For the past week, the topic of Ram 1500 plastic upper control arms has reignited into a hot topic online. Is it a big deal or who cares?
Ram 1500 plastic control arms?
Wait, what? Yes, it is true. 2019 Ram 1500 trucks and newer have been using plastic for upper control arms on certain trim levels of their trucks. That’s not the whole story.
Iljin, a South Korean Tier 1 supplier that provides parts on approximately 40% of the automotive platforms worldwide, approached Ram with the idea of using the plastic control arms it developed for uses on electric vehicles as a way to reduce weight.
Initially, according to a story on Compositesworld.com, these hybrid control arms used a combination of “Ultramid B3WG10 GF50, a 50% fiber weight fraction (FWF) injection moldable short-glass fiber/polyamide 6 (PA6) composite from BASF SE (Ludwigshafen, Germany)” and a steel reinforced plate the size of the control arm.
Ram engineers worked with Iljin engineers on the steel reinforced plate due to the use case for trucks is more demanding than electric vehicles.
“Although our plan was to offer similar driveline options as on the outgoing model, the new Ram 1500 half-ton pickup was designed to provide higher payload and towing capabilities — both of which impact overall chassis durability,” said Phil Cataldo, Stellantis design responsible-body on frame suspension according to Compositeworld.com. “That meant we started this program having to solve a technical contradiction: engineer an increase in capability/durability, but at lower mass, which was not an easy task. That made it critical for Ram engineering teams to push for innovations like the hybrid control arm in order to meet or exceed system and vehicle weight targets.”
Also, engineers developed heavily ribbed structure underneath the control arm for added strength.
“The significantly higher vehicle mass and concurrently higher loads and stiffness requirements of a light-duty truck meant that we had to meet far more challenging specs than on our previous EV programs,” adds Adam Herbolsheimer, Iljin North American sales director – chassis division according to Compositeworld.com. “Because this was the first time the technology had been tried on a light truck — and a flagship model at that — we had to meet the same performance requirements as the previous-generation control arm, which was a boxed section, steel-reinforced component. On top of that, our Iljin team had its own goal of reducing mass on the benchmark control arm weight by 15%.”
The article states the reinforced steel plate was removed after engineers made further improvements to the ribbing making the steel plate unnecessary.
“The upper control arm is the same part from the launch of the 2019 Ram 1500 (DT) and has been in reliable service for seven years (2018 CY launch),” Nick Cappa, Ram Trucks communications manager. “The arms are a composite that is integrated with a steel structure. We then e-coat the component to prevent corrosion. The final piece is more expensive to build but offers a significant weight reduction vs. steel or aluminum. The design is part of a lightweighting strategy, substituting composites for metal – which offer high-tensile strength at very low weight. It also is important to note the load on upper control arms is negligible compared to the heavier load on lower arms, which helped create the opportunity. Feel free to put a magnet next to the part.”
The other thing that is special about the hybrid control arms is they incorporated the ball joint into the plastic during the molding process. This should reduce the stress on those parts during operation which are expected to lead to longer service life on the parts for both the joint and the control arm. A Google search states the service life of an upper control arm should be between 80,000 to 150,000 miles.
Ram’s engineering team tested the hybrid control arms through various temperatures trucks would be used in and in real-world conditions as well as additional durability testing.
This hybrid setup was first used in the 2019 Ram 1500 truck and is now found in models throughout their lineup. For example, the off-road models like the RHO use an aluminum-forged upper control arm since it is expected to see much more high-speed off-road.
The Jeep Grand Wagoneer also uses the hybrid upper control arms.
Cracking and failure?
After publishing a YouTube video and short-form videos, many people have raised a lot of skepticism of these plastic control arms.
There’s been several who suggest one pot hole and the control arm is toast. Others state the plastic will become brittle and fall apart. Many claim these parts just won’t last obviously.
It has been 6 years since the parts have been used on Ram trucks. Searching online and checking the recalls on NHTSA.gov, there haven’t been that many issues reported. You’ll find a few forum members talking about a problem, but mostly that’s due to a lift kit or wheel issue and not actually the control arm that failed.
One TikTok commenter had an issue, and upon further discussion it was a police department using the trucks for police duty. They swapped out the upper control arms and haven’t had an issue since.
Many dealership service and parts people commented that they haven’t seen any fail nor have ordered any replacements. It is a big nothing item for them.
Our take
The upper control arm is there is help stabilize the wheel and allow the truck to flex when going over obstacles. It’s just going along for the ride whereas the lower control arm is much more in harm’s way for hitting rocks or other obstacles. The fact is the upper control arm is actually a good place for innovation since it isn’t as vital as other places in the suspension.
Plus, with the plastic setup, repair is simplified. You just swap out the whole part instead of trying to get the old ball joint out, fighting the rust and old bolts. While some people will argue they think that’s absurd and just want to replace the part that’s broken like the ball joint, not the whole control arm, I’d much rather spend a few more bucks and have a whole new part with new grease fittings if I’m doing the job. No sense being cheap.
