T-Rex Arms Vs. Long Arms – What You Need To Know About Bronco Radius Arms.

It still amazes me to this day how many Early Broncos still have stock radius arms. I have been to so many Bronco events and so many Broncos are lifted with 33″ and bigger tires and STOCK arms. Heck for that matter it amazes me how many Broncos have a “lift kit” and not a suspension system. There is a difference! Ok, let me backup for a sec. What is a radius arm? Look under a 1966-79 Bronco or even a 1964 to 79 F100 4×4 pickup. Take a knee behind the front tire and look under the body. You will see a bar that connects the back of the front axle to the frame rail under the door (just past the A-pillar). There is one of these on the driver and passenger side and they hold the front axle in place (front to back) at each frame rail. The front end is held on by what many people call a 3 link setup. Two radius arms and a track bar that is responsible for controlling (eliminating) side-to-side axle movement.

Why do we care about radius arms?? If you knew what I know you would care A LOT! This is not a sales pitch, It’s just the FACTS. If driving your Bronco, being in control, and enjoying the ride are important to you then continue reading because factory radius arms cannot do that when they stop being a stock Bronco. What does the radius arm do or in the case of a factory radius arm, what does it NOT do after your Bronco suspension is lifted over 2 inches?

The factory radius arm is naturally in a bind and once you lift the suspension it is put in a bigger bind which creates a harsher ride. The other issue is the length of the arm. As the suspension height increases the arm rotates the front axle forward and pulls it back slightly. This is a big problem because you need something called CASTER to make your Bronco drive really good down the road. The factory radius arm takes away all your caster when the Bronco is lifted. Some will argue you can add caster correcting C bushings and you can even add drop brackets at the frame. However, degreed C bushings and drop brackets don’t always fix the problem and sometimes can create other problems/issues to deal with. Plus, the other great virtue of a Bronco is its incredible turning radius. Well, what do we do when we add a lift…? WE ADD BIGGER TIRES! The bigger tires combined with a tight turning radius are going to now make those tires rub the radius arms in a tight turn. The noise and feeling is AWFUL. Everybody hates it but who wants to sacrifice their tight turning radius!? I know I don’t! It is one of the many things I absolutely love about the Broncos. So what is the solution? Duff radius arms! It is a no-brainer but first, you need to know which arms are best for you.

So, first, you need to decide if Duff factory length aka T-Rex arms or Duff Extended (Long) arms fit your Bronco best. You can’t answer that question until you know what the difference is and what each arm offers. Let’s start with the factory-length Duff arm first-

The T-Rex arm. Now don’t let this little guy fool you like he did me. I thought he was pretty useless at first glance. I mean look how short he is!? But this arm comes loaded with great features and fixes a ton of problems. In fact, its only real shortcoming (I kill myself) is it cannot flex/articulate as much as its big brother the Long arm. So, if your Bronco spends 70% or more time on the street and you aren’t looking to climb over big rocks and similar-sized obstacles or go really fast in the sand or the desert, then the T-Rex arm is a great fit for you. It can still do a lot of great off-roading with the added benefits of bolt-in application so no cutting drilling or welding is required. You get that awesome tight-turning radius back with those bigger tires. It is also worth noting, that ALL Duff radius arms are designed to free up suspension travel so they offer a softer ride. Do you really want to feel an amazing ride all around on your Bronco? Combine these arms with the Duff suspension and it is a GAME CHANGER. Still not sure which arm is best for you?

Let’s talk about the Duff Long Arm. The Big Brother to the T-Rex arm is almost 11 inches longer than a stock-length arm. This really is the do EVERYTHING radius arm for Broncos. But be prepared, it will require cutting, grinding and welding to install them as well as 3+ inches of suspension lift, the correct shock mounts and correct length shocks. Most Broncos using Long arms are running a 35 inch tire or bigger, wheeling on difficult (red & black) trails, going fast in the desert, and enjoying the whoops and jumps on the dunes. This arm also will make the on-road ride softer so a good shock like the Duff’s MS2020 and an aftermarket Hellwig sway bar may be required for panic situations to not lose control of the Bronco.  Another benefit the long arm offers for those who like whoops and jumps is the length of the arm reduces caster change throughout your suspension travel. 

NOTE: Both the T-Rex and Long arm utilize a second set of bushings at the head of the radius arm. These bushings allow articulation without all of the stresses to be the sole job of the C-bushing. This also allows for a smoother ride as it translates less sharp suspension movements to the vehicle and prolongs the life of the C-bushing.

Which arm do I prefer? Honestly, I love them both but prefer the T-Rex arm on Huck my 72 Bronco which currently has 33’s and a 1.5-inch long travel Performance Package. Now, on a Bronco with a 3.5-inch lift and 35″ tire or bigger, I want the long arm. Both arms work great on other Broncos and trucks like the 1978-79 Broncos and F100 & F150 4×4’s from 1964 to 79. 

Let’s not forget how awesome the long arm is for solid axle swapping any Ranger-based vehicle from 1983 to 97 and all F-150s and Broncos from 1980-96. Heck, I’ve seen the long arm swapped into vans, cars with off-road chassis, and even J**ps! 

Which one is best for you is a question you can now answer. What’s even more important is you start making your Bronco the most fun to drive while being confident behind the wheel. The Duff radius arms and so many other great products they offer can do that, so what are you waiting for!? Get on the website today and make the best decision for you and your Bronco right now and be blown away at how much better your baby drives, handles and off roads. Below are links to our various offerings for the Bronco Platforms.