I’ve driven the Jaguar I-Pace a handful of times, and it always proves to be an enjoyable experience. In case you’re not up to speed, this is Jaguar’s dual-motor all-wheel drive all-electric SUV. It’s quick, it looks cool in a running shoe sort of way, and it delivers a decent 234 miles of range.

Sure, it has its faults, particularly when it comes to the infotainment and climate control layout. But the electric Jag’s smooth ride comfort and direct steering feel are clear strong points, and its handling stays nicely balanced and displays sharp reflexes as far as I’ve pushed it. That is to say, a strong pace, but nothing that would land me in jail.

The suspension plays a big role in all of this, of course. I wanted to see what they’d done, so I recently put an I-Pace HSE up on jackstands and took a look underneath. Electric powertrain notwithstanding, I found this to be an utterly weird and fascinating machine. 

 

From this vantage it is easy to see the big air spring (yellow arrow). The use of this type of spring medium allows the I-Pace to run at different heights. It mostly runs at standard height, but can also lower the car at highway speeds to lessen aerodynamic drag. There’s an even lower mode to ease the loading of passengers and cargo, along with a raised-height off-road mode because, well, this is theoretically an SUV.

It looks like it has a double wishbone front suspension, too, with a high-mount upper arm (green). But we can’t be sure until we move in closer.

 

With the wheel turned, we can see that this is a double wishbone front suspension in the sense that it has a single ball joint (green) at the bottom. There’s lots of nice-looking forged and hollow-cast aluminum bits and pieces, too. But it looks odd in some other respects. The lower arm (yellow), for example, seems to have a joint of some kind in it.

Meanwhile, near the top, you can see how the tall upright (or hub carrier, if you like) is curved (red) to provide tire and wheel clearance. Use the wheel studs as a reference point and you can imagine how the tire assembly will nestle into that area.

 

The shock absorber (green) runs up the middle of what is a doughnut-shaped air chamber. A very tall tower of a doughnut, but you get the idea. But you can’t call this a coil-over. Do I hear bag-over? Anyway, a position sensor (yellow) is connected to the upper arm so the height-control system can regulate itself properly.

 

A high-mount upper control arm layout offers several benefits and one drawback. On the plus side, the arm’s greater distance from the ground gives it extra leverage that reduces the loads in the arm itself, its ball joint, its two inner pivots (yellow) and the structure that supports them all. Also, any deflective movement in the pivot bushings will have much less of an angular effect on the geometry of the steering axis because of the increased separation distance from the lower ball joint. Finally, it’s easier for the designer to put the upper ball joint in the ideal spot because there are no other components competing for space, as there would be inside the wheel.

On the negative side, there’s isn’t enough clearance between the tire (which has magically reappeared for this photo only) and the upright to allow for the fitment of tire chains or oversized tires. You’re pretty much limited to winter tires, which is no bad thing from a cold-weather tire performance standpoint, if you ask me.

 

Here we can see that the lower wishbone is made up of two links: a lateral link (green) and a curved tension link (yellow). This still counts as a wishbone because it functions as one unit. There is but one ball joint (red), and the extra bolted joint is not a pivot. The two-piece construction facilitates the use of aluminum forgings, and offers better isolation of harshness, the rearward component of road impacts, while still providing the lateral rigidity needed for accurate steering and steady cornering.

 

The front stabilizer bar (yellow) follows the same curved path of the lower tension link. Its link (green) connects directly to the upright, which means the stabilizer bar will deflect on a 1-to-1 basis with respect to wheel motion.

Meanwhile, the bottom end of the air-spring and shock assembly attaches to an aluminum fork (red) that surrounds the front drive axle on its way to its connection point on the lower lateral link.

 

A felt wheel arch liner makes it hard to clearly see the pivot points for the stabilizer bar (yellow) and the lower tension link (green). But there’s no hiding the liner’s square hole that admits cool air in the general direction of the brake rotors (blue).

 

Here is another one of the I-Pace’s weird features. Do you see it? It has to do with the brakes (green) and the steering linkage (yellow). They’re both mounted behind the axle. That almost never happens. In 95% of cases you’ll find these two components on opposite sides of the drive axle so they don’t compete for space.

As for the lower lateral link, the spring/shock assembly is attached (red) inboard of the ball joint at what looks to be a 0.7-to-1 motion ratio. The effective ratio is slightly lower than that, though, because the spring and shock lean over at something like 20 degrees.

 

This picture illustrates why brakes and steering almost never share the same space. This is a single-piston sliding caliper (yellow), but the presence of the steering linkage means there simply isn’t room to fit any kind of Brembo big-brake upgrade unless they rework the whole thing and fit the calipers ahead of the axle.

 

And so the I-Pace has these modest brakes. It can get away with it because this is an electric vehicle. Almost all of your routine braking will be done magnetically, so these are mainly here for unexpected stops. This does, however, send a clear signal that this is not an all-out sports car or an Autobahn-burner like the all-electric Porsche Taycan, which has comically massive 10-piston calipers. 

