Steel and aluminum really don't like each other, and in the presence of water start galvanic corrosion. The trick to breaking fasteners loose that may have become "stuck" is to shock them. If you can set the caliper on an anvil or vise, and smack the fastener straight down, into the caliper, you can sometimes fracture the corrosion and break the fastener free. This is how an "impact driver" works, but for your purposes it does NOT have to include the rotational component. A big, hard smack! straight on is enough.

If all else fails, these fasteners are rather soft and placing a drill bit right into the hex socket portion will allow you to easily drill the head off. The larger issue with doing this is finding a replacement metric fastener that is galvanized or DACROMET coated to replace the destroyed one.

I'm currently looking for a coated M8x50 as a replacement myself !! 😛

Good luck.

Thanks for the reply,

Wobbly, with the rebuild kit for these calipers you get two new bolts of the correct size, would that help you in your quest for the bolts you are trying to find?

Drilling the head off would not accomplish much. Both halfs of the caliper... are threaded. If I go the drilling route I will have to go all the way through and try to pick out the remaining pieces.

I have not tried just giving it a good smack, might as well.

Yeah the corrosion on the bolts from the other caliper was severe.

8166, you mention not getting the temp too high to not weaken a part. Which part? The caliper? If it is the bolt (cap screw) then weakening it would be OK prior to drilling, wouldn't it?

Southsound BMW parts says 85 through 95 k75 bikes used the same calipers. They also mentioned they were a discontinued item. Any ideas where to get a caliper or two. It seems there is a right and a left side and I need a right side.

Thanks, Pacific airhead

8166,

Yep, you are correct, a senior moment, only 1/2 of the caliper is threaded. Thanks for the resources.

I used to fly and work on airplanes, had lots of resources for that activity, this is all new. Great website!

Drilling out the cap screws rows worked great, start to finish about 1 hour.

Wobbly, with the rebuild kit for these calipers you get two new bolts of the correct size, would that help you in your quest for the bolts you are trying to find?

'No, but thank you' for several reasons. I'm working on a 1999 model with 4 bolts. Not clear they are the same bolts. The caliper in question needed simple disassembly and cleaning. It's already back on the bike and working. I don't generally use the rebuild kit unless there is leakage.

Drilling the head off would not accomplish much. Both halfs of the caliper... are threaded. If I go the drilling route I will have to go all the way through and try to pick out the remaining pieces.

If the corrosion on the bolts is profuse, then it may appear that way, but I highly doubt both caliper halves use tapped holes for the same bolt. That would not allow the bolt to draw the halves together, which must be the case for the two halves to seal against each other.

Wobbly, you are correct, there is only threads in one half of the caliper.

Drilling off the head of the cap screw made the removal of the screws easier and possible.

I hope that the caliper was not damaged by heating. I guess I will only know after reassembly and it is back on the bike.

Any ideas about how to keep those bolts/screws from getting so corroded? I thought about putting some anti-seize on them and adding a lock washer but have not so far. The bike is a 1992 and those calipers have probably never been apart so if they last that long this time that would be good.

I hope that the caliper was not damaged by heating. I guess I will only know after reassembly and it is back on the bike.

What you got is what you got. I'd use a good sharp flat file, or use the fine sandpaper and glass trick, to check the flatness on the mating surfaces. Then use 400 grit to remove any yellow crusty stuff from the piston bores. Reassemble with new fluid on all the rubber parts, and 2 new plated bolts. You should be OK.

The plating on the bolts is going to be key for the next rebuild in another 10 years. You'll want cadmium, galvanized, or Dacromet as your first choice. Yellow zinc chromate is a fair second. It's a good thing 2 new ones came with your kit, because almost all these can be found under the heading "non-obtainable". 😛

Any ideas about how to keep those bolts/screws from getting so corroded? I thought about putting some anti-seize on them and adding a lock washer but have not so far. The bike is a 1992 and those calipers have probably never been apart so if they last that long this time that would be good.

Aluminum parts hate steel fasteners when an electrolyte (like rain water) is around. I'm not sure exactly how you keep rain water off a road bike. And then you have the DOT 4 fluid begging the water to 'stick around for a while'. That's why I believe Never-Seize is preferable to thread locker in this application. Brembo may have liability issues and therefore must use a thread locker; you do not have that requirement from your legal department. Additionally, anti-seize will improve the quality of any bolt used in that application.

In order to get the 2 halves to seat and seal, you'll want to torque the bolts in stages. For an M8 bolt, 15 ft-lbs works well, if Brembo did not specify any other. The object being even torque for even tightening to allow the 2 faces to remain flat and seal their best.

Hope this helps.

Yes it helps, thank you. Good idea, torque in stages.