I just bought a new Brake Best front brake caliper from O'Reilly, from whom Ive been getting good parts/service for the S10. Its just a caliper, nothing can go wrong, right?





DANGEROUSLY WRONG

Upon checking the "stack up" of the banjo fitting and bolt (brass block on the end of the flexible brake line which bolts to the caliper body, see pix above)
installing the block between the two copper washers only left...

TWO THREADS OF THE BOLT IN MESH. (2 TIM)

S.O.P in the mechanical world for bolts/nuts etc is 4-5 TIM. Look at a standard thickness nut (not a thin nut for soft materials)- about 5T. My ME PE wife says 5T on a nut isnt exactly a written standard, but just look at industry practice.

The first thread doesnt count, its the "lead in" thread and its very thin- to nothing. The first two threads are for STARTING THE BOLT, NOT HOLDING ANYTHING.

References:

* Bolts into soft materials (granted, this caliper body is probably harder cast iron, not aluminum) but requires 1-1/2 to 2 times the bolt nominal diameter in thread engagement,
* 2 TIM allotted for simply "starting" the bolt into the nut (track bolt section)
* nut should be more than 2T from the end of a bolt thread (where the thread stops at the plain shank)

Standard Handbook of Fastening and Joining, Second Ed. Parmley P.E.

THIS IS EXTRA DANGEROUS AS IT IS NOT OBVIOUS. An obvious failure is a flexible line blowing out due to age or a fitting rusting. Whose going to expect this problem with a new caliper?
Me who doesnt trust Made in China....

Worse, its a risk of the threads breaking and bolt coming loose JUST SITTING IN THE GARAGE if the bolt was tightened and threads over-stressed.

Worse yet, over-stress these 2 threads when tightening the bolt, then in a panic, stomp on the brake pedal and put another several hundred pounds force on that bolt and BOOM!

A brake fluid pressure of 6 MPa = 870 psi. For a 1/2 inch diameter bolt, the force on that bolt from fluid pressure is about 170 pounds, not a great deal UNLESS the threads are badly over-stressed already.
Worse, "stomping on the brakes" is impact loading which tends to break things. Thats how HAMMERS work.

From Hydraulic-pressure-following control of an electronic hydraulic brake system ......, Chen et al, Sect 3.2 : https://www.tandfonline.com/doi/full...1816495#d1e174

One of these bolts give away and there will be a LOSS OF FRONT BRAKES since both front calipers receive fluid pressure from the same brake reservoir in the master cylinder.

A lack of bolt clamping force with the copper seals being pushed loose from braking pressure would result in brake fluid leakage. The brake fluid force is opposing the "clamping" force of tightening that bolt.

Also, the copper sealing washers are too small outer diameter, they dont 'cover' all but about the first one or two sealing "rings"
molded in the caliper housing. These are a deformable copper seal for the high brake fluid pressures, they deform when the bolt is tightened to "smash" down in between the rings to prevent fluid loss.

daveca, electronic/mechanical R&D engineer with 4 Patents and 40 plus years wrenching on old junk vehicles, and a M.E. P.E. wife in the nuke world.

PS There are FIVE (5) design mistakes in this caliper... try and spot them...