Grp Rods Pulled Threads

Discussion in 'Manton Push Rods Top Alcohol Tech Questions' started by SNAPPY, Sep 17, 2006.

  1. wildwade

    wildwade TAFC

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    Jeffd -you need to read snappy's post- it's NOT a torque wrench problem- we used the new digital that reads in BOTH directions and reads the highest torque achieved-DIGITALLY. Now does everyone understand it's not the torque wrench- stop the posting about torque wrenches! (better yet if you do not have a blown alcohol motor or car don't respond to this thread) sorry I'm cranky but seeing a new engine with a brad billet block throw the rods out will do it!
    and Mike we understand the stretch deal but when you have 75 min between rounds and you check rod bearings to tune you don't have time for that.
    bruce is right- if you find one that works use it and don't be like sheep and follow the flock- do your own thing! Just because joe blow say's there the bomb- they just might go "boom"
    please keep more info on rods, cranks, pistons, etc.
     
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  2. Mike Canter

    Mike Canter Top Dragster

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    The intent of the rod stretch gauge discussion was to plot it out in the garage before the race and after the race when you have time so you can make a lookup chart based on number of runs and on how much torque is required with your lubricant to get .006". I didn't mean to use a stretch gauge between rounds.

    The explanation on clamping force and pulling threads was more fror any other readers that may not understand it.
     
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  3. Dave Germain

    Dave Germain New Member

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    It seems that I have managed to break everybodies rods over the years. Grp included although they are a beautiful piece. Almost all of them were my fault except for the Howards, they just broke all by themselves. Somebody please tell me about the rod bolt stretch thing- how do I use one? Every rod is breakable if a person works hard enough at it. I would be bummed too if I killed a new billet block. There is a such thing as percentages of thread engagement. Maybe we should order rods with a higher level of thread engagement?
     
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  4. Fuel Cars

    Fuel Cars AA/AM

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    Dave, are you talking about thread length engagement, or, thread height engagement?

    Thread length engagement would require longer rod bolts and more material in the rod.

    Thread height engagement would require modified minors, but you could run into galling and false torque readings..

    Anybody know if the threads are rolled or cut? When done properly, rolled threads are stronger than conventional cut threads.

    Btw Dave, how did the paint scheme come out?
     
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  5. Mike Canter

    Mike Canter Top Dragster

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    From what I have been able to find out talking to different rod makers is that it is not so much the bolt that causes the problem it is the ability of the rod maker to cut the threads correctly in the the aluminum rod itself and therefore the importance of a NO-GO thread checker on new rods.
     
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  6. Fuel Cars

    Fuel Cars AA/AM

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    Mike, not questioning you or your sources, but that sounds fishy.

    Unless they are single-point cutting the threads, very highly unlikely, they are threading using industrial-standard thread taps.

    Heck, if it's that much a problem threading the rods, a reverse-entry heli-coil with a shoulder would solve that and would also be quite a bit stronger.

    As an added note, any manufacturing facility that machines parts should be checking their own work, i.e., check their threads with go/no-go gages, in the aerospace industry, that's standard. I don't think I should have to make sure the work I payed for is correct.
     
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    Last edited: Sep 18, 2006
  7. Russ Parker

    Russ Parker Member

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    BME rods make nice clocks...
     
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  8. Mike Canter

    Mike Canter Top Dragster

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    Paul, from a well known rod manufacturer, he states that cutting the thread in the aluminum rod is not the same as cutting the thread in a steel rod and there is a difference in the process. He stated that some rod manufacturers know how to do it correctly and consistently and some don't. I do not believe they are using a standed industrial thread tap. I am passing on what I found out and I by no means consider myself a machinist or an expert in this area but since they make aluminum rods as part of there main business I assume he knows what he is talking about.
     
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  9. Fuel Cars

    Fuel Cars AA/AM

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    Mike, thanx for the info, it almost sounds to me like they're rolling the threads, not cutting, thread rolling is a process that is harder to control and maintain.
     
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  10. Mike Canter

    Mike Canter Top Dragster

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    Paul, you might be right but I have no idea. He wouldn't tell me because it was a trade secret.

    I do know that I have never found a broken bolt in the pan after a rod failure. Usually if the cap comes off I never have a burned bearing but have one bent bolt and one bolt with thread in it which indicates that it lost torque and pulled out and bent the cap back. I don't know if that failure was due to a bad torque wrench or not. I did go out and buy the best Snap-On after that. We never use Excaliber (the torque wrench because it is so long looks like a sword) on anything but the motor. We have had brand new rods break the shoulder area on the first launch right off the line. I swear to this day that it was a faulty rod but you will never have a rod company tell you that just because o the libility of saying it.

