Throw-away fasteners! What's the deal?

[torqueman2002]

I know about the torque-to-yield head bolts, conn-rod bolts, and bearing cap bolts.

But, brake caliper bracket to knuckle bolts?!

I'm replacing the rear brakes on a 2016 Buick Encore AWD. Checking the AllData service information for torque specs., it specifies: "Install new brake caliper bracket bolts ....".

OK, I will follow the book, I am a retired GM service engineer, after all.    Ahem...

I dutifully order the needed bits 'n pieces (I'm liking the loaded calipers these days, easier and faster). Time to get the job going, and I find I received caliper bracket bolts for the front, not the rear. My fault. 

I want to get the job done, so I call the local Buick dealer - parts guy says he'll have to order them, he's never sold any!?

So, what am I going to do?

I'll clean up the old bolts and use them until the Amazon order arrives next week.

I'll reach out to a Powertrain calibrator I know, to see if he can ask a brake engineer.

But why? Are these bolts stretched beyond their normal usable range after installing?

Any ideas?

[Matt_T]

I doubt stretch is the issue with caliper bracket bolts. Maybe the bolts have a pre-applied threadlocker? That'd be a reason for the book to require replacement.

[goodfellow]

I doubt stretch is the issue with caliper bracket bolts. Maybe the bolts have a pre-applied threadlocker? That'd be a reason for the book to require replacement.

Agreed -- they have the special goo on them, and that's what GM wants you to use. For my own vehicles, I reuse caliper bracket and caliper pin bolts and apply blue thread locker. Haven't had issues yet.

[bonneyman]

I doubt stretch is the issue with caliper bracket bolts. Maybe the bolts have a pre-applied threadlocker? That'd be a reason for the book to require replacement.

Agreed -- they have the special goo on them, and that's what GM wants you to use. For my own vehicles, I reuse caliper bracket and caliper pin bolts and apply blue thread locker. Haven't had issues yet.

Yeah, but if Car Shield finds out about it they'll cancel your warranty! 

[torqueman2002]

Thanks guys.

It never occurred to me it was the 'special secret sauce'!

Heck, I've got both kinds of blue thread-locker, liquid and chap-stick.

I just came in from putting it back together with the blue chap-stick and saw your posts.

Guess all it needs is to have Mrs. Torqueman help bleed the brakes.

Oh, I was able to cancel the Amazon order for the new bolts with GM's 'special secret sauce'. 

[goodfellow]

Good going TM -- a "honey do" list that is completed going into the weekend is a plus 

I always wondered about that blue/gray GM thread locker compound. It is tough stuff and on Mrs GFs Traverse, even when using a 1/2" impact with a swivel impact socket, those caliper bracket bolts were exceedingly stubborn. I initially had to use a long 3/4" drive breaker bar to crack them loose. The thread locker held on tight right up to the very last few threads before the bolts could be even turned by hand.

[stokester]

I doubt stretch is the issue with caliper bracket bolts. Maybe the bolts have a pre-applied threadlocker? That'd be a reason for the book to require replacement.

Agreed -- they have the special goo on them, and that's what GM wants you to use. For my own vehicles, I reuse caliper bracket and caliper pin bolts and apply blue thread locker. Haven't had issues yet.

True.
While working at the Chevy shop there were some fasteners that were to be replaced such as those bracket bolts.  These replacements did have the thread locker on them and if GM Service Information said to replace them I did while other models directed using AC/DELCO thread locker on the original bolts after cleaning the threads.  Because the locker on the replacement bolts is dry I always wondered if it had something to do with the torque value required.  I'm sure the assembly line has a pile of the bolts with the dry thread locker and the torque value was determined based on that.

I always use blue thread locker on bracket bolts and torque to specs.

[walrus]

I've never used thread locker on those bracket bolts. Just crank them and walk away. But I'm doing my own vehicles so....

[slip knot]

I've never used thread locker on those bracket bolts. Just crank them and walk away. But I'm doing my own vehicles so....

Same here. A lot of things were never on my radar for thread locker use. I lube them but not thread locker