Massive brake and wheel failure while driving

[drburke]

"aka my Blazer tried to kill me"

There's no easier way to explain this, so I'll just do it in order. I'll be quick.

Driving 250 miles on the rainy highway yesterday, all is fine. I even had my grandmother driving it for an hour or so earlier in the day. Around 11PM after the rain had just stopped, I finally get to my exit. As I'm getting to the off-ramp, I start slowing from 80 as a normal person would. Around 25-30mph (estimating), my ABS kicked in full swing, sliding me to a stop on the empty ramp. I turn the truck off and wait for a minute, listening to my Braves try and rally from the D-Backs in the 4th. Once back on, I slowly start driving and notice the entire truck is wobbling and hopping, as if your rear driveshaft dropped and only the front had power. I get to the side of the ramp and get out, inspecting the other side.



Blown tire. Great, gotta love Guard Dogs. Whatever, I keep my tools with me. Got the jack, swapped out the spare.


Except the tire didn't blow out. It was fine.



The wheel itself shattered. The factory aluminum GM wheel that we all have.

Well, time to get off the highway. Got the jack, swapped the tires, and onwards ~4 miles down the road to home. Still hopping and wobbling not nearly as bad but enough to go only 35-40 with hazards on. Start hearing some minor clunking, getting louder the further I go. All is good alright until... red light! Press the brakes slightly from far away annnnnd ABS lockup, sliding to a halt again in the middle of the road. So I'm getting into a routine with this thing, with the ABS and my Braves and all. I wait a minute, then proceed on my way. However, the clunking got worse twice-over. So I get over to the side of road and get out. I inspect the tires again, all good. Check the driveshaft... well, that's good. But here's this:



That's my caliper. On the bottom of the wheel. All my wat is out in full force. So yet again, tire off but this time... so is my caliper!





...yeah. So I cleared out the caliper, plugged the brake line, and limped the last mile or so back home. I'm not quite sure WTH just happened. It looks like the caliper dropped, damaging the wheel, right? That's what I thought, but I didn't notice the caliper when I changed the tire the first time (whether it was or wasn't broken at the time, I can't confirm). It's finally daylight out so I'm gonna take a look at it today and look for any clues. I had no warning of this before it happened. I can only imagine what would have happened if it had done this while my grandmother was driving, or if it had done this at highway speeds. I like brakes, it seems this machine does not.

It's not related to offroad or any of the mods, but I wanted to share this with you guys anyway.

[Wahugg]

From the second to last photo, it looks as if the bracket just sheared off.

One thing to look for it to see if both bolts are present that hold the bracket on. I know a few members here have forgotten a bolt or left it loose allowing the caliber to rotate and make contact with the wheel.

-Wahugg

[Cable810]

Dang... Glad you didn't get into an accident!!!

[TBYODA]

[v7guy]

Interesting, glad you're ok.

Got any high quality pics of the break?

Were the bolts still in the axle?

[mattrustable]

It looks like to me, in the second picture with the rim failure, the caliper was already dangling around because I can grooves on the inside of the rim. Maybe the photo just looks that way but it does appear that way IMO. Glad your alright hope you can get it going soon enough

[The Roadie]

Yah, glad you're OK and no major incident. But the scored rim would have been a huge clue to the root cause. Without tire damage, there's no reasonable way other than a rock or caliper to shatter the rim in there.

In private piloting, there's this syndrome known as "get-home-itis" where the last leg of a long trip is the one with more incidents, such as running out of fuel (trying to stretch the range) or pushing through marginal weather (trying to avoid the expense of another overnight stay or getting in to work a day later than planned).

Any chance you had this sort of pressure influencing your decision process? Back when I was flying a lot, I had to consciously decide to land as a precaution and spend the night and pay for a hotel and rental car and miss work the next day, when even my instrument rating wouldn't have gotten me safely home in two situations. One was an unforecast snowstorm track that would have pushed me 40 miles out over the ocean east of NYC to avoid (beyond gliding distance of land while carrying passengers is a violation of my single-engine rules of engagement.), and the other was a short instant of vertigo (in a Cessna with no autopilot) while I was recovering from a head cold trying to get home to Massachusetts from Disney World). If these were at the start of vacation, the decision would have been instant. When I caught myself thinking for more than 30 seconds, I remembered the reading I had done on accident stats and then the decision was easy. I wasn't going to be one of those stats. Land, troubleshoot or wait out the problem, and profit in the long run. Passengers and their preferences don't enter into the equation because they're not the PIC (Pilot in command).

Useful way of thinking on trail rides as well. I blocked a trail for a 20 minutes once, embarrassed and inconveniencing a few Jeeps, but not willing to compromise safety for a horrible repair. They understood, once explained to them, and they dropped the redneck asshat personas they had been harassing me with.

