Rounded-off Caliper Bolt

Edit due to cellphone reading miscue: as others have said below, a pipe wrench is now your best resort along with heat. You can get a mini propane torch pretty cheap for the latter.

GOOD LUCK!

 

try a pipe wrench

 

That was my first thought, then I remembered: a pipe wrench is basically an overgrown pair of pliers, with big teeth, designed for gripping on smooth/round pipe, like your rounded bolt.

 

When you say "the 14mm bolt", you mean the one with the 14mm head, right? The one attaching the caliper body to the slide pins? (Under that 14mm head, I think it's an 8mm bolt.)

You don't mean the ones with, like, 17mm heads, that attach the caliper bracket to the knuckle?

The smaller bolts into the slide pins are not supposed to be any tighter than a modest 25 ft-lb or so. Probably you don't need much torque, just to shock it loose at first with something like this, maybe applied with sharp raps from a hammer on something like this.

I am wondering whether maybe the socket you began with was a bit of a sloppy fit. A bolt tightened only to 25 ft-lb usually won't give you much trouble as long as you make sure you've got a nice snug-fitting socket on it. It's the socket with a little bit of slop that can mess up your day.

-Chap

 

Maybe 12 point socket and bad luck?

Or someone else had them off, over torqued? I was the first one to remove ours, since factory, they were pretty easy to break loose.

 

Use vice grips, thats your best bet.

 

Oh this doesn't sound easy as the bolt you are describing may be attached 125 ft lbs of torque?
Not sure...but uh oh.

Keep spraying liquid wrench on the bolt while you decide you plan of attack.
Some heat may help if the bolt was installed with Red Loctite for example.

Vise grip and leverage may be the only home simple tools DIY option.
Get the car high up in the air on a lift/ jack stands.

My option, find a large nut, weld in the inside of the nut to the rounded bolt head.
Use brand new 1/2 drive six point socket or six point wrench.
Remove old bolt by socketing/ wrenching this new welded nut.
This trick may work.
(Counter clockwise to loosen!)

My only other though would be to Dremil tool the rounded bolt head to a hexagon shape again.
Slightly smaller head created to fit the next smallest sized socket whether standard, metric or Wentworth.
You could try this and if it fails, still have the welding option.

Good luck.

 

Uggh, looking at pics here: Brake Caliper Slide Pin Cleaning and Lubrication | PriusChat it appears the bolt head in question is on the backside.

 

Yes, but no big deal.

 

It's a fairly safe assumption that "14mm" bolt is socket size. The alternative requires constant referral to a table, to translate. Maybe we need some sorta mechanic's Geneva Convention on this?

 

the 17mm bolt is torqued at 137 ft. lbs, the 14mm bolt is torqued at 34 ft. lbs., if you're talking about the 14mm bolt, then you can use a vice grip to remove it, it's not that hard. If its the 17mm bolt, then do the same thing with the vice grip but have a pipe to stick it in the vice grip for leverage like a breaker bar.

 

Ixnay ixnay. 25. Not 125. Just 25, we're only talking about cute little M8 bolts that fasten the caliper body onto a pair of slide pins.

Just out of curiosity for the OP, what did those bolts look like, is it possible they were changed at some point? The ones I've seen new from Toyota are silvery in color, with a prominent number 10 (the strength class) embossed on the head.

I wonder if there had ever been a brake job done that swapped them for cheesier bolts, maybe they would round off more easily.

-Chap

 

Good lord, that tight, really? For my Gen 1 it is 25 ft lb (not 125! 25 ) for the smaller one, 79 ft lb for the larger one. Have they really raised the torques so much higher for Gen 3, despite using aluminum parts to Gen 1's steel and cast iron?

Any chance you were looking at the newton-meters column? 25 ft lb is 34 Nm. (79 ft lb is only 107 Nm though.)

I'd be very leery of putting torques that high on bolts those sizes....

-Chap

 

The last numbers are the ft/lb value, it's 25 and 110. Easy to miss, for sure.

Here's a snapshot, and I'll attach the related pdf.

 

damn I misread it again, lol Thanks Mendel.

 

Just going through the reading material. You da man!

 

Thanks for the attachment. Even then, didn't you flip the last two digits? Spec looks like 101, not 110.

On a serious note, I suppose I've got a bit of reputation on here as that weird guy who always suggests checking the manual yourself ...and this thread's a perfect example of why. Everybody's intentions are good, but miscues or misrememberings or even just digit flips creep in, and the best protection against that kind of telephone-game effect is to go to the source....

Also just a tiny touch of mental back-of-the-envelope checking can help with noticing mistakes. Even without bothering to do exact math in your head, you can kind of think "hmm, if 25 ftlb is 34 Nm, doesn't it feel like 110 ftlb should be something more than 137 Nm?" That was what made me do a double take and look more closely at the picture.

-Chap