ARP Assembly Lubricant....how to use the stuff

[Guest]

OK, so I hope to re-install my head tomorrow and I have ARP studs. Where does one apply the ARP Assembly Lubricant, on both ends of the stud? And their website seems to intimate that you should reduce the amount of torque if using their lubricant. Now, that said, this is the second go-round for this set of studs and they have been "stretched" once already.

Any comments?

 

[Brosky]

Bill,

I called ARP for the reasons that you state, with the exception of the torque, which is another matter. The studs should be perfectly clean and dry and you apply a thin layer to the threads wherever they come in contact with a mating surface. Bob at ARP said that the best studs and bolts are the ones that are already stretched, so they highly recommend using theirs over. Actually, he said that they are designed just for that.

OK, now the torque issue.

I went over to the machine shop today, because I wanted to see the progress on my engine. He was getting the rods ready to be resized and had the new ARP rod bolts installed. I asked him what he would use for torque settings and he said what was in the package for the ARP Moly Lube. If he was using 30W oil, it would be different. For what it's worth, Bob uses nothing but ARP bolts and studs on all of the engines that he builds.

There is a section of the ARP site that specifies all of the torque settings, both with their moly and with 30W oil.

 

[Guest]

That said, their published torque setting for with oil or with their lubricant show a rather large difference in the amount of torque used. Apparently, if one were to use the torque settings in the Bentley and used ARP studs and their lube, you would be <span style="text-decoration: underline">way overtorquing.</span>

 

[Brosky]

I know that Bill. And it bothers me. I just haven't dealt with it yet, because I'm a week away from getting my block back and just discovered this last night while digging around the ARP site.

Please keep me posted on what you decide to do.

 

[Brosky]

Bill,

I say that this bothers me because I checked with Erik earlier and he can't say for sure that he used the ARP or the Triumph spec for torquing the head studs. I know that we talked about it and he had the ARP sheet out when he was working on it, but I'm just guessing. He never snapped any off and I never had a leak, so it could have gone either way.

This amount of lube seemed to work OK when they were installed.

 

[70herald]

And their website seems to intimate that you should reduce the amount of torque if using their lubricant. Now, that said, this is the second go-round for this set of studs and they have been "stretched" once already.

Any comments?

Make sure the the nuts rotate smoothly on the threads. That way you can tell if there was any damage to the threads. If they bind you need to replace them.
The head studs on the Triumph are not supposed to be permanently stretched. Other more modern engine designs use bolts which are stretched beyond elastic stress levels and are for 1 time use.

If they are properly installed, the studs on the Triumph engines are only stressed to about 70% of the level needed to cause permanent deformation (what is technically known as "plastic deformation"). When the stress is released, the studs will return to their original length.

ARP recommends a lower torque when using their lubricant since their lubricant / procedure of tightening and loosening several times eliminates galling, a type of friction when microscopically rough metal surfaces begin to stick to each other. The atomic configuration of MoS2 consists of a sort of flat plates which slide against each other very easily. The multiple tightening routine ensures that the MoS2 is both well distributed and bonded (MoS2 is highly attracted to iron) to the microscopic irregularities in the thread surfaces. Since the friction level is significantly reduced the amount of torque needed to overcome friction is also significantly reduced.

Bottom line, ARP hardware is great stuff as long as the threads are in good shape reuse the studs and follow the instructions exactly.

 

[tomshobby]

I agree but the metallurgy references only apply if the alloy supports them. Making this one of the most compelling reasons to purchase quality studs (and other parts) from a trusted and reputable source like ARP. Ordering parts solely on a cost basis or without knowing the source, I believe, is a crap shoot.

 

[billspit]

My ARP rod bolts came with explicit directions on how to install them I had to torque and re-torque three times total. I'll bet their head bolts come with directions too.

A fellow car club friend used to race Spits years ago. He said they would drill out the bolt holes in the block, tap and and use a standard GMC head bolt that was quite cheap. That's a bolt, not a stud. I thought about doing this, but did not since I am not going to be using an insane compression ratio.

 

[RonMacPherson]

Problem there is that bolts, when cinched tight, have a tendency to "lift" the metal around the threads of the bolt hole. So you wind up with a surface that is not truly flat. Whereas studs, fingertightened do not pull the metal up and when you tighten down with the nuts you're pulling things together.

Now this is for high performance engines, something that is not run in a stressed condition may not cause any problems whatsoever. But thought I'd throw this into the info pile also.


According to Smokey Yunick, and Grumpy Jenkins, better to stud than bolt.

 

[Brosky]

As in another thread from my head swap, my ARP studs went through the five (5) torque process, which has now been changed to three (3), which makes Erik, very happy.

And yes, the paper that came with them said five (5) times. That was something neither of us thought up on our own. After you get through the third set, you are about sick of doing it.