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Driver Technology Explained
Dominic Pedler

Modern driver marketing involves an ever growing barrage of technical features to help you decide which might suit your game, Dominic Pedler deciphers a dozen examples of essential jargon you will inevitably encounter among the big sticks of 2009 and onwards...

With their huge 'footprints', geometric heads, sunken crowns and 'hot' – and now adjustable – faces, today's drivers are strange beasts indeed. But how do their ambitious designs really affect performance and which Unique Selling Points will really improve your game?

Here is a guide to the most common techie terms, illustrated with the latest models that you can read up in more detail elsewhere this issue and on our more extensive website pages. While several drivers potentially fall into each category under discussion (and some span several categories) we have chosen just a few examples that best capture each concept.


The golf industry's growing appreciation of the individual nature of a player's swing has led to the rise of multiple head designs for a given model of driver, truly tapping into the needs of different types of golfer. Leading the way is the Titleist 909 which comes in three distinct versions each with its own design rationale and some of the most high spec, premium shafts as standard.

This is an important evolution from the more conventional practice of merely offering one driver head style, perhaps with different weighting configurations according to loft option. After all, a golfer may require a higher loft but not necessarily the draw-biased weighting that is often packaged with it.

'Golfers have different swing speeds and angles of attack which dictate different head constructions, with players increasingly looking for different performance characteristics beyond distance,' confirms Richard Temple, Titleist's Senior Product Manager referring to the 909 DComp, D2 and D3 each with their own head size, shape, materials, construction and shaft options 'They want various types of ball flight, levels of accuracy and workability – and they are now much more particular about sound and feel.

You can't meet these requirements with a single driver.' Cobra adopts a similar philosophy with eight versions of the King Cobra S9-1, including Pro heads with both shallow and deep faces, dedicated Senior's and Ladies heads as well as the variously lofted, weighted, and face-angled M and F versions.


The biggest equipment story of last season was the retail debut of drivers with interchangeable heads and shafts, now deemed conforming courtesy of the R&A's rule relaxation.

Techie-minded golfers no longer have just moveable weights to tinker with, but can now dismantle the entire club and mix'n'match heads and shafts in a brave new world of self-customization. It allows a new generation of golfing perfectionists to tailor their equipment not merely to their swing but also to the course and the weather conditions, with different shafts and (indeed heads) offering different trajectories and patterns of roll.

The Callaway iMix and Nickent 4DX Evolver pioneered the concept at the 2008 Orlando Show with standard packages of a head and two shafts offering differing kick-points and flight trajectories. Taylor Made joined the club of with their R7Limited and R9 drivers, while the new Callaway FT-iQ is among the most exotic.

While the Callaway clubs fasten the two components with a carefully engineered rotating hosel, TaylorMade and Nickent use a high-tech bolt that screws in from the sole. Either way, traditional epoxy glue is now made redundant by a few turns of a wrench.


Arguably more practical to the average golfer are the very latest drivers whose heads and shaft can be manipulated more specifically to adjust the face angle of the clubhead.

The King Cobra L5V won an award for its Adjustable Flight Technology that allows you to unscrew the head and rotate it so as to close the face by one degree relative to the factory preset. Of course, many other drivers sport varying degrees of (nonadjustable) face angle in what is a variation on the anti-slice theme. But the beauty of adjustability is, obviously, that once you have worked on your swing you can then just turn the face back to neutral, effectively giving you two drivers for the price of one. Or, in the case of the more sophisticated offerings, several drivers in one.

The Nike SQ Dymo STR8T-FIT gives you eight options of face and lie angle, with three closed positions alongside neutral and open-faced options. Most elaborate is the 2009 version of the Nickent 4DX Evolver with its special hosel insert that rotates to encompass 26 different settings of face angle, lie angle and loft. [See also the Taylor Made R9 under section 7, below] Indeed, the wizardry of all these clubs is in the way the shaft fits into the hosel sleeve at a slight angle, rather than being perfectly parallel.

In this way, golfers should be aware that there is inevitably a loft ramification to a change in the face angle – the rule of thumb being a half-degree increase in loft for every full degree of face closure.


Here's a term that crops up in the descriptions of just about every driver (and indeed fairway wood, hybrid and iron) these days. Basically, the lower and farther back the CG is from the clubface, the higher the shot trajectory for any given loft.

With many golfers struggling for height at low-to-moderate swing speeds, most drivers are preoccupied with shifting the CG low and rearwards by various means. Most popular are the lightweight crowns (either composite or wafer-thin titanium now pushing the 0.5mm barrier), along with both rear weight plugs and 'limit dimension' bodies that can stretch some five inches back from the face.

Nicklaus Golf claims a similar approach in their Dual Point FastBack driver named after the 'precise alignment of the optimal face flex-point with the centre of gravity in order to enhance energy transfer and ball velocity'.

