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Went to torque down the last 2 rods, and it seemed that my new rod nuts were not a great match to the rod bolts. The thread was close enough that they screwed on - taking about 23 ft-lb according to my digital torque gauge just to move down the threads. I removed the socket and found a big pube looking string of steel wrapped inside it.....
I remember on the other 2 rods, they went down with no effort since they aren't locknuts.
When I tore down the old 951 engine, 2 of the rods had different nuts than the other 2. They were 11mm triple square which was weird. So I dug up the old nuts and they did the same thing - threading on with resistance. So that eliminates the thread being different for some reason. The bolts themselves also visually appear the same as what's on the other 2 rods that went in fine.
Anyone been in this situation before? I'm really thinking about getting aftermarket rods at this point. That torque spec is absolutely important so this isn't ok.
Actually now that I look closer, the 2 rods that are giving me issues actually have different bolts! The dimple at the end is slightly different. Guess I need to find some ARP nuts, or 2 good used rods with stock bolts.
Dear Micheal: since you are that far into it, I would just replace all the hardware with ARP. Great stuff. BTW, you'll have to get the rod re-sized at the machine shop after they install the hardware. JMHO..&.02 cents..
Actually now that I look closer, the 2 rods that are giving me issues actually have different bolts! The dimple at the end is slightly different. Guess I need to find some ARP nuts, or 2 good used rods with stock bolts.
Really? That's freaky.
All I know about this stuff is Porsche has a bulletin about nuts, and it says nuts with smooth flanges are to be phased out for serrated flanges.
Seems very odd to have the material peel like an onion skin. Tough to assess after the damage, but I suspect either the nut or the stud thread was damaged. You might be able to chase it with a chase not a tap in this case then use loctite.
I'm a little wary about using the rod that had the steel swarf come out of it. It looks like it was from the nut, but the bolt threads have some shiny exposed steel now. Not sure if I want to take the chance on it after all I've put into this engine.
Interestingly, the ARP nuts don't have serrations on the bottom like my OEM replacement nuts do. But according to ARP their torque value is still 55 ftlbs.
Looking back on it, I failed to mention in my original post that the 11mm nuts I took off appear to be ARP, hence why I said I needed to track down new ARP nuts since apparently that's what these bolts need.
$200 for the ARP bolts and however much to resize the rods (maybe time to do the $350 MichaelMount Rod mod?)...or $650 for new Molnar rods... ARP bolts included
I would just get aftermarket rods if I had to spend more than $100 honestly. I have no idea what the background of these rods are, they're not damaged or anything but they're still the weak link of the engine right now. I definitely can't be bothered to spend $200+350 just to still have rods with unknown fatigue life. If they were verified low miles I'd be all over it.
Definitely let me know... I'm not familiar with the standard Molnar 944-series offerings, but for that price, I'm game as long they're going to stand up to modded 2.5 951 power.
04-22-2017, 01:19 PM
Connecting rod hardware issue
