Anything yet?

 

Sadly i cant find the strength or tension of the stock miata bolts



Left is with spacers right is without.

To make this easy i rounded it off to 1000lb

I used 1" spacer, the other 1/2" is simply the distance from the mounting face to the distance of the nut it self on the rim.

The basics of bolts, bolts are good for tension however they are not too good about side flex so moment is bad, too much moment on a part thats not made to take it ends up looking like this



The way the studs are inserted, Motion is created naturally, in other words the bolt cannot move around up and down, it stays straight out to the side. This is why you see the half circle with the arrow there.

The basic behind the above picture is you have to have enough tension on the bolts to keep the force of friction high enough to hold that 1000lb (when racing that 1000 will be much much bigger).

Assuming the bolts have enough tension and the force of friction is in control of the entire situation. The aluminum will flex a tiny bit, the spacer it self will also flex a tiny bit and same thing with the rim. Its a small flex but its still there. The closer the nut is to the beginning of the rim.. the less flex you have the less moment the stud will be forced to take.



You can clearly see that the distance increases as the rim gets further from the hub. In the not to scale image above exaggerated to show the angle, lets call distance A 1/2" (first example rim measurement) and distance B 1" and a half... The next thing is the Tension. If the stud is offset by 1/16" the tension increases since the stud was originally 1/2", now its
.5^2+1/16^2=.25+.00390625=c^2=c>.503891

in other words the stud is now stretched by .003891.

With the bigger spacer you got

1.5^2+1/4^2= 2.25+.0625=c^2=c>1.52069

In other words the stud is now stretched by .02069...thats more than 5 times more than without the spacer.

The next on the list would be the tolerance of these things. The hub has a lip in the middle thats there to keep the rim centered if force of friction is not enough to hold the rim.



The last time i got a set of spacers in my hands, i could tell they were different by just looking at them. One hole was bigger than the other to the naked eye. Thats not something i want holding my rim positioned. 75% of the spacers dont even have those lips in place, they are just a flat cylinder with 4-5 holes in them and then the big one in the middle. dont forget that most spacers are universal and not many cars have the exact same size lip.



next on the list is the spacer with its own studs.


If its made by a reputable shop (good tolerances) its your best bet of a spacer. In my opinion if you are going to use a spacer use this type of spacer. The only negative to this spacer is that you have a set of nuts that are hidden by the rim.

This is the best explanation with the information i have. Hopefully after this oncoming semester of engineering i'll be able to explain it better.

 

And twice as many failure points because of those hidden lug nuts. I have no idea how they think you're going to get a lug and socket in and below that little counter bore. I was going to mention this earlier Cspence, whatever you do, make sure there's a locating bore for the miata hub, and a locating ring for the wheel's hub. AKA hubcentric, not lugcentric, hmkay?

 

Gotta choose your poisons here. I rather put some locktite on my nuts than have them ripped off

 

you lost me whit all dat math and junk!


what about getting stronger studs to withstand the pressure and force you speak of?

so we got three options!

A: go with a crazy et
B: go with a good ol-fashion spacer
C: go with a cool studded spacer!

Z: if your skurd............dont get ****** flares!

 

My thoughts exactly.


The one thing I noticed wrong in sketches above is that the spacers I was talking about are both hubcentric and wheel centric. Therefore the studs are not solely responsible for supporting the weight of the car and the rotational forces of the car while it is being driven. With the style spacer I was refering to, I would think that the hub would take on the majority of the stress vs the lugs which would just be holding the wheel on, not supporting the weight of the car. The only increase in stress on the lugs that I can think of would be the rotational forces from accelerating and decelerating since the wheel would be located further out on the studs. Even with this in mind though, I dont think this would cause any rise for concern since these forces probably wouldn't even be applied to the studs since the wheel would be clamped to the hub with 80+ft.lbs per stud....I'm thinking any forces would be applied to the hub as a whole. The picture below kind of explains my thoughts based off the custom spacers from Motorsport-Tech where the hubcentric "inside" bore would be 54.1mm (Stock miata) and the wheel centric bore on the outside would be 67.1mm for the 6ul. Any one else have some insight on this subject?

http://www.motorsport-tech.com/wheel_spacers.html

WHEELANDSPACER.jpg?t=1265231616

 

as long as the tolerances are perfect the center lip should keep the wheels centered and prevent the bolts from taking all the motion, if they are not right on you have 4 faces depending on the tension of the same bolts to keep them at friction higher than the maximum weight put on them, if that friction brakes, thats where the motion comes in and the studs will hold a lot more beating if the rim is right at the base then right on the end by the inch and a half area on my pictures.

No that first image is not wrong, you can see the center playing a factor.

i ran spacers with the extra screws and they came with their own nuts that fit in the hole with plenty of room to spare. You still use the stock nuts at the end when putting on the rim.

 

Here is what I ended up going with.....I posted this in my build thread, but figured I'd post it here too incase someone is ever doin some research.
https://www.miataturbo.net/forum/t33438-13/

The spacers weigh in as follows (WITH the shorty lugs):
30mm - 2.80 #'s (15.5 with the 6ul....not bad considering the 16x9.5 spinwerkes were going to be 16.5#'s)
19mm - 2.05 #'s (14.75 with the 6ul)

1-22.jpg?t=1267490069

DSC06072.jpg?t=1267490102

DSC06073.jpg?t=1267490135

 

thanks for the tool!

 

Lookin good dude! What you doin for wheels?

 

the flares need to be painted white and the car needs to be lowered and i am gonna run the xxrs that i have on it with a .5" spacer with 225 rs3s.

 

I still gotta paint my flares....I'm still rockin the gel coat

 

You all set with it?

 

Didnt get to read whole thread but got the main point love the flares wish i had them do have the ogs tho and are in love with them but willing to part with them for right price

 

whats the RIGHT PRICE?

 

haha, you're tired of people making fun of you huh? i was thinking of getting those for street wheels at one time before i got rid of those flares. i was gonna paint them to match my car though. those do look ridiculous without flares. takes it back to 1990 "euro" lowrider look! lol.. might as well be wires, 100 spoke daytons holmes. orale!

 

yea not much on the flare look think 0 offset and drop looks better. But these tires handle so good even with the Mexican look. 600$$ is good price or throw me a offer

 

So has anyone figured out 15x8 +0 spacer size for these flares?

I'm hoping to test fit son, and try a locals 15x9 tirerack wheels.... Trying to figure out a spacer i can use with both.

 

Question.
What about TE37V's. If I run the 15x10 et-35, will they poke any from the flares?
Im unsure because of the extreme negative offset. I think they make 15x9 et-15 also

 

you have the coin for those???? dang... I'm second in line wondering about the 15x8 0 et