(Update!) Caliper bolts missing!

[drno4]

Edited 11/11/23:

Checked the bolts again the other day. Top bolt loose. Bottom bolt tight as all get out. I had just tightened them both equally 10 days ago.

My theory is that one of the two caliper pistons was fully or partially seized, therefore putting uneven pressure on the rotor, which in turn caused the bolts to get out of torque. 20-year-old original calipers, showing some rust. Upon further inspection, that left rear rotor had warped slightly, possibly also due to uneven caliper pressure over time.

Solution: new rear rotors, calipers, and pads (on both sides), and a brake fluid change--all installed last night. Also installed new parking brake shoes and hardware while I was at it, which has made our parking brake functional again! Winning!

(original post and thread now follows, below)

+++++++

Hey all,

2003 Yukon Denali XL. 198K.

Heard a scratching/rubbing noise from the left rear wheel today.

Got home, removed the wheel to inspect. Got ready to remove the brake caliper and bracket, to inspect further. Then I noticed the two smaller bolts that tie together the caliper bracket and caliper WERE MISSING! Gone. Not just loose...they were not THERE. (All bolts on the right side were in place as usual.)

Went to Lowe's and got two M-8 1.25 25mm bolts to replace the missing parts.

Last time I worked on those brakes was one year ago. Zero problems since then. I have NEVER had this happen to any of our vehicles before.

I will likely never know what caused the bolts to disappear...but I am curious to hear your theories.

 

[OR VietVet]

Since both were gone and I am assuming, I hate to do that, that you were the last to have the wheel off and touched those brakes, you did not tighten the same as the other side. I used to teach my techs in the shops I ran, that when hand starting a bolt or nut, do not tighten them down all the way by hand. Leave them started but loose. That way you were least likely to glance and assume you already tightened. In this case, both are gone and you may not have tightened as good as you should. Depending on the amount of miles driven since you last were in there, it takes time for a loose bolt to unthread and fall out.

Again, this is just a guess.

 

[drno4]

Since both were gone and I am assuming, I hate to do that, that you were the last to have the wheel off and touched those brakes, you did not tighten the same as the other side. I used to teach my techs in the shops I ran, that when hand starting a bolt or nut, do not tighten them down all the way by hand. Leave them started but loose. That way you were least likely to glance and assume you already tightened. In this case, both are gone and you may not have tightened as good as you should. Depending on the amount of miles driven since you last were in there, it takes time for a loose bolt to unthread and fall out.

Again, this is just a guess.

Thanks, my friend. I take zero offense at the assumption; it is the most likely explanation. I did those brakes 7,000+ miles (12 full months) ago, and have never had this happen before on any of our vehicles. I torque my stuff to spec religiously; but I suppose it could have been a lapse of attentiveness on my part. If so, I am shocked it has taken this long for them to drop out entirely (or at least for me to notice). That said, I'm glad I heard the noise today and checked!

 

[OR VietVet]

Thanks, my friend. I take zero offense at the assumption; it is the most likely explanation. I did those brakes 7,000+ miles (12 full months) ago, and have never had this happen before on any of our vehicles. I torque my stuff to spec religiously; but I suppose it could have been a lapse of attentiveness on my part. If so, I am shocked it has taken this long for them to drop out entirely (or at least for me to notice). That said, I'm glad I heard the noise today and checked!

I should have said this earlier as well. You may have only done it to one bolt and when the other is doing the work for two, it loosened. Could have fallen out at way different times. I would also check the female bore where those bolts thread in to.

 

[drno4]

I should have said this earlier as well. You may have only done it to one bolt and when the other is doing the work for two, it loosened. Could have fallen out at way different times. I would also check the female bore where those bolts thread in to.

Thank you. The replacement bolts I installed tonight went in and grabbed as they should, so I don't have any concerns with the female bores. I appreciate you and your helpful input!

 

[rockola1971]

Wondering who the OP pi$$ed off. Didnt just recently get new or increased life inurance? Does the wife know?

 

[tom3]

Wondering who the OP pi$$ed off. Didnt just recently get new or increased life inurance? Does the wife know?

And probably with a rear caliper off the Em Brake is probably not working either.

 

[nonickatall]

Hey all,

2003 Yukon Denali XL. 198K.

Heard a scratching/rubbing noise from the left rear wheel today.

Got home, removed the wheel to inspect. Got ready to remove the brake caliper and bracket, to inspect further. Then I noticed the two smaller bolts that tie together the caliper bracket and caliper WERE MISSING! Gone. Not just loose...they were not THERE. (All bolts on the right side were in place as usual.)

Went to Lowe's and got two M-8 1.25 25mm bolts to replace the missing parts.

Last time I worked on those brakes was one year ago. Zero problems since then. I have NEVER had this happen to any of our vehicles before.

I will likely never know what caused the bolts to disappear...but I am curious to hear your theories.

It always takes greatness to recognize your own mistakes and stand by them.

I consider myself a relatively good mechanic, but I also forgot to tighten a tie rod on my wife's 7 Series BMW. I still loved her back then and she didn't have life insurance yet.

And after 20 km, while parking, the tie rod came loose. Luckily nothing happened.

Since then, I have always completed work steps and never interrupted them.
I collect screws as I work in boxes after work step, so that I can see if a screw is left over.
I also always tighten relevant screws twice, such as those on the axle, brakes and wheels, if I'm not already using the torque wrench.
And I keep going over everything in my head twice, to make sure i forgot nothing.

Except at the car on my wife. I allways have to force myself tieying the bolts correct...

 

[drno4]

Since both were gone and I am assuming, I hate to do that, that you were the last to have the wheel off and touched those brakes, you did not tighten the same as the other side. I used to teach my techs in the shops I ran, that when hand starting a bolt or nut, do not tighten them down all the way by hand. Leave them started but loose. That way you were least likely to glance and assume you already tightened. In this case, both are gone and you may not have tightened as good as you should. Depending on the amount of miles driven since you last were in there, it takes time for a loose bolt to unthread and fall out.

Again, this is just a guess.

VietVet, see my updated first post. (Thoughts?)

Thank you also for serving (presumably, given your screen name). I have two uncles who also went to Vietnam. ❤

 

[OR VietVet]

VietVet, see my updated first post. (Thoughts?)

Thank you also for serving (presumably, given your screen name). I have two uncles who also went to Vietnam. ❤

I read it and agree that it could be a culprit. I have seen many many many many times were there was a seized caliper and warped rotors and still the bolts were not loose. I would keep checking because there may be a problem with the female hole the bolt goes in to.