ASRF Australian Street Rod Federation TAC ADVICE SHEET 1/20
There have been a few reports from the Rodders lately of nyloc nuts coming loose on some suspension components, such as ball joints and tie rod ends.
These issues have apparently been seen on some Holden replacement parts. Apparrently the owners were sure that they had torqued the nuts correctly and also were aware that they should not fully tighten a nyloc more than twice, but they still found the nuts had worked loose.
So a few reminders are in order.
It is recommended that a nyloc nut only be tightened twice over its life and then discarded and not used again. Usually a good check of the holding ability of the nylon insert would be a strong resistance to turning as the thread goes through the plastic. If it spins down easily like a regular plain nut, then it must be discarded.
On ball joint and tie rod ends where there is no hex to hold on the other end, we might find the tapered shank wants to turn in the taper hole as the nut is tightened, requiring the ball joint to be pushed hard up into the taper in the stub axle to stop it spinning. This is sign that the nylon is OK.
On street rods we usually do some trial assemblies before the car is finished, in which case you should do the test fit ups using a regular plain nut, and then fit the new nyloc on the last assembly.
There are a few other things that might cause a ball joint nut to come loose;
1/ Check that the tapers match correctly and don’t allow the shank to rock back and forth as this will certainly cause a nut to work loose.
2/ Check that the taper shank doesn’t pull up past the level of the surface that the nut tightens against as this will see the nut tight against the shoulder and not against the face of the flange. If you have this issue use a thick washer with a hole large enough for the end of the shank to go through.
3/ Issues are more likely when tapers have been bored larger to suit mixing parts such as L300 front ends using Holden Stub axles or Commodore tie rod ends on Holden HK to WB steering arms.
4/ Never use nylocs on components that get hot such as brakes or engines. There are other type of locking nuts that are better suited , ie deformed thread or star washer types such as below. Good bolt retailers will be happy to help here.
Lastly, we have seen some rodders attempt to open up tapers using die grinders and similar, which is sure to cause problems with things working loose, so please if you need tapers made larger, entrust the work to a quality machine shop who have the right taper reamers.
Peter Koning, ASRF TAC
This information can be found on the ASRF website at https://www.asrf.org.au/tac-advicesheets/