Guidance

Modify goods vehicles before they're registered

How changes to goods vehicles before they're registered will be approved by the Driver and Vehicle Standards Agency.

About goods vehicle approval

All goods vehicles (including N1 light goods) must be approved as ‘complete’ or ‘completed’ vehicles before they can be registered.

They can be approved by either:

This guide tells you how common changes will be approved by DVSA through the IVA scheme.

How vehicles comply with the rules

When manufacturers supply vehicles for the European market, they almost certainly will:

  • comply with various European directives
  • have been given a ‘certificate of conformity’

Any change to the vehicle could make it non-compliant. For example, changes to a heavy goods vehicle in these areas are likely to need proof of compliance:

  • noise
  • emissions
  • fuel tanks
  • rear under-run
  • front under-run
  • steering effort
  • braking
  • electro magnetic compatibility (of the base vehicle)
  • anti theft

Vehicles leaving the manufacturer that are incomplete (eg with no body) will need a further approval before they’re registered. Any changes to the base vehicle would potentially need approval and will be taken into consideration if the vehicle is taken for an IVA inspection.

Change the wheelbase within the manufacturer’s approved dimensions

You must give proof that the new wheelbase dimension is within the range approved by the manufacturer if you make it longer or shorter. This is to make sure that the braking system is still compliant.

You need to give proof from the vehicle manufacturer. Include this with the other supporting documents when you send your application.

The system components must be the same as those fitted by the manufacturer (other than extending wiring and brake piping).

You won’t need to have the vehicle tested if you can give this proof.

You’ll need to go through the process as though you’ve changed the wheelbase outside of the manufacturer’s approved dimensions if you can’t give this proof.

Change the wheelbase outside of the manufacturer’s approved dimensions

Your vehicle must be tested at an authorised technical service if the wheelbase is changed to a dimension outside of the manufacturer’s approved dimensions. This is to prove that the braking system is still compliant.

‘One-off’ vehicles

The test results for the actual vehicle in a test report from the technical service will be enough to prove it is compliant if the vehicle is a ‘one-off’.

Several vehicles with the same specification and conversion

You should use the vehicle as a ‘precedent vehicle’ and get a ‘model report’ if it’s going to be the first of several vehicles of the same specification having the same conversion.

The ‘model report’ inspection process will be different depending on whether the vehicle has:

  • hydraulically-operated foundation brakes
  • air-operated foundation brakes

Hydraulically-operated foundation brakes

The vehicle must be examined with:

  • the wheels removed
  • axle brake components accessible

The vehicle needs to be tested by DVSA at a non-DVSA site to confirm the vehicle specification is the same as documented in the report. This is done separately from the IVA inspection.

Further vehicles will not normally need to be dismantled for inspection.

Air-operated foundation brakes

The relevant components will be visible, so it’s not usually necessary for them to be dismantled.

The vehicle will need to be tested by DVSA to confirm that the vehicle specification is the same as documented in the report. This is done at the same time as the IVA inspection.

Increase the design gross vehicle weight (GVW)

You’ll need further testing at an authorised technical service if you want to both:

  • apply to increase the GVW above that given by the base vehicle manufacturer
  • keep the manufacturer’s design axle weights

The testing is to make sure that the braking system is still compliant at the new weight.

The GVW can be increased to a maximum of the sum of the existing axle weights.

‘One-off’ vehicles

The test results for the actual vehicle in a test report from the technical service, subject to acceptance, will be enough to prove it is compliant if the vehicle is a ‘one-off’.

Several vehicles with the same specification and conversion

You should use the vehicle as a ‘precedent vehicle’ and get a ‘model report’ if it’s going to be the first of several vehicles of the same specification having the same conversion.

The ‘model report’ inspection process will be different depending on whether the vehicle has:

  • hydraulically-operated foundation brakes
  • air-operated foundation brakes

Hydraulically-operated foundation brakes

The vehicle must be examined with:

  • the wheels removed
  • axle brake components accessible

All vehicles assessed against a ‘model report’ need to be tested by DVSA at a non-DVSA site to confirm the vehicle specification is the same as documented in the report. This is done separately from the IVA inspection.

