Torque spec variance with Anti-Seize

Question

I see a lot of variances with torque specs when a fastener is lubed with anti-seize. Some places say 25% less torque is required for same clamping load, some places say 40% less is required.

I'm rebuilding the chassis on my jeep and have had to cut out about 8 bolts now. When reinstalling bolts I am covering them in anti-seize to avoid future issues during removal. I only recently learned enough about fastener tech to understand that I have been over torquing fasteners for a while now.

What percentage do you other mechanics use in this scenario? My factory service manual doesn't provide wet values so all I have to go off of is what LocTite recommends.

Answer 1

If I'm using anti-seize, I still don't reduce the torque on the fastener. I use the amount specified by the application. The reason being is, in most places where torque is a factor, getting the clamping load even is more important than is the factoring in the amount the lube will reduce the need for torque. The anti-seize will work as a lubricant on the threads. You will get a more accurate torque with it than you would with dry hardware. With dry hardware, you can actually be twisting the fastener, which interferes with the overall torque reading (the extra friction caused by the dry threads allows twisting of the hardware and an inaccurate torque reading). Lubricating the threads takes care of this problem, which is what the anti-seize would be helping with.

Even ARP Fasteners agrees that fastener assembly lubricant is important prior to doing your torquing of the fastener. In this video, yes they are advertising their product, but they reiterate pretty much everything I've said.

If it is that important, you should use a dial indicator to pull a stretch on a bolt, which is far more accurate than anything else. This takes into account all variances in the different fasteners and gets the clamp exact.

Answer 2

Although prior answers are indeed correct, the lubricant question is mere pedantry for any fastener that is not critically torqued.

Head bolts (ARP and otherwise) are an obvious exception, but as such these are usually provided with a special lubricant, or clearly stated as a lubricated torque with something like 30W motor oil.

There is no way any chassis component on your Jeep requires critical torquing. Whatever overtorque results from lubrication and torquing to a dry specification can be ignored. You are not going to come anywhere near the elasticity of a Grade 8 fastener. This is not a TTY (torque-to-yield) application.

My feeling is a 25% undertorque might result in improper clamping force, which is far more serious an issue that the "overtorque" resulting from lubrication. That number is far too high anyway, as even a "dry" specification assumes CLEAN and dry.

It's along the same lines as the shadetree parable of never using anti-sieze on wheel studs - 'cuz your wheels will fall off...

To further be a stick-in-the mud, when was the last time you had your torque wrench calibrated? I'm guilty of such things myself. That SnapOn your father bequeathed to you may be a beauty, but I have little doubt that the average torque wrench with some age, and which was sometimes put away under tension, can vary by 10-20% all by itself.

Answer 3

Angle of turn is the answer. A dry bolt/nut will resist turning (higher torque) giving less grip/clamp a wet bolt nut (less torque) will turn easier. So find /work out the correct angle of turn when grip or clamp is the critical criteria.

Answer 4

Depends on the type of anti seize and how much. The key with wet torque is to be consistent with the amount of lubrication. 30% might be a good starting point... But other factors would include how clean the threads are dry... are they damaged? do they have a lot of crud on them?

One way to check is to torque the bolt as you normally would dry then draw a line across the bolt where it meets on the wheel. Take it off then torque that bolt again with lube finding the amount of torque needed to line it up as it was dry.

However I wouldn't advise it. You may have the same clamping force as required by the owners manual. But on a part that rotates/moves/vibrates heavily torque is more important to prevent the bolt from backing out.... I wouldn't gamble with any lube on lugs.