1998 S80T6

brakes work really well and have been maintained, including regrinding front disks.

however, when at a lights or other standing (in drive or neutral), the brake pedal gradually sinks a little way to the floor.

Is this normal or a problem somewhere

 

Master cylinder

 

Have brake pads been replaced lately?

 

pads replaced about 4k ago

 

Has the pedal felt like this since then?

 

To be honest it has been like this for maybe 4 years, which was before the pads replacement and disc grinding.
I haven't gotten round to posting it before now.

As said previously, the performance is fine just didn't expect the pedal to sink at standstill

 

Sounds to me like there may be AIR in the system somewhere..may need bleeding...good luck

 

First thing to try is to find an EMPTY lot of something like that. Then safely hit about 40MPH then try locking up the brakes to activate the ABS and see if the pedal gets better.
If it doesn't then try bleeding the system.