How important is it, if a mechanic tells you one of your rear sway bar links is broken, to replace it? Is it necessary to do both at once as the mechanic suggests?
Hard to tell without seeing (what’s year/model/miles), but usually it’s the bushings in the links that wear out, and if one side’s bad, both sides might need replacing. And if one side’s bad, it would cause noises in the rear and poorer handling.
Little problems lead to big problems, nip it in the bud!
The cost should not be to high. If you normally drive easy you may never know the difference. In an emergency situation the handling might negatively effected…more “push” in the front end. I would consider it a safety issue.
You might notice some extra body roll and maybe some clunking in the rear but you will not flip your ride. If you have a state safety inspection your car will fail without them.
If the rear sway bar links are long bolts without a sleeve for proper spacing be careful that they are not overtightened or they will break during turning.
If you want an intelligent answer, responders need the year, make, model and mileage of the vehicle you are talking about…
Broken suspension parts should ALWAYS be replaced.
The vehicle in question is a 95 Mazda 626.
Of course I would replace or repair the sway bar. However, I once owned a Chevrolet without a rear sway bar; it only came with the optional; “handling package”. I did order a Heavy Duty police weight sway bar and the car handled much better afterwards.
So, you are not driving a death trap, but the car will handle much better if you fix it!
A faulty anti sway bar can cause oversteer or understeer depending on which end of the car it is on. You should fix it.
However a Mazda 626 may have these components as an integral part of the design. Your old Chevy it was likely an afterthought and not crucial to the suspension design.
An anti-sway bar was definitely part of the suspension design on that 626, so as andrewj implies, it is a vital part of the suspension on that car. The failure or the absence of an anti-sway bar on that car will definitely make for less secure handling.