OEM Front Caliper bolt size? 18 or 22?

[steaksauce28]

I replaced a wheel hub today on my 2011 V6 and purchased new AC Delco front caliper bolts since I had to take the caliper off. When I popped open the new bolts they were 22mm and a bit shorter. The OEM ones I took out were the expected 18mm. Did Rockauto send me the wrong part?

The part I bought is ACDELCO 18K17018. Listed as Front on their website.

[redcoats1976]

good question.i have heard rumors of people reusing those bolts but not sure its a great idea.

[NOT A 45]

Originally Posted by redcoats1976

good question.i have heard rumors of people reusing those bolts but not sure its a great idea.

I reuse these bolts all the time in the field without any issue. When I say all the time, I mean every time!

[Bigdumogre]

I worked in a dealership for 11 years and we always reused the bolts and never had a problem. Only bolts I would ever replace where the head bolts. Everything else pretty much gets used again.

[Crazych66]

I will be the one to say don't reuse the old bolts. I did and one of the front caliper bolts backed out and all four were not completely tight. I ordered a set of reusable ones from screaming chicken.

As for the size, the ones on the SS are 18mm. Hope that helps.

[gtstorey]

Originally Posted by steaksauce28

I replaced a wheel hub today on my 2011 V6 and purchased new AC Delco front caliper bolts since I had to take the caliper off. When I popped open the new bolts they were 22mm and a bit shorter. The OEM ones I took out were the expected 18mm. Did Rockauto send me the wrong part?

The part I bought is ACDELCO 18K17018. Listed as Front on their website.

Head size doesn't really matter, diameter of bolt and grade of bolt are important. (assuming there is clearance for the head). Shorter is probably ok but depends.

I reuse the bolts also, but usually hit them with some blue Loctite.

[NOT A 45]

GM is out of control with these torque to yield fasteners! The spec on that caliper bracket is 30 ft/lbs + 90 degrees. Like I said, I never replace these bolts and I do a bizillion brake jobs. Doing my wifes Cruze right now....re using the bolts.

[steaksauce28]

Originally Posted by gtstorey

Head size doesn't really matter, diameter of bolt and grade of bolt are important. (assuming there is clearance for the head). Shorter is probably ok but depends.

I reuse the bolts also, but usually hit them with some blue Loctite.

Got it! I think what’s odd to me is that if the GM replacement bolt was 22mm (the size of the lug nuts) someone would’ve mentioned it by now. I just really feel like they sent me the wrong part in the right box.

They did seem to thread just fine though….

[redcoats1976]

Originally Posted by NOT A 45

GM is out of control with these torque to yield fasteners! The spec on that caliper bracket is 30 ft/lbs + 90 degrees. Like I said, I never replace these bolts and I do a bizillion brake jobs. Doing my wifes Cruze right now....re using the bolts.

good to know,blue loctite is a good idea,right? might do my fronts this winter

[Rainbow1616]

Originally Posted by NOT A 45

I reuse these bolts all the time in the field without any issue. When I say all the time, I mean every time!

Ditto, never had an issue
I will never buy new caliper bolts unless they break which is unlikely.

[ElderJ]

I believe I had this exact same issue when I replaced my brakes, but it was on the rear (don't quote me). Rockauto caliper bolts were different sizes than my original bolts. I just reused the original.


I'm also glad to hear that a lot of you guys have reused the old bolts w/o issues. The way the documentation on repairs is stated, the bolts are torque spec'd and will snap like a pretzel if I try to reuse them.

[kevint]

Originally Posted by gtstorey

Head size doesn't really matter, diameter of bolt and grade of bolt are important. (assuming there is clearance for the head). Shorter is probably ok but depends.

This. I can't speak for the V6 but my SS uses grade 10.9 M14X2 flanged hex head screws with an underhead length of around 55 mm.* The head is 18 mm across the flats. This is standard hardware and you can get a bag of 5 (60 mm underhead length) off mcmaster-carr for less than $12.

I wouldn't go shorter because you'd risk having less thread engagement. I'm looking at an old caliper bolt right now and judging by the wear marks it looks like the last 25 mm of thread is what was engaged with the caliper.

*I should add that I think the knuckles are the same across all trim levels, so the hardware used to mount things to the knuckles should be also be the same.

[NOT A 45]

Originally Posted by kevint

This. I can't speak for the V6 but my SS uses grade 10.9 M14X2 flanged hex head screws with an underhead length of around 55 mm.* The head is 18 mm across the flats. This is standard hardware and you can get a bag of 5 (60 mm underhead length) off mcmaster-carr for less than $12.

I wouldn't go shorter because you'd risk having less thread engagement. I'm looking at an old caliper bolt right now and judging by the wear marks it looks like the last 25 mm of thread is what was engaged with the caliper.

*I should add that I think the knuckles are the same across all trim levels, so the hardware used to mount things to the knuckles should be also be the same.

I'd prefer to stick with the factory bolts instead of some aftermarket ones that probably came from China.

[kevint]

Originally Posted by NOT A 45

I'd prefer to stick with the factory bolts instead of some aftermarket ones that probably came from China.

okay