Jimny lift selection, suspension terms & things to know

People new to modifying 4wds get bombarded with a lot of suspension terminology and also obfustication about differences between lifts (or their similarities).

If there is a term you see in the ad blurb for a lift kit, or you’re unsure of what lift kit will suit your gen4 Jimny then this is the article for you.

Note that it primarily applies to the 3 door JB74 ‘GJ’ Jimny. The 5 door JC74 ‘JJ’ Jimny XL does basically run the same suspension but spring rates at least likely differ, and I don’t have any first hand experience to lean on. You can extrapolate from what I say about the 3 door lifts but I’m limiting myself factually to it.

Sections

[I’ll fill this in when it is written]

Lift selector: what might work for you

This is upfront but if you want to understand a bit more you’ll want to dig deeper into this article.

If you want an upgrade to the actual weight capacity then you’ll need a GVM (gross vehicle mass – total maximum allowable weight for the vehicle) upgrade. Unless you’re in Queensland this locks you into offerings from Ironman or Tough Dog only. In Queensland there is a route to upgrade the GVM to the sum of the weight limits of the front and rear axles, but all of these details will get discussed below in the GVM selection.

If you aren’t getting a GVM upgrade you have a wider selection of lifts which is what I will now discuss. As of early 2024, my recommendations based on what people have found with different lifts, things that are more easily bought/fitted in Australia and also looking carefully at the differences between lift brands. If you are getting someone to fit your lift kit then potentially their choice of brand to deal with might be a factor to consider in your decision making.

If you mostly want to improve the ride quality and are ok with a small to nonexistent lift then the H&R springs and upgraded shock absorbers (either Koni or Bilstein) are worth getting. Total suspension travel ends up about the same as standard, you don’t have any more ability to carry weight, but the car will ride better especially on road but offroad isn’t compromised. I would not recommend this option if you have a bullbar, or if you think you’ll go offroad reasonably extensively. Downward travel on these shock absorbers is basically the same as stock so even with a small 20mm lift you might actually have little to no additional wheel travel over stock.

If you generally are lightly loaded in the back and you mostly like the ride of the car on a relatively normal road then the OME 40mm lift through ARB is a good choice for you. The spring rates are the same as standard (though higher for the front if you have a bullbar) but taller. If you carry a lot of camping gear a lot of the time then the lower spring rate in the back

If you are more heavily loaded in the back then you will want something with a higher spring rate and for this you have a lot of choices. Two good options are the Dobinsons 50mm lift or the Formula 4×4 lift through Fulcrum. The Pedders Track Rider lift also looks to use very similar spring rates to these other two though I haven’t measured it. The Black Raptor 50mm lift from JimnyBits, either in the normal or in the premium with adjustable shocks is a good option.

If you want ultimate flex then another option is to look into the Japanese lifts, especially if you are not running much more base weight than a stock car. A lot of the Japanese lifts run relatively soft spring rates which is great for flex.

Once you start going beyond a 40-50-60mm sort of lift options get more limited and you really need to understand more of what you are doing. Potentially there will be nothing off the shelf for what you are after; that said most people seem to be happy with going with 4xfourart for the taller of the lift options, and the 80mm Tough Dog is not quite so well loved in this segment.

Lift basics: height and carrying capacity

I’ve already touched on this but I want to dig deeper into the fundamentals.

GVM upgrades: what are they and do you need them?

GVM upgrade versus a lift: are they the same?

In theory no, they aren’t the same though practically for the Jimny both GVM upgrades get you a 40-50 mm suspension lift. This is because you need to upgrade the springs to higher spring rates to accommodate the higher total mass of the vehicle when it is fully loaded to the revised GVM.

Pre versus post rego

Suspension components

A Jimny has an incredibly basic set of 3-link suspension front and rear attached to solid axles. This makes the suspension components pretty simple but also good to learn what is what when you’re looking at the key components.

Shock absorber

Spring

Radius arm

Panhard rod

Drag link

Suspension glossary

Springs are the main element that set your suspension up. They resist the weight of the vehicle and what you put in and on it, and then they also control how the wheels move when they encounter bumps or holes offroad. In a gen4 Jimny they are ‘coil springs’ i.e. just a bit of metal wound around and around and around. They sit between the axle and mounting points on the chassis.

Shock absorbers are the other key element that sets how your car rides and handles. They are sometimes called dampers as they dampen oscillations set up by the spring – a car with no shock absorbers will sit at the same height as one with it, but will then bounce repeated after hitting a bump. The characteristics of how the shock absorber resists this bouncing gives part of the ride quality of the vehicle (the springs set the other part of it – it’s all about them working together). Adjustable shock absorbers let you vary this bouciness, usually an all in one adjustment for Jimnys but potentially they can be adjusted for how fast or slow they both resist being compressed (compression damping) or how they extend (rebound damping). Shock absorbers mount also to the chassis and to the axle.

