All New Lock Nut Hardware?

When rebuilding one of these things...Are there certain applications where the old fasteners can be re used? I can certainly see places that I want to use new bolts and upgrade to locknuts...but where does a guy stop?

how do we determine when and where to use lock nuts on a daily driver?

My last full resto was my Formula Vee race car... EVERY nut was a nylon locker.

 

I use lock nuts, washers, or both, on EVERYTHING!!

Eliminates the need to keep checking the torque/tightness, and gives peace of mind.

Body and panels and such I use grade 5, and those are cheap, but susp., crossmembers, and other brackets that bolt directly to the frame I like grade 8, but those get pricey.

 

Same here, if the fastener is supporting a load or torque I'm using grade 8, otherwise grade 5. I'm turning away from any nylon style lock nuts, read this article and sticking with all metal locking nuts. I have found a local dedicated nut and bolt store that has decent prices and almost half the cost of the big home improvement stores.

 

Use lock nuts on any critical application (ie: steering, axles, suspension). Use what ever kind of locknut you what.

Bolt grades depend on application. Reversing and variable loads require higher strength fasteners. Steady loads require lower strength fasteners. There is no point in making a bolted joint stronger than the base material, it is better to break a bolt than have a failure in the base material.

Bolts should be torqued to roughly 75% of their Yield strength. See Chart.
http://www.engineershandbook.com/Tables/torque.htm

 

Thanks...I have also read that there is no point in using harder stronger bolts in some applications...my experince and common sense tells me to use lock nuts on everything. already commited lockers to the steering box/gear to frame...trans cross member, and master cylinder kit. Convinced to use them throughout the build now....

Read a book by Carol Smith he worked on the Ford GT-40 program...he wrote three things that have always stuck with me...But have never had any one else agree to.

1) there is no such thing as a lock washer, that by the time the nut is tight enought to do its job...the washer is so squished it is of no use.

2) any lock nut...in a critical application should never, never be reused.

3) all lock nuts should only be tightend to clamping force and have three threads showing beyond the nut, anything more and it to is deformed beyond use.

 

I disagree with that statement. Sure a lockwasher gets squished flat once the bolt is torqued but if the bolt/nut ever begin to work loose, the lockwasher springs into action.

So a lockwasher won't keep a bolt/nut torqued to spec, it will act as a safety device to prevent fasteners from working themselves entirely free. That is why you rarely see lockwasher used in applications where torque spec is critical (such as head bolts) but see them often in areas where bolt presence is more important than torque.

Lockwashers serve no purpose in applications where a fastener cannot be torqued at all, such as wheel bearings, where a castle nut and cotter pin is the best answer. Here, oftentimes, the lockwasher would not get compressed enough to do its job.

But to say lockwashers are useless because they get squished is a fallacy.

To answer your question about reusing fasteners and lockwashers, I think it is OK in certain applications. Reusing a lockwasher is acceptable if it is not deformed or broken. Same goes for a fastener. Bolts subjected to high torque and heat variances should be prime candidates for replacement, such as head bolts that get stretched by design.