Joined: Aug 2017 Posts: 425 Threads: 30
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Location: Wellington, NZ
I know this might get a lot of conflicting answers but...
I know the torque setting on the Phoenix rod big end bolts is 35 ft-lbs. They are ARP bolts. But is that dry or with lube? The ARP site talks about their fancy lube which isn't too expensive. Do people just use that? Or clean oil? Blue Loctite? Does it matter?
Simon
Joined: Aug 2017 Posts: 741 Threads: 8
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Location: N W Kent
On any rod, the clamping force you're aiming for is whatever was used when the the big ends were bored and finish honed, as then you should have a perfectly round surface. That clamping force in turn comes from the bolt torque used when the big ends were fitted up for machining; obviously, lubrication of the thread has some effect on the transfer of bolt torque to clamp force.
Whatever may have been used -I would suspect a drop of oil- I doubt that the expensive ARP lube was used back the machine shop. Personally, I use a Loctite Nutlock type product when I put up big ends, it does act as a mild lubricant till it sets.
BTW, if you really do want to use the ARP lube, PM me your postal address and I'll put you a sachet in the post. I buy a fair few sets of ARP bolts (I never re-use big end bolts) and the carded sets always come with a sachet of the ARP lube.
Joined: Aug 2017 Posts: 3,417 Threads: 107
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Tightening torque is partly used to generate axial force, and partly to overcome friction. The lower the friction the higher the clamp force. This is important in critical fasteners like big end bolts as you may take the bolt into yield, or conversely it may be insufficiently tight. You are right to worry Simon; and Stuart, I share your doubt about fancy lubes.
Last time I had to ask this question the reply I got was 'in engine assembly condition', which meant with oil. However I know nothing about Phoenix or where your spec came from - may be best to go back to them or the bolt supplier. If all else fails you could conduct a torque - angle test to establish yield point and work backwards.
Joined: Aug 2017 Posts: 425 Threads: 30
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Location: Wellington, NZ
22-08-2018, 08:24 AM
(This post was last modified: 22-08-2018, 08:25 AM by jansens.)
I managed to get some ARP lube in the end. Thanks Stuart for your kind offer though.
I did try to buy some locally and the local auction site had a small sachet for $4 but it was in Australia and they wanted $15 shipping. I could only find large tubs of it in local stores. In the end I rang the guys who did my balancing. They are really an engine rebuilding place so I figured they'd have some. He mentioned they also get the little sachets in packets of ARP studs but they didn't have any about right then but if I could pop in and he'd give me some in little plastic bag. You don't need much for 8 bolts!
So the bottom end is all done up now to the correct torque (and it still rotates, handy!).
Since I was there I asked what they used on their head gaskets. He asked what kind it was and I said it was the copper kind and he said they always use a spray of Hylomar on those.
Simon
