2021 Ram 1500 TRX Suspension Deep Dive | Belly of the beast
I think we can all agree that we've been waiting a long time for a Gonzo truck like the 2021 Ram 1500 TRX. After all, it's been over a decade since the Ford F-150 Raptor came out, and it was such an instant hit that I expected its direct competitors to respond much sooner.
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We all knew something was finally brewing in 2016 when the TRX concept was unveiled at the Texas State Fair. I was there and was one of the many who gave the assembled Ram Major an enthusiastic thumbs up. That was what they had hoped for before they turned the project green. The pace of development is what it is, and since the redesigned current-generation Ram 1500 is a requirement that understandably had to come first, it's no surprise that we now see it only as a 2021 model.
You might bite your tongue that I missed the Tundra TRD Pro or the Chevrolet Silverado Trail Boss, but neither of them follow the formula set by the Raptor: Big engine, much wider stance than the base truck, vastly improved suspension Travel, huge tires and puffy fenders to cover it all. Only the Raptor and the TRX fit into this shape. For now.
Before I started, I first pointed the TRX at my RTI ramp and measured its flex index score. Please excuse the shaded nose; The truck went further than I suspected and literally drove out of the picture. But something in my subconscious warned me not to keep the garage door open, which was a fluke because the ram's nose landed in it.
The TRX hiked its front wheel 29 and 7/8 "off the ground before the rear left tire reached the point of lift-off, which is an 87.4" climb on the deck of my ramp. Divide that by the TRX's 145.1-inch wheelbase, multiply by 1,000, and you get a flex index of 602 points. It could have been a few points higher, I think, if I could have adjusted the steering a little better. But the non-slip surface of the cheese grater on my ramp was firmly embedded and had none of it.
This is an extremely good score for a full size pickup truck. Let's take a closer look at what made this possible.
The double wishbone front suspension track on the TRX is 6 inches wider than a regular Ram 1500, and you look at the parts involved. The lower wishbone (yellow arrow), upper wishbone (green), and steering knuckle (red) merge to increase the stance of the TRX by 3 inches per side.
We are also clearly able to see the massive Bilstein Blackhawk e2 (white) coilover kit and its powerful coil spring at linear speed. And by that I don't mean progressive rate.
The lower wishbone bolts on the same inner pivot points as a standard Ram 1500 and the position and bracket of the rack (yellow) are also identical. As was to be expected, longer steering links (green) also had to be attached due to the additional suspension width of 3 inches per side.
Below, the inverted C-shaped protrusion (red) on the lower end of the steering knuckle is a steering stop that comes in contact with a built-up portion of the lower wishbone so that the rack itself does not experience shock loads.
The Bilstein Blackhawks have a shock absorber body with an outer diameter of 68 mm and have remote oil and nitrogen gas reservoirs (yellow) that are centrally mounted. The left and right sides are stacked on top of each other well above the underride protection plate and connected to the shock absorber by means of strong, braided stainless steel hoses (green), which use a rigid stainless steel tube for strain relief in the area where the hoses are located, hammers with the suspension in the Terrain up and down.
Please note the number on the top of the picture: 330mm. This is not the stroke of the shock, but the entire bike path. That works out to exactly 13 inches, folks. That's at least 4 inches more than a regular Ram 1500 and, more precisely, exactly the same as a Raptor.
These shock absorbers are electronically controlled with magnetically controlled variable rebound and compression bypass circuits built into the piggyback housing (yellow). The main valve in the cylindrical shock absorber body is arranged like a single tube shock absorber on either side of the main working piston, but the piggyback's variable damping mechanisms are fed by oil in a concentric annulus surrounding the main pipe. Because of this, in some written descriptions of this shock absorber, you may see a double tube, although the primary valve is more like a single tube.
The lower end of the main chamber (green) hides three stages of increasing position-dependent compression that originates from a secondary piston on the nose of the main piston. At the very bottom there is a cup into which a progressive internal hydraulic stop is inserted. It's the same feature that the original Bilstein-equipped Tundra TRD Pro had, but with the added benefit of the electronic super-trick variability we see here.
