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. 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.
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
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
Lift height is the height that the car sits at rest on a flat surface. This 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
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.
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
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.