So with my recent BMW adventure barely starting off (car isnt even in the states yet, wtf) I am already getting grief from one of my friends coughharvboi05cough about switching it to have regular studs/nuts instead of bolts.
I cant seem to understand the benefits of switching from a strength side. Sure its a little easier not having to balance the wheel while getting the bolts started but there has to be a better reason.
Given: both bolt/studs are made from the same material and have cold rolled threads.
i’m no engineer so take this as you will. Threads have to have room to thread in, while a stud is pressed in. It would seemingly be stronger. but again :whoknows:
I consider a hardened nut stronger than the internal threads of a hub flange personally, but since an average wheel is only torqued to ~100lbft of tq, you’ll never tear them out with such little tq. shear strength is irrelevant unless you’ve eliminated the hub pilot interface with some lame spacers or poor fitting aftermarket wheels without hubcentric rings installed, and unless you’re running wrinkle walls and 1000hp on the street you’re unlikely to shear them off on DOT tires with the k factor available from street tires and however much power you have. So in other words, who cares? the double ended stud conversions SUCK, especially with tuner lugs, so avoid them like the plague if you’re considering switching over.
while that makes sense the way I think about it is that the scenario is just the same but on the other end for the wheel bolt.
In that same regard I think it might have something to do with how the torque is applied at the seating area. With a stud the torque is still being applied to the threads as the nut turns and the nut is turning independently from the stud but with a bolt the friction at the seating face is giving the bolt head more chance to shear off. Idk if I am explaining that correctly.
---------- Post added at 09:51 PM ---------- Previous post was at 09:47 PM ----------
Ok, half point for the stud side. (lost half a point due to the second bolded sentence)
If you run different wheels it is a lot easier to change bolt length than stud length. Audi gives you a little plastic stud to help assist wheel install also.
When I worked at Holtz I never had problems with getting the BMW wheels to stay on, they had some sort of light press hub centric ring that held the wheel on if you were careful.
I’m sure a simpler reason would be to implement something like this:
I was only made aware that there was a difference between the two a few years ago, lol. I just figured different people called studs “bolts” sometimes as a matter of semantics. I’ve only owned vehicles with studs… (maybe my truck has bolts but I’ve never checked.)
What do semi-trucks use? Which is preferred by racing organizations?
I would have to get it on paper to really make a decision, but having bolts seems like the better of the two as far as strength is concerned. My thought here is that with bolts there is one less part in the mix. The bolt threads directly into the hub. When you have press fits and other interactions between parts it can cause stress risers.
I would assume that studs are the part of choice for most manufacturers because it costs a lot less to replace one stud that stripped, than to rework or scrap out a hub plate.
But either way studs are WAY more convenient, and would be my choice given the option.
Hmm. I missed that, but I wasn’t focusing on the application of torque. That’s only for installation. So unless you passed the yield strength of the material during torquing, it shouldn’t be a problem. I’d be more worried about the stresses in operation.
