Coil spring - replace both ?

red_eye

paddedjohn wrote: »

OP, how long are you keeping the car? if for a few years then it would be advisable to replace the springs in pairs. Just replacing one can cause to uneven ride height, an increase in braking distance and make the handling less responsive.

Just to point out its the springs that are the actual shock absorbers, the others are dampers and dont actually absorb any shock at all.

other way around with out dampers (shock absorbers) the spring will just bounce the car. springs are there to support the vehicle weight (with out springs the dampers would bottom out):D

paddedjohn

red_eye wrote: »

other way around with out dampers (shock absorbers) the spring will just bounce the car. springs are there to support the vehicle weight (with out springs the dampers would bottom out):D

Sorry no, its the spring that absorbs the shock whilst the dampers dampen the affect of the shock.
As you rightly say, without springs the dampers would bottom out thus sending the shock of any and all bumps in the road surface right through the structure of the vehicle.;)

Mankysteve

Personally I would change both but wouldn't loose any sleep if I didn't

Nearly_Old

Change one spring or both? If it's a BMW it appears to depend on whether it's still in the warranty period. There are quite a few cases of rear springs breaking on the Z4 and if it's within the warranty period BMW usually just replace the broken spring. However if the car is over 3 years old and out of warranty the usual response from the Stealer is: "Springs must be replaced in pairs as it's a safety issue!"

Personally I do change them in pairs when they have been on the car for a longish time (10 to 12 years) to try and keep the same spring rate on both sides.

Tetley_the_Cat

The input energy is absorbed by the spring and the dissipation damped out by the "shock absorber" which is better called a damper.

Ultimately though, there is no need to replace nowadays either dampers or springs in pairs as all are individually tested to a working life where the degredation at the end of design life is no more than 20%. Design life in Europe is generally taken as being 10 years or 150,000 miles.

So the reality is that the replacement scenario in pairs used to be true in the days of leaf springs and lever arms etc but certainley for the last 15 years it's not been necessary.

A falicy more driven by old wives tales and fast fit centres than engineering reality!!