Radius arms are the links leading forwards and backwards from the chassis to the axles. Their role is to control the position of the axle forwards and backwards. The front ones go from the middle of the car forwards to the front axle, and the rear ones go from the middle of the car backwards to the rear axle. Among other things this is where the factory jack points are. They are terms radius arms as they define the radius of the circles around which the axles rotate as the suspension moves up and down. This means the axle moves not just up and down, but also can move a bit forwards or backwards as the suspension moves.

Panhard rods are the links that lead sideways from the axles up to the chassis. They control the position of the axles side to side. As the suspension is compressed or extended the axles do move a little sideways with these, but they keep the axles mostly centred. Adjustable length panhard rods are how you correct the position of the axles with respect to the chassis at static ride height. Panhard rods also control where, vertically, the suspension appears to rotate around as the car rolls in corners. Relocated panhard rod mounts/brackets alter this roll centre to help the car’s handling after a lift. Generally only performed on the back of the Jimny for smaller (40-50mm lifts) but a revised mount lower on the chassis is needed at the front for taller lifts (in the 80+ mm range). Note the difference: adjustable panhard rods get you side to side adjustment, and the panhard bracket relocation varies the roll centre of the car. They are not equivalent changes.

Lift height is the height that the car sits at rest on a flat surface. To remove any variance if you fit different wheel diameters or different sized tyres, the official measurement is from the centre of the axle to the highest opening part of the relevant wheel arch, as illustrated below. The lift height is often measured in mm (e.g. 20, 40, 50 or 60 mm lift) or inches (e.g. 1.5″ or 2″). It is a measure of the difference between the static ride height without the suspension lift kit installed and after it has been installed.

The exact amount of lift depends on a lot of factors but the simple thing to understand it is a product of the combination of the weight you have on the car and also the spring rate (and preload) which I’ll explain more in a moment. Lifts can be done as a suspension lift or a body lift though only a suspension lift is common and easily legal with a gen4 Jimny in Australia. Suspension lifts increase suspension travel (articulation – discussed below) whereas body lifts change the separation between the car’s body and the chassis. Since only one of these is common I’ll stick to discussing suspension lift stuff in this article.

Suspension travel is the amount of length that the suspension travels between fully compressed and fully extended. The fully compressed length is set by the bump stops in the car, whereas the fully extended position is set by the extended length of the shock absorbers. Two lifts might sit at the same height (discussed below) but one might have more suspension droop, meaning more wheel travel and so more ‘flex’. It’s also possible one lift includes extended bump stops which will limit the ‘upwards’ travel of the wheel. This means less overall wheel travel but stops things like larger wheels hitting the body of the car. Most Jimny lifts do not include extended bump stops by default.

Spring rate is the amount of force it takes to compress a spring a certain distance, usually measured in N/mm for us metric folk. A Newton is a measure of force, but for these purposes it can be thought of as the weight force and is 9.8 x the mass in kg. The vast majority of springs in 4wds are constant rate springs and so their rate does not vary as they compress. (Progressive suspension gets stiffer the more you compress it; digressive suspension get softer as you compress it. This gets to be a deep argument about what’s right as a choice especially offroad where digressive suspension might make sense. Fundamentally, there’s a reason why most springs end up linear rate and it’s not worth overthinking beyond that).

The spring preload is the amount of force applied to the spring initially, essentially it’s where the spring is somewhat compressed in its initial sitting position and this sets the ride height of the car. It reflects the force that is initially in the spring. Adding spring spacers increases the preload on the spring which increases the ride height, meaning there is more force required to overcome this initial load on the spring. Two manufacturers might have the same lift height but achieve it through different means e.g. stiffer spring rate versus softer rate with more preload. If you have more preload but a softer spring, the spring will take overall less force to reach the end of its travel, but it requires more force initially to move it. On the other hand, if you have a stiffer spring it’ll require less force to move it initially but it’ll require more force to reach the end of the travel. Great for avoiding bottoming out the suspension, but less good for flex offroad where you want the wheels to be able to move up and down.

The spring rate will let you estimate the amount of sag the suspension will have for a given load. The simplest example would be, say, taking 50 kg of stuff camping. It will get loaded into the boot directly above the back axle. If we compare the OME and the Tough Dog springs then the OME has 2 x 22 N/mm springs, versus the 40 mm Tough Dog with 2x 30.9 N/mm springs. The OME runs 10mm more preload, though, as the springs are longer. They have the same ride height statically, so we can ignore the initial preload. 50 kg is a weight force of 490 N, so the OME will drop 11 mm to carry this weight and the Tough Dog 8 mm. Not a huge difference, but if you’ve added 50 kg of drawers or something to your car then 10mm spacers will take this up for the OME lift; adding the same spacers to the Tough Dog lift in fact give you a little extra static ride height. This isn’t to say go stiff for springs for carrying weight, it depends how much and how often you’ll take that weight as to the best choice here.

