jlucas

Swapping rotors and pads today for the first time on the Z in prep for MidO next weekend. Now the shop manual says to replace the caliper bracket mounting bolts. On other cars I've owned there have been similar statements about various hardware pieces but rarely does anyone replace them.

Being new to Corvettes, I thought I'd double check and ask you guys. Any reason to change the hardware? any reason to put on some threadlocker? (if so, what type) I've got seperate rotors for street and track so I'll be in there frequently for the swaps.

Lancer033

never replaced mine, they've been off the car more than a dozen time now. just clean them up with a wire brush and put new locktite on

Falcon

Yep, Lancer does what I do. Wire brush the old caliper bracket bolts, put on some blue loctite and you're good to go.

0Randy@DRM

Once a year you guys should replace them or about 6 sets of pads. They are cheap and if one broke, good bye.

Randy

jlucas

So is everyone putting loctite on them? Temp range on blue loctite is only 300 deg.

Falcon

But if you use red, you might never get it loose.

Randy, that's good advice. I'll put new ones on the next time I change rotors.

StArrow68

Just for info, the bolts they sell have red on the ends, is that meaningful?

ErnieN85

Yes that is the high temp stuff!
Means they are harder to get off!

A whole lot of people seem to have trouble getting bolts out with blue (heat to about 500 to remove)

The red supposedly needs even higher temps to breakdown.

Myself i have never had trouble getting them out (probably next time now)

ghoffman

I know this sounds like blasphemy, but I do not ever use Locktite on anything, ever, and especially not on high temp systems, and since heat is how you loosen it so what's the point on a brake?
When I started at TRW in the Space vehicle biz, we had an issue with screws backing out on a big booster rocket called the IUS (Inertial Upper Stage). Being the new guy, I got the task of figuring out a solution. FYI, in Mechanical Engineering school, they typically never spend much time on threaded fasteners, it is considered so mundane. Well, to make a long story short, after that study, the screws never backed out again, and they do not ever use Locktite or split "lockwashers" or nuts that are crushed on the end. The error that is most common is when using a "locking" nut such as a Nyloc or smashed nut, the proper torque is the specified value over and above the running torque necessary to overcome the friction of the nut. Otherwise, the running torque detracts from the proper value and the fastener is in fact, under preloaded.
What did work and is always is reliable is to get the fastener properly preloaded. To do this, the threads and the area under the head must be clean, and free of burrs, and if possible, use a thick flat washer for the torque to be accurate.
If you do use Locktite, it is essential that you clean out the old crap in the threads in both the male and female threads, so that the torque is accurate. I am not saying not to use it, I am just saying what I do.

ErnieN85

I have found the same. and very rarely use it (do have it)
when I was building aircraft engines we did use safety wire. But that is a whole different kettle of fish!

Rx7Rob

I loctite red EVERYTHING on the dirtbike. I've never had a bolt that couldn't be removed.

The factory brake bracket mounting bolts on our cars don't have loctite, they use Vibratite. You put it on the bolt and let it cure before installation. I get it from McMaster.

I use the Vibratite on the caliper mounting bracket bolts and loctite red on the caliper to slider pin bolts.

Zoli007

I never used any loctite on my M3's caliper bolts and I had those off 10 times if not more. Just get them nice & torqued down & you shouldnt have any problems.

I doubt the M3's mounting hole & bolts were significantly different than the vettes. (havent had the vette's off yet)

Falcon

See. There you go!

You ask a question and you'll get answers! Hopefully, in there somewhere is the answer you can live with. They've given me a whole new thought about Loctite and such.

0ATI Performance

There are two failure modes of a bolt/nut coming loose. The first is simpling losing the original clamping force. This matters more on some bolts (those in tension, like cylinder head bolts), than others (those in double-shear, like some suspension bolts). The second failure is the bolt/nut coming completely out/off, which can lead to disaster.

Good quality (i.e. AN or high-grade) bolts and Nylocs are the best answer. Stay away from stainless steel and cheap hardware store fasteners. There is a reason a Nyloc is a pain to get fully on/off. Loctite Red seems to act similar in that it takes effort to get the fastener all the way off. Without either, the bolt can vibrate out much easier. Hopefully the driver will feel some sort of clunk when the bolt first becomes loose before it falls out.

I also agreee with Gary on making sure that the bolt surfaces are clean and smooth. If your washers bend or get gouged when tightening, they are no good.

Torque specs can also be inaccurate. What matters most is bolt stretch (preload). The actual torque to achieve this will vary depending on the other friction caused by uneven surfaces, rust on threads, previous unremoved threadlocker, etc. A lubricated bolt requires less torque than a dry bolt. Sometimes critical torque specs reflect this.

There is a pretty good book "Nuts, Bolts, and Fasteners" by Carroll Smith that is highly recommended reading (actually the whole series).

Z06 Silver Bullet

I will likely replace mine next time as I never use loctite and change pads way to often

JVetthead

Well.. I have had the bracket bolt fail...
Lucky only moving 20mph or so, RF locked up and would not roll fwd but it would roll backward. Luck again shined as I was only 100yd from my driveway! so backed it around and parked it..
So, the lower bolt had backed out and let the caliper cam-lock into my 18" CCW wheel..Yep I have all the 10# of GM (C5) manuals just hadnt read the brake section yet.
If this were to happen on the highway or the track it could have been really bad news!
Pay attention to the tq values and use locktite on those bracket bolts if you choose not to replace them..

jlucas

I've also heard back from 2 friends who run Nationals in T1
- one said he never loctites - never had one come loose
- one said he always loctites since he actually had it come loose one time without

YMMV I guess.

yellow01

I think mileage actually has a lot to do with it.

What I mean is, for someone who plans to redo the bolt every 6 months or less for a standard pad change loctite and/or some type of insurance for the bolt loosening is a good idea.

For others who regularly undo (replacing every X times understood) you are torquing and checking frequently (for me before and after every track weekend to change pads) the story is a little different. If one of these backs out it isn't going to spinoff, it's going to slowly back out. Checking regularly can avoid issue.

JMHO.