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Discussion Starter · #1 ·
I am not sure how many times I've replaced my brakes in my 8th gen over the years but the most recent time my front brakes were replaced I did not perform the installation. Years ago when I read up on how to replace the brakes Many forums suggested that the two small screws that attach the rotor to the vehicle or optional because when the wheel is on the lug nuts will keep the rotor secure. These screws are often referenced as installed at the factory during assembly to keep the hub in place. Despite what the internet said I always reapply the screws because if they came on the car it doesn't take much effort to put them back on. I've been fortunate enough that in 10 years there has only been one occasion where I had to drill them out order new ones and reapply those. And that was on the back.

I developed a faint knocking sound in the front of the vehicle when driving at low speeds and braking. You can barely hear it but with the radio off at a low speed you can hear it just as the vehicle starts to come to a stop and as you let off the brakes you can hear it briefly. It is not consistent. My front brakes have been installed for 3 years without issue but it's been long enough and the pads should be changed and this is a new sound that was not there before so I figured I would look at it while I am working on the car.

While disassembling the front brakes I had an AHA moment and was able to isolate the noise as sound of the rotors bumping against the wheel studs. The screws keep the rotor in place. Although the rotor will never slide off and it's relatively tight when the lug nuts have been tightened, there is still a small amount of play since the holes on the rotor are slightly bigger than the bolts when the rotor is assembled. The shop that replaced my brakes 3 years ago did not put the screws back. I have always put the screws back which is why I never developed the sound. In fairness, I drove this car around for 3 years without a peep until now so they almost got away with it.

I just thought I'd share this little tidbit that after a decade of owning this car and hear that those screws were optional let it be known that they aren't. Cheers
 

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Elvira
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Cogent argument for replacing those hub retention screws.

I always replace them on all my cars too.

So did you replace them this time and the bump noise is gone?
 

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Turbo lag
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This certainly makes sense, since the holes for the stud is bigger than the stud itself and thus have play.
I've haven't had those screws for years though, and have never had those problems.

My only question is:
Do you know if the wheels are properly torqued? Properly torqued, those lug nuts has 45000N of clamping force each. Which translates to a force of friction to ~2000lbf with a cd of 0.2 for steel. I find it hard to believe for the rotor to move outside of the most extreme of braking (maybe).
 

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Discussion Starter · #6 ·
To the other question, I did not install these rotors so I can't speak to how they were torqued. I stopped changing my oil a few years back when I moved because the closest place to take the old oil was too far but they rotate the tires during oil changes so even if it was torqued properly, the wheels have been removed, rotated, etc several times since the install. Technically that could have contributed or caused the sound but at the end of the day, this was the sound of a rotor bumping against the wheel stud which would be prevented if there were something to secure the rotor in the absence of tight wheel lugs.

If I put on my honesty hat on for a second, it's a **** phillips head screw. It requires nothing special to reinsert. No special tool and 10 seconds. The only fathomable reason it would ever be not reinstalled when removed is shear laziness or that they were lost or damaged during removal. If for no other reason, it should be reinstalled because that's what's necessary to return the car to its original state and no honest mechanic should leave them off if they were on the vehicle when it was brought to them.

Car companies cut costs at every turn, if it was useless, I, personally don't think they would be there. Over the years the time and money spent manufacturing, buying, shipping, and installing those screws, I cant imagine Honda let that go on knowing the part served no purposed.

Can you skip them? Yes. I did for 3 years and had zero issues other than a faint knocking sound after 3 years. But I don't think we can say they serve no purpose.
 

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The only purpose of the screws is holding the rotor during assembly or brake service, nothing more. With 5 bolts clamping on the rotor at 80 ft-lbs, if we still need the screws to contribute, aren't the car a clatter box? Few fasteners are as tight and those lug nuts. It's indeed optional.
 

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After spending an entire day fighting with those screws (I live in the rust belt, so they were completely fused to the rotor), I ran an oversized drill bit through the threads in the hub so you cannot install those screws anymore. It hasn't caused me any problems so far.
 

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IIRC, those are JIS (not Phillips) head?

Also IIRC, there are only 2 per rotor and they're not all that big so my guess is that keeping the rotor in place during driving conditions isn't their primary purpose... ?
 

