Rob
Well-Known Member
Lets start with a bit of brake history on my truck. About 30k miles ago when I bought it the brakes were average and after driving enthusiastically between several roundabouts I managed to warp the front discs. I later found out that I had one rear seized calliper and the front callipers weren't in great shape either. So I rebuilt all the callipers (my maintenance skills have improved significantly since then so the job might not of been to an "acceptable" standard) and I do remember that some of the pistons on the front had some rust and possibly one a tiny amount of chrome pitting. I did not replace the discs or the pistons just cleaned them up as I was a skint student back then.
Under a long period of moderate braking or brief periods of heavy braking I feel the obvious signs of warped discs (vibration through the steering and pedal). From what I have been told there are 2 conditions where you get warped disc symptoms:
1) The discs are temporarily deformed as one side is heated more than the other due to uneven brake load from the pads.
2) The discs are permanently warped due to uneven brake load from the pads. You generally feel this even under light braking.
Generally condition one leads onto condition 2 if the cause is not addressed. Since the time when I first experienced brake warping I only get symptoms once the brakes get hot which leads me to believe that it's condition 1. As I am doing another major front axle rebuild I have finally decided to sort the front brakes. So I started with measuring disc thickness, runout and pad thickness:
Front left disc thickness: 31.8mm
Front left disc runout: 0.12mm
Front left pad thicknesses: 2.3mm and 3.9mm
Front right disc thickness: 30.9mm
Front right disc runout: 0.13mm
Front right pad thicknesses: 1.1mm and 2.6mm
Front disc thickness spec: 30-32mm
Front disc runout spec: 0.15mm max
Front pad spec: 10-4mm
Now I am a little unsure as to what I should do The disc runout is in just in spec and they are plenty thick enough.There seems to be a large variance in pad thicknesses after 20-25k miles of use. Also it seems the the right side is doing more work than the left side. Should I rebuild the callipers again? Should I change the discs even though they are in spec? Before you comment yes I will change the pads.
Under a long period of moderate braking or brief periods of heavy braking I feel the obvious signs of warped discs (vibration through the steering and pedal). From what I have been told there are 2 conditions where you get warped disc symptoms:
1) The discs are temporarily deformed as one side is heated more than the other due to uneven brake load from the pads.
2) The discs are permanently warped due to uneven brake load from the pads. You generally feel this even under light braking.
Generally condition one leads onto condition 2 if the cause is not addressed. Since the time when I first experienced brake warping I only get symptoms once the brakes get hot which leads me to believe that it's condition 1. As I am doing another major front axle rebuild I have finally decided to sort the front brakes. So I started with measuring disc thickness, runout and pad thickness:
Front left disc thickness: 31.8mm
Front left disc runout: 0.12mm
Front left pad thicknesses: 2.3mm and 3.9mm
Front right disc thickness: 30.9mm
Front right disc runout: 0.13mm
Front right pad thicknesses: 1.1mm and 2.6mm
Front disc thickness spec: 30-32mm
Front disc runout spec: 0.15mm max
Front pad spec: 10-4mm
Now I am a little unsure as to what I should do The disc runout is in just in spec and they are plenty thick enough.There seems to be a large variance in pad thicknesses after 20-25k miles of use. Also it seems the the right side is doing more work than the left side. Should I rebuild the callipers again? Should I change the discs even though they are in spec? Before you comment yes I will change the pads.