Jayco caravan suspension upgrade 

After some significant  research and development Johanson Brothers Motorsport has developed a Jayco caravan suspension upgrade to improve the weight carrying capacity, handling and safety of your caravan.

Customised Old Man Emu Nitrocharger sport shock absorbers that have been specifically matched to suit Jayco Caravans are now available for most models and perfectly compliment our custom Kings springs range.

Heavy Duty Gas Shock suspension upgrade

Jayco caravan suspension upgrade with OME Nitrocharger
Nitrocharger – Jayco Gas Shock absorbers

These shock are a twin tube heavy duty off-road gas pressurised shock, that delivers outstanding performance on and off road.  

Old man Emu and ARB have a long history of providing Australian made reliable off road suspension, and we have leveraged their knowledge and experience to bring their product to the caravan community.

Caravan suspension upgrade

Ring now 0412666658 to discuss your particular requirements for a Jayco caravan suspension upgrade with an Automotive engineer and  licensed certifier with over 50 years experience.

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Upgrade ATM springs all Jayco models

Custom springs available for Jayco caravans are now available, with engineered Axle Group Load up to 3700kgs and ATM(Aggregate Trailer Mass) up to 4000 kgs( with suspension modification).

Update 2023 – Now ATM upgrades to 4500kgs with suspension drawbar and chassis modifications

With the assistance of King Springs we have designed custom springs to suit most Jayco models that will carry extra weight to support ATM and GTM increase. Restoring ride height and bump stop clearance and reducing sway.

We have engineered these springs and a suspension modification to safely allow a certified weight carrying capacity increase.

Available for most Jayco models including Silverline, Starcraft, Journey and including all outback models.

Enquire now by clicking the link to see how we can help you- Compliance Certificate Enquiry – Vehicle Engineering

Uprated springs for caravans

At Johanson Brothers Motorsport we place huge value on research and development, and getting it “right”.

So when we found some caravan springs were seriously under rated we took to the task and through testing and computer modelling we engaged King springs to help us create the “perfect” spring.

A lot of production caravans have fantastic suspension, however the springs are usually rated lower than required when fully loaded or subject to a ATM or GTM(GVM) upgrade.

We have a range of custom springs available for heavily loaded vans that can increase load carrying capacity(legally) to 3500kg and beyond. These springs also reduce sway, correct ride height and wheel alignment at higher loadings.

Call now and see what we can do to improve the ride, handling and safety of your caravan.

Now in stock, 25mm lift for Jayco Sterling and Outback series.

Clearing a defect notice on a modified vehicle NSW RMS

What is a defect?

A defect notice can be issued by RMS, NSW Police or the EPA, when a vehicle is found to be on a public road with defects that may make them unsuitable for registration.  Things like vehicle noise, vehicle modifications, bald tyres, etc are common sources of defect notices.

Clearing a defect

After repairs have been completed the vehicle must be presented to an unregistered vehicle or blueslip inspector to have the vehicle infected and the defect cleared.

What if my car is modified?

Modified vehicles require a compliance certificate (previously called an engineers report) for the modifications from an AVE (Authorised Vehicle Examiner), Signatory or VSCCS Certifier, before attending a blueslip inspection.


Caravan GVM GTM ATM Upgrade

Tare weight, GVM, GTM, ATM, GCM whats it all mean?

Tare Weight

Tare weight is the unladen mass of the vehicle as originally manufactured, that is all tanks empty, no accessories like gas bottles etc.

GVM/ATM – Gross Vehicle Mass/Aggregate Trailer Mass

GVM is Gross Vehicle Mass, this is the maximum weight of the vehicle when fully loaded.  As applied to caravans or trailers the correct terms is ATM or Aggregate Trailer Mass which is the GTM (see below) plus the weight placed on the ball of the towing vehicle or ball weight.

When recorded for a trailer or caravan in the authorities system there is no facility for ATM so GVM is used.

