Af­ter­mar­ket sus­pen­sion

As fac­tory sus­pen­sion set ups be­come ever more so­phis­ti­cated, does the af­ter mar­ket still of­fer aplug‘n’ play op­tion?

Evo - - BRIEFING - by Brett Fraser

UN­LESS YOU’R E a pro­fes­sional chas­sis engi­neer, there’s a strong ar­gu­ment for leav­ing your car’s sus­pen­sion well alone: a large team of ex­perts spent tens of thou­sands of hours fine-tun­ing the ride and han­dling to be just-so, there­fore the chances of you im­prov­ing upon all their hard work are, well, slim.

How­ever, the big names in af­ter­mar­ket dampers – Koni, Bil­stein, KW, Öh­lins, etc – cre­ate prod­ucts that are de­vel­oped by pro­fes­sional chas­sis engi­neers who have honed their skills in mo­tor­sport and have strong ties to the types of car mak­ers that find favour in evo (KW, for in­stance, sup­plied the coilovers for BMW’S ex­treme M4 GTS). This is why, de­spite the evermore so­phis­ti­cated na­ture of dampers fit­ted to cars by their mak­ers, the af­ter­mar­ket con­tin­ues to thrive, with cus­tomers pre­pared to trade pro­duc­tion-car com­pro­mise (even on some very high-per­for­mance mod­els) for a sharper fo­cus in ex­treme con­di­tions on road and track.

While in some ways it was ever thus, the af­ter­mar­ket has had to evolve quickly to mir­ror re­cent changes in the high-per­for­mance mar­ket. A decade or so ago, elec­tron­i­cally con­trolled mul­ti­stage dampers were still some­thing of a nov­elty; these days you’ll find them on top-end hot hatches. So the lat­est af­ter­mar­ket of­fer­ings pro­vide a sim­i­lar adap­tive damp­ing ca­pa­bil­ity for cars that don’t have it as stan­dard, and for those cars that do they pro­vide coil-over­damper units (coilovers) that plug into the ex­ist­ing elec­tron­ics and re­tain the full func­tion­al­ity of the orig­i­nal sys­tem.

KW and Bil­stein, for ex­am­ple, have af­ter­mar­ket adap­tive damper set­ups, based on a coilover con­fig­u­ra­tion. (Öh­lins, mean­while, has been de­vel­op­ing elec­tron­i­cally con­trolled sus­pen­sion tech­nolo­gies – CES, or Con­tin­u­ously con­trolled Elec­tronic Sus­pen­sion – for OEMS since the 1980s.) Bil­stein calls its di­rect re­place­ment adap­tive damp­ing sys­tem Damptronic, and it’s com­pat­i­ble with cer­tain Porsches, BMWS, Mercedes and a hand­ful of oth­ers. KW’S sys­tem is known as DDC (Dy­namic Damp­ing Con­trol) Plug & Play, and for the mo­ment is avail­able for just a few BMW and Volk­swa­gen mod­els. Given how sen­si­tive many mod­ern whole-car elec­tronic man­age­ment sys­tems are to out­side in­ter­fer­ence, the fact that these re­place­ment units can sim­ply slot into the place of the orig­i­nals is tes­ta­ment to the close re­la­tion­ship be­tween some car mak­ers and af­ter­mar­ket sup­pli­ers.

The list of cars for which adap­tive damp­ing can be added where it isn’t present from the fac­tory isn’t enor­mous yet, as the kits have to be tai­lored spe­cially for in­di­vid­ual cars and it’s a com­plex process, but on it you will find Audis, BMWS,

Porsches, VWS, Mercs and the Range Rover Evoque. The KW DDC ECU sys­tem pro­vides three set­tings ac­ces­si­ble via a sin­gle but­ton on the dash­board – Com­fort (when the but­ton il­lu­mi­nates blue), Sport (pur­ple) and Sport+ (red). Bil­stein’s Ride­con­trol sys­tem of­fers the choice of Com­fort or Sport, again cour­tesy of a fa­cia-mounted but­ton.

Both these Ger­man ri­vals also pro­vide the ded­i­cated chas­sis fet­tler the op­tion of wire­less con­trol of the damper set­tings through an app on your smart­phone or tablet – KW’S sys­tem works only on IOS de­vices, while Bil­stein’s IRC mod­ule is also An­droid com­pat­i­ble. Both sys­tems pro­vide the reg­u­lar ar­ray of modes (Com­fort, Sport, etc), but they then al­low you to fine-tune damp­ing rates by small per­cent­age points at a time and on in­di­vid­ual axles, as well as set­ting the ride heights for spe­cific con­di­tions. You can also store up to five per­sonal

You can store up to five cus­tomised set­tings – one for your daily com­mute, per­haps, an­other for a lap of the Ring…

cus­tomised set­tings – one for your daily com­mute, per­haps, an­other for a lap of the Ring…

Öh­lins has fo­cused its af­ter­mar­ket at­ten­tions on fur­ther de­vel­op­ing ‘reg­u­lar’ coilover tech­nol­ogy and claims the re­sults, in terms of damper re­ac­tion times and over­all chas­sis per­for­mance, are su­pe­rior to what can be achieved with elec­tron­i­cally con­trolled sys­tems. The Swedish com­pany’s Road & Track range fea­tures what it calls a Dual Flow Valve (DFV), whereby the damper re­acts as swiftly dur­ing the re­bound phase as it does un­der com­pres­sion. This means that the wheel stays in bet­ter con­tact with the road sur­face af­ter, say, hit­ting a sharp bump that would oth­er­wise bounce it off the deck.

The ad­van­tages of DFV, says Öh­lins, are man­i­fold. With­out sac­ri­fic­ing ride com­fort, your car can run with far stiffer springs – in the case of the Porsche 911 GT3 RS, twice as stiff as stan­dard – re­duc­ing squat, dive and roll, and keep­ing the tyres in bet­ter con­tact with the road sur­face, while im­prov­ing steer­ing re­sponse and sta­bil­ity, too. Com­pared with a Pasm-equipped 997-gen­er­a­tion GT3 RS on a 1min 30sec track, reck­ons Öh­lins, its Road & Track setup gives an ad­van­tage of 1.6 to 1.8sec per lap, de­pend­ing on the driver. A boost in con­fi­dence for less ex­pe­ri­enced track driv­ers is also claimed.

Ad­justa­bil­ity re­mains a key draw of af­ter­mar­ket dampers. KW’S three-way coilover kit for the BMW M2 am­ply il­lus­trates this point, with 16 set­tings for re­bound con­trol, 14 for high-speed com­pres­sion (straight-line driv­ing and very quick cor­ners), and six for low-speed com­pres­sion (as you turn into sharper bends). Work­ing out the ideal setup might take you a while…

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