If you're a fan of subtle, finely engineered cars that pack a punch, then you've no doubt cast an appreciative eye over an E34 M5 at some point.
After all, this generation of BMW's high-performance saloon ticks a plethora of boxes for Q-car fans. Rear-wheel drive and a manual gearbox? Check. A powerful naturally aspirated straight-six with individual throttle bodies? Check. Bigger brakes, upgraded suspension and an LSD? Check. check, check.
All of these elements, in conjunction with a crisply styled four-door body and BMW's superbly designed interior, combined to deliver an understated yet immensely capable performance saloon. 'It's the most impressive piece of road-going machinery yet to emerge from BMW's Motorsport division,' said Autocar in September 1988, 'and it's a class apart from its rivals.'
It's the engine that's the centrepiece of this generation of BMW super-saloon. When right-hand-drive E34 M5s arrived in February 1990, under the front-hinged bonnet was a 3.5-litre, 24-valve S38B36 engine. This sonorous six screamed 'motorsports' and, thanks to a brace of cable-operated throttle bodies, punched out 315hp and 266lb ft. Even though the E34 weighed in at 1,745kg with a driver onboard, it could reputedly accelerate from 0-62mph in 6.3 seconds.
The more powerful S38B38 went into production in late 1991. This larger 3.8-litre engine produced 340hp and 295lb ft, which helped cut the E34's 0-62mph time down to 5.9 seconds. Performance was further improved with the launch of the Nürburgring pack, which included stiffer anti-roll bars and a mode switch for the 3.8's electronically controlled dampers.
Many of these parts became standard-fit after May 1994 - along with a six-speed manual transmission - when the pack was discontinued. Several special versions of the E34 M5 were also offered, including the UK-market 'Limited Edition' that commemorated the last right-hand-drive examples rolling off the line in July 1995.
Buying an E34 M5 is not a casual undertaking, however. You may get lucky and snap up a sound £10,000 example that gives you comparatively trouble-free motoring or end up with something that induces countless financial nightmares. Consequently, it's worth looking at several cars to get to grips with what a good M5 looks and feels like.
Whatever you do, unless you fully understand what might be involved, don't be tempted by a cheap example - as recommissioning a tired M5 is likely to cost just as much, if not more, than the car itself.
Bodywork and interior
The hand-built E34 M5 is a high-quality piece of machinery, make no mistake, but even the youngest examples are now 23 years old. Rust can, as a result, be an issue. Check the underside of the car carefully, particularly around the jacking points, and also inspect the arches, the bottom edges of the doors, the sills and the area around the fuel filler.
You've little to worry about on the interior front. The materials and switchgear used in the E34 resist wear and tear well and, even at higher mileages, should be in good condition. Excessive wear could point to a hard life or, in some cases, a far higher mileage than what's claimed by the odometer. Just make sure that everything functions as expected, including the ventilation controls and electric seat adjustment, and check that the M5-specific instrument cluster is present and correct - it should have red needles and an oil temperature gauge.
Many E34s have marks on their bumper rubbing strips; if these annoy you, replacements are available for around £35 a corner. Otherwise, carry out the usual cosmetic and crash damage-related checks. If the example you're looking at doesn't have the original rear no-cost spoiler, worry not - as a reproduction spoiler is available for around £80. Panels aren't exclusive to the M5, either, so won't break the bank.
Engine and transmission
Two engines were used in the E34 M5 - the 3.5-litre S38B36 and the 3.8-litre S38B38. Some may state that the S38B36 is a 3.6-litre engine, as suggested by its designation, but it displaces 3,535cc. BMW opted for 'B36' to differentiate from the earlier 3,453cc S38B35 used in the E28 and E24.
Proper maintenance is essential to ensure the longevity of these otherwise durable powerplants. Check the history for signs of regular servicing and try to ascertain the quality of the fluids used. Routine servicing isn't overly expensive, particularly at a specialist, but attention must be paid to establishing whether the valve clearances have been checked; ideally, they should be inspected and adjusted - if necessary - every year or 15,000 miles.
