Failing nylocs?

[Mole]

I've just fixed a problem with the handbrake lever which had worked loose having lost one of the bolts and both nylocs securing it to the brackets in the transmission tunnel. A colleague at work recently had the same happen with fixings for his bike panniers.

 

Now it is just possible that I forgot to tighten them, but given the meticulous care I took during the build I think this is improbable. I guess being so inaccessible, the post-build check probably wouldn't have picked this up.

 

It got me to thinking that if these two had come loose in the space of 7,500 miles (over a year), how many other bits are working loose as well? Now scheduling a complete spanner check for the weekend!

 

Has anyone else experienced losing their nylocs?

 

 

SV 52 CAT - can moles fly - you bet!

[R2D2]

Nylocs are a cheap anti-vibration nut and aren't really that great depending on how many time they have been used.

 

The problem with a locking nut is that it is virtually impossible to torque tighten them correctly with a torque wrench. The stiction that the locking feature introduces makes the torque reading almost meaningless and I think that in most cases nuts come loose because they are not tightened correctly despite everyone's best efforts. Even when you don't have to torque tighten a new nyloc can be relatively stiff and it is easy to under tighten a bolt.

 

If you have nuts that don't need torque tightening but must not shake loose I would use a Kaynar or K Nut wherever possible.

 

These lock using an ovalised portion in the nut and are a use once and discard device but very secure.

 

They are all reduced hexagon and have an excellent strength to weight ratio.

 

They are generally made for aircraft applications by Fairchild and are hideously expensive if you buy them with CAA/FAA Release Notes but Trident Racing Supplies sell them for very good prices and are very helpful.

 

You not only improve locking but save some weight at the same time.

 

[Tony C]

If you check the Torque Wrench section of 7faq the recognised technique of torquing locknuts is to check the torque required to wind the nut down the thread, out of contact with the item you are tightening the nut onto, and add that torque to the recommended torque value.

 

Locknuts "can" be used more than once if the locking portion is checked to still give a reasonable amount of torque, as above, but in a safety critical location should only be used once.

 

BRG Brooklands Aero Screen SV 😬 It is only with the heart that one can see rightly; what is essential is invisible to the eye. (Antoine de Saint-Exupery)

[P Brews]

K-Nuts are a much better solution than Nylocs. You should be able to use them about half a dozen times before they lose their locking. Try www.clarendoneng.co.uk.

[Joe 90]

I can't recall a nyloc coming undone (in 100,000 miles) as long as it was new. I'm surprised at anyone attempting to torque up a nyloc, and would suggest going by feel. Are there any nylocs on a Caterham that qualify as critical?

 

Starting all over at 40.

[scooby dooby doo]

quite a few - rear hubnuts, aframe to chassis, dedion to a frame, diff to chassis, engine mounts to chassis....

 

HOOPY

R706KGU Hoopylight R