HELP Caliper bolt fell out
 

Last night i was driving normallly and my lower caliper Frame mounting bolt on the passenger rear wheel fell out lodging the caliper against my wheels and gouging a nice groove in my new set of Volks.
Anyway I turned the rotors two weekes ago and im sure I tightened the bolts to the specified 34-49 ft pounds required in the manual on page P-27 for item #11. What the manual doesnt state is wheather or not you're supposed to be using loctite on the threads.

Does anybody know about the loctite that can help me out????

Thanks,
Ken

No locktight requirerd. I bet you did not torque it as I have never had any failures of any type with any brakes on any cars that I owned in my life and I am 62. I have always done my own brakes.

I have owned my FD since June 1992.

it had to of been torqued because I used an impact gun

You never use an impact to torque fasteners that require precision torquing unless the impact is designed strictly for that fastener. And those are normally only found in manufacturing facilities.

Did you check to insure that the threads are not now stipped?

That's your problem.

I agree with Chuck, check the threads. I never use locktite on the caliper bolts. If anything I use anti-seize as the heat cycles on those bolts tend to lock them in place (similar to the exhaust bolts). Not so much in the rear as the fronts.

Yep...tighten by hand and use anti-seize.
No impact gun needed.

I stripped one of those bolts just tightening by hand, by going quick and not using a torque wrench. On my car (1993 R1) the bolts are not really long enough to engage all the threads in the hole - it was as if Mazda picked a bolt size, then added the extra washer without updating the BOM for a longer bolt.

I've since replaced them with a slightly longer bolt, although finding a grade 10 in the right size was a little time consuming.

Thats odd. My bolts seem to bottom out perfectly. I remember once attaching the caliper w/o the rotor and seeing the bolts bottom out flush with the steering knuckle taking up all threads.

thanks for the help guys im gonna tighten by hand this time and use the torque wrench to ensure its torqued properly.

Ken

Keep in mind this is on the rear - do your rear bolts also bottom out?

I was referring to the front calipers. :)

We are waiting for the cause of the failure!

ok i found the cause, and its my fault, i put on a new set of ceramic pads two weeks ago, when i opend the box one didnt have a hole in the backplate for the anti-chatter clip to go into so i drilled one, in addition to that the other pad didnt have any bevels on the leading or trailing edge and i didnt realize it. im sure this caused to much stress on the caliper frame and backed the bolt out until it failed.

It was a VERY dumb and DANGEROUS mistake that i made to drill my own anti-chatter hole in one pad and not even notice the other pad not being beveled, in turn i only scraped up my new wheels, but it could have been much worse. I was taught a very expensive lesson i wont soon forget.

I feel stupid as hell right now

Ken

That doesn't sound right to me.

EBC pads are the only beveled leading/trailing edges of any pads that I ever used.
Something new they recently started. But EBC have the spring holes in them.

Most pads are not beveled and do not cause any problems.

Ditto on Eggie's comment!

well if only green stuff pads are beveled then three of four of the new pads were wrong as only one wasnt beveled

Did you ever figure this out?

I figured it was a combination of not tightening the caliper bolt with a torque wrench, modifing the one pad to except the anti-chatter clip and one pad not being beveled at all. i got it re-assembled yesterday and went for a drive with no advers effects and checked the bolts on both side when i got home to make sure nothing had backed out. I will be keeping a close eye on the brakes and will report anything that happens.

Sounds good. IMO, skipping the torque wrench is the real culprit, but I've been wrong before! :)

"I figured it was a combination of not tightening the caliper bolt with a torque wrench, modifing the one pad to except the anti-chatter clip and one pad not being beveled at all"

Your problem was not that you did not torque the bolts, the problem was that the bolts were not tight enough. The part about it not being beveled and the clip, would not cause the bolt to back out. One of the hardest thing to learn is how tight a bolt should be. Use a torque wrench in the begging to learn how tight certain bolts should be. Torque wrenchs do require maintance, they do need to be recalibarated.

There is noting wrong with using an impact gun on the brakes, i do it at work all the time. And so do all the other auto mechanics.