A chassis extension can improve your vehicle’s handling and towing

ByTim ScottOctober 14, 2020
7 MINUTE READ
A chassis extension can improve your vehicle’s handling and towing

Not only can you carry more in your vehicle, but a chassis extension can also improve your vehicle’s handling and towing.

A chassis extension takes away the long rear overhang that’s a feature of most of our utes and can work wonders for your capacity, and not just because you can fit more on your new tray. We spoke to Hugh Ager, the fabrication guru at Limitless Chassis, to find out what’s involved in a chassis extension, sometimes referred to as a chassis stretch.

chassis extension on a ute

RV Daily: First off, is a chassis stretch really a chassis extension, as in, you insert more chassis steel to make it longer as opposed to stretching it. I know that sounds a bit obvious but let’s clear that up from the off!

Limitless Chassis (LC): Yes. We cut the original chassis clean in half, somewhere under the seats and add in a new custom-made section. Doing this means that all your standard parts move backwards, so it doesn’t affect them. For example, if you break down, you can easily buy all the standard parts from a local parts store or wrecker if you’re in the bush. It also allows you to run long-range fuel tanks and install extra water tanks under the cabin of the car, which is good for weight distribution.

Chassis extension insert section

RVD: What’s the process? How much extra hardware is involved? You have to lengthen drive shafts, etc.

LC: I’ll try to simplify the process as it’s very technical. Firstly, we cut the chassis according to the Australian Design Rules (ADRs), and then fabricate a new section that is the same or higher spec then the factory design. We weld in this section, along with cross members, plates and braces, depending on the vehicle and length of the extension required. Finally, for the extension, we seal all the edges to stop water ingress, then it’s heavy-duty chassis paint.

Then it’s onto the tail shaft, which we extend the front section only (the least stressed section) so that, again, you can get a replacement standard rear section if yours wears out or breaks. The brake and fuel lines receive extensions, and most of the utes have joints in their lines around where we extend them. Wiring is the fun part; most can be re-routed, some need patch harnesses, all of it needs securing and protecting from stones, so we go to town on this element.

Before we finish, we have to modify the tray to suit; mudguards, fuel fillers, lights, and lockers – all these parts will have to move. Some people opt for new trays, and some ask us to fit their canopy directly to the chassis meaning they gain 150kg of load by not having a tray on the back. Others don’t even know what they want yet, so they take a bare cab-chassis away with them.

Extended Hilux

A HiLux with 300mm extra but no tray as the customer hadn’t decided

RVD: We featured the story on why your towbar length and tow vehicle wheelbase matters, so how does a chassis extension help with towing, handling?

LC: First and foremost, it’s about weight distribution. The current series of dual-cab utes have huge rear overhangs, and all the weight is right out the back, behind the rear axle. By extending the wheelbase, you place the wheels further under the load, thereby moving the weight into the middle of the vehicle and making it more balanced.

 

Here’s something you can try in your ute. When you accelerate from the lights, does it feel like it’s trying to do a wheelie and drive from behind the rear wheels? If so, your tray is too long and the weight too far back. Ideally, you’re looking to achieve an overhang of 1200-1300mm measured from the centre of the rear wheel to the rearmost point on the tray. Wheelbase length changes the whole dynamics of the vehicle’s ride and handling. It makes everything smoother, more controlled and less prone to jumping around on bumps.

Imagine you’re driving over a bumpy dirt track in the Suzuki Jimny; you’ll be bouncing forward and backwards very quickly as the two closely set axles hit the bumps. Now jump into the Ford Ranger, and you’ll instantly feel the difference. It takes longer for the second axle to hit the bump, so the suspension has time to settle and ride the bumps rather than pitch over them. Now clamber into a RAM, again it will be even better. The front axle hits the bump 10 minutes before the rear catches up, so the car is settled by the time the rear hits the bump.

A New Caravan Drawbar

A 1970s Franklin benefits from mods that include a longer drawbar

So to sum up, the longer the wheelbase, the more settled and stable the car is and the better it will handle. Towing is the same. Having a longer A-frame on a trailer makes it more stable, and it follows the lead of the tow vehicle rather than bouncing around and being twitchy over the bumps like a short A-frame trailer does.

RVD: What vehicles can benefit from this modification, and what are the limitations? Is this for utes and trade-type vehicles only?

LC: All and any vehicles can benefit from a wheelbase extension. We can only perform them on ladder chassis vehicles, which includes all the utes (two and four-wheel drive), plus Patrols and LandCruisers with cabin chops, and then all the light trucks such as the Canters and 4X4 Mitsubishis. The only limit is your imagination; oh, and turning circle. We generally stop at 1000mm extensions, because you really should buy a truck if you need a tray that size. That said, we have made a few single-cab utes with 3000mm trays on them.

