Thread: Discovery 2 brake rotors and pad options

Originally Posted by rick130

If it isn't a typo, according to the TRW catalogue the pre 3A VIN # (ie ours) has the bigger piston?
48mm vs 45mm Catalogue

MC bore is the same on all VIN's

Ahhhh, and just like that there is a front brake caliper upgrade. Same pads across the 2 caliper types AFAIK???

Legend, thank you!

dia 45mm = SA1590mm2
dia 48mm = SA1809mm2
increase in front clamping pressure = 13.7%?

The earlier D2 caliper has the bigger 48mm piston, so the clamping force is greater for it for a given line pressure.

Maybe there's too much flex in the big piston caliper?
Or they were trying to reduce pedal travel and increase pedal firmness in the later car?

Originally Posted by rick130

The earlier D2 caliper has the bigger 48mm piston, so the clamping force is greater for it for a given line pressure.

Maybe there's too much flex in the big piston caliper?
Or they were trying to reduce pedal travel and increase pedal firmness in the later car?

Ahhh it went that way. They revised the brake booster at the same time.