Birds’ B1 Dynamic Package brings out the best in the BMW M140i F20, markedly improving its behaviour when pressing on and proving you don’t need to buy a full-on M car to have serious fun… Words: Bob Harper. Photography: Malcolm Griffiths.
Little Red Riding Good
Birds proves you don’t need that full-on M car…
“I’ll keep this one forever,” says Kevin Bird with a laugh, and having sampled his latest creation it’s easy to understand why. Kevin has been fettling BMWs for longer than he probably cares to remember and reckons that the M Performance versions of the 1 Series hatch and the 2 Series coupé could well be the last of the great driver’s BMWs. With a compact foot print, relatively light weight and plenty of performance straight out of the box these ‘M-lite’ models can also be equipped with a vital component that’s crucial for driver involvement – a manual gearbox.
In an ideal world Kevin would have preferred the engine to have been normally aspirated, but like most of us the swift resurrection of the turbocharger caught him by surprise. Having said that, the B58 in the M140i isn’t a bad unit by any means and is quite amenable to producing significantly more than the 340hp with which it leaves the factory. In its standard form though the F20 M140i doesn’t really need any more power as it’s pretty much teetering on the edge of what can safely be deployed on the road and a chassis that’s a little underdeveloped doesn’t help matters much.
The combination of bespoke springs and dampers, along with the diff, are what Birds calls its Dynamics Package
And that’s where Birds come in as its B1 series of upgrades have been designed to get the best from the M140i and turn it into the truly rewarding drivers’ car that’s been partially hidden from view in its factory guise. Like the vast majority of BMWs it’s designed with German roads in mind and almost without exception they’re a lot smoother than the ones we spend our time on here in the UK, and that’s when an M140i can become unsettled. The rear of the car seems too stiff and it becomes flustered and exhibits less than perfect body control, when paired with its open differential it can become a handful when pressing on.
Birds first port of call was to right the ills in the car’s suspension, but it’s a more complicated picture than a simple set of off-the- shelf springs and dampers. First up there are run-flat tyres to contend with, and no matter how far they’ve advanced from the early days in the noughties when BMW was first using them they’re still not as responsive or comfortable as a set of conventional tyres.
There’s no doubting the performance gain – it really does feel as quick as an M2
So first on the list of upgrades is a set of normal tyres and Kevin’s been very impressed with Goodyear F1 Asymmetrics that work well in our soggy climate, and that’s what’s fitted to this M140i.
Next up is the suspension itself, and while there are a host of aftermarket set ups to choose from, Kevin wasn’t impressed. All too often more overtly sporting suspension kits are stiffer than the standard offering which can, in some cases, make matters even worse.
Having previously worked wonders on both the E9x 3 Series and E8x 1 Series platforms Birds carried out similar modifications and felt a marked improvement but there was something particular to the F-generation chassis that wasn’t allowing Birds to get the best from the car’s hardware.
A chance meeting with James Weaver and his chassis engineer Peter Weston at a track event led to Weaver and Weston agreeing to assist Kevin in the set up of the 1 Series. This involved a huge amount of measurement data including items such as corner weights, spring stiffness, damper rates and bump stop stiffness to name just a few. After careful assessment of the data Weaver and Weston advised on new spring rates and damper settings and Birds arranged for Eibach to produce the springs and Bilstein to re-valve the dampers to the new settings. Additionally, the front track was widened slightly too.
The third part of the package was required to address one of the main failings of the standard M140i – its open differential. In certain circumstances the open diff allows the M140i to spin its unloaded rear wheel which obviously leads to a less than controlled rear end. A lack of traction means that the engine’s power cannot be delivered to the road which would be a waste given how much attention has gone into improving the car’s suspension.
Putting the hammer down really does emphasise the transformative changes
The simple answer is to fit a Quaife limited-slip differential that sends torque in a progressive manner to the wheel with the most grip. The combination of the bespoke to Birds Eibach springs and Bilstein dampers along with the Quaife diff are what Birds calls its Dynamics Package and come to in the region of £3650 (including parts labour and VAT) if fitted together as a package. The individual items can be purchased separately, but it works out a little more expensive if you do it this way, and if your car has the electronic adaptive dampers fitted there’s an additional cost to code them out of the system.
While many owners might be happy with the Dynamics Package on its own there are a number of other changes that Birds can make to the M140i to make it an even sweeter steer. While many first owners opted for the automatic gearbox those equipped with the six-speed manual can also make the shift a little bit better. The standard throw of the gear lever is a little long and a short shift kit is available to give the ‘box a significantly more ‘snicky’ feel to it. At the same time Kevin’s not a big fan of the feel of the standard clutch and the weighting of the pedal can be changed thanks to what Birds terms a Clutch Modulation Modification.
