Hello!

I wonder if anyone knows the piston size in the 3 piston front calipers for the early xj6 and also what size the master brake cylider has?

Thanks!

 

Or the four piston caliper size if it has the same rear caliper.
I´m trying to find what balance the xj6 hade between front and rear brakes.

 

I know the Series II. The, 4 piston fronts... each piston is 48mm or 1.89 inches. The rear 2 pistons are 43mm or 1.69 inches.

I would assume the rears stayed the same from Series I to II as the Series II increased in weight. Most of that additional weight is front-ward. USA bumpers, A/C compressor and related components, emissions equipment and the additional structure behind the dash were all far forward of the cars center.

So on a Series II the piston area is 11.22 sq/in front and 4.48 sq/in for the rear.
With smaller rotors out back than in front as well. So the brake bias is a bit over 60% forward biased.

The m/c bore is 15/16 all the way through.