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Thread inserts in the Norton head

Discussion in 'Norton Commando Motorcycles (Classic)' started by comnoz, Oct 8, 2019.

  1. cliffa

    cliffa

    Joined:
    May 26, 2013
    Hi Jim,
    Actually I should have reworded it I guess. I didn't mean to test to failure, but maybe a margin for user error or torque wrench inaccuracies perhaps 20% over? What i don't understand is if the insert is flush with the surface and bottoming on the barrel or gasket why would it strip the thread in the head? Aren't the heads even strong enough to compress the gasket without fear of failure of the inserts (outer) threads?

    Cheers,

    cliffa.
     
    Last edited: Oct 10, 2019
  2. comnoz

    comnoz VIP MEMBER

    Joined:
    Dec 10, 2008
    When I install inserts for an actual job I install them 20 or 30 thousandths below the head surface.
    The inserts always pull and settle a little bit and you don't want them to touch the head surface or even the gasket with any pressure.

    I will redo the test with the Bigsert and the standard helicoil with them both below the surface and use a solid spacer. This time I will use the low mileage head that I used to pull the stock stud. Since it is not annealed like the high mileage head was, I expect considerably higher torque readings.

    I did not test my insert as I did not want this to be construed as a sales pitch for my work. My insert is adequate. I will leave it at that.

    This test was simply done to dispel a common but incorrect belief concerning Helicoil coil type inserts. If you read the Helicoil literature they do state that the coil insert is the best choice in aluminum -and they are correct.

    And the ARP stud has .500 of thread on it. It would be nice if there were more.
    But it makes no difference in a solid insert or in a 1/2 inch long helicoil insert.. Jim
     
    Last edited: Oct 10, 2019
    cliffa likes this.
  3. cliffa

    cliffa

    Joined:
    May 26, 2013
    Hi Jim,

    Thanks for clarifying.

    I don't think anybody on here would accuse you of sales pitches :).

    Cheers,

    cliffa.
     
    Last edited: Oct 10, 2019
  4. Time Warp

    Time Warp .......back to the 70's. VIP MEMBER

    Joined:
    Dec 3, 2012
    I'll take a guess on the alu/bronze insert (with 20 TPI thread)
    800 in/lbs and the stud started to fail. ;)
     
  5. comnoz

    comnoz VIP MEMBER

    Joined:
    Dec 10, 2008
    Ehh, the only one that will do that is the 1/2-13 wire helicoil with a 3/8th to 1/2 EZ-Lock inside it. The nut will give first.
     
  6. jseng1

    jseng1

    Joined:
    Nov 26, 2009
    3/8-16 ARP studs with threads longer than 1/2" are available as shown in the photo below (modified stud for iron barrels). A 5/8" long timesert would probably out perform a 1/2" long heli coil, but that comparison is not being made. It makes no sense to use a 1/2" long insert when a 5/8" long insert will fit (5/8" long Timesert shown). 3/8"-16 thread Helicoils are not available in 5/8" length (unless you made it custom).


    [​IMG]
     
    Last edited: Oct 11, 2019
  7. lcrken

    lcrken VIP MEMBER

    Joined:
    Mar 15, 2009
    It's pretty easy to shorten a longer Helicoil to whatever length you need, by just snipping of a coil or two from the top. I've done it a number of times, and it doesn't seem to have any effect on the function of the insert.

    Ken
     
  8. lcrken

    lcrken VIP MEMBER

    Joined:
    Mar 15, 2009
    And, Helicoil inserts are available in 3/8-16 thread size in .562" (5/8") installed lengths.

    CORRECTION: The above is incorrect. As jaydee75 pointed out below, .562" is 9/16", not 5/8". Stanley does not make the Helicoil brand in 5/8" length for 3/8-16 threads. One would have to buy the 3/4" length and trim it to 5/8". My apologies for the brain fade.

    Fun fact. You can also get them in that size in titanium. Just think of all the weight saved:). But they cost almost $6 each, and the stainless ones are only about $0.75 each.

    Ken
     
    Last edited: Oct 12, 2019
  9. cliffa

    cliffa

    Joined:
    May 26, 2013
    Titanium inserts - Ken, for gawds sake don't tell Fast Eddie, or he'll be working out how many threads he needs to replace in order to trade off the fact that he's fitted an electric foot to his 920. :eek:
     
    swooshdave likes this.
  10. lcrken

    lcrken VIP MEMBER

    Joined:
    Mar 15, 2009
    Lots of info in the Helicoil catalog and data sheets available here

    https://www.stanleyengineeredfasten...allanguages=[English]&f:brandlist=[Heli-Coil]

    This is their installed strength chart for 3/8-16 inserts

    3-8-16 Insert Strength.JPG

    For our case, the Aluminum 356-T6 spec is probably the one closest to the Commando head alloy, so you would want the insert length to be at least 1.5 times the diameter, or 9/16" to not pull out from torqueing a 170,000 psi bolt. 170,000 psi is a reasonable value to assume for high quality studs. That's what the ARP high strength stainless fasteners are rated at. I'd go to a 5/8" one just for a little extra safety margin. And I would use a stud with 5/8" thread length.

