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I did my brakes yesterday and realized that of all of my various wrench and socket sets I have lying around few if any feature a 18 mm size. My friend the engineer says that nobody makes bolts in that size so of course nobody makes wrenches in that size but correct me if I'm wrong my trailblazer has 18 mm bolts that hold the caliper mounts on.

I got the job done but it involved use of a crescent wrench at times and I'm curious if there was an SAE equivalent to get those bolts off?
 

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2004 GMC Envoy SLT 4.2
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I did my brakes yesterday and realized that of all of my various wrench and socket sets I have lying around few if any feature a 18 mm size. My friend the engineer says that nobody makes bolts in that size so of course nobody makes wrenches in that size but correct me if I'm wrong my trailblazer has 18 mm bolts that hold the caliper mounts on.

I got the job done but it involved use of a crescent wrench at times and I'm curious if there was an SAE equivalent to get those bolts off?
18mm = just over 11/16 inch. 19mm = 3/4 inch.
 

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2003 Chevrolet Trailblazer LT EXT
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I have socket sets from SK tools and Craftsman that both came with 18mm sockets
Wrenches on the other hand dont seem to include 18mm
18mm bolts are also used on Audi from my experience
 

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2002 chevy trailblazer_lt
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If I but a set I then buy the 'missing' wrenches as well. Seems whenever I am at the Upull yard I am always loaning out wrenches !!
 

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2004 GMC Envoy SLT 4.2
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Is the 11/16 close enough for government work or will it mess up the head?
I'm not sure you'd be able to fit an 11/16" socket or wrench on an 18mm nut or bolt head .
If you're doing any kind of torque-required work , I'd advise using the correct socket or wrench .
 

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18mm is also a requisite for your power steering and some AC fittings. If you buy an 18 millimeter wrench, be sure to also buy it in crowfoot flare nut and combo flare nut styles.

The best version is Snap-On because of the position of the drive faces being offset by about 22.5° so you can get better purchase on the fitting.

Don't buy a 12 point though, they aren't powerful enough for heavy work and will open up, ruining the fitting.
 

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But using an 11/16" in place of an 18 millimeter on a hydraulic fitting will crush it into a parallelogram and it won't ever be trustworthy again.

Ya might as well use a Crescent wrench or some slip joint water pump pliers.

That small difference is critical.
 

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2004 chevy trailblazer_lt
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You're not wrong and your friend is clearly not a GM engineer.
I had to pull out the 18mm wrench to replace my rear sway bar links recently. Inner nut took a 18mm wrench outer took a 17mm socket. Replacement moog parts took 18mm on both sides. Calipers took 18mm socket and 18mm wrench to hold the slide pins.
 

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2008 chevy trailblazer_lt
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I make custom fasteners for a living. 18mm hex isn't common but we do make them! They are out there.
 

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I'm not sure you'd be able to fit an 11/16" socket or wrench on an 18mm nut or bolt head .
If you're doing any kind of torque-required work , I'd advise using the correct socket or wrench .
Most ignorant people overtignten fuel and hydraulic fittings too. On those aluminum AC fittings, it's not the nut that does the sealing ... but the o-ring. Overtightening those fittings is destructive.
 

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Most ignorant people overtignten fuel and hydraulic fittings too. On those aluminum AC fittings, it's not the nut that does the sealing ... but the o-ring. Overtightening those fittings is destructive.
But , just a little more can't hurt . LOL

Been on that road a time or two . Lessons learned . ;)
 
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