RUSTY HEAPS

A Mostly British Obsession

JCW Brakes, Part 2

Welp, the brakes on the JCW Paceman are done, and the wear sensors were salvagable, so yay!

Driver’s front brake, picture at article top is driver’s rear brake.

One thing which did catch me out: on the rear calipers, the piston can only be retracted with a special tool, since they have to be screwed back in, rather than just squeezed…must have something to do with the handbrake. Fortunately, the Freeland NAPA had a tool I could borrow (for free!), and that was all I needed to complete the task.

I cleaned the wheels while they were off the car, and rotated the front wheels to the back, but keeping the wheels on the same side of the car. The rears did have slightly more tread than the fronts; I’d guess the tires have about 10,000 miles before they need replacing, but that’s at best a guess.

Having bolted everything back together, I took the car out to bed the brakes this evening–a task best done when there is no one else out and about. I lucked out in that regard, I had the road to myself, at least in the direction I was traveling.

I followed the same procedure I did when I last changed the XJ6 brakes, which seems to have worked well there. The general idea: get a lot of heat into the brakes quickly, and then let them slowly cool off. This will drive out oily contaminants that the cleaning of the new components didn’t catch, and temper the discs at the same time to help them resist warping in the future.

To do this, you gently motor to a safe place where you can take the car repeatedly up to 60mph and then brake as hard as you can without locking the brakes. I did this eight or nine times–I think the last article I read on the topic recommended five to ten hard stops. You’re then supposed to drive the car with minimal use of the brakes (if possible) at a decent clip for 20 to 30 minutes, to allow the brakes to cool slowly (the slight drag of the pads as you drive, and the small amount of braking you’ll undoubtedly have to do, allow the discs to cool down more slowly than they would if you just parked the car after the hard stops). Once done with that, let the car sit overnight, to completely chill the components out, and you should be golden.

Discs look OK after their first drive.

They say if you can avoid heavy use of the brakes for a couple hundred miles after bedding them in, that would be best, but it’s not essential.

1 Comment

  1. WHOA!!! I had no idea so much was involved replacing breaks!!!

    As the new owner this is incredible! I am adopting you as my new Mechanic haha

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