Broken rear caliper bolt *or* why I use anti-seize on everything
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Driver School Candidate
Joined: Dec 2011
Posts: 22
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From: PA
Broken rear caliper bolt *or* why I use anti-seize on everything
Changing the rear rotors, the lower bolt on the passenger side broke off in the knuckle. Those bolts cost $10, dealer only part, and they are a super rare size M14x1.5 . in the past I've drilled out broken bolts and used heli-coil thread repair kits on my GM cars, but heli-coil doesn't make a kit for this size bolt. I am having trouble even finding a tap in that size and had to order one from the UK through ebay. What a pain in the ***, I'm really kicking myself for not heating that bolt with a torch first.
If the UK tap doesn't work, I'll probably bore out the caliper and knuckle slightly larger and cut 5/8" coarse threads into it. I've read in other threads how the caliper bolts are special in that they "stretch" when they are torqued to spec, but they only need to be tightened to 58 lbs/ft so I'm sure any standard home depot bolt will handle that. And you can be sure I'm putting these bolts back in loaded with anti-seize. I've seen some people here recommend using thread locker compound on caliper bolts, but from my experience living in the rust belt that is a bad idea, unless of course you enjoy drilling out broken bolts.
If the UK tap doesn't work, I'll probably bore out the caliper and knuckle slightly larger and cut 5/8" coarse threads into it. I've read in other threads how the caliper bolts are special in that they "stretch" when they are torqued to spec, but they only need to be tightened to 58 lbs/ft so I'm sure any standard home depot bolt will handle that. And you can be sure I'm putting these bolts back in loaded with anti-seize. I've seen some people here recommend using thread locker compound on caliper bolts, but from my experience living in the rust belt that is a bad idea, unless of course you enjoy drilling out broken bolts.
Last edited by matrix; Feb 10, 2012 at 11:16 AM. Reason: corrected bolt size, was right the first time
Pit Crew
Joined: Feb 2010
Posts: 174
Likes: 4
From: West Palm Beach
homedepot does not sell graded bolts, I would not use them where graded bolts are used.
Id just buy them at the dealer and be done with it then trying to find them. You should try a local Fastener place.
Id just buy them at the dealer and be done with it then trying to find them. You should try a local Fastener place.
Racer
Joined: Feb 2006
Posts: 1,514
Likes: 82
From: Northern VA
Problem w/ applying anything to the bolt is you change the torque (e.g., 76 ft-lbs on a bare bolt isn't the same as on a bolt w/ anti-seize or grease....someone on ih8mud did a test/writeup on this). The reason why the caliper bolts cannot be reused is because they are aluminum. They are Al since the knuckles are Al. If you use a steel bolt, you risk stripping the threads in the knuckle=$$$$ repair. It's cheaper to pay the $5 for a bolt online. If it were me, I'd use anti-seize, too, just sparingly, and maybe torque a few of ft-lbs less. I snapped off a lug bolt on my truck when living in NY state (too much salt...PA is the same). Even torque on each bolt is the most critical. Unfortunately, dealers never torque them carefully. They use an impact wrench, which doesn't sense torque. One bolt can be many ft-lbs off the others. I find my lug nuts are always unevenly torqued unless I specify them to hand torque them (which is what i do...otherwise, I loosen them when I get home and retorque). One time, one lug nut was so tight my 650 ft-lb impact struggled to loosen it while the other nuts were under-torqued.
Thread Starter
Driver School Candidate
Joined: Dec 2011
Posts: 22
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From: PA
thanks for the info guys! I decided to do the repair the right way, I'm using the following kit:
http://www.timesert.com/html/mtrcsert.html
http://www.timesert.com/html/mtrcsert.html
Thread Starter
Driver School Candidate
Joined: Dec 2011
Posts: 22
Likes: 0
From: PA
The time-sert kit worked well.. I wasn't able to drill the hole out exactly perpendicular to the surface of the knuckle, but at that point all I could do was go forward with the repair. Test fitting the bolt in the new threads, it became visible how crooked the new threads were...about 5 degrees off. I thought about boring out the caliper bolt hole to give the bolt more room, but there is a solid steel sleeve inside it, I would have had to pull the caliper and used a drill press on it. Decided to try and line things up while assembling... I got the crooked bottom bolt started, then lined up the top and tightened, and finally tightened the crooked bottom one. I was worried the geometry of the caliper and rotor would be affected by the crooked bolt, but as soon as I snugged down the caliper against the knuckle the bolt gave enough for everything to line up.
Haven't test driven yet, but I'm pretty confident this repair will hold up for a while. Since the next step would be replacing the whole knuckle at a dealership, I'm happy with spending $100 for the time-sert kit.
Haven't test driven yet, but I'm pretty confident this repair will hold up for a while. Since the next step would be replacing the whole knuckle at a dealership, I'm happy with spending $100 for the time-sert kit.
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joshoowa
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