Aircraft grade means an awful lot of different things. There are literally thousands upon thousands of different "grades, sizes, types" of aerospace hardware. Here are just two manufactures:
SPS:
http://www.spstech.com/home/
PB Fastner:
http://www.pbfasteners.com
How aerospace fasteners are made:
https://www.youtube.com/watch?v=HGgR5viXFAY
How Commercial / Industrial bolts/nuts are made:
https://www.youtube.com/watch?v=3kxcw08p_oY
Note the tension testing near the end of this video. Common threaded fasteners are intended for tension loading, not shear.
Axle hardware would be the CV joint bolts?
If yes, the problem here, they often loosen in service and result CV joint to drive flange failure causing minor to serious problems. Know this problem is common and happens to every threaded flange CV joint with bolts. It happens on Porsche, VW, Fiat and many, many race cars that used this CV joint method.
Porsche 914 deserves special mention here as those German Porsche engineers applied theory to practice with the idealized belief it will always work. These Porsche CV joints have two large pins and M8 internal hex/triple square cap screws. The idea was the two large pins would locate the CV joint to the drive flange and the four cap screws would provide the tension required to keep it all together. Problem is, in the real world where shock loading is very real and materials are elastic, the whole joint flexes and eventually the pins and locating holes obround with the cap screws loosening with shock loading and load reversals.
-At the end of every LeMons race session (some hours and hours of racing), the torque wrench comes out for a retorque of every one of these M8 cap screws.. ever one of them are always loose to varying degrees. If one of these came un-done, there would be a flying axle with CV joint swinging around in the engine compartment.. Not good at all. Each time the Porsche gear box gets removed, all these M8 cap screws are removed and recycled, never to be used again. At some point, I'm going to modify the entire joint and fix it once and for all.
The outers use Fiat CV joints with Lancia Scorpion stub axles, MS21250 bolts, nuts and all that. They have yet to loosen since their initial installation.
Bernice
I flat despise this overly common method of threaded drive flange with bolts to attach CV joints to the flange and axle. Most of the industry has moved away from this replacing this threaded joint with internal/external splines and a spring ring. Works much better and far less prone to this joint working loose.
Proper aerospace hardware ( I'll use MS21250 bolts, MS20002C washer and matching nut for this joint and it absolutely fixes the problem) applied properly does resolve the problem of CV joint bolt loosening in service quite nicely. It does require drilling out the threads on the flange and spot facing the opposite side surface for the bolt head or nut to seat properly.
It is worth mentioning that the much despised and un-appreciated Lancia Scorpion has properly a designed CV to drive flange joint. As delivered, the joint is done with hardened washers, correct M8 internal hex cap screws and lock nuts. This is why they don't have the same problem as the x1/9.
Bernice
a long time ago I wanted to use aircraft grade hardware for the axle bolts
and was told that the tensile strength was good(stretch),but the shear strength would be the same and have to drill and tap to a larger size bolt for strength. It's scary to actually have a possible grenade spinning behind you.
thankfully no one was hurt (cept maybe pride)
keep us posted on the repairs
mikemo90*aol.com
