Holiday time – No relaxation for springs
Rösrath, August 2017 – Seeing heavily-laden cars on the motorways in summer quickly makes you realise the pressure suspension coil springs are under. Crumpling under the weight like this is only one reason for a possible fracture.
The actual causes of damaged springs are manifold. There’s surface damage brought about by rust, the use of weight-reduced springs made of high-strength steels, which may impair toughness over time, and then there’s the ever-worsening road conditions.
In the past, this only ever affected older cars, but nowadays, a broken suspension is even possible in a relatively new car too. Something workshops would be well advised to bear in mind when checking these safety components.
The first warning signal is rust: This usually occurs at the lower end of the spring, where road dirt, stones and spray water “attack” most. Constantly in motion, this accumulation of grime and moisture on the spring plate acts like sandpaper against the spring’s protective coating. At some point, a rusty spring put under even more stress by a heavy load may be unable to hold the tension and break. Strange noises may also be an indication that a break is about to happen. In a suspension strut assembly, the spring often no longer sits correctly on the shock absorber and can cause squeaking and creaking noises.
Springs are safety parts, so it is essential to look at the quality of the spare part being used as a replacement. Spidan suspension coil springs are made of heavily-loaded steels, additionally coated with rust protection that can withstand even the toughest environmental influences. Where necessary, plastic sleeves are pulled onto the spring ends that rest on the spring plates.
Miniblock springs with a typical barrel shape (sometimes called barrel springs) have quality criteria that is immediately visible to experts – spring wires that taper in the direction of the spring ends. Without this inconstant wire, the desired progression is not possible and vehicles buckle outright when loaded. “Unfortunately, dangerous constructions such as these are constantly found on the market”, says Steffen Junge, Team Leader Product Management at GKN Driveline for the automotive aftermarket. “Dramatic deterioration in driving behaviour is not the only consequence, the coils can even touch during deflection and be damaged. Vehicles with such springs potentially pose a safety risk. Spidan springs therefore always meet the requirements of the OE design.”