So I had an idea the other day. There's a lot of discussion about using the metric 5x120mm wheels on our cars, and whether or not this poses a danger to the studs. I started thinking about affordable ways to solve this problem. I've seen some folks have the wheels modified, but I wondered if there wasn't an easier solution. I wanted to get some feedback from people to see what they think about this idea.

Take a standard acorn lug nut, and machine the hex portion away so that you're left with essentially a very thick, tapered washer. Either elongate the hole, or just drill it bigger. By doing this you could install this over the stud and have it seat properly on the wheel, then you could use a washer and a nut to tighten the wheel. It will tighten the wheel without putting a shearing or bending stress on the stud. As long as the wheel is hub-centric to ensure proper positioning, this seems like it could be a simple, cheap way to run 5x120 wheels on our cars without worrying about compromising the studs.

Anybody care to chime in?

 

u guys do relize the difference in the pattern per stud is only .005 right or a total of .025 difference across the entire pattern

there is more tolerence in the factory machining then that

 

Wobble nuts do exactly that...however I never used them and never had a problem

 

First you math does not add up.

120.65-120=0.65mm=0.0256" difference in nominal diameter. It is safe to assume each lug would only see an offset of half of that or around 0.013".

Please prove this claim. I would be beyond shocked if any mass produced aluminum wheel produced in the last 40 years is off by more than 0.01" in bolt circle. The lug holes would be drilled by a jig, probably with 5 drills permanently rigged together. Why would you expect they would accept it being off by over 0.01"? General machining tolerance is ~0.005" and I would expect most wheels to be manufactured to around 0.003".

Regardless, even if the tolerance is 0.01" or worse, you are assuming best case scenario. You are assuming the wheel bolt pattern would be 0.01" larger which matches well with the BMW pattern. What if it was the other way around and the wheel is small by 0.01". Now your situation is even worse. It is always best to shoot for nominal.

 

Jim,

As twin_turbo pointed out, there are products out there called wobble nuts that do exactly what you have described. And yes, you would need to feel very comfortable about your hub centric fit to trust the location of the wheel on the hub. If the wheels are not hub centric, then that means the wheels were probably drilled with one of the lugs holes being a datum point, so you may lose some tolerance by assuming the wheel bore is actually the center of the wheel. Finally, IIRC, the oem hub snout is tapered, so your actual hub-centric area may be quite small. Something to think about.

Do you have or are you considering aftermarket brakes? If so, I have had some aluminum hubs made that are dual drilled for both 5x4.75" and 5x120mm. Of course, not as budget as wobble nuts, but something to think about.

John

 

u forgot to take into account the bolt pattern is on the studs , the holes in the wheels are drilled larger , when the metric rims are drilled the holes for the studs are large enough to keep the studs stright , and when u tq the lugnut down it will actually wear into the aluminum rim centering itself

tq all the lugnuts down then lossen them and then tq them all down like normal, next time u take the rim off look at the were the lugnut meets the rim and u will see what it did

with aluminum wheels this is fine , on a steel wheel this may present an issue


my math does add up the pattern is .0256 bigger which is roughly .005 per stud

 

I find this very hard to believe but would love to see a picture. Are you suggesting that the lug seats on normal wheels will quickly wear away as well? If with properly mating parts, you of course still have steel on aluminum.

You don't divide by the number of studs. The issue is diameter not stud to stud distance. The diameter is off by x then each stud is off by x/2.

 

Correct

 

I have heard both success stories and failures with people who use wobble nuts. I think it boils down to proper hub centric fit as well as torque values on the nuts. Seems like most of the failure stories I have seen are from hacks who use impacts guns to install the nuts.

 

I'll never run 5x120's on my car. But I drive my car to the limits. You are putting some stress on the wheel studs, significant or not I'm not putting my car and body at risk to find out.

 

When I get around to replacing wheels with 120 pattern ones, I'll reference this thread:

https://www.thirdgen.org/forums/whee...t-pattern.html

(Machine the wheels or buy wobble nuts. I have wobbles in my eBay saved items. )