I am in the middle of changing my T3 disc rings over and it occurred to me that 12 of these little 1/4 inch screws per disc are the only things that holding my car back from going straight into a wall at the track coming down from 120 mph. I think they are titanium but here is my question, what forces are exerted on this screw? how much weight is it resisting? think about it. By the way the disc doesn't lock in, its just held there my the screws and a little nut torqued at 13 nm.

 

Are the fasteners magnetic? I would doubt that they would be Ti?

In any event, those high strength bolts see a shearing force vs tension. Whatever the value they have is multiplied by a factor of 12

Im not a degreed engineer, but i play one at work

 

12 screws per disc distributing all the weight isnt that bad. Thats 48 of those screws. And the weight largely depends on how much traction your tires provide. But again its all distributed across 4 wheels, with 12 bolts each.

I believe the sheer strength of the bolts is what is important in this application.

 

Also although negligible, the friction between the adjoining faces of those tabs on the rotor hat and rotor itself play a contribution. Agree with the above that the shear strength of the bolts is the major contributor in transferring forces from your brakes to your tires.

 

here another thing to think about....

you have 5 lug nuts that basically do the same thing during braking, acceleration..... and in addition, they have to deal with corner loading.

if the metal was the same strength, those 12 bolts have way more strength then the 5 lug nuts.

 

There's three small dowel pins in the engine flywheel that power the entire car. The cap screws are there just to keep the cover on the pins. Ever think about that?

 

reminds me of this

 

Without bothering with the math, shear strength on a 1/4" screw is well over 1000lbs. Times 12 for number of fasteners, times two for both sides of the car. You literally CANNOT brake those screws before something else in the system will fail.

(MSME, over 10 years of new product development and R&D, proprietor of SSB designs)

 

Hi Dallas

Our inquisitive OP thought the bolts were Ti? Is that possible? I would think steel would be the choice (maybe grade 5) (certainly not grade 8)

Joe

 

Its very highly doubtful they're TI, most likely some form of SS. I know some of the wheel builders have an option for TI fasteners but its quite the cost adder. Standard parts wouldn't start there.

 

Centrifical force.