Is tie rod end and Inner arm shaft kits the same?
Buying the wrong car parts is frustrating and keeps your vehicle off the road longer. You might see "Inner Arm Shaft" and "Tie Rod End" on a parts list and assume they are the same because the names sound somewhat similar.
No, a tie rod end and an inner arm shaft kit are not the same. A tie rod end is a steering component used to turn the wheels, while an inner arm shaft kit is a suspension component that acts as the mounting pivot for a control arm to the frame.
I handle these parts every day at GSW Autoparts. I often see customers mix them up, especially when repairing older trucks or vans. I’ll explain exactly how they differ so you can buy the right part the first time.
What is a Tie Rod End on a Car?
You turn the steering wheel, and the car turns left or right. This happens through a chain of parts, and the tie rod end is the final link in that chain.
A tie rod end is a ball-and-socket mechanism that connects the steering gear (or rack) to the wheel knuckle. It is responsible for pushing and pulling the tires to steer while allowing the suspension to move up and down.
Working close to the production line for years, I’ve learned that the tie rod end is the most active part of your steering system. Every time you drive, this part is moving. It handles thousands of micro-adjustments per mile.
Its structure is simple but vital. It contains a ball stud enclosed in a housing. This stud can rotate and pivot. Why is this important? Because your wheels don’t just turn left and right; they also bounce up and down with potholes. If the connection were a solid steel bar, it would snap when you hit a bump. The ball joint1 in the tie rod end2 allows for this flexible movement.
When this part wears out, you get "slop" in your steering wheel. You might turn the wheel an inch, but the car goes straight. That’s dangerous. At GSW Autoparts, we polish our ball studs to a mirror finish to ensure they move smoothly and last longer. If you hear a "clunk" when turning, it’s often this part.
What are the Types of Tie Rod Ends?
You might look at a diagram and see two different-looking parts both labeled "tie rod." This adds to the confusion about what to buy.
There are two main types: Outer Tie Rod Ends and Inner Tie Rods (often called Rack Ends). The outer connects to the wheel, and the inner connects to the steering gearbox. They screw together to form the complete steering linkage.
Understanding "Inner" vs. "Outer" is where most people get confused with "Inner Arm Shafts."
The Outer Tie Rod End is the one you can see easily by looking behind your tire. It is usually angled at 90 degrees (L-shaped). Because it’s next to the wheel, it takes the most abuse from road dirt and water.
The Inner Tie Rod (Rack End) is different. It is basically a straight rod with a ball joint at the end. It hides inside the rubber dust boot attached to your steering rack. Its job is to provide extra length and articulation angles.
When we package these at GSW Autoparts, we often box them together as kits. But you need to know that these are strictly for steering. They control the direction of the tires. They do not hold the weight of the car. That is a critical distinction. If you remove a tie rod, the wheel will flop side-to-side, but the car won’t fall down.
Here is a quick way to identify them:
| Part Name | Shape | Location | Job |
|---|---|---|---|
| Outer Tie Rod | L-Shaped (90 deg) | Near the Wheel | Connects linkage to the knuckle. |
| Inner Tie Rod | Straight Rod | Near the Engine | Connects steering gear to the outer rod. |
What are Inner Arm Shaft Kits?
This is a part many average car owners have never heard of, but it is critical for the suspension of vans, pickups, and older SUVs.
An Inner Arm Shaft Kit is a suspension assembly that serves as the mounting axle for a control arm (usually the upper arm). It consists of a heavy-duty steel shaft, bushings, and mounting bolts to secure the suspension arm to the vehicle’s chassis.
I want to dive deep into this because it’s a specialty at GSW Autoparts. We supply thousands of these for vehicles like the Toyota Hiace, Mitsubishi L300, and various pickup trucks.
Unlike the tie rod, which is for steering, the inner arm shaft is for support. In a double-wishbone suspension system, you have an upper control arm and a lower control arm. These arms need a hinge point on the frame so the wheel can move up and down. The inner arm shaft is that hinge pin.
The word "Kit" is important. You aren’t just buying a metal bar. A proper kit includes:
- The Shaft: A hardened steel bar that bolts to the frame.
- Bushings: Rubber or metal sleeves that slide over the shaft to absorb shock.
- Retainers/Washers: To hold everything tight.
When I inspect these on the production floor, I check the surface hardness of the shaft. It has to be incredibly tough. If the metal is too soft, the movement of the control arm will grind grooves into the shaft. Once that happens, you get a terrible squeaking noise, and your wheel alignment (camber) goes completely off. No matter how many times you align the wheels, if this shaft is worn, the tires will lean in or out.
This part holds the weight of the vehicle and the force of braking. It is a stationary pivot, whereas the tie rod is a moving link.
Is a Tie Rod End the Same as an Inner Arm Shaft Kit?
Now that we have the concepts down, let’s compare them directly to clear up the confusion for good.
They are completely different. A tie rod end is a moving steering link used to turn the wheels, while an inner arm shaft kit is a stationary suspension pivot that connects the control arm to the frame to support vehicle weight.
I believe the confusion comes from the word "Inner." Mechanics talk about "Inner Tie Rods" and "Inner Control Arm Shafts," and it sounds like the same thing. But functionally, they are worlds apart.
Think about your own body.
- The Inner Arm Shaft is like your shoulder joint. It connects your arm to your body and holds the weight. It lets your arm move up and down.
- The Tie Rod End is like the muscle or tendon that pushes your hand left or right.
If you are installing a tie rod end, you are fixing loose steering or wandering on the highway. If you are installing an inner arm shaft kit, you are fixing suspension clunks, squeaks over bumps, or tires that are wearing out due to bad camber angles.
At GSW Autoparts, we advise our wholesale clients to double-check their vehicle diagrams. Inner arm shafts are mostly found on trucks and vans with double-wishbone suspension. Many modern small cars with MacPherson struts don’t even use an inner arm shaft (they use simple bushing bolts). However, almost every vehicle has tie rod ends.
The Breakdown:
| Feature | Tie Rod End | Inner Arm Shaft Kit |
|---|---|---|
| System | Steering | Suspension |
| Movement | Push/Pull (Active) | Pivot/Hinge (Passive) |
| Supports Weight? | No | Yes |
| Main Component | Ball Joint | Steel Shaft & Bushings |
| Signs of Failure | Loose steering, wandering | Squeaking, bad camber alignment |
Conclusion
Tie rod ends control steering direction, while inner arm shaft kits secure suspension arms to the frame. Knowing the difference ensures you order the correct part for a safe and stable ride.
About the Author
Root is a Content & Operations Specialist at GSWAUTOPARTS with 5 years of industry experience. With the advantage of being close to the production floor, Root excels at documenting product details and manufacturing processes. He focuses on translating technical insights about rubber and chassis parts into clear, useful information for customers.
