What size Allen wrench do you need to change front brakes on 1998 gmc safari?

There's no single Allen wrench size that covers all the bolts on a 1998 GMC Safari's front brakes. You'll likely need multiple sizes. The caliper mounting bolts are usually a larger size (possibly 13mm or 14mm, but *not* an Allen wrench size), while smaller Allen wrenches might be needed for other components within the caliper assembly itself, like bleed screw or caliper pin bolts. These smaller Allen wrenches could be sizes like 7mm, 8mm, or 10mm.

It's crucial to consult a repair manual specific to your 1998 GMC Safari. This manual will show you exactly which fasteners are involved and the correct size for each. Trying to guess could lead to stripped bolts, and damaged parts.

Instead of using Allen wrenches for caliper bolts (if they are indeed a larger size like 13mm or 14mm), you should be using the correct sized socket wrench. Using an improperly sized or damaged wrench can easily round off the bolt heads.