One day I'm going to show you all of this in one snippet, but for now these shocks are exclusive to the TRX and everyone is left with tight lips. If I had to guess and knew there was a tube-in-tube arrangement here to feed the adjustable valves in the piggyback chamber, I'd bet the 68mm shock body contains a 46mm piston - a well-known Bilstein size.
Electronically controlled shock absorbers require suspension height (yellow) and G sensors (green), and we see one each here.
Don't expect to screw all of this onto your regular Ram 1500 and add flared fenders. The pivot points (yellow) for the upper wishbone are about 2 inches higher than on your non-TRX truck. A higher mounting point and larger steering knuckle will reduce the stress on all upper joints and mounting points, which is required because this suspension is designed to absorb large impacts.
In case you were wondering, the lower wishbone itself is the official Jack Point. Good, because my jack doesn't have the reach to lift this beast by the frame with long journeys.
Other views make the lower wishbone look bulky and massive, but we can see that from this shot I took while it was parked on my RTI ramp, it is much more weight and stress optimized.
Seen from the rear, the front stabilizer (yellow) can be clearly seen. It was in front of the axis prior to the 2019 Ram 1500 redesign, but moved here because it's more effective, easier to balance forces, because it's opposite the spool, and because there's more space to pack.
From here it looks like the coil is 65 to 70% of the way from the inner pivot point, so the joint spring and thrust movement - with a modest deduction for its inward lean angle relative to the arm. The stabilizer link appears to be almost dead, or maybe a little out of the way, so it's in the 50% range. Engineers need to take these into account and make their springs, shock absorbers and stabilizers stiffer to achieve the desired effect on the steering wheel.
Besides all that beef, I wouldn't blame you if you thought the brakes looked small. But they are not. This two-piston sliding caliper contains a pair of 57mm pistons, and the diameter of these ventilated rotors is quite generous at 378mm (nearly 15 inches).
Back here, the well-known (and so far exclusive) link-coil suspension of the Ram is fully effective. But check out these links! Get a load of this coil!
The coil springs have a preloading speed and you can see that here. I spoke about them to a ram engineer and he told me they were over three feet tall. I believe it because in the ramp photo we saw earlier I measured 22 inches left rear at full tilt. This leaves a few centimeters of preload so that no retaining clips are required.
The soft top coils (yellow) are close together and I was able to make the truck bounce dramatically when I hit the tailgate. However, you want a long spring with a soft initial engagement when you land a jump, for example. The lower coils (green) are further apart and stiffer. Inside you can see the stop (red) and the witness mark where they make contact when fully compressed.
Oddly enough, the driving frequency of the rear suspension is lower than that of the front axle, which is not common practice. You want the rear to catch up forward after a single event for the vehicle to line up, and more rear stiffness does that. But off-road they want to prevent the stern from jerking at high speed over closely spaced desert whoop-de-doos, so they went the other way. I can feel the rear end of a single intersection on my street is different, but they use variable damping to make up for this.
The shock arrangement is similar here, but there are two differences. Due to the progressive spring and its stop, there is no internal three-stage hydraulic surge stop inside. It is easier to see that the shock absorber is reversed with the body of the shock absorber at the fixed top end.
This arrangement is superior from the point of view of unsprung weight, but also in terms of packaging. I followed the hose and found the remote reservoir (yellow) hidden behind the fender trim.
Like the front, the Huckepack contains an electronically adjustable compression and rebound valve. In contrast to the front, there is 355 mm of bike path back here. That's 14 inches people. The Raptor is listed as 13.9 inches. That's a virtual tie - unless you're a Ram fanatic. Is it strange that the bike path is printed on the shock body? Yes, but where else are you going to put the label?
The strong 22mm shaft of the Bilstein Blackhawk (yellow) has a hard chrome finish that you * don't * want to be dented by flying stones - which can often be the case when you hit the hammer on 702 hp Hellcat- Drop anger. That's why they're hidden behind these thick shaft protectors (green), with a unique shape that gives them even more impact resistance.
