Torque Wet or Dry?

Specifically for the brake caliper job Cleveland specifies in the manual that the torque settings are dry and anti-seize should not be applied to the back plate tie bolts.

See here

See Appendix A3 for torquing instructions and the torque table.

[ local copy ]

I use MoS2 paste on anything that is stainless steel or spark plugs, elsewhere I put carefully selected types of Loctite on threads that are critical and vibration loaded. Shakeproof washers are definitely not safe and those bloody safety wires cost you , well, blood, endless hours to do and undo, same with split pins and the like. I can´t see copper as a good lubricant, but definitely MoS2 is recommended for extreme pressure purposes. When I was toolmaker apprentice decades ago I did quite a few die sinking mould inserts where you fabricate a hardened shaped and polished punch that gets sunk/pressed into a “soft” piece of suitable steel block to form the negative cavity for plastic injection moulding. The punch was pressed into the steel insert at a speed of about 0,10 mm per second several centimeters deep and the ONLY lubricant for the punch was a smear of MoS2 paste on it. After one operation you had to get the punch out of the piece of steel for the next several inserts , maybe tens of them, so you better kept everything really well lubricated. And yes, I confess, I extremely rarely use a torque wrench, for head bolts on a car engine at best. There is a saying: You can never do a bigger mistake by feel than you may do by a “calculation” – with regards to torque wrenches . . . Or similar: You may do a real big f-up , but for a real BIG, I mean a BIG f-up you need a computer . . . Vic

Jacko wrote:

I don’t know why Lycoming forbids graphite thread lube

Nothing corrodes aluminium more than graphite (galvanic corrosion). Can’t imagine copper paste being too good either though. At least engine oil won’t do any harm in this respect.

I don’t know why Lycoming forbids graphite thread lube. Maybe a metallurgical thing. However, the Autolite stuff definitely contains graphite and is commonly sold to and used by aircraft technicians. What about the Champion anti-seize compound, does anyone know what that consist of?

Does anyone know the composition of the modern anti-seize compound? It is likely to be a common industrial product relabelled and sold at an obscene profit.

That Lycoming instruction is outdated. The spark plug anti-seize compound is much better. I do not know shops that still use engine oil. Not recommended.

Jacko wrote:

From Lycoming Service Instruction No. 1042AC:

Use a copper-based anti-seize compound or engine oil on spark plug threads starting two full threads from the electrode, but DO NOT use a graphite-based compound.

Thank you for this! Very enlightening.

Given that the anti-seize compound is quite slippery, it thus sounds like the spark plug torque is specified “wet”, so putting oil on the thread is probably OK.

That would be the safer way to do it because if you specified it “dry” then any slippery stuff on it would over-stress the threads and there would be many problems in the field.

I used to use copper grease carefully (not in the first 2 threads) and it still got into the oil analysis.

Archer – this post should point to a suitable plug spanner.

From Lycoming Service Instruction No. 1042AC:

Use a copper-based anti-seize compound or engine oil on spark plug threads starting two full threads from the electrode, but DO NOT use a graphite-based compound.

and as long as the copper grease is applied sparingly, and as instructed, I don’t see a lot of it getting into the engine oil.

As for wet or dry, as NJ wrote, RTFM.