[Tom Wells]

Hello Boss 351 cobra,

I have the BAER 13" conversion with the PBR front calipers - not exactly the same setup you have, but probably a similar problem.

I use the stock diameter Jag rear disks and XJ rear calipers. Well actually, they are vented disks from CWI, but otherwise the same as your setup.

I put the proportioning valve near my right knee next to the drivetrain hump so I could adjust it easily.

At first with the proportioning valve wide open, the rear brakes gave too much effort - they seemed to be trying to stop the car without much help from the fronts. Some help, but not enough.

A bit of rotation of the proportioning valve to decrease the effort at the rear brought the front brakes to life! Stopping became quite effective.

Bottom line: you should be fine with the Jag rear calipers (not XKE, but XJ) and the proportioning valve.

For a bit more money you could get Wilwood rear calipers from CWI.

Classic Jaguar uses the 4-piston front Wilwoods with the stock rear calipers and apparently that works well.

Good luck!

Tom