BIRDS BMW M235i
Tuner’s upgrade package aims to create a modern-day E30 M3 – with 390bhp
AFTER 38 YEARS IN business – a good many as sole UK importer of Hartge’s tuning parts – there isn’t much that Bucks-based Birds BMW doesn’t know about the inner workings of the Bavarian brand’s dynamic make-up, or how to modify the company’s myriad suspension and damping setups for the peculiar demands of Blighty’s bobbly blacktop.
Perhaps the most intriguing ‘dynamic package’ it currently offers is for the M135i and M235i, cars we love for their outstanding turbocharged straight-six engines and stonking performance. Nevertheless, they fall a little flat in the chassis department, not least by failing to put their 321bhp to the most effective use. Birds’ demonstrator is an M235i and the mission, according to Kevin Bird, is to ‘provide the driver with the best possible combination of ride, handling and traction attributes for fast and safe road driving’.
Identifying the M235i’s principal problems as the absence of a limitedslip diff and the inability to smear the rubber of both rear tyres more or less evenly on the tarmac when that lusty powerplant is being exercised, Birds’ main weapon is a component that’s become synonymous with its business: the Quaife ATB differential. At a stroke, the thinking goes, three irritants vanish. No more need for management-pegged power in the lower gears when the beans are deployed from a standstill, no more inner-spinner when punching out of a tight bend, and no more hyperactive traction control, either.
Next on the hit-list are ride comfort and body control, which Birds considers sub-par whether or not Electronic Damper Control (EDC) is fitted. Kevin Bird reckons EDC is worse – too soft in Comfort for medium speeds, too hard and crashy in Sport. ‘Even if it worked,’ he says, ‘why do you have to press a button to get the car to handle properly?’ So Birds offers its own springs and Bilstein dampers with custom-spec valving. The front track is also eased out and there are changes to the front and rear geometry to improve stability.
Kevin Bird has a soft spot for the E30 M3 and reckons this Birds B2 Dynamics Package matches the E30 for body control and traction. In fact, this M235i demonstrator has had a remap to take it within touching distance of 400bhp and underline the superiority of the Quaife diff.
During development, which involved input from ex-sportscar racer James Weaver, significant efforts were made to contain body roll without resorting to beefier anti-roll bars, and while acknowledging their potential for biasing the chassis away from understeer, Weaver’s preference for the road was to use damper tuning to control the body instead. That said, anti-roll bars to Birds’ own spec are an option for those wanting a stiffer, sportier feel with less understeer, although they’re not fitted here.
The first impression is one of sheer thrust, the way this Quaife- equipped M235i simply hooks up and goes. The meaty engine responses are sharp without being edgy and delivered without the faintest hint of reactive nerves from the chassis. Although the helm answers inputs alertly and accurately, it filters out the rigours of bumpy roads with poise. There’s a huge amount to like, here: true responses and acutely resolved feedback; thumping torque and urgently delivered top-end power.
The abiding impression is of tautly controlled suppleness that makes the suspension’s indifference to mid-bend disturbances all the more gratifying. Customers can opt for the complete £9643 package (which includes the engine remap, the Quaife-diff Dynamics Package, 18-inch wheels and tyres, and anti-roll bars) or cherry pick as they wish.
‘There’s thumping torque and urgently delivered topend power’