 

As if it were possible, things get even more distinctive at the rear. It starts off pretty clear-cut with a single camber link (yellow) at the top, but there’s unusual stuff lower down. It’s a type of multilink, but we can’t yet say what sort.

 

Before we go there, let’s get the easy stuff out of the way. The shock absorber is obvious enough, and you can probably guess that the bellows (yellow) hides another air spring. You have to peer into the shadows to see the rear stabilizer bar (green) snake through it all.

 

I fully expect it to take time for the picture to fully resolve, so we’ll look at this from more than one angle. The upright (green) is a massive hollow cast aluminum piece that contains the rear wheel bearing and rear hub. The shock absorber (red) bolts to it at a direct 1-to-1 motion ratio.

Now let’s look at the contorted hollow cast aluminum piece (yellow) that functions like a lower wishbone. I say that because it has two pivot points on the inside and just one at the upright. The forwardmost inner pivot is raised up, however, and that allows room for a short folded steel toe-control link (white) to run underneath it. Why do it that way? All will become clear in due time.

 

This shows the same parts from a different angle, and all of the colors are the same. I’ve mainly added lines to illustrate that our lower monstrosity indeed functions like an A-shaped wishbone.

 

This short detour shows you where the stabilizer bar’s link (yellow) connects to that lower wishbone. You’ll need that in the next slide.

 

We’re almost there. The big cavity in the middle is where the spring mounts to the lower wishbone, but I’m sure you guessed that. The tick marks suggest that its motion ratio is about 0.6-to-1 or thereabouts. The lonely tick mark at about the 0.8-to-1 position is about where the stabilizer bar link connection would be if we had X-ray vision. This view also shows the toe-link (green) very clearly, as well as the eccentric at its inner end for adjustments.

But there’s a problem. All of this is well and good for holding the bottom in place, but what is keeping the top end and its single link from flopping fore and aft? How does this suspension brace itself when acceleration and braking torque are applied? The answer is hidden at the end of an extension (white) built into our lower wishbone. 

 

This extra lobe (yellow) is a hidden part of that massive contorted lower arm we’ve been staring at the past few frames. This is not an A-shaped lower wishbone, it’s an H-shaped one. But that alphabetical anomaly doesn’t actually interfere with the way it works as an A-shaped wishbone. It just gives it an extra function — the extra function we were looking for.

The extra lobe provides a place to mount this short torque link, and this little link does nothing but control acceleration and braking torque. This is what keeps the upright (and therefore the upper link) from moving fore and aft. It prevents the entire works from twisting itself in knots when you stand on the accelerator or mash the brakes.

 

You could say this link is integral to how it manages to work. In fact, they actually call this an Integral Link and, what’s more, this link gives this particular kind of elaborate multilink suspension a particular name: integral link suspension.

Why go to all this trouble? For one, Jaguar has used the concept for some time. They know it well. You’ll see something like it on the XE, XF and F-Pace. It also doesn’t take up much space, as there are no longitudinal links or arms. That’s important when you’re trying to maximize passenger space and the size of your EV’s battery.

Mainly, though, this design allows the various bushings at the ends of the links and arms to be better optimized. With the integral link taking up the torque reaction, a bushing’s lateral characteristics can be stiff to make the handling responsive, while their longitudinal attributes can be soft to allow the suspension to flex back to take the edge off potholes and other sharp-edged bumps.

It takes a lot of expensive forged aluminum links and hollow aluminum castings to make integral link work, but Jaguar can afford to charge what it takes.

 

After all of that, the brake seems a bit of a letdown. It consists of a simple single-piston sliding caliper, a ventilated rotor, and an electronic parking brake actuator.

 

My HSE test subject was shod with 22-inch wheels and 255/40R22 tires, and they are not light. Much of the aluminum we saw in the last frames was probably necessary to offset these monsters. I just about choked when I saw my scale settle in at 72 pounds apiece.

By all rights the I-Pace should ride horribly with these wheels and tires. But it doesn’t. The suspension concept lives up to its promise: It feels rigid and responsive when it comes to lateral inputs like steering and handling, but the air springs, their dampers and the nicely-optimized bushings do an excellent job of taking the edge off bumps and impacts.

I’m not saying it’s a rolling couch; it isn’t supposed to be. A bit of firmness in the context of control is just fine if the suspension isn’t overtly hard and harsh. And that’s exactly what the I-Pace manages to offer: sporty reflexes and a smooth ride despite comically large wheels and tires.

Contributing writer Dan Edmunds is a veteran automotive engineer and journalist. He worked as a vehicle development engineer for Toyota and Hyundai with an emphasis on chassis tuning, and was the director of vehicle testing at Edmunds.com (no relation) for 14 years.

Read more Suspension Deep Dives below and let us know which cars you'd like to see Dan put up onto the jack stand next ...

Porsche Taycan Turbo Suspension Deep Dive

Toyota GR Supra Suspension Deep Dive

Related Video:


Share This Photo X