RVD: Are there vehicles that are easier to modify than others?

LC: They’re all the same but a little different. We cut them in different places and use different styles of cuts depending on the particular chassis and the material used. The most straightforward vehicle would be the Ford Ranger; everything under the ute lines up perfectly and the new PX3’s are finally being made to a good standard that matches the likes of Toyota and VW.

RVD: When a customer brings a vehicle to you, are there other mods that can be done, or should be done at the same time to make the most of the process, especially in terms of towing (for our readership), but also payload capacity and off-road travel, if applicable?

LC: Each and every vehicle we work on goes through the same process. We find out exactly what the customer plans to do with it, or what they want to get at the end of the process, and we tailor it to match their ideas. If they don’t know what they want, we keep talking and asking questions until they get exactly the modifications they need for their situation.

We are a one-stop-shop and handle the whole process, as much or as little as you like. We manufacture trays, standard ones or fully customised, and perform GVM upgrades, as well as suspension and electrical work, etc.

We also do extensive caravan modifications, and a lot of customers will bring both vehicles in for modifications. In fact, we see just as many caravan chassis as car chassis. With the caravans, we’ll do ATM upgrades, drawbar replacements, suspension upgrades and we even do full on-road to off-road conversions.

An on to off-road conversion on a caravan

Cruisemaster retrofit of independent suspension on a leaf-sprung caravan

RVD: What’s the engineering certification involved and is what you do a country-wide approved process?

LC: The engineering process is pretty simple, and the customer doesn’t have to lift a finger. You drive in with your vehicle and a week later drive away fully MOD plated and ready to go. As with many other companies in the country, we use a third-party company to certify our builds, which means all our builds have been certified by someone who doesn’t work for us; the perfect form of quality control. I’m an automotive engineer, but this way there is no question of the vehicle falling short of the correct regulations. All our chassis are certified for Australia-wide use.

RVD: How is registration affected and, say, as with a GVM upgrade, any concerns if it’s pre or post-registration?

LC: Registration isn’t affected, unless you convert a wagon to a ute, like the 200 Series for example. Extending the wheelbase makes no difference. The chassis extensions need to be done after first registration.

RVD: Is there any comparison or similarity to having a six-wheel conversion installed?

LC: They aren’t that comparable, extensions are usually better for the average user. There is no denying the load-carrying capacity of the six-wheeler will beat an extended chassis 4X4, however, the practicality and usability of the extended wheelbase is where it’s at. A 300mm extension still fits in the garage at home, and a 450mm extension is easy to park at Coles. Try either of those with a six-wheeler, and that’s before you tell the wife she has to use it on the school run, she’d choose the extension over the six wheels any day. Costs wise that usually settles the argument, we’re around a third of the price of a six-wheel conversion, starting from as little as $6000.

RVD: As we’ve read, you’ve stated the pros already, but are there any cons? We know it won’t be cheap, so this is for someone who really wants to hang onto their vehicle?

LC: As I’ve mentioned, the cost is about the same cost as purchasing a 2in lift kit and a set of mud tyres, $6-7000 normally. A lot of people ask about the ramp over angle, but we’re serious 4wders, and we don’t really notice any negatives there. Tight twisty tracks aren’t a problem either, I drive a Patrol with 600mm extra in the chassis, and it goes further than anyone else on the tracks. The biggest con is that you will need a reversing camera, you lose track of where the back is when you’re reversing into a space. Honestly, I can’t really think of any cons, you balance the load, smoot out the ride quality and make it easier to tow, what’s not to like?

Extended Amarok 3

RVD: At RV Daily, we recognise that many tow vehicles are dual role but how does a chassis extension benefit those who tow, especially regarding payload capacity, GVM and GCM.

LC: Okay, as most of your readers will know, GCM upgrades are no longer possible. GVM upgrades are strict and tightly controlled. As mentioned previously, we listen to you and ascertain your intended use and only recommend the GVM cost and process if you genuinely need it.

Most people will use their ute empty for 80% of the time and only load up for holidays/tip runs. So let’s set up the vehicle for that 80% and add airbags to the chassis that we’ve reinforced for precisely this reason and only use them when you need them. Everyone loves a bad airbag story, but we reinforce the chassis so that it can handle them if that is the route you wish to choose.

RVD: Is there anything else that you think should be mentioned that we haven’t thought of?

LC: The resale value of the vehicle. You don’t see second-hand chassis extensions come up for sale very often for the simple reason that they are in demand. From what we see, they retain around 60-70% of the cost of the extension at resale time, meaning that your extension only really costs $2-3000, that’s another win right there.

For much more information, you can talk to Hugh at Limitless Chassis

You can find Limitless Chassis at 9/39 Dacmar Rd, Coolum Beach, Queensland, 4573 or call 0401 292 739.