2003 sequoia brake caliper bolts falling out

[hikermike]

This has happened 3 times on different wheels. They were tightened up before this last time my son accused me of being negligent and forgetting and to wimpy to tighten. (I'm 78)
So he did it so we both witnessed him doing it. It's been 2 months, we're driving back from seattle and it sounds like bare pads scrapping the rotor. Got home and pulled the wheel and the caliper was loose and both bolts missing. Anybody else have this problem? There are no washers on the bolts. (Any of them..never has been) I've changed the rotors many times. (474.000 miles on the car) The dealer had the bolts and the part diagram showed what could be a washer but there was no number and the parts catalog showed no such part for the washer. Therefore, there was no washer in stock and he said I could find the part at any parts dealer. My local any parts dealer found the same situation. the catalog showed no washer.
any thoughts on this? Could the caliper metal be work hardened so the bolt can't snug up? I doubt this as the new bolts seemed to be a little soft and screwed in like they were 'seizing" as they went in. (i.e., they went in with slowly increasing resistance over many turns, not just srew in quickly with only a quarter turn to torque them.)

 

[Malleus]

It's been a long time since I had a Sequoia, but I think there is supposed to be a washer there - try 90201-12452. I can't imagine that's the problem, but if you don't have them, may as well get them. Any dealer should have them, they've been in use for 50 years, on almost every Toyota.

These are the caliper to hub mounting bolts, not the caliper to torque arm bolts, which are the ones you are supposed to use to replace the pads.

FWIW, the service manual says these mounting bolts are not reusable; I never do, but I'm the only person I know who doesn't. Torque is 73-lb·ft (front) and 70-lb·ft (rear).

 

[Dindu Nuffin]

Or

 

[hikermike]

thank you all for the suggestions!

 

[Jgrauman]

Technically caliper bolts are one time use according to Toyota. Usually higher torque specs stretch the bolt to a place they can't recover. Get some new ones and use some thread locker