Thin hub-centric spacers are not easy to find, and will not be available for all applications. Using a 2mm thick spacer, I would think that normal hub-centric rings would still engage enough onto the hub centre.
@chrisp , all this talk about how hub-centic rings work has raised another question for me to ask. Is the centre hole in the 2mm spacers large enough to clear the angled part at the base of the hub centre. It would need to just clear it to be able to sit perfectly flat against the wheel mounting surface. It looks in your pics like it might, but it doesn't hurt to ask. It could be your problem if it is not quite clearing.
Well, I'm stumped. Please let us know if you find the solution. I am very interested as to what is happening.
After listening to all the thoughts on this , here are some things. Lug holes, Mag shank lug hole , 11/16 diameter, .6875 to .705 depending on mfg. ideally .688" with a 1.25 spot face and edge break chamfer. Sometimes 1.375 spot face for 5/8 drive stud application as the washer / flange nut is larger. Acorn lug, most all modern era wheels, conical seat 60 degree , hole size thru wheel up to .620" depends on mfg and stud size range for wheels 7/17" to 14mm studs. 60 degree seat , and 1.1 to 1.3" diameter counter bore for socket clearance. E-T Uni Lugs, Conical seat with 5/8" shank , were made for our uni lug system. But today shops use them to get more stud engagement when using spacers, provided that they fit in the lug hole and do not extend beyond the back side of the wheel and bottom out. note: minimum lug to engagement is 10 full turns on stud and torqued to correct ft. pounds for the stud being use Next the mounting face of the wheel must be flat to concaved .006", if it is convex it will need to be re-machined. The hub needs to be flat and the spacer if used should be flat and parallel. Hub rings are a great help if vibration is a problem, and can be made of aluminum or plastic. Lug centric wheels have been used for decades without issue, with proper installation. Install , stud clean and dry, as lube will alter the torque value, drive short distance and re torque, generally good, if need repeat and you should be good to go. hope this helps
Thanks etwheels "note: minimum lug to engagement is 10 full turns on stud" That is an interesting fact I never knew about, I always wondered if there was some kind of rule of thumb. The problem is on hold for now because : 1 the order for the rings got canceled after 2 months by the US manufacturer because of tariffs issue, 2 the customer is away for at least 6 month and I can't keep his car this long.
I know this is a bit late but I think your issue might centre around the relative flatness of the disc/wheel/hub faces or that you’ve not machined the hub diameter quite right, did the disc slip over the hub easily?
If you were to have the wheel hub centred you would need a hub centred spacer rather than the float one in the first pictures as it does not look like the hub would would be suitable for a hub centring ring.
Isn't 6 full turns a standard engineering practice? If so, 10 is that plus a good margin, which seems to make sense. @chrisp How many turns have you got? I bought a car with similar wheels which had about 3 turns on the nuts. I near ****ped myself when I found that. Extended Taper (ET) nuts cured that. Chris
I am not a expert but I think Oneball is on to something. Looks to me like the rotor is made to be hub centric on a hub. Are those rotors originally for a FWD car with CV joints, etc.? Looking at 1st pics it appears that rotor can wiggle around on smaller hub. Also lug holes in rotor are bigger than lug diameters. So rotor can just wobble/wiggle around when installed?? Then also wheel is not hub centric. So when car taken out for drive, rotor is just "sandwiched" between hub and wheel with no register- then brake use- vibration-etc causes lug nuts to loosen?? Very interesting thread, I am following.
You could bore out the center hole in the spacers to match the wheels, then use a deeper hub ring to make everything concentric. You could also weld the hub ring to the spacer and then re-machine it on a lathe to make everything concentric.
In the machining world, thread engagement length was 1 1/2 times the diameter of the thread. 1/2" stud, 3/4" engagement.
I was very careful machining, it slips on without play, I need to wigle them out, I would think it's a tad too tight. I don't remember how many turn the original nuts were taking, I remember I wasn't confortable with them but it seems they were on the car for years but it also seems the previous owner didn't drive it much. Anyway they're et nuts now but didn't get a chance to really test drive the car. The rotor kit is from Clark's Corvair, I don't know what they're made for originaly. I couldn't get centering rings, I'll have to find a new source. I don't want to spend the time to machine them because it's on my dime and centering rings are very cheap.
Being too tight and the disc not sitting perfectly against the flat face of the drive flange is what I was worrying about.
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