The back links (yellow) are not Ram 1500 transmissions. They are much longer and much stronger, and are closely related to Ram 2500 pieces. This is especially true for their swivel sockets (green) - although they are tuned differently for TRX, their dimensions are identical to those with high angularity that can be found in the Ram 2500 Power Wagon. The Power Wagon needs suspension that articulates. It does.
It's also worth noting that the 3-inch extra track width here comes from wider axle tubes (red) outside of the shock absorbers at the rear.
The link-coil suspension is more commonly called the five-link suspension, and this Panhard rod (also known as the tie rod) is the fifth link. The far end in the dark distance (yellow) is the fixed end that is bolted to a bracket on the frame, while the near end (green) is connected to a bracket on the axle tube.
But what is that yellow thing (red - psych!) In the middle? Could it be a fifth shock absorber?
That's it. It extends between a bracket mounted on the rear housing and a barely visible frame cross member. It's there to tame the axle winding and the leap in power. This type is usually not required on a link coil suspension, but there are 724 reasons this makes sense: 8 high-angle suspension connector sockets, 14 inches of rear travel, and 702 horsepower.
This view gives you a better idea of where it is. It also shows that there is quite a bit to be gained by extending and redirecting the rear diff vent hose (yellow). As it sits, the "ford" depth is 32 inches here - just like the Ford Raptor.
This is possibly the stealthiest part of the rear suspension. You see a Dana 60 stern (yellow) with fully floating axles. The raptor as we know it doesn't have that. I don't know of any other "half-ton" truck with a full float. What does that mean? The axle shafts are separated from the outer hub drive flanges. They are toothed at the outer end and screwed together. It's a stronger setup that is not suitable for payloads, but rather for hard landings and high-speed impacts.
What you don't see is a rear stabilizer bar. There are only unused holes (green). With the exception of the TRX, all rams with link coil suspension have one. This is not the case as the articulation of the suspension is given priority. In this case, it is also less necessary because: a) the track width is a full 6 inches wider; and; b) The payload is a modest 1,310 lbs. That's still a decent payload, outperforming the Raptor by 110 pounds.
What about towing? The TRX is good for 8,100 pounds. The Raptor crew cabin is just a tad behind at £ 8,000. It's almost like someone making sure they beat their rival with just a touch on the datasheet.
The rear brakes consist of 375 mm (14.8 in) ventilated discs and sliding calipers with a single 57 mm piston. They also have an electronic parking brake actuator which I really appreciated when I hit the brakes and stepped out of the cabin on my ramp (more like a fall).
These are massive LT325 / 65R18 tires - with a T-speed of 118 mph. That works with 35-inch tires with old money. The rims are 18 x 9 inches and have a screwed-on aluminum decorative ring in beadlock style, which is not a real beadlock as it does not entirely overlap the tire sidewall (yellow).
The entire assembly weighs in at - get ready - 103.5 pounds. OK, the front one was 103 pounds. Nevertheless, it was very important for me to lift the truck as little as necessary so that I could get it on and off with minimal lift.
Would you like to upgrade to a real beadlock? Mopar has you covered. I removed the 12 screws and exposed the 24 holes the Mopar upgrade part will need. When these are in place, you can run extremely low toe pressures and still leave the bead in place and prevent the tire from timing itself if you give it a ton of torque. Or you could still use these and paint.
I hope you can understand now why this truck is so impressive - and I haven't even said much about the engine. This is well-executed off-road suspension with no cut corners, and the Ram engineering team took full advantage of the built-in advantage they had: link-coil suspension.
For Ford, I hope the rumors of a link coil tail in the new generation Raptor are indeed true. It seems almost certain that the new Tundra will have a connection coil, and we can only hope that they will develop a broad gauge version of the Tundra TRD Pro to compete against the Raptor and TRX. It is a good time to be a suspension nerd, all I can say.
Contributing writer Dan Edmunds is a seasoned automotive engineer and journalist. He worked as a vehicle development engineer for Toyota and Hyundai with a focus on chassis tuning and was director of vehicle testing at Edmunds.com for 14 years (no relationship).
You can find all of his Suspension Deep Dives here on Autoblog.
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