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Elvira
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JIS is correct

My thinking for the screws purpose is to align the rotor alleviating the possibility of the rotor stud holes from being placed in a position to allow the studs to touch the rotor. It centers the studs in the rotor holes.

It's acting as a locating peg / alignment peg call it what you want.

With no locating device the stud could rub up against the rotor in the hole provided for it if the rotor is rotated off a few degrees.

If the stud is within a couple thousandths, or literally touching the rotor you've set yourself up to get the knock that started this thread.

The consensus that it was only for the factory to hold the rotor on during manufacture didn't make sense to me when I noticed the screw twisting/locating the rotor "back" into alignment. Hence the tapered head screw.

Oh yeah IMHO
 

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Wow.
there is still a small amount of play since the holes on the rotor are slightly bigger than the bolts when the rotor is assembled.
Lol, no. With rotors correctly installed and lug nuts properly torqued, there 100% is no "play".

The retainer screws serve no point other than to make a brake job take far longer than it needs to (I do my own) and are indeed optional. I'd argue they should be thrown away at the first opportunity, especially if you live in a climate that has winter.
 
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The screws can be very hard to remove and serve no other purpose than at the factory during assembly. When they are on the line moving through the assembly process, the manufacturer found a way to keep the rotors on the hub before placing the tires on. They didn't want the rotors falling off while these cars were not completed yet. Thats the only reason they are there. Considering that plus how hard it can be to remove them sometimes, serves as a good enough reason to not reinsert them. Your helping yourself/or the next mechanic later by not reinstalling them.
 

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I'm curious if the Honda repair manual that's used by the service technicians instructs the mechanics to replace the screws
The Honda service manual for the 8th Generation gives a torque value for the screws of 7.2 ft-lb (6 x 1.0 threads). For an optional part it seems really odd to give a torque value, so I do install them, and you can buy bags of them. I use a new pair each time; costs very little and they come out easy.

I like having the rotor not floppy while I'm installing the caliper. I acknowledge the screws can stick, and sometimes you need an impact screwdriver to break them free (bought one after some harrowing experiences).

They are also, if I recall correctly, a JIS #3 screw head rather than Phillips, so they won't cam out as readily as a Phillips can. You can buy JIS screwdriver bits and they will ease the job. From what I understand Phillips drivers will not properly bottom in a JIS screw and can damage the head because they cam out. I think this gives these screws a reputation for being a pain.
 

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The Honda service manual for the 8th Generation gives a torque value for the screws of 7.2 ft-lb (6 x 1.0 threads). For an optional part it seems really odd to give a torque value, so I do install them, and you can buy bags of them. I use a new pair each time; costs very little and they come out easy.

I like having the rotor not floppy while I'm installing the caliper. I acknowledge the screws can stick, and sometimes you need an impact screwdriver to break them free (bought one after some harrowing experiences).

They are also, if I recall correctly, a JIS #3 screw head rather than Phillips, so they won't cam out as readily as a Phillips can. You can buy JIS screwdriver bits and they will ease the job. From what I understand Phillips drivers will not properly bottom in a JIS screw and can damage the head because they cam out. I think this gives these screws a reputation for being a pain.
Yeah their optional in my opinion and many other mechanics. The problem with those screws is primarily the heads. The heads rust and bond to the rotor by the time the rotors need replacing, even if you put new ones on. The threads of the screw are always fine. Im just not the type thats wants to go through all that everytime I have a 20minute Job held up by two rusty screws turning it into who knows how long. Me personally, I like to work on my car quickly and efficiently. Brakes have become a necessary but boring aspect of maintenance. No need to add frustration to it. I dont knock anyone for replacing them, just giving my opinion on what I believe, do in my own case and why.
 

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Yeah their optional in my opinion and many other mechanics. The problem with those screws is primarily the heads. The heads rust and bond to the rotor by the time the rotors need replacing, even if you put new ones on. The threads of the screw are always fine. Im just not the type thats wants to go through all that everytime I have a 20minute Job held up by two rusty screws turning it into who knows how long. Me personally, I like to work on my car quickly and efficiently. Brakes have become a necessary but boring aspect of maintenance. No need to add frustration to it. I dont knock anyone for replacing them, just giving my opinion on what I believe, do in my own case and why.
I hear ya. I used to leave 'em out too after some ugly times. The impact driver fixed that, but I agree, to each his own. Appreciate the reply.
 
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