[drburke]

My only reservation to the rim + caliper issue is the fact I didn't notice it when I changed the tire. After I noticed it and removed the tire again, the caliper literally fell on the ground because it was already sheared. Regardless, I still don't know what else would have caused the wheel to shatter except that. I guess it's one of those things I'll never really know because I didn't see it happen.

I'm confused at what you're getting at, Roadie. I drive from Atlanta to Savannah round trip roughly every weekend (500 miles), give or take a weekend or two. It's never had any problems before now. Nothing was out of the ordinary, which seems strange to me.

I still don't understand why my ABS fully locked up on a normal stop-- twice (same night). The only issue I've been having was a code for the rear axle swap, but I've read that's normal.

I repaired it and all is well for now. I'll post up some pics in a little bit.

[Trail X]

I recall someone else having a brake failure somewhat recently (I'm not sure he posted up about it) that was very similar. If I recall, he had one bolt on the caliper fail, which allowed the caliper to rotate up, essentially creating a ratchet effect on the rim. It would lock up in one direction, and be free to rotate in the opposite direction of rotation. It looks like that is what happened when your wheel shattered. One bolt had probably been sheared for a while, and the second one was holding on (looks like the caliper is still in the normal spot in your first photo). It might have looked close enough to correct that it didn't catch your eye at first. The first ABS lockup event was possibly caused by a combination of things, the first being the complete lockup of one tire when the ratchet effect happened with the caliper. The ABS kick probably also gave it enough momentum and power to break into the wheel itself. Its possible that the complete ABS lockup is an effect of the ABS computer being confused by both the complete wheel lockup from the caliper ratchet effect, and the mismatched VSS signals from the stock signal frequency ratio. The second bolt on the caliper probably failed on the second ABS lockup event, when it became the weakest link in the ratchet system, where before it was the aluminum shell of the wheel.

That's my take.

[KE7WOX]

The exact same thing happened to a friend last month, he was driving a BMW E30 of sorts. His was a bolt that backed out, not sheared off and the caliper was free to pivot on the remaining one, same results pretty much, shattered wheel and all.

The wheel looks fairly scratched, so my guess is that it had been rubbing and when the brakes locked up the caliper finally broke through the wheel. Something that hasn't been mentioned, have you looked at whatever is left of the bolts to see if there's evidence of over-torqueing or of corrosion?

I think that were Roadie is getting at is that you might have completely overlooked the caliper (it could have been slightly off but you missed it) due to the pressure of trying to get home.

I'm still trying to figure out the ABS lockup though. When my ABS was inop, it took quite a bit to get the brakes to lock up, but this was a very unique situation, so maybe the ABS computer was just as confused as we are.

[mikekey]

Holy crapola! This almost happened to me if not for JorDanee's excellent hearing and having the window down during our Kentucky roadtrip.

I had the top bolt in the caliper work it's way out. The caliper started to jump while braking. Luckily, we were traveling at about 15mph and I had a set of spare caliper bolts with me. It put a nice scratch in my rim. I can only imagine I'd have the same experience if the windows had been up, music blaring and going a lot faster.

[dvanbramer88]

The right front and left rear caliper bolts NEED loctite.

Same thing happened to my dads truck. Right front caliper bolts backed out and the caliper was scrubbing on the rim. Luckily for him, nothing catastrophic happened before we caught it and fixed it.

[mikekey]

Yeah, I put Blue loctite on mine now.

[dvanbramer88]

Yeah, I put Blue loctite on mine now.

Us too.

[drburke]

I've debated this for a few days now, and after repair I've come to a similar conclusion. Here are some pics:








Hi-Res link

Notice the missing bolt, it's probably on the road somewhere along with the rest of my brake line and the brake pads. I'm 100% sure I reinstalled everything during the rear swap, including the caliper bolts (reused from the old axle). It appears what James and KE7WOX mentioned is exactly what happened; the bolt was forcefully removed somehow, dropping the caliper in the ABS event. Why the ABS kicked on, I'm not sure but as mentioned, with wet roads, high speeds, rapid deceleration and the caliper (most likely) slipping off, the system probably got confused and engaged. While I still don't remember anything weird with the caliper, this is only situation that makes sense.

Actually, perhaps it was the severed brake line/caliper slipping that engaged it? When it noticed a irregularity, it kicked on, further worsening the situation via snowball effect.

Either way, it was a $160 fix. Unfortunately, it seems that'll be my last fix to this rig. While it's done me good throughout the last two years, it's been decided to let the machine go. With a school transfer to a suburban area, it's no longer feasible to use this as my DD-- I don't fit in parking garages! I know I'll regret it later on, but it's the responsible choice right now unfortunately. The other vehicles have been sold too, so I'm pooling the money together for something newer.

With that said, if anyone wants a full armor suite complete with bumper lights and stinger bar (or hell, an entire truck to continue on), let me know. I'll post in the classifieds as soon as I can clean everything up.