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Monday 24th October 2011


DB7 BUYING GUIDE: POWERTRAIN


There are two distinct engines used in the DB: a supercharged in-line six-cylinder and a normally aspirated 6.0-litre V12. There was a single 6.3-litre V8, a one-off customer car, and the V8-engined Le Mans racers but we'll stick with the production motors here.


Starting with the 3228cc straight six, it has a bore and stroke of 91.0 x 83.0millimetres, 24 valves and an Eaton roots-type supercharger that created 335bhp at 5500rpm. Torque of 368lb.ft at 3000rpm helped get the car from 0-60mph in 5.8 seconds and on to 165mph, but it was the mid-range shove that impressed early road testers most. Coupled to a five-speed manual gearbox or four-speed auto, the DB7's 3.2-litre engine remained unchanged till the car was dropped from production in May 1999.

However, buyers could order a Driving Dynamics pack that included a freer flowing exhaust and larger supercharger intercooler. Together, these changes could release up to 50bhp more from the 3.2-litre engine, though Aston did not quote exact figures.

Cars with these modifications are likely to have a 'Works Prepared' badge, though check the car's history file to be certain the work has been carried out. Current owners can still benefit from these upgrades from Aston Martin.


Although regarded as fairly trouble-free, the supercharged six-cylinder engine needs its oil level checked very regularly, so this should be part of a weekly routine. Cracked exhaust manifolds can occur and any rattles from the timing chain are a sign the tensioners need replacing immediately. Otherwise, service intervals are every 7,500 miles and the timing belt must be changed at 30,000-mile interludes. The rear axle will need its oil changed at the same mileage as the timing belt.

One problem that has reared up for the DB7 is its air conditioning evaporator. Non-functioning air con could just mean the fluid needs changing, but if the evaporator has failed it will be a lengthy and expensive job to have it replaced as it takes two days and the removal of much of the interior to complete the process. Regularly driven DB7s will be much less prone to this, so treat low mileage, pampered toys with extra circumspection.


Moving on to the V12 engine, it is an all-alloy unit just like its 3.2-litre counterpart. This means both engines must have the correct anti-freeze topped up to the right level. The V12 only uses OAT anti-freeze and mixing it with cheaper alternatives can result in the engine becoming sludged up or the radiator splitting. Otherwise, this 420bhp 6.0-litre motor is very strong and the six-speed Tremec manual or five-speed ZF auto gearboxes are tough and trouble-free. Even in its ultimate 435bhp GT form, the V12 is understressed, though it does perform best when pushed further up the rev band than the 3.2-litre six.

The DB7 Zagato used the same engine and gearbox as the Vantage but the six-speed transmission has a quick shift fitted. There's also a shorter propshaft to allow for the truncated wheelbase of the Zagato. The USA-only DB AR1 convertible was only sold with a six-speed manual gearbox, which was fitted with an AP twin-plate racing clutch and quick shift mechanism.

Buying Guide Contents
Introduction
Powertrain
Body
Rolling chassis
Interior
Insurance
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Author: Chris-R
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