Bolts= 3/8-24 1,1/4 nylock= 3/8-24 grade 5

 

Some might say not to combine grade 8 with grade 5 but I'm not sure it is a critical difference.

 

I found them at lowe's and pep boys. (Pep boys was actually 63 cents cheaper for pair, $1.99)

 

Lowe's has them also: Shop The Hillman Group 2-Count 3/8-in Zinc-Plated Standard (SAE) Nylon Insert Lock Nuts at Lowes.com
$1.14 per pair

 

Can not use standard (SAE) for driveshaft, minimum grade 5.

 

We include them with every new shaft sale so you will be getting some with your order. Thank you

 

Lowes shows the grade as all-purpose. There is no such thing as an "all purpose grade".

IFI-100/107: Prevailing-Torque Type Steel Hex and Hex Flange Nuts Regular and Light Hex Series (grade letters (A, B, etc)
ASME B18-6.6: Prevailing Torque Locknuts (Inch Series) = N2/A, N5/B,F, N8/C,G
SAE J995: Mechanical and Material Requirements for Steel Nuts (Grade 2, 5 & 8). They define yield, tensile strength and hardness for each grade.

The ASME std calls out hardness and chemical composition for the different grades. Not tensile or yield strength.

From a garagejournal thread "any lock nut with a nylon insert will be grade 2 only as the metal cannot be any stronger or the crimping process for the nylon insert cannot be done. All of the higher strength lock nuts will be all metal with a distorted top."

For the driveshaft application most of the load the bolt sees is shear. The nut is there to provide tension to hold the flanges in contact.

You can reuse the nuts. Carroll Smith's Nuts, Bolts, Fasteners, and Plumbing Handbook states that the nylon insert is not damaged by installation and therefore they can be reused many times and a FAA Advisory Circular (FAA AC43.13-1B) allows nuts to be reused if the prevailing torque is within specification.

I would assume that lawyers are the reason the RAVE says to replace nuts and bolts.

 

if you haven't figure it out the RAVE call for all new fastens on every job.
I believe the FAA also requires every nut to be safety wired; which is why they say they can be reused.
Personally I would never use and old nylock especially on something like a drive shaft.
jmho

 

FRom the FAA circular: http://www.faa.gov/documentLibrary/m...Chapter_07.pdf

The word safetying is a term universally used in the aircraft industry. Briefly, safetying is defined as: “Securing by various means any nut, bolt, turnbuckle etc., on the aircraft so that vibration will not cause it to loosen during operation.” These practices are not a means of obtaining or maintaining torque, rather a safety device to prevent the disengagement of screws, nuts, bolts, snap rings, oil caps, drain *****, valves, and parts. Three basic methods are used in safetying; safety-wire, cotter pins, and self-locking nuts. Retainer washers and pal nuts are also sometimes used.

Self-locking nuts are used in applications where they will not be removed often. Repeated removal and installation will cause the self-locking nut to lose its locking feature. They should be replaced when they are no longer capable of maintaining the minimum prevailing torque. (See table 7-2.)

Table 7.2 doesn't have 3/8". If you use 7/16-20. The min prevailing torque is 8 inch-pounds. Prevailing torque is the amount of torque needed to run the nut down a thread

 

Is it me or are there a lot of pilots on this board?

Sorry to hijack. These aren't the droids you are looking for.