Warn­ing on fake shocks

Im­i­ta­tions will not last past the first pot­hole

The Witness - Wheels - - MOTORING - ADRIAN BUR­FORD • Adrian Bur­ford is a me­dia con­sul­tant for Bil­stein SA.

BIL­STEIN South Africa, the lo­cal im­porter and dis­trib­u­tor of Bil­ste­ing as pres­sure shock ab­sorbers, has warned mo­torists not to be misled by coun­ter­feit ver­sions of the brand’s Airmatic spring/ damper, the fit­ment of which will se­verely com­pro­mise a ve­hi­cle’s sta­bil­ity and safety.

Damper assem­blies with in­te­grated height- ad­justable air springs are fit­ted to a num­ber of up­mar­ket SUVS and sa­loons and pro­vide the best of both worlds: ex­tra ground clear­ance when off- road and the se­cure han­dling that low­ered ride height pro­vides when on the tar.

Th­ese com­plex, so­phis­ti­cated assem­blies com­bine elec­tron­i­cally- con­trolled hy­draulic damp­ing with air spring­ing and can re­act in­stantly to road con­di­tions, driver in­puts, and speed. Un­for­tu­nately, they are fre­quently copied or in­ad­e­quately re­fur­bished and sold at a price much lower than the orig­i­nal — of­ten with the in­fer­ence that their per­for­mance will be the same as or sim­i­lar to that of the orig­i­nal.

Th­ese coun­ter­feit­ers go to great lengths to pass their prod­uct off as a Bil­stein, but there are a num­ber of key vis­ual dif­fer­ences that can be used to ver­ify the au­then­tic­ity of the prod­uct.

For starters, a fake “Airmatic” was 40 mm too long. Di­men­sional ac­cu­racy is crit­i­cal and if the sus­pen­sion is forced to work through an ab­nor­mal arc, it will cause not only in­cor­rect ge­om­e­try un­der cer­tain con­di­tions but also pre­ma­ture fail­ure of rub­ber bush­ings and mount­ings and ac­cel­er­ated wear of other com­po­nents such as con­stant velocity joints.

It also re­vealed that while the re­mote valve cylin­der which con­trols the trans­fer of oil into the main damp­ing tube of the shock was an orig­i­nal Bil­stein part, it had how­ever been har­vested from a dis­carded assem­bly and had been at­tached to the fake in a com­pletely non- func­tional man­ner. In fact, there was no link be­tween the two, so while the fake unit still con­trolled the ride height, the al­limpor­tant tech­nol­ogy to con­trol damp­ing rate had been ren­dered in­op­er­a­tive.

In­spec­tion of a re­fur­bished assem­bly re­vealed the use of an in­cor­rect length air bel­lows which was also se­cured by in­ad­e­quately crimped re­tain­ing rings.

The in­flat­able bel­lows is the sus­pen­sion spring, and its in­tegrity is there­fore crit­i­cal: if it is punc­tured, the on- board com­pres­sor will strug­gle to main­tain the cor­rect ride height. If the crimped- on metal re­tain­ing band fails — which it could at any pot­hole — the re­sult is far more dra­matic and the ‘ spring’ will col­lapse in­stantly, with po­ten­tially cat­a­strophic con­se­quences.

Due to the safety- crit­i­cal na­ture of the is­sue, Bil­stein South Africa ad­vises con­sumers and the mo­tor trade to be aware of the dan­gers of at­tempt­ing to re­pair th­ese items, or fit­ting nono­rig­i­nal re­place­ment com­po­nents. To this end they have is­sued a se­ries of images which will as­sist in iden­ti­fy­ing a fake assem­bly.

Key dif­fer­ences in­clude:

1. The ex­tended length of the fake assem­bly which was found to be 40 mm longer than an orig­i­nal item. 2. On a Bil­stein unit the re­mote valve cylin­der is in­vis­i­bly laser welded onto the damp­ing tube, whereas on the fake item un­even “spot” weld­ing is ev­i­dent where it at­taches us­ing a sim­i­lar in­ter­face. 3. One of the most ob­vi­ous dif­fer­ences be­tween the real and the fake is how the yoke, which strad­dles the ve­hi­cle’s sus­pen­sion arm, is at­tached to the damper tube. The Bil­stein item has an open tube which is pressed onto the shock body and then welded both above and be­low. The fake uses a cast­ing which is closed at the bot­tom, has a longer boss and is welded onto the shock body on the up­per side only. 4. Viewed from be­low the gen­uine part has a dim­ple in the cen­tre of the end cap, and the fake is smooth 5. The edge of the bel­lows on the Bil­stein unit is ex­tremely ac­cu­rately and pre­cisely aligned rel­a­tive to the steel crimp­ing ring. Ex­tra crimp­ing marks and a large and/ or ir­reg­u­lar over­lap of the rub­ber are tell- tale signs that the bel­lows has been re­placed, or that the en­tire unit is not a Bil­stein prod­uct.

Some of th­ese dif­fer­ences are only ap­par­ent by re­mov­ing and ex­am­in­ing the unit care­fully but one of the most ob­vi­ous — and im­por­tant - give­aways in situ is the area at the bot­tom of the damper, where the fork joins the tube.

The fake has a longer boss which is clearly welded to the tube on the up­per side. And fi­nally, if the quoted price for the Airmatic assem­bly is very low, it is likely too good to be true.

Old valve cylin­ders are har­vested and ‘ spot’ welded to the main damp­ing tube, mak­ing damp­ing in­op­er­a­tive.

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