Caster is the angle between the steering axis and vertical. It is a measure of how well the steering will self centre: most cars run slightly positive caster which is the steering axis leans back a little. Negative caster will require the car to turn less, but it will have less stability. Positive caster will make the car slower to respond to the steering, the steering will be heavier but it will be more stable and more prone to self centering.

The specs of the Jimny have the factory caster at 1º55′ (1.916….º caster), +/- 1º. As the car is raised up the suspension pivots around the radius arm, which serves to rotate the axle forwards as the car rises, and rotates backwards as the car falls. In practise this means the caster becomes more negative as your raise the car and more positive as you lower the car. Because a lifted car sits higher than an unlifted one, this means the caster is a bit more negative than the factory specification once a lift kit is installed. Exactly how much only depends on the height of the lift, no brand will be better or worse for caster change: height is height.

Caster correction is about changing the caster angle so that it ‘corrects’ for the difference in the caster at the static ride height for a suspension lift. The amount of correction required does vary on the exact amount of the suspension lift. It is often achieved by replacing the bushes in the radius arms, but replacing the radius arms with different geometry will achieve the same thing and potentially more fully correct the change needed.

Toe is the amount the front wheels point in or out. The front toe is the only thing adjustable in a Jimny’s wheel alignment. It is unaffected by the installation of a lift kit correctly. The car should slightly toe in i.e. front wheels point a little in towards each other. Toe is adjusted by the toe bar between the two front wheels, behind the axle: it is adjusted equally on both sides to set the toe to ensure that the steering angle remains equal on both sides.

The steering drag link is the rod that connects the steering box on the chassis on the drivers side down to the opposite wheel. The drag link is what sets the relationship between ‘straight ahead’ from a physical geometry perspective of the front wheels and the steering wheel. When you raise the suspension on a Jimny, the steering box gets further away from the

Dropped crossmember / offset crossmember bracket is about fixing an issue specific to a gen4 Jimny. To aid in crashworthiness of the car, an additional chassis ‘cross-member’ connecting each side of the chassis together was added. This crossmember can interfere with the propshaft/front drive shaft as the suspension droops: in general, suspension lifts above 45mm require the crossmember to be changed somehow to give more clearance to the driveshaft. Different manufacturers achieve this differently: some, such as Ironman or Tough Dog, simply provide brackets to space the standard crossmember down. Some, such as Black Raptor through Jimny Bits, replace the crossmember entirely. There are other solutions that provide additional clearance by being notched or they go above the propshaft completely, but these are generally not part of a suspension lift but instead additional parts you buy separately to a lift kit.

Brake hoses is another element to consider. The need to replace these does depend on the lift chosen; although people talk about it related to a lift height, it’s actually the maximum droop of the lift set by the extended length of the shock absorbers that necessitate these. In order, one and then both of the rear brake hoses need to be extended for lifts, and then the fronts also need it at about the same amount of droop that requires relocating the crossmember. Extended brake hoses are just that, longer brake hoses to account for the longer suspension travel of a lifted car. Most kits include what they need for the shocks they have, but if you are going a bit more custom then it is something to consider putting some thought into getting right.

Supporting data

Standard suspension measurements

Major lift kits and what they include

Lift kit	Approx RRP	GVM?	Height	Caster correction	Shock type	Panhard rods	Crossmember bracket	Panhard relocation bracket	Headlight levelling	Brake hoses
Old Man Emu (ARB)	$2200	No	40 mm	Optional, offset bushes	Twin tube nitrogen	Uses factory	Optional, brackets	Optional		Optional
Tough Dog 40 mm	$1400-$1500; $3k+ GVM	Yes, optional	40 mm	Optional	Twin tube foam cell	Uses factory	Uses factory	Uses factory		Included (rear left)
Tough Dog 60 mm	$2600	Yes	60 mm	Included; offset bushes	Twin tube foam cell	Adjustable included	Includes brackets	Uses factory		Included (all)
Ironman	$1400-$1500, $3k+ GVM	Yes, optional	45 mm	Included; offset bushes	Twin tube nitrogen	Uses factory, but optional	Includes brackets			Included (rear, both)
Dobinsons	Standard: IMS:	No	40 mm	Included; offset bushes	Standard: twin tube nitrogen IMS: monotube	Uses factory	Included	Uses factory	Included	Included (all)
Fulcrum Formula 4×4	$2250	No	50 mm	Included (as replacement arms?)	Twin tube nitogren	Uses factory	Full replacement	Uses factory	Included	Included (all + DOT3 brake fluid)
Pedders TrakRyder		No	40-50 mm	Optional; offset bushes	Twin tube foam cell	Uses factory	Includes brackets	Uses factory	Included	Included (rear, both)
Black Raptor (JimnyBits)	$1900 (all options, 2024 exchange rate)	No	50 mm	Optional; offset bushes	Oil only; adjustable on premium	Uses factory	Full replacement	Uses factory	Optional	Optional