    Ken
     
    Last edited: Oct 12, 2019
  11. Time Warp

    Time Warp .......back to the 70's. VIP MEMBER

    Joined:
    Dec 3, 2012
  12. lcrken

    lcrken VIP MEMBER

    Joined:
    Mar 15, 2009
    Well, there might be a galling problem between the Ti inserts and the Ti bolts and studs I'm sure he will also want to use:rolleyes:.

    Helicoil inserts are also available in Inconel, phosphor bronze and Nitronic 60. Nitronic 60 is supposed to be very gall resistant, so maybe best for stainless fasteners like the ARP stuff, but they are about $3 each in this size, so still way more than the common 304 stainless inserts. I'll just continue to use thread lube instead.

    Ken
     
    cliffa likes this.
  13. comnoz

    comnoz VIP MEMBER

    Joined:
    Dec 10, 2008
    Those helicois are just the thing for turbos ect which run at temps that would make a Norton head into a puddle on the ground....except maybe the phosphor bronze which might be interesting.
     
  14. lcrken

    lcrken VIP MEMBER

    Joined:
    Mar 15, 2009
    And don't forget the bragging rights! "Hey Bubba, you got them there titanium inserts in that piece of angle iron holding the Harely mufflers on yer Commando?"

    Ken
     
    Fast Eddie and worntorn like this.
  15. jaydee75

    jaydee75

    Joined:
    Jul 2, 2012
    For the record, .562 is 9/16.
    jd
     
  16. Burgs

    Burgs VIP MEMBER

    Joined:
    Dec 14, 2013
    Hi
    Helicoils work best when you read the instructions correctly, we made 10 off large Sterndrives years ago and the original engineer called for Helicoils in every thread in the aluminum castings, something like 600 in each leg, from 6mm to 20mm, my initial thoughts at the time were yuk as I had repaired quite a few other peoples stuff ups in my time.
    I ran some similar tests as Jim has done and was also surprised at the results, when I was testing I followed the instructions to the letter, and found that getting the end of the Helicoils below the surface sufficiently was of utmost importance, it locks the coil in place so they don't screw out, depth of the tapped hole and correct length of insert also critical.

    I have just finished fitting Full Torque (Lock & Stich)1 1/8" inserts into a Caterpillar 789 (190 t) rear dump hub, and they have a very odd external thread on them, bit like a hook, had to hand tap them ouch, these are the recommended Cat inserts for this particular job. When installed there is a tool for drilling two holes for the fitting of locking dowels/small pins.

    Just a bit of my experiences thread inserts.

    Thanks Jim for tests Jim great stuff.
    Burgs
     
  17. cjandme

    cjandme

    Joined:
    Feb 5, 2011
    Sikorsky Blackhawk H60's use thread inserts on the main rotor hub, during overhaul if they fail drag torque you gotta replace them.. Usually Lots of heat is needed to get them to let go. Not that this is really relevant to Jim's Norton head "thread". Pun intended - - - - thanks for conducting these comparisons through, most interesting.
     
    Last edited: Oct 11, 2019
  18. Onder

    Onder

    Joined:
    May 11, 2010
    If you are only doing a few holes then the difference twixt 50p and 3 quid is of little import. Does it help in the long run as the head
    inevitably softens? Parts used to be a big expense in mechanics now it isnt so much the parts but the labour (for those of us without
    a tool room).
     
  19. lcrken

    lcrken VIP MEMBER

    Joined:
    Mar 15, 2009
    You are quite right. Just another old guy brain fade moment. Thanks for pointing it out:oops:.

    I will edit the original post with a correction. My apologies to JS for incorrectly correcting him.

    Ken
     
    Last edited: Oct 12, 2019
  20. lcrken

    lcrken VIP MEMBER

    Joined:
    Mar 15, 2009
    And to make it more embarrassing, I couldn't find a 5/8" length 3/8-16 helical wire insert from any other manufacturer (Recoil, Precision, E-zlock, etc.). It seems like they all mostly pick lengths as a multiple of the thread nominal diameter, i.e. 1.0x, 1.5x, 2.0x.

    Ken
     

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