Lube recommendation for connecting rod bolts. | FerrariChat
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Lube recommendation for connecting rod bolts.

Discussion in '308/328' started by E-Dino, Apr 19, 2013.

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  1. E-Dino

    E-Dino Formula Junior

    Aug 11, 2012
    378
    San Diego
    #1 E-Dino, Apr 19, 2013
    I was wondering if anyone had a recommendation for the lube to use on the connecting rod bolts. I purchased new nuts as recommended in the manual, but when I torque them up I am getting a sticky popping feel when I get close to the 6.6 Kgm Tq. Currently I am using oil on the bolt and nut but is there something else that is recommended or commonly used?

    Thanks,
    Paul
     
  2. E-Dino

    E-Dino Formula Junior

    Aug 11, 2012
    378
    San Diego
    #2 E-Dino, Apr 20, 2013
    Not much chatter on this topic. Maybe this isn't the engine build group. I may be a fool for slick advertising, but after poking around the internet, trying to get smarter, I came across this stuff...

    [ame=http://www.youtube.com/watch?v=6-XXVk_vwKw]ARP Ultra-Torque Tested on Horsepower TV - YouTube[/ame]
     
  3. mike996

    mike996 F1 Veteran

    Jun 14, 2008
    6,871
    Full Name:
    Mike 996
    #3 mike996, Apr 21, 2013
    The service manual should state IF lubricant is to be used and, if so, what type. DO NOT lubricate a fastener that is supposed to be torqued dry; it's a good way to fracture it. The common lube - though by no means only lube that was usually specified when lube was required for a specific fastener - was 30 wt motor oil.

    Specs usually state whether the fastener is to be torqued clean and dry or clean and lubed. Do what the specs say! Torquing a lubed vs dry fastener will change the actually torque (stretching) by 30+ percent. IOW, if a fitting is supposed to be torqued dry to 100 lbs, and you lube it with engine oil, the fitting will have the equivalent of 130+ lbs on it. Other lubes can be more slippery and will result in even higher actual torque on the fastener and a higher chance of breakage.
     
  4. E-Dino

    E-Dino Formula Junior

    Aug 11, 2012
    378
    San Diego
    #4 E-Dino, Apr 21, 2013
    Mike, Thanks for the response. i was hoping someone had experience with these nuts and was willing to share. I wanted to make sure I got this step right so after investigating stretch gauges and torque wrenches I decided to upgrade my torque wrench and bought a new fangled electronic digital wrench. I am not sure but this may be part of the problem because when you get close to your torque setting the sound changes from beeps to a solid tone. This causes you to decelerate as you are torquing and I think the friction changes. I have since gone back to recalibrate my click style wrench and I think I will use that from now on. But I am still not really comfortable with the lube. The manual says you have to replace the nuts every engine rebuild. Some web sites say you should only have a few torque cycles on a bolt. Some sites say you need several torque cycles just to get the torque right (like that link I showed above). Nowhere in my manual can I find any mention about using oil or anything (so I would assume that means dry?). So what if I take everything back apart and clean it and torque it dry and I still get this sticking pop feel at the top of the torque? Has anybody else had this happen to them?
     
  5. mike996

    mike996 F1 Veteran

    Jun 14, 2008
    6,871
    Full Name:
    Mike 996
    #5 mike996, Apr 21, 2013
    If there are no specifics mentioned in the Ferrari service manual (I have never looked) re lubed/unlubed for torquing, one could check the torque figures for the specific grade/thread/size of the fitting which are available in various tables in books/on-line that will specify torque with or without lube/what type. Most US auto service manuals actually stated at the head of the torque specs page something like, "All torque specifications are for clean, dry threads," or "All torque specifications are for clean threads lubricated with SAE 30 wt motor oil."

    It doesn't really matter which way you do it as long as you apply the appropriate torque for the condition (dry/lubed).

    The most accurate torque wrenches are beam type with dials but frankly for most use, it doesn't really matter as long as it's a reasonable quality wrench. Digital wrenches are easier to read but they are not more accurate. Click-type torque wrenches are the most popular and easiest to use and are perfectly fine for most normal use as long as you don't try to use them (or any torque wrench) at the limit of it's range. For example, if a wrench has a range of say, 10-100 ft pounds, it's accurate range will generally be in the 25-75 ft lb range. So for a wide range of torquing, you need a minimum of two torque wrenches - a 3/8" drive (which you will use most of the time) and a 1/2 drive. Three is better - adding a 1/4" drive.
     
  6. E-Dino

    E-Dino Formula Junior

    Aug 11, 2012
    378
    San Diego
    #6 E-Dino, Apr 22, 2013
    Thanks again Mike, your advice is spot on with most of the good info I can find on the web. What I guess it boils down to is RTFM. However, my FM is not so good. What I was hoping for was that some of the folks that have built these motors would share their own experiences. Actually what I would really like is to sit at a cafe in Italy with the guy that designed this motor and talk with him about stress and strain and have him tell me "Non preoccupatevi uomo sciocco, il motore andrà bene." or "Il vostro un idiota. Si sta per saltare in aria."

    Until that fantasy comes true, any help is appreciated. Thanks!
     

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