Unsticking Stuck Caliper Bolts

[MSW]

Since many probably didn't see it in the brake pad thread, I'll embarrass myself by asking the question again here.

I'm trying to change the front brake pads on my 2005 Baggie for the first time since the bike rolled off the showroom floor (6 years, for the math-challenged). I knew the bolts would be stuck but good, but these haven't budged a millimeter. I've soaked both the heads and ends of the bolts overnight with penetrating fluid, but no luck. I even rounded off one of the small inner bolts (predictably), and when I drilled it and tried to remove it with the screw extractor, the screw extractor broke off in the bolt.

Anyway, I'm really worried about damaging a part that can't easily be replaced, so I haven't tried anything further. My first thought was heating the bolts with a propane torch, which works on things like the sprocket bolts, but I don't want to warp anything (or ruin the finish on the caliper, if I can help it).

Any brilliant ideas? Have I missed something horrible, like "you idiot, those are reverse-threaded screws!" I'm feeling as stuck as one of these bolts.

Thanks in advance for any insight/advice/magic tricks you want to share.

[Bill Jurgenson]

the only cure for a Grimeca caliper is the waste bin.

[Bill Jurgenson]

the only cure for a Grimeca caliper is the waste bin.

[Old Dog]

Bill is right, get a brembo. Skorpion (could be the same for baghira) uses the one off the Mito - relatively cheap on ebay. Total transformation, gone is the on off switch and hello to responsive brakes.

[edfmaniac]

Try using a float punch that will fit inside the hex socket and a decent sized mallet to tap on the bolts before trying to back them out. This process works miracles on stubborn threads. Don't break anything off by using too much force. A lot of lighter strikes will still get the job done. If you want a cool tool, they also make a device that combines this striking action with the twisting action of a wrench. I forget what they are called but you set the direction, like a ratchet, and when you hit it with a mallet, it gives a slight twist. Good luck.

[MSW]

Thanks for the suggestions, guys.

Bill and Old Dog, I would love to put anything other than the crap Grimeca caliper on the Baggie, but as far as I know, there is no convenient replacement part. I seem to recall a couple of guys across the pond getting an older model VFR caliper to work, but I think even that required a modification to the bracket. If that's the case, I might as well go for a Brembo and have a custom bracket made up.

edfmaniac, I think what you're describing is an impact driver. I actually have one of those (I'm no stranger to rounding off bolts and screws!). I did try tapping the bolts with a center punch, but I was hesitant to try the impact driver. If all else fails, though, I'll give that a shot.

I also thought about heating up the whole unit in an oven that I use just for automotive purposes (curing painted parts, etc.). I imagine that the rubber seals inside the caliper are designed to withstand at least a couple hundred degrees, wouldn't you think?

Thanks again for the input!