What size allen needed to remove break pads - 2008 Chevrolet Chevrolet Impala LS

Brake pad i them selves are a fairly easy job. However, to do the job correctly the rotters must be turned on a lathe. If you take the rotors off and bring them to a shop then you should change the barrings, the barrings must be packed with grease and reinstalled all this is simple but takes skill. you can also just buy new rotors and then just turn the old ones at your leasure for use in the future.

But that said,
to change the pads you will need a "C" clamp, a screw driver and some break cleaner. open the hood and take the cover off the master break cylinder. if you can remove some of the fluid. as you depress the wheel cylinder fluid will build up in the master cylinder resivware and over flow, you might be able to catch this with rags. Don't let this get on the paint. You may also need a set of allen wrenches. use the allen wrench to remove the two bolts that hold the break assembly in place, with the bolts all the way out remove the assembly by rocking it back and forth. once off remove the pads (pay close attention to any clips and the position of the pads there could be a difference between the inside and out side, left or right). after the pad are off place the "C" clamp over the puck and slowly tighten until it is all the way in, just hand tight, don't crank hard or fast, take your time. this is the easy part. after it is in remove the clamp and install the pads in the revers order mentioned, tighten down the bolts real tight. after all the pads are replaced the brake fluid will look real yucky. and rusty, pump the break peddle and see if you get a good peddle. you should as long as you did not remove the lines. use the break cleaner to clean off any grime or dust on the rotters and pads.

3/8 hex allen wrench is the most common tool to use for chevrolet/saturn/pontiac/buick/gmc

it takes a 9mm hex head for the front!! just to be safe! call an auto parts store to find out if it is allen or torx bit.

You'll need some metric size wrenches. Usually a 13mm and a 15mm or 16mm. Some also use an allen head socket. Auto Zone sells a rack of 5 allen sockets to fit most autos using that set up.

If you purchace an allen key set you will get the exact size , but normally it a metric 8 or 10 mm . And you will have added to your toolbox.

first off, you need to buy the break pads, break caliper spreader, and you need to know if the bolts have a allen wrench head or a torques head, you can find that out by turning your wheel all the way to the left after you remove the front left tire, take a small hand mirror and look on the back side of the calliper, once you know what it is, you need the socket or wrench that fits it, remove the bolts, then the calliper will pull off by wiggleing it off, then remove the outside pad, take the break calliper spreader and place it the way the break pad sat and screw it pushing the calliper cylinder back as far as possible, then take the calliper spreader off and remove the other pad, install the new pads into the break calliper and replace the calliper back onto the router, (the round disc the calliper was on) line up the holes on the calliper and replace the bolts.......once you have put the calliper back on you must pump the peddle untill they are hard again, about 3-6 times or untill you cant go to the floor anymore. once they are solid again, replace your tire and you should be good to go.....................hope this helps.

For a wrench or for the acctual bolt size.
To remove front pads..you need 8mm allen socket to pull the caliper guide pins, then 17 or 18mm..To remove rear pads...you need 13mm socket for lock bolt on guide pins and 15mm open end wrench (thin section to hold guide pin while you remove lock bolts..I ground down a spare wrench). You DO NOT have to remove rear carriers to change rotors..just remove lock screw and angle rotor out. The B5 Passats don't have the electronic parking brake so you don't need VAG Com to change pads.
Installation tips:
Clean and regrease the guide pins with "synthetic caliper grease"
Rear lock bolts come with preapplied thread locker and "are not to be reused"..I just wire brush the threads and use some Loctite Blue on em. I smear just a little antisieze on the inside bore of the rotors and on the lock screw threads to prevent corrosion and make next rotor change ez. Torques:
Front caliper guide pins:18 ft lb
Front carrier bolts: 89 ft lb
Rear guide pin lock bolts:26 ft lb
Wheel lugs: 89 ft lb

If that is the problem...put your allen wrench or socket on the bolt. Then put a CRECENT wrench on that end of your ratchet....you need leverage....trust me, it will break loose.

Yes 7mm allen socket is needed to remove the pins.

no 10mm or 12mm you will also need a ebrake caliper reset tool