Aston Martin V12 Service and MOT

Given some of the horror stories about Carbon Ceramic Brakes (CCB) many people ask why Aston fitted them.

Although they offer a nice reduction in unsprung weight, steel brakes are more appropriate for a road car. CCB brakes are more about keeping pace with the competition and stying – if you look through the wheels you can see why – CCB brakes look amazing.

Just like many other performance car competitors at the time it was rumoured at launch that the brake discs were good for the life of the car. In reality, a CCB disk will last three pad sets. So if the car was in a pro driver’s hands around the Nürburgring a pad set would last around 500 miles – a 1500 mile life for a disc. More realistically, on the road, typically 15.000 miles is normal for front pads and 20,000 miles for rears. In other words, front discs are good for about 40,000 miles.

But is not just the pad lifespan itself that is an issue. If pad wear is close to limit but the wear led indicator hasn’t yet burnt through (so there’ll be no warning light on in the dashboard) in regard to the phosphor bronze brake pad mounting pins. These mounting pins, located on the backing plate of the pad, mount the pads friction material and start to protrude through the friction material before the wear lead indicator light comes on. This results in the pins grooving the CCB disk potentially causing irreversible damage to the disk. So it vital to check the pads regularly both before and during service to ensure that this potentially expensive issue does not occur.

CCB disk lifespan can also be compromised by in a number of ways. Extremes of heat (track use) and also frequent cleaning of the car with acidic wash solutions can also shorten the lifespan of the disc. In the second case, this is because the acid attacks the CCB surface drawing out the carbon and shortening the disc’s life. So at purchase, it is vital to do a condition check and sanity check that wear is commensurate with mileage because discs are very expensive (c£7K front disks from a dealer) to replace. Thus expert inspection is essential to inform you of when brake renewal is likely, In turn, vitally important in informing a purchase decision.

During a Bamford Rose service, we check both the pads and the inside and outside faces of the discs to check if they are wearing correctly. Any abnormalities are identified. Then if required we perform the rejuvenation cycle to re-establish a transfer layer on the disc returning a degraded disc back into normal service which, if it had not been attended to, could lead to expensive premature replacement.

The dealer network has limited experience in this whole area. The skills to bed in pads and rejuvenate a disc are specialised. The entire brake assembly needs to be run through a heat fade brake cycle of several very high speed ABS stops to reset. To do that safely you’ll need to have an extremely high driving standard! If this procedure isn’t done properly you’ll get brake squeal, poor performance and premature wear of your already wildly expensive brakes. This is another reason why Bamford Rose is special – this attention to detail means that annual maintenance identifies problems with your CCB’s and corrects them before it is too late.

The importance of attention to detail during service or work at Bamford Rose is highlighted by the issues that can impact ASM pipes for sport-shift vehicles. These pipes are extremely difficult to examine with the undertrays in situ which is another reason why we always remove them during service or work on your vehicle.

The rubberised feed and return pipes from the C hydraulic fluid reservoir to the pump are vital components of your vehicle. However, there is no set replacement interval for these pipes. Like all rubberised pipes, they will eventually age, perish and fracture which is why they need replacing.

The consequences of not checking these pipes can be severe. If a perished pipe fractures the ASM fluid, which is under considerable pressure in the system, will leak out of the system. The ASM pump will run but there will be no gearshift and the vehicle will be disabled and require recovery.

A common problem affecting all V12 engines is that of Positive Crankcase Ventilation (PCV) valve failure. The PCV system removes unwanted gases from the crankcase.

The PCV system consists of a tube system, a one-way valve and the intake manifold (a vacuum source). The unwanted gases, called “blow-by”, are gases from the combustion chamber which have leaked past the piston rings into the crankcase.
If left unchecked this additional gas would cause increased pressure in the crankcase that would cause a big parasitic power loss. This is because the rotating crankshaft and moving pistons and connecting rods would be less efficient in a highly pressured crankcase. However, these gases cannot simply be vented back into the air as they are full of pollutants and, as a result of entering the crankcase, are further compromised by being combined with the oil that is sprayed into the crank crankcase to lubricate the engine.
These gases need to be exited from the crankcase and recirculated back into the inlet manifold to be sent back into the combustion chamber to be properly combusted. The PCV one-way valve regulates this process and prevents oil from being sent back with the recirculated gas.

The Aston V12 PCVs are beak type valves, within a rubber pipe, which over time are prone to becoming brittle and failing. When the valve fails it stays open allowing the oil to exit with the gases back into the manifold. In the worst case, 0.5 litres of oil can be lost every 1000 miles. There is 2 litres difference between the maximum and minimum oil levels for the V12 and this problem can consume the oil much faster than normal. Left unchecked if your V12 is doing the mileage and consumes the oil reserve the rear big ends of cylinder 6 and 12 which are the last in the oil feed circuit can seize up (the oil can also contribute to other problems see our section on V12 Exhaust Catalyst Failure in our Engine Repair section). So another reason to check your oil regularly!

The PCV valves should always be checked at service. The easy way to check this is by looking at air filter because if the filter has staining from engine oil you know the PCV valve has failed. This is because the circuit goes from the engine to inlet manifold pre throttle so if PCV valves have failed the oil that has been let through with the gases will gravitate into the airbox and be absorbed by the air filter. Unfortunately, the replacement of these valves is not as simple a job as you might think because to get to the valves to replace them, the entire inlet manifold has to be removed which is a very labour intensive task.

Exhaust silencer bypass valve failure

The Valve exists to allow the cars to comply with drive by noise legislation. Over years of the valve opening and closing, the valve assembly can fail. Sometimes the spindle arm joint can fail and sometimes the spindle itself can crack inside the exhaust.

A franchised dealer would simply change the entire back box exhaust assembly which for the parts cost alone is around £1800 plus VAT.

At Bamford Rose, we have the tools and techniques to repair the valves using OE parts and in total we would typically charge £4-500 in time and materials to do so.