How Soon After Brake Pad Warning Light Do I Need to Change Pads?
 

Hi,

I replaced all four rotors and pads on my 1991 420SEL 30,000 miles ago. The brake pad warning light came on yesterday. How soon do I need to replace the pads? Can I drive for a few more weeks? Also is 30,000 miles normal for pad replacement?

Thanks in advance

The safest way is to check the thickness of the pads - sorry I don't know the limit for your car.

30,000 miles sounds about right for pads on a LWB W126....I usually only get around that on mine. Once the warning light is lit solid you don't have all that long....maybe 1500 miles of average driving. I'd still physically check them.

Great. Thanks for your response. The sensor is not on solid yet. I just need a few weeks and a few hundred more miles.

Dave, it's difficult to say how long or how many miles the brake pads will last before damaging the rotors without knowing your driving habits. It would seem that you do a considerable amount of highway driving ... based on that I would say up to 2,000 miles. Obviously as soon as you replace the brake pads the cycle starts on the new brake pads so it's a good idea to maxmize the wear on the existing brake pads. However, if you're a procrastinator it may be wise to change the brake pads sooner rather than later.

The big question is what shape are the rotors in? If they are in tolerance for thickness and runout, don't risk ruining them by going metal on metal.

If they are already warped or too thin, then you risk less my pushing the envelope.

Unfortunately, the brake warning sensor indicator does not always mean worn pads. It could be that the sensor itself is not on properly like what happens to my 123. Although I have ot had it happen for a long time.

But that does not mean you should ignore it. I would at least chk the thickness of the pads.

New pads are 11 mm thick.
Sensors are triggered at 2.5 mm pad thickness.
Discard thickness is 2 mm.

All the relevant and required information.
Thanks
mak