tesla Model 3 upper front control arms and carried out tests and computer assisted engineering (CAE) to assess the flexibility and durability of the composite component. The image above shows the composite Tesla control arm demonstrating a maximum deflection of 3.91mm under test loads. Our CAE included analysis of mode of failure, and identified the causes of the leaking seals that affected the integrity of the ball joint.

We examined the OE revised steel version of the upper front control arm and realized that the ball joint seal issue was still present, and that the OE revision of the composite control arm was extremely heavy compared to the original, and potentially much heavier than it needed to be based on our own engineering calculations and experience in suspension component design and testing.

How did SH Auto Parts redesign the Tesla 3 control arm?

SH Auto Parts redesigned and reengineered the Tesla 3 control arm from first principles, to IATF 16949 standards, to improve on the rigidity and strength of the original composite component, fix the ball joint seal failure issue, and keep weight down without compromising on performance. The result, shown above, is twice as stiff as the original composite upper front control arm, with maximum deflection of 1.75mm under the same test conditions and 0.2kg lighter than the revised Tesla OE component.

The SH Auto Parts stamped and formed upper front control arm for the Tesla 3 and Tesla Y is more rigid than the OE composite control arm, lighter than the Tesla revision, and not prone to ball joint seal failures. We were awarded a patent for our improved design, and manufacture it as an upgrade for Tesla 3 & Tesla Y suspensions. If you are looking to reengineer or redesign control arms for ODM, OEM or after market auto suspension components, contact our skilled engineering team to discover how we can help.