This is in contrast to the many conventional, deep-faced heads requiring an unduly high tee to strike the ball with an efficiently high launch angle and low spin rate. But you don't always need an extreme shape to lower the CG and get the ball up, as Ping have shown with their V2 Rapture which does the job through more subtle tapering of the crown and a pair of relatively heavy tungsten weight pads in the rear sole. Remember, while super-low CG works for many golfers, it's not for everyone, hence the rise of 'progressive internal weight distribution '.

The Crews TourLink D-460 is a good example, with its elaborate internal 'rib and dimple' pattern and external rear weight pod being configured individually for each of the three loft options so as to optimise their respective spin and launch angles.


'High MOI' has now replaced the rather tired 'perimeter weighting' among the essential marketing mantras – though in many ways they both promise the same thing: a more stable clubface with a less-than-perfect contact.

You don't need to be square to have a high a MOI – the Benross Innovator X is more triangular – but boxy shapes have breathed new life into the driver market by clearly conveying how weight is directed to the 'corners' of the club for extra stability. Nike even named their SQ Sumo2 5900 after the R&A's MOI limit of 5,900 grammes-per-cm2 with the concept refined further in the Nike SQ Dymo2 (whether in non-adjustable or STR8-FIT versions.)

It's important to specify that this particular measured definition of MOI relates to a club's resistance to rotation about the axis that goes vertically down through the point of the clubhead's centre of gravity. A high figure MOI will make your drives straighter on off centre hits – but only if you mange to square the face at impact. Nike, along with Callaway's square Big Bertha Fusion FT-i models paved the way for dozens of exotically shaped rivals, albeit with varying degrees of angularity, and nowadays at all price points.

MD Golf's High MOI offerings are particularly good value whether in the square model of the Ti-460 series or the more conventionally shaped Seve Icon driver designed by the Spaniard himself.


With the new rules limiting the efficiency of energy transfer between clubface and ball having finally come in on Jan 1, 2008, the old 'High COR/Hot Face' chestnut is being gently relegated as a marketing mantra. Leading drivers are now on, or near, the 0.83 maximum (or the equivalent in terms of the Characteristic Time measurement which the R&A now specifies). But they still achieve the maximum allowed ball repulsion in a variety of exotic ways.

The Mizuno MX-700, for example, showcases a 'hot metal' construction using the advanced Ti9 grade of titanium whose grain structure in the 3mmthin face allows for more flexibility in the sole-to-crown plane – traditionally the most rigid area that limits the scope for maximising ball speed.

This appears to be a sophisticated evolution of the tapered titanium alloy insert which debuted in the Titleist 907 series, thinner at the top where it meets the crown precisely to promote the latter's flexibility at impact. The rationale is, paradoxically, that thin crowns are the key route to powerful ball speed as, being far thinner than the face itself, they can deform upwards on impact before recovering – hence the 'spring-like effect'. This works by causing less deformation – and therefore less energy loss – of the golf ball itself, leading to more distance (even if calculations of non-conforming faces range merely from an extra 2-12 yards).

Look out, then, for modern crowns of just 0.5mm, like the Cleveland Launcher and Ping Rapture V2 – or 0.3mm in the case of the magnesium alloy crown of the Nickent 4DX Supermag – even though these are usual marketed for their lower centre of gravity and higher ball flights. Arguably the most cutting-edge concept is the nitrogen-filled chamber in the head of the PowerBilt Air Force One designed to create high-pressure support for the ultra-thin face – just 2.8mm – that can itself flex to provide a more effective and faster ball speed


Once you have your maximum 'COR', the trick is then to apply it not just to a single point on the clubface but across the widest possible area. Hence references to 'effective hitting area' (updating the affectionate 'sweet spot') which we can look at in terms of both the physical dimensions of the face and the specific technologies that ensure off-centre hits perform more solidly.

Among the largest club faces for 2009 are the mighty 48.5cm2 surface area of the Taylor Made Burner and the 46.8 cm2 of the Cleveland Launcher. Seriously confidence inducing dimensions. Meanwhile, elaborate ways of ensuring a wide effective hitting area even on slightly smaller surface areas usually involve 'variable face thickness': typically thinner at the traditionally less flexible outer areas and thicker at the naturally more flexible centre. The Ping Rapture V2 has a precision-machined variable thickness face to achieve a more consistent performance for impact points all over the face, as does the Wilson Smooth which Padraig Harrington recently put into play.

Callaway have had particular success with their Hyperbolic Face with its 'X'-shaped internal configuration milled into the back, again to increase impact efficiently across the area. Debuted in last year's Hyper-X, the structure is back in the FT-9 and the driver of the brand new Big Bertha Diablo range.


Taylor Made got the ball rolling back in 2005 with the r7 Quad featuring four external weight bolts that were adjustable (between rounds only, of course) to encourage your preferred shot shape. Not to be confused with pre-configured factory weightings (see below), such drivers come complete with a tool kit and a selection of weights to help you dial-in both your preferred trajectory and draw/fade bias.

