First this is not a brand issue so we can put that to rest. This is NOT and OE defect or the result of a weak arm. It is a WEAR issue created with the mild steel tab on the arm and a loose endlink nut. The stud sliding up and down elongates the hole and results in failure. We have seen a number of worn holes because the endlink stud and nut were not tight. Our shops have been able to 'repair' them with hardened washers and new tight nuts. Once again, the complete failure is rather unique, but not wear in the hole from loose endlinks.
If you have installed a larger aftermarket bar and do not get the endlink tight you can expect the hole to elongate, to wear faster because the load is higher.
Once again, this is NOT a brand issue and applies to ANY and ALL brand larger bars. It is a mild steel tab subjected to a substantial load. The assembly must be made tight and kept tight.
Removing the OE nuts on the ball joint studs and installing them is awkward at best. We have our own system for this that works for us at Pedders. Torque is a gift to the automotive world. We love torque under the hood and the instant acceleration it provides. Toque is also a solution to removing endlink nuts.
1. Clean the threads with a wire brush
2. Spray the threads and nuts with penetrating oil
3. Allow the penetrating oil to soak in
4. Pull out your biggest baddest air gun. Hit it full on. The instant acceleration will break the nut free and remove it
This is no different than breaking your tires free on a burnout. The car stands still while the wheels spin free. In your home shop it may or may not work. It will be dependent on your line pressure, the CFM and you air gun. Torque is the key. The more the better for removing the nuts.
The endlink nuts have quench. They have built in resistance to prevent them from coming loose. When your remove them they lose some quench. Every time you tighten the nut or remove it it loses more quench. You can replace the nuts with new OE or new nyloc nuts of the appropriate grade. You can add a hardened washer on the nut side. You can reuse the OE nut with some LocTite. I LocTite almost everything under the car except drain plugs and lug nuts, but that is a different story.
All of these will work IF you get the nut tight.
When you spend sufficient time under a car you learn the feel of a tight metal to metal assembly. You learn the sound of your gun. You know when it is tight. There are GM assembly torque specifications to follow. When you get down to it a seasoned technician will be very close with their torque based on the assembly and bolt size to the OE torque spec because they have done it so many times. They just know. Please save your indignation for not using a torque wrench on this particular assembly. Given the space constraints and number of times the endlink nuts come loose we made the decision to use the gun. If we break it, strip it or whatever we replace it. Time to move on.
In a home shop there will be many that are as good or better technicians. Based on the number of endlink nuts that have come loose they are a problem for many at home and in shops regardless of skill level. Most failures are just lost nuts. PQ had real damage. That brings us to getting these endlinks tight.
1. Clean the threads with a wire brush so tight is tight and not rust binding in the threads before it is really tight
2. Thread the nut on with your fingers to make sure it is correctly threaded
3. Bring out the air gun and make it tight
What can go wrong? You can strip the threads on the endlink ball stud. You can strip the threads out of the nut. You can crack the nut. These are all things that will go wrong if you allow the air gun to just hammer away. You are tightening an all metal assembly. When it beds it is tight. The extra torque from the air gun will get you there. When it all bottoms out stop. If you are not comfortable with this, then do it by hand, BUT they have to be tight or you'll lose a nut, damage the hole or cause a complete failure.
Pedders does supply our bars with endlinks. You can see in this picture the face of the ball stud that mounts flush to the arm is robust. The washer that is installed on the nut side is large and thick. The nuts are nyloc. These combine to make the assembly secure. Feel free to use an air gun. We have yet to strip any threads or crack any nuts. If you do let me know and I'll replace them. We believe that tight is the priority because of the wear we have seen on many DIY installations. Other companies will have different recommendations and you should follow them.
The key take aways from this thread is how critical it is to get the endlink nuts tight to GM torque specifications the first time and knowing that the OE nut loses quench every time it is turned. With proper care at the time of installation your endlink nuts should remain tight in place and your lower rear control arms will provide excellent service. There is NO brand issue. Your OE arms are good to go. Get the endlink nuts tight the first time.
Buy a 55 gallon Drum of LocTite and just dip everything