Air-operated foundation brakes

The relevant components will be visible, so it’s not usually necessary for them to be dismantled.

All vehicles assessed against a ‘model report’ need to be tested by DVSA to confirm that the vehicle specification is the same as documented in the report. This is done at the same time as the IVA inspection.

Reduce the design GVW

You can apply to reduce the GVW from that originally nominated by the vehicle manufacturer. You don’t need to make a physical change to the vehicle to reduce its GVW.

To apply, your vehicle must:

  • have originally been issued with an EC ‘incomplete or ‘complete’ approval at its original manufacturer’s weight
  • be of a type produced by the manufacturer that has a ‘variant’ at the reduced weight
  • keep a usable ‘payload’ (this would be decided by the DVSA)
  • have its original manufacturer’s plate
  • be fitted with a ‘second stage’ manufacturer’s plate showing the revised weights

Increase an axle weight

If the design weight of an axle allocated by the manufacturer is limited by the capacity of the tyres, the weight can be increased by:

  • fitting higher capacity tyres
  • getting a declaration from the vehicle manufacturer that the vehicle complies within existing approvals with those tyres fitted

You’re allowed to increase the Great Britain allocated weight to a maximum of the manufacturer’s design weight up to a maximum of 10,170kg.

Increase the original ‘design weight’

If you need a weight greater than the ‘design weight’ allocated by the manufacturer, you’ll need to give proof that the vehicle:

  • has the ability to carry the increased weight
  • complies with the EC Brake Directive
  • complies with the EC Steering Effort Directive (if applicable)

The proof can be:

  • a declaration from the vehicle manufacturer
  • a combination of a declaration from the vehicle/component manufacturer about component capability and proof from a technical service that it complies with the EC directives

‘One-off’ vehicles

The test results for the actual vehicle in a test report from the technical service, subject to acceptance, will be enough to prove it is compliant if the vehicle is a ‘one-off’.

Several vehicles with the same specification and conversion

You should use the vehicle as a ‘precedent vehicle’ and get a ‘model report’ if it’s going to be the first of several vehicles of the same specification having the same conversion.

The ‘model report’ inspection process will be different depending on whether the vehicle has:

  • hydraulically-operated foundation brakes
  • air-operated foundation brakes

Hydraulically-operated foundation brakes

The vehicle must be examined with:

  • the wheels removed
  • axle brake components accessible

All vehicles assessed against a ‘model report’ need to be tested by DVSA at a non-DVSA site to confirm the vehicle specification is the same as documented in the report. This is done separately from the IVA inspection.

Air-operated foundation brakes

The relevant components will be visible, so it’s not usually necessary for them to be dismantled.

All vehicles assessed against a ‘model report’ need to be tested by DVSA to confirm that the vehicle specification is the same as documented in the report. This is done at the same time as the IVA inspection.

Fit an extra axle

When you fit an additional axle it will change the vehicle configuration and increase the design weights. You will need evidence that the vehicle is compliant with the EC Brake Directive from a technical service.

Convert to a known manufacturer’s approval and variant using their original components

Where a vehicle is converted to meet with a known manufacturer’s approval and variant (using manufacturer’s original components), you’ll need to either:

  • send a declaration of compliance to a known approved standard from the vehicle manufacturer
  • take the vehicle to a technical service for a ‘comparison’ test against a factory EC approved vehicle

Convert using non-original manufacturer component or using manufacturer’s components to a non-original manufacturer configuration

You’ll need to have calculations and testing from a technical service to prove the vehicle complies with the EC Brake Directive:

  • using non-manufacturer’s components
  • using manufacturer’s components to a non-manufacturers configuration

You’ll need to give proof of the components’ capability at the requested weights (eg suspension and axle).

