Should you run a drop pitman arm on your WJ? The pros and cons explored in detail. And what is the best pitman arm solution for your WJ Grand Cherokee?
For those of you short on time, or who skip to the end of books…. I’ll give you the answer now…. NEVER run drop pitman arms on WJ’s with stock style steering boxes.
Now that we have that out of the way, for those of you who want to know the details….. “but Sean, why not? My lift kit came with one.”… Read on.
Pitman arms have four key details that dictate what vehicle they work on, and how they work on that rig.
- The length of the lever arm: the distance from the sector shaft hole to the steering joint hole.
- The height of the drop: the distance below the sector shaft seat that your steering joint sits.
- The clocking: where in rotation the pitman arm can be mounted up to your steering box.
- And finally, the steering joint hole size and type. These are normally tapered to fit a stock Tie Rod End, but can be various size holes, various angles of taper, or even straight through for a heim style steering kit that uses bolts.
Why is this important? Lets dive in deeper:
- Lever arm length is critical for the following reasons:
- It dictates how much swing or steering angle you can get. The longer the arm, the more swing, the shorter the arm, you loose steering angle
- It dictates how much leverage the steering box has on your steering system. And, inversely, how strong the pitman arm is. The shorter the lever arm, the less leverage, but the more load the pitman arm can take.
- Drop height is critical for these reasons:
- Fitment. Sometimes stuff is in the way like a radiator or sway bar, so just the right amount of drop is needed to clear things.
- Bump steer – this is a VERY complicated topic that we will cover in depth in a future article.
- Max steering angle. All flex joints, tie rod ends, heims, etc have a maximum amount of misalignment, or flex. As you lift your rig higher and higher, you need more flex to allow more axle droop.
- Pitman arms have what are called key splines or master splines. These larger flat areas in between the splines line up with flats on the steering box sector shaft, and dictate exactly how the arm mounts up. They usually can only be put on in 90 or 180 degree increments, which means there are only two or four ways around the face of a clock that your pitman arm can be installed.
- The wrong pitman arm, or key splines in the wrong location, mean your arm sits in the wrong orientation under your rig, which throws off your steering geometry, your drag link length, and potentially causes issues with fitment, or even reduces your available steering angle.
- Steering Joint Hole
- This is the easy one, it is very common to drill or ream these holes to a larger size to accept a larger, stronger, joint. It is critical you size your hole to the tie rod end or heim joint appropriately, and when doing any reaming, the angle and depth is critical. This job is best done with a lot of care, or done by a professional.
Now that we’ve covered that, what does that matter when installing a drop pitman arm on a WJ Grand Cherokee?
Take a close look at the photo above. You can see the key splines are lined up, but the clocking AND the lever arm length is different.
We’re comparing pitman arms from two different vehicle types….. right?
What you’re looking at is a stock WJ pitman arm (above) and a drop pitman arm commonly sold to WJ owners below.
Remember those four criteria we laid out on critical pitman arm measurements? Well, this aftermarket WJ drop pitman arm is wrong in THREE of the four!!! And it’s not uncommon that parts sold to consumers as fitting your rig actually end up causing more harm than good. This is the perfect example.
- The drop arm has a shorter lever arm, which actually reduces your Jeep’s available steering angle. What’s more, is vendors selling this product will sometimes come right out and say that, without actually saying they are selling you a part that was designed for a different vehicle, and isn’t right for your’s.
- Installing a pitman arm that has more drop than your old one, without correcting track bar geometry, will actively harm your handling and road safety. DO NOT DO IT! You will create what’s called bump steer, where your steering wheel will move left and right without your input as you drive over bumps or dips. Or, even worse, if you’re holding your steering wheel, your tires will move left and right with your steering wheel still pointed the same way!! It’s massively unsafe, and can also be a factor in death wobble.
- A further note, when correcting track bar geometry (future article) DO NOT install a drop bracket on the chassis/frame side. It also further harms your handling. This is critically true on the WJ platform specifically, the engineering reasons behind that are complex, and we will explore them at a later date.
- Key spline…. this aftermarket drop pitman arm clocks your steering into the wrong spot!! Your drag link length is now incorrect, the swing radius where your pitman arm sits is incorrect, and in general, it’s just all wrong.
- The hole is the same! Yay, one for four 🙄
Having said all of that, we have recently been made aware a major retailer of budget (cheap) Jeep parts has started making WJ pitman arms that are clocked correctly. We still wouldn’t suggest running them, as other problems exist, including their high failure rate, we’ve seen over a dozen snap totally in half.
This looks safe!
Yet another drop pitman arm failure
In summary, on the WJ platform, we never ever recommend drop pitman arms.
So what is the best pitman arm for your WJ Grand Cherokee?
If you are running a drop arm, we recommend switching it out ASAP to a stock one (see recommended Amazon product). Do note, if you have a drop trackbar bracket, you will also have to remove that to avoid bump steer. The proper way to fix steering geometry on a lifted WJ is an OTA/OTK (over the axle trackbar, over the knuckle steering) kit, and you’re in luck, Trail Forged is the only maker of such a kit for your WJ! See links below for our full blown Ultimate Kit (full OTA/OTK kit), or each component available individually as well.