[chamfamdad]

How important are the 2 screws that hold the rotor to the wheel hub?

I just changed the rotors and one of the screws was being difficult so I had to drill it out. Do I really need to replace it or can I live without it?

 

[aggrex]

I don't reuse the ones that survive removal.

 

[tinylo]

I'm a little OCD, but I like to use them especially when replacing calipers and bleeding brakes. Keeps the rotor on without screwing two lug nuts all the way on and back off. I picked up some stainless steel M6-1 x 12 flat head allen drive screws and use those.

 

[jimmaki]

How important are the 2 screws that hold the rotor to the wheel hub?

I just changed the rotors and one of the screws was being difficult so I had to drill it out. Do I really need to replace it or can I live without it?

Don't sweat it, it's not relevant to operation. Only if you remove a tire/wheel, it keeps the rotor from coming loose from the hub just in case it's not rusted on good enough. Usually you have to give the rotor a good whack to set it loose after the screws are out if it's been a while since the last time the rotor was off. It's usually a good idea to give those screws a jolt with an impact screwdriver before trying to loosen them with a regular screw driver.

 

[Rocky]

please get another screw or two.

the forces in play create movement that could reduce braking ability

 

[2020 Touring]

please get another screw or two.

the forces in play create movement that could reduce braking ability

False -- many manufacturers don't use them. They're a convenience item to help during vehicle assembly, and little more. They are designed accordingly, which is why they routinely require drilling out.

Btw, when I researched this same question a few years back when I REALLY didn't want to put those screws back after the pain I went through to remove them. This quote from another message board sums up my findings on the matter nicely:

I can't possibly imagine how that little bolt would do something if 4-5 large nuts/bolts torqued to 75+ isn't holding it steady against the hub.

 

[The Todd]

please get another screw or two.

the forces in play create movement that could reduce braking ability

The forces on the screw, vs. the lug nuts torqued down tight? OK

 

[denzpilot]

If you want to replace them, pretty much any auto parts store will have them, but as 2020 Touring said, it’s an assembly line thing. Some car makers use them and some don’t. If they were important, all cars would have them.

 

[plplplpl]

I still have mine, not that they weren't hard to take out, but they did eventually come out unscathed, which is why I reused them. On the other hand, if they had been damaged removing them, I would have tossed them aside with no qualms. It's also my understanding that their raison d'être is in the assembly process, sort of like that plastic bar behind a 1st generation glove compartment you need to remove with a hacksaw the first time you set out to change the cabin air filter.

 

[Nail Grease]

If the screws were drilled out, I don't think getting new ones is going to be of any use. What's done is done.

 

[denzpilot]

If the screws were drilled out, I don't think getting new ones is going to be of any use. What's done is done.

I’ve had to drill a few out, and there’s always been enough remaining exposed material to grab with vice grips and twist out.

 

[scorrpio]

Impact screwdriver is the tool of choice to remove those without stripping them out.

When you say 'drilled it out' - is the screw now fully removed? If so, I would not put the other screw back in to avoid balancing issues.
If only the head is drilled out and the rest of the screw is still in there, then put the other screw back in.

Primary purpose of those screws is to retain the rotor in place while the wheel is off. Makes it easier to work on the brake. Of course, same can be accomplished with a pair of lug nuts and maybe some washers.

 

[dr bob]

I see those screws as a way to keep crud from getting between the hub and rotor whenever the lug nuts are loose. The screws are cheap and readily available. Use some anti-seize on them and also on the interface to the hub so they don't corrode in place. They just need to be "snug", no more. The general torque spec for 6mm bolts is is something like 6lbs/ft assuming there's full penetration. It's about what you can apply with three fingers wrapped around the screwdriver handle. It just needs to stay in.

Impact screwdriver is indeed the weapon of choice for removal as mentioned by others. Another inexpensive yet priceless tool for tasks like this. Anybody with motorcycle work in their past knows this tool extremely well.

Stainless, while interesting, is softer than carbon steel. While the screw itself won't rust, the steel rotor will if not protected by the anti-seize. OK to use stainless, but it's no substitute for anti-seize.

 

[2020 Touring]

Primary purpose of those screws is to retain the rotor in place while the wheel is off. Makes it easier to work on the brake. Of course, same can be accomplished with a pair of lug nuts and maybe some washers.

Or the brake caliper, unless that has been removed.

 

[dr bob]

The caliper sort of holds the rotor in place, but it's hardly secure and subject to more movement if you happen to drag the wheel over the rotor on the way on or off. It might be "OK" to depend on it until you remember to put a replacement screw in next time you service the car.

Way beck when, in a business school example case, GM explains that a bolt or screw is something they need to design and spec, purchase, inventory, workflow to the line in the factory, then catalog, ship and inventory, distribute to dealers, inventory there, install under warranty when one fails. Times however many of that series cars are built. Bottom line: If there was a way to avoid having them the factory would have done so. With that in mind, I see no reason to leave them out. But that's just me.

 

[aggrex]

The caliper sort of holds the rotor in place, but it's hardly secure and subject to more movement if you happen to drag the wheel over the rotor on the way on or off. It might be "OK" to depend on it until you remember to put a replacement screw in next time you service the car

On most of my vehicles in order to replace the rotor the pads, caliper and caliper bracket all have to be removed. Most of the time the corrosion at the hub adds another obstacle before I can remove the rotor. IME the two small screws seem to be made of soft metal and usually deform before removal thus they are not reused nor replaced in my vehicles.

 

[nieuport17]

screws are used to hold the rotor on the production line. I have never replace them after using impact driver and lot of cursing.
I change my own rotors, never once where the rotor would just fall off. It is always rusted on. Always need a large hammer or use bolts on the two holes of the rotor.

 

[dr bob]

There may be reasons why I hesitate to let others work on my car.

 

[kirkhilles]

My guess is that if you were to look at all of the vehicles on the road, I'd bet half (or maybe more) of all vehicles have one or more missing. If it's a critical part, then I think they'd find a better way to design it.

 

[Astrobuf]

How important are the 2 screws that hold the rotor to the wheel hub?

I just changed the rotors and one of the screws was being difficult so I had to drill it out. Do I really need to replace it or can I live without it?

I like to have these screws there. Makes installation easier.

The trick to getting the out is:

Use a JIS Screw driver. I have one (Vessel Megadora, sold on Amazon) that is a kind of impact driver, works great. If you dont have a JIS Screwdriver, use a hammer on your screwdriver to jar the screw a few times b4 attempting to turn it. I've found some heat on the screw will help too.

I recently bought a shake and break attachment for my air hammer which should work too, just haven't used it yet.

Replace screws with Stainless flatheads. A little antisieze. You will never have problems. Good hardware stores will have the SSTL screws