Taylor Made simplified their own concept in the r7 Limited, and also the latest R9 both using three weight ports (heel, toe and central rear plug) allowing for three separate weighting configurations using the 16g and pair of 1g weights. When you include the further eight set-up combinations of adjustable face and lie angle, the R9 can display some 75 yards of ball flight variation (in terms of horizontal dispersion) depending on how you set it up from the club's total of 24 potential settings.

Somewhat simpler is Mizuno's MP-600 which adopts an effortless FastTrack system of sliding weights where you simply loosen the two 8-gramme pegs and slide them to one of the six numbered positions along a semi-circular groove running around the rear. The 15 possible flight variations promote varying degrees of bias from fade to draw, and also influence trajectory and spin rate.

The Snake Eyes Viper TI Tour is another that comes with a handy guide to exploiting the twin 2g and single 6g weights; while special mention also for the Benross Innovator X for the single, centrally-located rear port which accommodates interchangeable 3-gramme and 9-gramme weights. This restricts the user to tweaking only the vertical trajectory, rather than also lateral dispersion, but the latter can be far more fickle and consequently difficult to harness through weight adjustment alone.


Driver aerodynamics are back in fashion with some scientists claiming that many 460cc drivers suffer undue wind resistance from their deep faces, thereby compromising stability and clubhead speed. The Yonex Nanospeed-i aims to correct this with an intricate rear sole section that ensures the air flows closer to the structure at high speeds for a faster,more stable flight. The rather elaborate undercarriage is obscured at address, leaving a crown whose pentagonal lines are much less space-age than they sound.

The Adams Speedline is another whose various curves and 'scoops' are claimed to create less drag and airflow turbulence. 'Extreme geometry drivers continually test with higher drag and lower club speed,' said Scott Burnett, Director of Advanced Product Development. 'By changing the aerodynamic properties of the face and crown in order to keep the airflow attached, we were able to deliver a significant distance advantage for the average player and tour pro alike.'

As with the Yonex, Adams claims a figure of 3-4mph extra clubhead speed – equating to an extra three to nine yards – according to the wind tunnel aero-physicists at Texas' A&M University. It certainly worked for Bernhard Langer when he won on the Champions Tour, last Autumn, with a Speedline prototype and again this season with the commercially available model.


With the vast majority of golfers suffering from a slice, dedicated draw designs have snowballed in the last few years – with Taylor Made even developing an entire Draw family of clubs led by a Burner Draw driver. Technically speaking, we need to revisit centre of gravity – though this time not in the 'high/low' or 'front-to-back' plane but the 'heel-to-toe' plane, with draw designs typically loading up the heel with extra weight allowing the lighter (and therefore faster moving) toe to square more effectively at impact.

This is the rationale behind the Callaway Opti-Fit weighting system whereby golfers can choose heads for drivers such as the new Big Bertha Diablo and FT-9 in either Draw or Neutral versions, each with pre-configured stainless steel 'web' weights precisely positioned for the appropriate performance. Other manufacturers offer similar opportunities – though these are often determined by the choice of the loft, the assumption being that golfers requiring a more draw-friendly construction tend to be those who also require a higher launch angle off the tee.


Another 'blast from the past' (being traditionally associated with persimmon drivers), gear effect has made a comeback in recent years as both a design and a marketing tool. The term describes the compensating side spin, and resulting curving shot shape, that causes a shot off the heel to display a fading ball flight – and vice versa off the toe. This is a potentially confusing concept as you would intuitively expect the exact opposite – i.e. a shot off the toe to have inherent clockwise slice spin.

The phenomenon is down to the off-centre strike causing the clubhead to twist about its center-of-gravity promoting the ball to slide and roll slightly sideways across the face – literally with a gear-type effect on the face – and to launch with draw-biased side spin. Hence most woods have a slightly curved face (horizontally from heel to toe), known as 'bulge', which allows the ball to start its flight slightly away from the target line, before the opposing side spin kicks in. Bulge is usually paired with 'roll' referring to face curvature now in the vertical plane.

While perimeter weighing has made the gear effect principle and hence the bulge and roll of metal woods far more subtle than their persimmon predecessors, the terms are still relevant, with Srixon showcasing in the latest WR drivers that claims to reduce side spin in conjunction with the thin walls of the high-impact Powerface. The Bridgestone J33 is a 460cc driver with a super-thin Low Modulus Crown which flexes slightly at impact to add effective loft and enhance the vertical gear effect of the face which, in turn, decreases the unwanted backspin that can compromise distance.


Offset club heads were one of the earliest anti-slice measures and remain one of the most popular – being also found in dozens of models of irons. They work through simple physics dictating that the toe of the clubhead tries to align itself dynamically at impact with the line of the shaft as it meets the hands. This ensures that in an offset club, the toe has slightly further to travel to catch up and will therefore necessarily cause the face to be slightly closed face at impact.

Many drivers either highlight the offset feature or offer it as an option to the main range. Our favourites are the Nicklaus Golf DrawBack, the MD Golf Superstrong Ti-460 Offset and the latest 12o offset option of the Wilson Spine, all especially marketed for their right-to-left ball flight – for right-handers, of course....

Reproduced with kind permission of Golf International.

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