Mods and Consequences
Built from 1976 to 1989, and always equipped with a glorious straight-six engine (M30 in all editions, aside from the M88equipped M635 CSi), the BMW E24 6-series is fast, refined and very luxurious. If extra performance is a key requirement, buy a car with a 3453cc engine – you’re unlikely to find anything else anyway, as the 2788cc 628 CSi and 3210cc 633 CSi are now very rare.
The 6-series is more of a GT than an out-and-out performance machine, but even the earlier cars still handle pretty tidily. However, from 1982 the E24 was based on the E28 5-series, meaning a significantly improved driving experience.
These Series II models came with metric TRX 390 wheels (about 151/ 2 in diameter) and the series 3 (Highlines from late 1987) had TRX 415 (about 161/ 2 in diameter). With suitable tyres costing around £400 per corner, many owners fit E34 5-series or E32 7-series wheels. These come with 225/60 15 tyres which have a slightly tall profile; the ideal would be 205/60 or 215/60 rubber. E39 5-series wheels fit with an adaptor because the central hole is larger – use plastic items, because the alloy alternative corrodes in place. E39s can provide 16in wheels (with 225/50 16 tyres) or 17in items (with 235/40 tyres). You could also fit E31 8-series 16in or 17in wheels.
Lenso and Dare Wheels both offer replica BBS ‘Basketweave’ styles. What you shouldn’t do is fit 18in rims – the car was designed to run on 6.5 x 14 wheels.
The standard brakes are OK but can wilt with hard driving. The front calipers and discs from the E32 7-series go straight on ( you’ll need the caliper carrier too); Euro Car Parts sells them for under £100 each. This gives larger and thicker discs, which coupled with upgraded pads should be all you need for road use.
The rear calipers from an E34 540/ M5 or E32 740/750 can be used in conjunction with discs from
the E34 540/M5. As these are ventilated they’re double the thickness of the standard car’s. This will result in a longer pedal travel, which requires the use of an E32 750 master cylinder.
‘If performance is a key requirement, buy a car with the 3453cc engine’
AnTi-rOLL BAr The M635 anti-roll bars can be used on the standard model but watch out for the mounts cracking and splitting; they will need to be strengthened. The E28 M5 used even bigger antiroll bars but these will need reinforced mounts. CAMsHAFTs Fast road profiles are available from the likes of Piper. These give no more than an extra 12bhp at the top of the rev range so the value is marginal, but if the old shaft is worn because the spray bar has become blocked, then why not? sTEErinG BOX The steering box mount is weak and can start to tear away from the subframe, which is a good reason not to go to overboard with big wheels. You can box the mount for extra strength or buy a kit, such as the one from Mwrench. sUsPEnsiOn The M635 was 15mm lower than the standard 6-series. But if you drop your E24 by 30mm (that’s common with other cars) speed humps will become an issue. Most owners stick with Eibach springs and Bilstein dampers. EXHAUsT £100-150 £460 £40 £600+ £450 An improved exhaust manifold is available for SIIs from Fritz’s Bits, which can also supply a better exhaust system for about £700. An alternative is to fit a Highline manifold, as these have a much more efficient design.