This lot of upgrades should certainly make the M140i a significantly more entertaining steer, but the first thing that comes to many peoples’ minds when modifying any BMW is more power. Whether the M140i actually needs more get up and go is a moot point with a sub-five second 0-62mph time already in its armoury, but Kevin’s discovered that customer demand is there so Birds can also offer a power upgrade. Again, this isn’t an off-the-shelf concoction, rather one that Birds has had designed to its parameters and requirements. As we went to press the headline figures were yet to be finalised but it’s in the region of 430hp – a gain of around 90hp over the standard car and a significant boost in torque too. Perhaps best of all, it comes with a manufacturer matching warranty for peace of mind.
More power puts extra strain on the brakes so Birds also offers an upgrade, although with the M140i receiving the M Performance four-pot callipers up front as standard equipment it’s probably only the most committed for drivers that will need them. Birds Alcon set up offers bigger vented discs along with six-piston callipers for the ultimate in fade resistant braking.
So that’s the theory, but what are the upgrades like in practice? Our first visit to Birds to sample its red rocket unfortunately coincided with the monsoon conditions you can see in our pictures, but we did return for a second drive to try the car in the dry so we could get a full feel of the car’s abilities. The first thing that strikes you is how standard it looks – debadge this M140i and if it were in a less vibrant colour you’d really be able to pass under the radar with no clue to its potency. And that’s just the way I like my performance cars – suitably understated.
The second thing to strike you is that the clutch is weightier than normal, although some of this might be attributed to the fact that I almost exclusively seem to drive autos these days. It’s definitely heavier than I was expecting, but after a couple of less than slick pullaways from standstill you do get used to it and even in crawling traffic it doesn’t really give your left leg a workout. The gearbox though has a lovely action with a nice short throw which bodes well for when you’re on a charge.
It’s the chassis changes that really bring this car alive and they’re ably demonstrated in the poor weather where the standard car can quite often feel a little out of its depth. It’s so much more confidence inspiring than before with the diff hooking up the drive really well and there’s an unquestionable feeling that the whole car feels more keyed into the Tarmac, even if it is streaming with water. There’s more bite to the steering and the moderately wider track gives more precision and a little bit of welcome feedback, too.
There’s no doubting the performance gain, the M140i lunging forward with an additional ferocity – it really does feel as quick as an F87 M2 – and I can’t imagine that you’d actually need to be able to travel any faster than this. The Birds remap works – as you’d expect – without a hiccup and keeps the standard characteristics of the standard engine – oodles of low down and midrange torque – yet adds an extra element to its top end. It might be a turbocharged unit but it still loves to rev and has pretty decent throttle response too.
What I really need though are some dry roads that I know well so I can really judge the chassis changes, so once the pictures are in the bag it’s time to head home and deposit a very soggy photographer back to his car. A return visit in the sunshine and with dry roads is called for and once I’ve a few spare hours it’s back to Birds for another go. This time the clutch feels fi ne and the ‘box still delights but it’s the precision of the chassis work that really shines through.
Putting the hammer down over some familiar roads really does emphasise the transformative changes to the car and it’s from the rear that you feel the greatest difference. In the standard car the rear end feels somewhat crashy and bouncy when you encounter mid-corner imperfections or when driving quickly over undulations. The Birds car though is so much more composed with the springs and dampers combining beautifully to deal with everything that’s thrown at them as adroitly as possible before preparing for the next onslaught. It feels settled and less super stiff than before which could lead to an unpleasant corkscrewing feeling as the suspension tried to keep up.
It’s now hugely confidence inspiring and allows you to crack on without worrying if the suspension will be able to keep up. The whole car feels more in touch with the road and as the M140i is now in better contact with the surface the Quaife diff can get to work. Traction is no longer an issue and you can confidently hustle the M140i from one corner to the next knowing you can rely on it and receive consistent control and feedback. And all the while the glorious straight-six struts its stuff as you snick-snick between gears with the stubby gear knob with its well-judged short throw.
Downsides are few and far between – the clutch might be a little stiff for some, but you don’t have to have that particular mod carried out, and while the low speed ride might be a little bit stiffer over surface imperfections, it’s certainly not overly harsh or something I feel I couldn’t live with, especially when the chassis is so much more rewarding and involving when travelling at speed.
It’s easy to understand why Kevin reckons he’ll hold onto this car forever – it’s a cracking little car that could be used day-to-day without a qualm, yet when the mood takes you and the road opens out in front of you will reward with a sublime drive every time.
CONTACT Birds Web: www.birdsauto.com Tel: 01753 657444
Birds M140i Upgrades:
B1 Dynamics Package (suspension and Quaife LSD) £3633.60
Engine management (430hp) £2698.80
Short shift gear change £540.00
Clutch modulation modification £114.00
B-series Sport Springs £954.00
B-series Sport Suspension (springs & dampers) £1874.40
Exchange Quaife limited slip differential £2014.80
Alcon front brake kit £3228.00
Goodyear 18-inch F1 tyre set £675.60
* All prices quoted include parts, labour and VAT