‘One-off’ vehicles

The test results for the actual vehicle in a test report from the technical service will be enough to prove it’s compliant if the vehicle is a ‘one-off’.

Several vehicles with the same specification and conversion

You should use the vehicle as a ‘precedent’ vehicle and get a ‘model report’ if it’s the first of potentially several vehicles of the same specification having the same conversion.

The ‘model report’ inspection process will be different depending on the type of brakes the vehicle has:

  • hydraulically-operated foundation brakes
  • air-operated foundation brakes

Hydraulically-operated foundation brakes

All vehicles must be examined with:

  • the wheels removed
  • axle brake components accessible

All vehicles assessed against a ‘model report’ will need to be tested by DVSA at a non-DVSA site to confirm the vehicle specification is the same as documented in the report. This is done separately from the IVA inspection.

Air-operated foundation brakes

The relevant components will be visible, so it’s not usually necessary for them to be dismantled.

All vehicles will need to be tested by DVSA to confirm that the vehicle specification is the same as documented in the report. This is done at the same time as the IVA inspection .

Change a vehicle function: rigid-to-artic, artic-to-rigid or rigid-to-drawbar

You’ll need to give proof that a vehicle which has had its wheelbase changed to convert it from a rigid to an articulated or an articulated to a rigid is still compliant. The process you need to follow will depend on whether you have changed the wheelbase:

  • within the manufacturer’s approved dimensions
  • outside of the manufacturer’s approved dimensions

You’ll also need to give proof that changes to the exhaust system meet the rules.

You’ll need to give proof that the vehicle meets the EC Brake Directive as a vehicle capable of towing a trailer if:

  • the vehicle has not been given a combination weight
  • the combination weight given is not large enough

The proof can be:

  • a declaration from the original manufacturer
  • proof of compliance given by a technical service

The process for a one-off vehicle and several vehicles of the same specification and the inspection rules will be the same as increasing the design gross vehicle weight.

Make a change to the exhaust system

Noise

A static noise test will need to be done where an exhaust system has had a ‘minor’ modification after base vehicle manufacturer approval. This will be done at the time of the IVA inspection. It will be approved if it is less than 99 decibels.

The following count as a ‘minor’ modification:

  • changing the length of the tailpipe after the last silencer by more than 2 metres (less than 2 metres will be accepted)
  • any change to the length of exhaust pipe forward of the last silencer
  • any significant change in the direction the exhaust pipe outlet faces

For any other changes to the exhaust system, you’ll need proof that the vehicle complies with the EC Directive for noise. The vehicle will need to do a ‘drive-by’ test at a technical service.

Emissions

You’re allowed to modify the exhaust system after base vehicle manufacturer approval as long as:

  • the modification is after the last silencer on the system
  • the emission control device is identical to that fitted at the time of original approval

You will need proof from a technical service that any other modifications comply with the EC Directive for emissions.

‘One-off’ vehicles

The test results for the actual vehicle in a test report from the technical service will be enough to prove it’s compliant if the vehicle is a ‘one-off’

Several vehicles with the same specification and conversion

You should use the vehicle as a ‘precedent’ vehicle and get a ‘model report’ if it’s the first of potentially several vehicles of the same specification having the same conversion.

Fit an extra fuel tank or modify an existing one

Where an extra fuel tank is fitted, you’ll need to give proof of compliance to the EC Directive for Fuel Tanks which proves it is either:

  • an available option supplied by a vehicle manufacturer for use on an EC approved vehicle
  • a component having an EC approval to the required standard

Fit a tail-lift

Any tail-lifts that are fitted that are stowed in a position where a rear under-run would normally be fitted must meet the EC Directive rules for the rear under-run.

More information

Contact DVSA if you need more guidance.

DVSA vehicle approval advice

N1 light goods vehicles: passenger.lightvehicles@dvsa.gov.uk
N2 and N3 heavy goods vehicles: hgvtech@dvsa.gov.uk

Published 29 October 2014