GTM – Gross Trailer Mass

GTM or Gross Trailer Mass applies to caravans and trailers and is the maximum weight that can be transferred to the ground via the wheels.

GCM – Gross Combined Mass

GCM or Gross Combined Mass is the combined maximum weight of towing vehicle and trailer or caravan combined.

Now for some examples and maths!

Lets take a typical example we see every week, a 200 series Landcruiser and a Jayco caravan.

Car GVM 3350kgs towing capacity 3500kgs

When fully loaded to the manufacturers maximum this gives a GCM of 6850kgs

Our Jayco Silverline caravan has a GVM of 3300kgs, coupled with our vehicle gives

Car GVM 3350kgs + Van GVM 3300kgs = GCM 6650kgs

These limits are the maximum weights you can legally carry, without knowing you could be breaking the law or perhaps worst case not covered by insurance in the event of an accident.

Can we upgrade or increase these limits legally?

Yes is the short answer, how that can happen and by how much is variable depending on the vehicle construction, aftermarket replacement parts available and modifications that may have been done or need to be done.

The 4WD is rated at 3350kg GVM, most will be aware that after fitting a few accessories and throwing in a fridge and some drinks your car is now overweight. This is where some improved suspension and a compliance certificate can increase the GVM legally.

How with a new car? – Second stage compliance

Second stage compliance is where a aftermarket manufacturer like Lovells, Pedders, Old Man Emu, etc. have created a kit of components and applied for certification of those components to increase a vehicles GVM.

Second stage compliance can only be performed on a new vehicle before registration.

What about my used car? – VSCCS Compliance Certificate

After suitable components and modifications have been performed a Compliance Certificate (formerly called an engineers report) can be provided increasing the GVM, GCM, GVM or ATM.

How increasing about GCM or towing capacity?

GCM can be increased and we have performed some serious testing in this department, so we know what works!

Upgrading GVM on the car can reduce the GCM or Gross Combined Mass, this can be restored or increase on most vehicles with appropriate modifications.

Why is the GVM on my caravan so low?

Are you overweight? Well your van anyway 🙂

It is unclear why some manufacturers rate their caravans so low, however this problem is compounded by the accessories that may be fitted post manufacture, such as solar, extra batteries, additional water tanks, Air conditioning or a generator.

We have amassed a large database of caravans and modifications that may be done to safely increase GVM/GTM and in most cases a significant improvement in caravan stability when fully loaded.


Call now and talk to Greg 0412666658 if you have any questions or use the contact form here Compliance Certificate Enquiry


Coffs Harbour – Vehicle Certifier


Great news!

Greg has been appointed as a Vehicle certifier for your vehicle modifications. The old vehicle engineering scheme has been dropped and replaced with a certification scheme.

  • Lift kits/wheels
  • GVM/GCM/GTM upgrades
  • Motorcycles
  • Passenger cars
  • Commercial
  • Bus
  • Heavy Vehicles

Make an appointment Here or,

Call Greg now on 0412666658 to discuss your requirements.


Note:  Engine Certification coming early 2019


Welcome to Johanson Brothers Motorsport

Johanson Brothers have been racing and building, repairing and servicing race cars, rally cars and motorcycles since the early eighties.

Previously based in Canberra as Johanson Rotary and Johanson Automotive we are now based at Woolgoolga on the NSW North Coast just north of Coffs Harbour the home of the Australian WRC – Rally Australia.


Full Rally and race car preparation, including fabrication, seam welding, roll cage design and construction.

Suspension, driveline and brake upgrades and modifications

Race Auto Electrical services, Rally servicing.

Managed rally services, driver training and rally entry coaching.

Corporate event management

Race plan

Leased rally/racing car and services


Race, Rally, Rallycross, Track, Safari and long distance.

Tarmac ,Gravel , Dirt, Desert


Dealers and stockists of DMS Shocks, Monit, Sparco, Hella, Rallysafe, Century Batteries, Wiseco Pistons and many other well known brands, our facility is located just 20 minutes north of Coffs Harbour on the Banana Coast.