Car Clinic: Reasonable length of test drive, jacking a pick-up and uneven brake wear

• TIM’LL FIX IT Tim Shallcross used to train AA patrols to fix cars. Now he advises the Institute of Advanced Motorists.

• LADY DRIVER Emma Smith is a journalist specialising in consumer issues and a regular Driving contributor.

• THE DEALER Jason Dawe is our used-car expert and has appeared on Top Gear and the Morning Show.

Q | For how long can I reasonably expect to test-drive a new car before I make a purchase? A few minutes in the company of a garrulous salesman never seems enough. Can I also ask to try my children’s car seats in the back? And do I need to worry about insurance while I’m test-driving?

MR, London

A | Most dealers will offer an accompanied test drive  lasting between 10 and 30 minutes. If you need longer (and most people do), just ask. Many car manufacturers actively encourage extended test drives, in which prospective customers can take the car for 24 or even 48 hours.

An extended test drive will give you a much better idea of real-world fuel economy and how the car behaves on your usual routes, and will give the whole family a sense of what the car would be like to live with. If the salesperson is reluctant, talk to the sales manager or the dealer principal (the head of the dealership): either has the authority to make the necessary arrangements.

If you take an accompanied test drive with a sales representative, you are almost certainly covered by the dealer’s insurance policy. This may also be the case if you are going on an extended solo test drive, but you should check. In some cases you will be asked to sign an insurance declaration form and pay a small fee, typically £10-£20, to be added temporarily to the dealer’s insurance.

If the dealer is not able or willing to cover you, call your insurer and arrange a temporary extension to your own insurance policy. Although you may already be covered by your own policy to drive other vehicles, this is very rarely comprehensive cover, so it would leave you liable for damage to the test car. There might also be an excess on third-party payouts — check the policy.

Asking to try out a child seat is a reasonable request. If the dealer has a problem with it — or indeed with the extended test drive — find one who is more accommodating, or discuss the matter with the customer care department of the relevant car maker.

JD

Q | Why does Nissan think it is acceptable to equip its Navara pick-up with a jack that is not rated to the weight of the vehicle? The one supplied with my 2012 model is rated to only 1,800kg. Even unladen, the vehicle weighs nearly 2,900kg.

EB, Salisbury

A | Nissan UK confirmed that your Navara’s jack is designed to lift a maximum weight of 1,800kg. That’s because it is not intended to lift the entire vehicle but just one corner of it. When a tyre is being changed, the vehicle usually needs to be lifted just enough to take the weight off that tyre. Nissan says that, if used correctly, the jack will not be required to bear more weight than either axle. As the maximum load is 1,470kg for the front axle and 1,750kg for the rear, the jack should be more than up to the job.

Always refer to the car’s handbook to find where to position the jack under the vehicle, as guessing at this can be very dangerous.

If you want to raise your Navara’s entire axle — to engage in some DIY work — you should instead invest in a pair of axle stands. Prices start at £20 at halfords.com, and for £30 the site does a pair of ratcheting axle stands good for a weight of three tons and favourably reviewed by buyers.

ES

Q | I recently had to replace one rear brake disc, and its pads, on my three-year-old Peugeot 3008, as the pads were worn down to the metal. The other rear disc was OK and its pads still had 6mm of lining left. Why might one side have been so worn? Does the handbrake operate on just one side, or is this a problem with the 3008?

VF, Holmer Green, Buckinghamshire

A | The handbrake operates on both rear wheels, and this problem is not specific to your Peugeot but can occur on any car with disc brakes.

When you put your foot on the brake pedal, a hydraulic piston and a sliding frame in the brake calliper force the brake pads to squeeze the rotating disc and slow it down. When you release the brake, the pressure is relieved and the pads should retract to allow the disc to rotate freely. However, the amount of movement involved is very small — less than a millimetre — and as the brakes are exposed to dirt, water and salt from the road, the sliding frame can become dirty and corroded, and may stick.

This rarely affects braking performance because the hydraulic pressure applied to engage the brake easily overcomes the frame stiffness, but a stiff slider will prevent brake-pad retraction and keep the pads in contact with the disc, wearing them out prematurely.

This scenario is more likely to occur with the rear brakes, which are applied with less force than the front brakes to reduce the chance of them locking up and causing a skid. Because they are used less, they are more prone to becoming clogged up and even seizing.

The handbrake mechanism can also become stiff and reluctant to release fully, causing the same problem.

A thorough DIY mechanic might strip the brakes after the winter to clean them and make sure everything was moving freely, but this is not normally a part of any scheduled maintenance.

Nevertheless, the garage that replaced your disc and pads should also have  cleaned the callipers on reassembly to ensure the problem did not recur. TS

Got a car problem?

Email your question to carclinic@sunday-times.co.uk, or write to Car Clinic, Driving, The Sunday Times, 3 Thomas More Square, London E98 1ST, with a daytime phone number, your address and as much detail about your car as possible. We can’t reply personally, so please don’t send original documents or SAEs. Advice is offered without legal responsibility.