Help...Missing Bolt for Dual piston Brakes

[Lawfree]

I recently did a complete rebuild of the front brakes and suspension on my 80" Cutlass Calais. One of the two 18mm SFI flanged head bolts came loose and was lost. This caused the caliper to "lift" and I now have @ 1/2" more backspace on a brand new A/R wheel! The Head of the bolt is marked SFI 10.9; it has an 18mm flanged hex head, is @ 14mm in dia X 40mm long and has fine threads. I have not been able to source a replacement anywhere, and local dealer is useless without a part number. If any member can come up with a P/N or source it would be greatly appreciated.
note: This is what GM considers a "critical" application fastener and the replacements for the newer vehicle come with
some type of white thread lock already on the threads. It is supposed to be reusable too. No torque was listed because the thread lock was "supposed" to hold it. Both the the bolt,& threads were cleaned prior to torqing to @ 40 ft./lbs and I still lost this bolt, the other was about to fall out and I about wrecked my car . I found two other of the same bolts loose. In the future I plan to "remove" the factory thread lock material and use something good like locktite.

 

[DSM]

thread lock compound will not hold a bolt that isn't properly torqued to start with, and at 40 ft-lbs you weren't even close. That bolt should be 81 ft-lbs, per the factory service manual. Even that strikes me as low, since an M14 grade 10.9 bolt doesn't develop 75% max clamp load until 140 ft-lbs. GM uses these same bolts on just about all the dual piston caliper applications (lengths vary by application). For example, on the Camaro they are torqued to 135 ft-lbs and on the C4 and C5 Vettes, 160 ft-lbs.

The Chevy dealer is the best place to get replacements. If your dealer can't help, find a different dealer. Any GM dealer should be able to look it up. Giving them a VIN sometimes helps....I pulled this one at random off the internet 1GNCS18W32K176268 for a 2002 S-10 Blazer, 2WD, 2-door. They all had the dual piston front brakes and with that info, the dealer should be able to easily look up the caliper mounting bolt. I don't have a part number, but as I recall they are about $4 each (its been a while since I bought some). I'm using these exact same S-10 bolts on my third gen Camaro which has been converted to C5 Vette brakes because the C5 bolts weren't long enough to reach through the adapter brackets to the caliper. I torque mine to 135 ft-lbs.

DO NOT remove the factory threadlock compound (there is no good reason to do so). DO torque to 80-100 ft-lbs! You shouldn't have any issues. If you ever take it back apart later, then you can clean off the residue of the factory locking compound and use Loctite Blue (medium strength) on the clean threads.

Hope this helps.
Don