The 3.8 uses a coil-per-plug ignition system. If the engine doesn't pull cleanly through the rev range, it could be that a coil pack is on its way out. Each one costs around £40.
Inspect the radiator and water pumps for any signs of leaks, as the last thing you want to do is overheat an S38 and be forced into replacing its head gasket. If the temperature starts to creep upwards while in traffic, it's likely that the viscous fan coupling has failed. A replacement is around £80 and easy to fit. They can also seize solid, causing excessive fan noise and unnecessary load.
A rattle from the front of the engine when starting from cold can be the result of a tired timing chain tensioner. In any case, it's worth replacing it for peace of mind. The tensioner from a later S50B32, costing £80, can be used.
A particularly loud idle that fades after a few minutes is sometimes diagnosed as a cracked exhaust manifold. It is often, however, the normal function of the M5's emissions-reducing secondary air injection pump. It can be deleted if desired, though.
Both the five- and six-speed gearboxes are durable and the clutch action on an E34 should be comparatively light and smooth. The differential is also very stout and should prove trouble-free.
E34 M5s, with a modicum of care, are capable of enduring high mileages. Unless resale value is a key concern, don't discount good high-mileage examples.
Suspension and steering
Both 3.5- and 3.8-litre M5s have a self-levelling suspension set-up at the back. The dampers themselves can leak; refurbishment is your best option here, as new units are few and far between. Leaks can also develop in the hydraulic lines that supply them, while a sagging rear end can be the result of failing accumulators or a knackered regulating valve.
The 3.8s also feature 'Electronic Damping Control' and the dampers used in this system are ruinously expensive if you want to replace them with original items. If the car has an EDC mode switch, operate it during the test drive and make sure you can feel a difference between the two modes. If the dampers are not functioning properly refurbishment by a specialist such as Nagengast is your best option. In either instance, with regards to ditching the SLS or EDC, replacing with an aftermarket alternative is not a straightforward or inexpensive option.
Age and neglect will have taken its toll on many an E34 M5, with worn bushes and shot ball joints resulting in odd noises and sloppy handling. Fortunately, suspension and steering components are easy to find and not overly costly. While sorting all of the above can be prohibitively expensive, a car that's been cared for properly shouldn't be too problematic.
The E34 M5's fast-ratio recirculating ball steering box can wear, resulting in a noticeable degree of free play. Adjustment is difficult in situ but can remove the slop.
Wheels, tyres and brakes
There were two factory two-piece wheel options, dubbed 'M System I' and 'M System II'. The M System I wheels have distinctive 'turbine' brake cooling ducts in their outer covers, while the M System IIs have 'throwing star'-style covers. Replicas of the M System IIs are around but they are cast as one piece, so easy to identify.
The standard wheel size was initially 8Jx17 all round, with optional 9Js for the rear in both M System I and II designs - with 9J being standard on some limited-production editions. Tyre sizes for the 8Js were 235/45 ZR17s, while the 9J wheels are shod with 255/40 ZR17s. Expect to pay upwards of £120 for a brand-name tyre, in any case.
Later cars featured staggered 'M Parallel' wheels, which use 245/40 ZR18s all round. Suitable tyres command a slightly higher price of around £150. In any case, check the wear pattern on the tyres - as issues here can indicate tracking or bush-related problems. Good tyres and signs of proper alignment are indicative of a well-maintained M5, for one thing.
Brake consumables for the 3.5- and 3.8-litre M5 are readily available; a complete set of brand-name discs and pads for an early M5, for example, will set you back less than £400. Late M5s have floating discs, which often command a premium. Do check the condition of the brake hard lines - as well as the hydraulic and fuel lines - underneath the car, too; replacing these is a costly and time-consuming process.
SPECIFICATION - BMW M5 (E34) 3.5/3.8
Engine: 3,535/3,795cc straight six
Transmission: 5-speed manual (3.5/3.8)/6-speed manual (last year of 3.8 production)
Power (hp): 315/340@6,900rpm
Torque (lb ft): 266/295@4,750rpm
Price new: £43,465/£52,480
Price now: £10,000 upwards
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