Replacing Brake Pads Mercedes Sprinter
The replacement of disc brake pads on the Sprinter whether front or back is a straight forward operation and can be completed quite quickly.
For the purpose of this posting I will outline the replacement of the rear brake pads. Front pad replacement is by much the same method and does not require a separate write-up as the procedure is more or less identical.
First chock the wheel on the opposite side to prevent the vehicle moving when the handbrake is released later in the operation. Then slacken and remove the wheel bolts, if these are tight and cannot be easily removed see this previous posting. Once removed the road wheel can be taken off and work may begin.
Identify and retrieve the two black plastic bungs that cover the removable caliper slide pins, using a 7mm hexagon key unscrew both slide pins and lay them safely out of the way. Due to the operating environment the slides are sometimes quite tight and may need a sharp tap in the right direction with a copper hammer.
Lever a screwdriver between the central hub applying pressure to the caliper leaf spring allowing it to be dislplaced from the two holes in the body, remove this item and store safely.
Using a stout screwdriver, small lever or pry-bar, lever the brake pads away from the disc by a few millimetres. This should allow you to slide off/out the central part of the caliper casting containing the piston away from the fixed hanger bracket and then lie it out of the way, ensuring not to stress the brake hose or electrical cable to the pad wear indicator that will in some cases be attached to it.
Remove the old pads, there is a spring clip that inserts into the caliper piston to locate it, the outer pad is not held by any other mechanism. Both pads are located onto the fixed hanger bracket in machined slots that accept the shaped ears on each end of the pad. Once these are removed wire brush the hanger and clean the rust from the slides. Wire brush the other part of the caliper and remove any scale or debris that could foul the new pads.
Next attach a 17mm spanner to the hub with a wheel bolt and add one other to lever against. Carefully release the handbrake (make sure you chock at least one of the wheels not been worked on) Strike the edge of the disk with a soft copper hammer as you rotate the disc using the spanner. This will break away the scale that forms on the edge of the disc, do this all around the edge. Place the edge of a file between the fixed hanger and disc then run the hub round by hand and clean off the scale both on the outer edge and lip of the disc. Brush down the area to remove all debris.
It is a good idea while the disc is nice and clean to measure its thickness to make sure it is above the specified wear limit. (Min Thickness on Mk1 Sprinter Rear Disc 14mm) This is best done using a Micrometer or Vernier Caliper. If worn below specification, replace the disc/hub assembly at your earliest convenience. It is also worth a brief mention that if your brake disc has a raised lip at its edge that cannot easily be removed can either be reduced with a die grinder or file. If some raised area remains, some pad manufacturers recommend that on fitment you file a small chamfer on the outer and inner edges of the pad friction material to aid bedding in in these circumstances.
Use a G clamp or push-back tool to compress the brake piston back into the casting. I have always found it beneficial when doing this to lift the dust boot slightly and give a quick blast of WD40 or similar to assist the free movement of the piston back into the caliper. Once this is done you can proceed.
Check the new pads fit freely into the hanger and that they can move within the slides both in and out. If not check for rust scale remaining on the slides and clear it away. If the slides are clean and there is still binding of the new pads, check for paint build up on the face edges of the pad ears. Clean this off lightly with a file and retry. Once satisfied of a good fit, use copper grease to coat the edges of the ears of both pads, apply some copper grease to the piston face where it touches the pad and also a smear the prongs of the spring clip that fits inside the piston. Insert the inboard piston pad and clip it into place, locate the outboard pad into the hanger and slot it into place. Smear copper grease on the two areas of the outboard pad that contact with the casting then slide the two parts, caliper and hanger together.
Take the two slide pins removed earlier and clean them of any dirt or coating of grime. The caliper slides dividing braking force between the two pads on either side of the disc. Any debris could prevent easy movement and imbalanced or sticking braking. Lightly use a file if necessary, but be aware these are chrome plated and it is nice to keep this coating for its anti-corrosion properties.
Re-fix the pins after giving them a liberal coating of copper grease (Marine grade grease is a good alternative); it is sometimes beneficial to also apply a little grease to the female part of the slide before reassembly.
Once the slides are in place and retightened, refit the plastic plugs to the slide housings and replace the caliper tension spring in the same manner in which it was removed, using a screwdriver to lever it against the hub centre.
From the cab apply gentle pressure to the brake pedal and by moving the pedal in 50mm strokes pump back the pads to contact the brake disc. Check the operation of the disc brake and be sure it is not binding.
After a final check all is well, wire brush the hub centre and wheel centre, smearing a coating of copper grease on the contact areas, this will prevent the wheel from sticking/rusting to the hub centre due to corrosion making the whole disassembly much easier in the future and prevent embarrassment at the roadside if the wheel could not be removed in an emergency.
Wire brush the wheel bolt threads and refit. There are several schools of thought around wheel bolt lubrication. The factory will say no to any oil or grease – as it affects the bolt torque when tightening them to the correct level. I am personally an advocate of a fine coating of engine oil to ease the future removal of the wheel bolt, also a little rag wipe of oil applied to the dome of the nut that bears onto the wheel itself. Make up your own mind on this one, but I will continue to do what I have done for the last 35 years without issue!
Replace the other pads and you are good to go. Be aware that it will take a few miles for the pads to bed –in and braking during this time may feel a little spongy and require increased pedal effort to stop. As time progresses the pedal feel will begin to harden and normal braking will resume.