600 ft GRP Rods

Discussion in 'Manton Push Rods Top Alcohol Tech Questions' started by alcohol paul, May 25, 2009.

  1. Eric David Bru

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    Brian, if one doesn't have time to check each rod bolt with a stretch gauge, what torque wrench would you recommend??

    Do you recommend stretching them each time or just the first time? If only the first, what torque thereafter?

    Thank you,
    EDB
     
    #61
  2. linkplas

    linkplas New Member

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    a very good friend of mine who runs a top alcky dragster in New Zealand had the same problem. a new set of GRP's let go on just a couple of runs. the hole was BIG!. the few that didnt bust seemed to have loosened the bolts.
    Not assigning any blame here, just stating what was found...maybe the threads pulled causing the cap to loosen.

    always one of those touchy subjects. Ive run billet rods for 40 passes with one set of bolt replacements and no issues....and I know guys who have had rods go on pass #1.

    cheers
    Dave
     
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  3. underby6

    underby6 Active Member

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    #63
  4. WANNABE

    WANNABE New Member

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    I don't want to start too much junk, but we just went through a big load of crap recently with big name steel rods. (A few different US made companies.) The rod bolts would back out until the bearing would start to bite and K-boom. The rod would read like it was an oiling problem, but the other rods in the engine would be loose. I know two engine builders here that asked to get all of the engines back with these new rods in them. EVERY ONE had rod bolts backing out and losing their clamping force. They were pulling bolts out of the old thrown away rods to save these big dollar engines. Many engine builders have been round and round for the last year on this deal. Lots of top sportsman type engines. The verdict is a new alloy in an old standard part number fastener. I just hope that this is not what is happeneing with this mess.
    One of the signals was the torque numbers did not match the corresponding stretch numbers. :(
     
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    Last edited: Jun 3, 2009
  5. alcohol paul

    alcohol paul Jr. Dragster

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    I just put a rod in the vise and turned the bolt until something happened........The threads pulled out of the rod.
     
    #65
  6. Dale Finch

    Dale Finch New Member

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    Thanks Brian for replying. Will is right too. We should never just trash someone's product. I have worked with GRP's for about 6 years. I never took Brian's advise to check the bolts with the stretch gauge. Once you do you will never not do it. A top #3 car owner showed us how to do it and considering how many bolts are produced there are varying results. He had impeccable notes on each rod and bolts. Remember rod companies don't build bolts.

    I am laughing Randy. I thought I was the only crazy one with a & b's etc on rods. With different lengths and rod cycles one better keep track or it will get expensive.
     
    #66
  7. Mike Canter

    Mike Canter Top Dragster

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    Those were GRP rods with the L-19 bolts? You must have screwed up (lol):eek:. That is interesting. The only logical explanation would be that if they were a part of the original set that kicked the rods out that started all this then maybe the threads were already damaged by whatever caused the rods to go:D.
     
    #67
  8. hemi altered 378

    hemi altered 378 Blown Altered

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    you know, sometimes things just break, bad batch of metal...etc. we broke a brand new M300 mag drive shaft....no one could explain that one. things happen
     
    #68
  9. nitro4100

    nitro4100 New Member

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    hmmmmm I was talking about the guy that said he thought he put the cap on backwards the night before, Not trying to be a smart a$$ LIKE SOME PEOPLE. My point was If it had a number on Rod and cap facing towards pan rail It may not have happend. I was just trying to be nice about it. I have seen a ton of fuel teams stamp them. I like your idea on the length a,b,c
     
    #69
  10. AlkyDennis

    AlkyDennis Member

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    hmmmm....Didn't he say ..."The bolt will break before it pulls the threads in the rod. "

    Sounds like someone owes you a few sets of good rods to make up for the damage!:eek:
     
    #70
  11. secondwindracing

    secondwindracing top alcohol

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    use a go no go tool..and remember always back off the torque wrench whe you are done with it.Dave
    also if you have time when you knock off the pan set the wrench at what you put the rod bolts in at and see it it will tigten before it clicks if it does pull the rods out and put a new set in..Dave
     
    #71
  12. Brian@GRP

    Brian@GRP New Member

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    Alcohol Paul
    The next thing I would check on your rods is to machine half way through the threads on this rod and look at the cross section of the thread profile. If it had fatigue or embeding on the loaded face of the thread you should see this under magnification. I would be glad to do this for you and provide magnified photo's. I know what it costs to break a rod so I will do everything I can to help you figure this out.

    Brian Scollon
    GRP Connecting Rods
     
    #72
  13. pete9857

    pete9857 Member

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    rods

    Nitro4100, I do stamp my rods. It was late, sweating, tired, bad lighting, hungry, etc.
    I make no excuses. I should have loaded it up and done nothing. I've been building engines and racing for over 35 yrs. That was only the 2nd time that I lost a rod.

    Glenn
     
    #73
  14. Fuel Cars

    Fuel Cars AA/AM

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    I don't care what grade aluminum you use, a freshly and properly drill and tapped aluminum chunk of metal will still have their threads stripped out if you insert a hardened steel bolt and over-torque it.

    And a go/no-go gage will only check the entry point of the threads and only checks the pitch diameter. You can have an internal thread with minor oversize to almost the pitch diameter and if the pitch diameter was ok, the thread gage would check ok, but, the threads would be substantially weaker because of the oversize minor.

    You can also play "tricks" to make the threads check good with a go/no-go gage on threads that are out-of-tolerance for their class.

    Also, threads by design based on size and class, have approximately 80% contact area between mating parts and that is with both parts being at nominal tolerance, in other words, 2 perfect parts.
     
    #74
  15. Dragsterbus

    Dragsterbus Member

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    Ok apart from the added weight and greater clearance needed , why don't rods have a press in stud and nut that can't pull out ?
     
    #75
  16. Bottlefed

    Bottlefed New to Blowers

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    If you don't mind added wieght and clearence then you could use a 5/8ths inch bolt and it would be cheaper and stronger.


    R/G
     
    #76
  17. Dragsterbus

    Dragsterbus Member

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    5/8ths !! Hey only asking :D
     
    #77
  18. Fuel Cars

    Fuel Cars AA/AM

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    The quickest and cheapest would be to use heli-coils or threaded-inserts.

    I still think a reversed-shouldered insert would be the best.
     
    #78
  19. alcohol paul

    alcohol paul Jr. Dragster

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    Brian,
    Parts are bagged, tagged and will be on the way to you Monday. Thanks in advance for your help.

    Paul,
     
    #79
  20. nitro4100

    nitro4100 New Member

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    Glenn very understandable, It happens
     
    #80

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