Thought this might help someone who's never done these before.
Ok now a disclaimer first of all; I am not a qualified mechanic and any advice offered here is to be taken at your own discretion. I will hold no liability or responsibility for what might happen if you choose to follow the following set of procedures.
Like I said, I'm not a mechanic but I feel that I have enough experience of this sort of thing to do my own, and have done on every vehicle I've ever owned. The brakes on the 2.5 TDi T4 which I am basing this on are as easy as any other vehicle's braking system. BUT
if in doubt get a qualified mechanic to do it.
First the fronts:
Lift the bonnet and unscrew the brake fluid reservoire lid, but leave it loosely on top of the reservoire (it helps to keep any dirt from dropping in).
Start by making sure that the handbrake is on then jacking the front of the van up til the wheel is not quite off the ground, loosen all of the wheel bolts a half turn (or there abouts) now continue to jack the van up til the wheel is clear of the floor, remove the wheel bolts and remove the wheel. This is what you see...
This is the front brake caliper and disc.
Start by prying the spring clip from the caliper,
put it somewhere safe.
Look at the rear of the caliper and identify the two 21mm bolts that hold the caliper in place;
remove these. For this, it is likely that you'll need a good impact type socket and a breaker bar or length of scaffold pole. Oh, and some strength.
With these bolts removed, you can now start to work the caliper (complete with old pads) free of the disc, this sometimes results in swearing and grazed knuckles.
Once the claiper is free from the disc be careful not to twist, kink, bend, or stretch the rubber hydraulic hoses as if these rupture you'll be stuffed.
I place mine on top of a large plastic box placed inside the wheel arch.
Remove the slider side pad by simply pushing it towards the piston side pad, this will push it out of its locating grooves.
With the slider side pad removed you can now remove the piston side pad, which is held onto the piston by spring clips which clip inside the piston. This usually needs to be pryed away with a screwdriver (be careful not to pinch the rubber dust seal).
Take your wind back tool if you have one and locate the end onto the piston screw the barrel part into position then place the plate into the locating groove and tighten it up.
This is a pic of the tool being used on the rear caliper but it works the same way on the front...
Give the tool a half turn at a time to allow the fluid in the system to settle (this lessens the risk of pushing fluid past the seals).
If you don't have a wind back tool a G clamp can be used with some care for the front calipers (not the rears though).
Once you have pushed the piston back far enough (pretty much all the way if you're renewing the pads) get your new pads and remove the anti squeal shims and put a coat of copper-slip on the BACK
side of the pad, replace the shim then put another coat of copper slip on the outside of the shim. DO NOT GET ANY ON THE FRICTION SURFACE OF THE PAD
as this will stop your brakes working.
Hold your caliper and look at the rear side of it, if the slide is extended.. like this...
push it back in so it's like this...
now replace the new piston side pad and make sure that it's pushed fully into the piston so that the spring clips hold it there.
Now replace the new slider side pad.
You're now ready to replace the caliper with new pads back over the disc and replace the two 21mm bolts (put a dab of copper slip on the ends of the bolts too).
Once the bolts are done up tight (sorry don't know the correct torque setting) but make sure they're proper tight!!
Now replace the spring clip, line it up and just push it in the centre and ...ping!
Check you've tightened everything. Stick your foot on the brake pedal a couple of times till it firms up, check your brake fluid level, top up if necessary.
Put the wheel back on and do the other side..
Now the rears...
Jack up and support the rear of the van and remove the wheel in the same way as the fronts. This time though it is essential to make sure you have chocked the front wheels and that you're working on level ground as you are going to be working without the handbrake on. It's also a good idea to put the van in gear.
Take the handbrake off.
This is what you see with the wheel removed...
Look at the back of the caliper and locate these two 13mm bolts
Just behind these there are two nuts which are attached to the rubber boot things, hold this nut still with an open ended 15mm spanner and undo the 13mm bolt and remove, repeat for the other one.
Once you have these removed remove the handbrake cable end by levering out of its locator..
This should allow the caliper assembly to pull out (rearwards) leaving the old pads in the retainer on the disc.
Again be careful here not to twist, kink, bend or stretch those hydraulic hoses, do not leave the caliper hanging on the hoses; NOT GOOD!!!
If the caliper doesn't want to move from the disc, loosen the top 18mm bolt a turn or two.
To do this you will need a good 18mm 1/2" drive socket, a breaker bar, a scaffold pole and some biceps.
With this bolt loosened it should give enough to wriggle the caliper out.
Pull the old pads off the retaining clips. Get your new pads and coat the backs and shims with copper slip as per the fronts, being very careful not to get any on the friction surface of the pads or the disc.
Take the windback tool and put it together as before...
and wind the piston in as before, half a turn at a time until it's fully retracted.
Now locate the new pads into the springy locating clips (on the pad retainer part of the caliper, still attached by the disc) so that the friction side is against the disc (obviously? read what happened last time I replaced mine in the dark), don't expect these springy clips to hold the pads there; you'll need to keep a couple of fingers there as well for a minute.
Start to push the caliper over the pads until it is in position.
Now do the 18mm top caliper bolt up nice and tight.
Now locate the bottom 13mm bolt first, you'll need to pull the caliper up a bit to get this lined up, again holding the 15mm nut still with the open ended spanner, do it half up then replace the top 13mm bolt in the same way. Now fully tighten both bolts and recheck the 18mm one at the back of the caliper.
Once this is done replace the handbrake cable in the locator on the lever arm.
Go to the cab and press the foot brake a couple of times til it firms up, then as before check the brake fluid level and top up if necessary.
Replace the wheel and do the other side.
Hope this has been of some help to someone, it's not a big job and I've got it down to about 20 minutes a corner now.
Any questions please ask or if you feel I've left anything out please add.
Oh, Copper slip rules!!! If your pads come with a sachet of nice blue gluey stuff, chuck it and use the old copper slip instead. No more squeally brakes. Hoorah!