Will
Dork
11/29/12 7:06 p.m.
Until now, I've never owned a car with the rotors screwed to the hub. But I'm about to do brakes on my MR2 for the first time--are these screws necessary, or do they just keep the rotors from falling off on the assembly line until the wheels are bolted on?
I mean, it seems to me that the calipers and ultimately the wheels are going to keep the rotors in place. As I said, none of my other cars have this feature and none have ever lost a rotor. But if I'm wrong, educate me, please.
Assembly line mostly. I have heard reports they do dampen potential warp/shudder by holding the rotor steady against the hub.
I run them on the BMW.. ran without them on the Fiat...
As an added bonus, they're easy to strip when you're trying to remove them.
I always run them, on cars with lug bolts anyways. When your rotor keeps spinning on the hub and it takes you a frustrating half hour to get your lug bolts in, you'll see the value pretty quickly.
On a car with lug studs, I wouldn't bother.
Makes hanging the caliper a bit easier, other than that, no. Many fiats and derivatives thereof have 2 bolts holding the drum/ rotor on, one of the bolts has a spike coming out of it that goes through a hole in the steel wheel, makes hanging the wheel easier on a car that uses wheel bolts.
Will
Dork
11/29/12 7:31 p.m.
Sort of what I figured. Thanks--hope the old ones come off without too much fuss. I won't put them back on.
The only reason I kept those screws on my FC is because you can use the screw to pop the rotor off the hub. OEM-style FC RX-7 rotors have an extra threaded hole where you can insert the retaining screw. Quite helpful when the rotor is seized to the hub. A bolt with the same thread pitch works too, and is less prone to strip, I just never happened to have one handy when I needed to remove a rotor. Use an extra-big Philips head, it's less prone to stripping the soft metal.
Ranger50 wrote:
I have heard reports they do dampen potential warp/shudder by holding the rotor steady against the hub.
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.
Call me weird. I just like having them there. Impact screwdrivers are like $10 from HF.
+1 on poopshovel's impact screwdriver advice.
wbjones
UltraDork
11/29/12 8:37 p.m.
I hang on to them .. use them to hold the rotor in place while doing brake work .. then remove them and put away in the brake job box ... they WILL get stuck in there
Hondas have them, we remove them with a chisel, we never even try to remove them with a screw driver, impact or otherwise, they seldom get stuck or damaged, I've left them off without a comeback , but 99% of the time I put them back on.
Down south -leave 'em in. Up nawth- get 'em out at the earliest opportunity ,before they rust in place.
02Pilot
HalfDork
11/29/12 9:01 p.m.
I always anti-seize the hell out of them on my BMWs; consequently I've never had a problem with them sticking after the first removal. Removing them when they haven't been coated is a giant pain, and often destructive.
Did the brakes on a friends Ford Flex, I had to drill them out as they wouldn't even come out with easy outs. Take em out and pitch em into whatever circular file is nearby. Kinda like GM's little star washer that threads on a stud on drum brakes
I would always antisieze and replace them in customer's cars. We had some in stock in case they were damaged at both the Honda and Audi dealers I was at. The last thing I wanted was for a customer to get a flat tire, see the missing bolt and come in raising trouble because I left the bolts out of their brakes. That habit has carried over to my own cars as well.
If you must...
Bolt Depot sells stainless socket flat-heads
Socket head (ie. allen wrench) and stainless, 40 cents apiece. A good Ace Hardware should have the same. If yer gonna do it, do it so's ya don't regret it, I say.
(My dear old sainted Fadder uster say that phillips heads were Japan's curse on us for WW2. 'Course, he wouldn't have ever been caught dead in a PewJoe frenchy car, neither.)
I cursed these things on my s2000. Only 1 came out with a screwdriver, the rest had to meet the hammer/chisel or the drill. That was after breaking 4 impact driver bits too. Berk them things.
I like having them in the north. I source a few stainless countersunk machine screws from McMaster Carr, and throw a bit of anti-seize on them. Works like a charm!
Honda? Put them back on. They do help with vibration. Anything else? I don't/wouldn't bother.
Ian F
PowerDork
11/30/12 7:19 a.m.
I've had to drill out a few that have siezed on MINI's - which use an effing phillips screw (my VW at least has a torx). The last one even my hand impact driver wouldn't budge. As a last ditch attempt before drilling the mofo out (BTDT) I put my air impact gun on it using the bit driver from the hand impact - that got it out.
Definitely slather the SOB with antisieze upon reinstallation. I need to keep new ones around just in case - especially for MINIs.
Not having them on can be annoying when swapping wheels when the rotor rotates. I had to drill out one on my g/f's MCS, leaving just the stud remenant. That actually works ok to keep the rotor from spinning.
wbjones
UltraDork
11/30/12 8:02 a.m.
Bobzilla wrote:
Honda? Put them back on. They do help with vibration. Anything else? I don't/wouldn't bother.
never ever felt any vibration with the CRX ... with it's track use, they seem harder to get out on it than the Integra ( even with a-s )
we never use them on the race cars ( SRF and spec Miata ) so I don't see any reason to leave them in on my street car and certainly not on the track car