    I have also seen rods actually split the beam lengthwise and I am sure that was due to detonation. I have also had some rod failures that have totaly mistified me. There was no clue why it went.

    We had a brand spanking new Jon Kaase Ford hemi nitrous motor that kicked the rods out on the first burnout because we think the driver came up too fast on the rpm while in the bleach box rather than pull out a little. (nitrous style burnout). We found out it had an Oklahoma guarantee which we found to be only good in Oklahoma and we were in Georgia and so was Jon.

    We currently use Brooks rods in the Ford and so far never had a failure but sooner or later it is bound to happen. Different racers swear by different rods. Racers never want to switch from what they have had success with. I have had a small rod company offer a new style rod that was cryogenically cooled and had tons of neat features in the beam area but couldn't find a blown alcohol racer usng them and we sure where not going to be his test motor unless he would pay for all rod caused damages.
     
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  11. Dale H.

    Dale H. Member

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    Paul, you must not have been racing very long!Seems like half the stuff you buy anymore don't fit,or is the wrong size,or needs fiddled with to make work, despite the exourbanant price!(lol)

    Threads are rolled on rod bolts.The threads in the rods are either cut or formed using taps.The thread H limit on the taps can be changed for different
    materials.

    Dale
     
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  12. Will Hanna

    Will Hanna We put the 'inside' in Top Alcohol
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    few points

    i'm not an engineer nor do i have any experience in mfg to definitively comment on some of the discussion here. however, i've done bottom end for a number of hard running teams that buzz the motor pretty good. the few times i've done bottom end on a car that kicked the rods, other causes were associated.

    in looking at how some people do bottom end, i'll share some of my methods.

    i use torco assembly lube exclusively. i also use it liberally, and apply it liberally to the rod threads. hot or cold. some believe in using engine oil on the threads. this is just what i've used, and we regularly took cannon's car over 10,500 without fail.

    i think it's important to walk the rod cap up evenly when reassembling. i use an electric impact hit one bolt a little and then run the other bolt all the way in...never run the first bolt all the way in.

    the same method on torque. i give the first bolt one decent pull with the wrench, then do the same on the other bolt. then i go ahead and pull the bolt to 90 and do the same with the other bolt. sneak up on the click and barely click it. no matter how hard the thrash, always double check the torque on the rods after your done. i think it's more of a fail-safe method to go back through 1-8 after you're done, rather than double checking while you're on a particular journal. whatever is going to make you forget to torque a bolt may make you forget to double check it as well. if you don't put the pan on until you've re-checked all of them, it helps eliminate chance of error. it's never too much of a hurry not to double check. when youre thrashing, it's more the reason to double check.

    i also have pretty hard standards on what bearings i put in it. everyone concentrates on the bottom width of the rod bearing, but i think now days more people run the hard v bearing (if you're not, you should be) and you need to look at the end to end clearance. a bearing shouldn't measure less than 2.503 or so. if it measures 2.498 or so, you can gently try to work the bearing back out, starting at the base of the bearing. the bearing needs to be able to clamp itself in the rod, and if it's less than 2.5, it's not clamping.

    i know this isn't directly related to the root of this thread, but it's just a few successful methods i figured i would share. one point is right - if you find something that is working, stick with it. i learned bottom end directly and indirectly from tom conway, so that's where i got my training working for shelly.

    i still stand by my statement there isn't a better alcohol rod out there than grp. yes they advertise here, but i'm also picky on who i endorse. maybe it's going to bite me one day, but with the grp's, if i don't feel anything funny during assembly, i'm gonna sit behind them and send them down track.

    my .02:rolleyes:
     
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  13. eli

    eli Banned

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    QUOTE Mike Canter. Racers never want to switch from what they have had success with. I have had a small rod company offer a new style rod that was cryogenically cooled and had tons of neat features in the beam area but couldn't find a blown alcohol racer usng them and we sure where not going to be his test motor unless he would pay for all rod caused damages.[/QUOTE]


    Mike back in the day we used Mickey Tompson rods and every once in a wile we had them cryo. frozen and we never broke a rod. "it`s the only way to treat alumanum" :D ;)
     
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  14. TOL

    TOL Active Member

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    Two dumb questions if I may...... What is an L19 bolt? For a high RPM application, is it best to use a forged AL rod versus a billet rod?
     
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  15. TAFC577

    TAFC577 New Member

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    as bad as we all treat our torque wrenches , they should be recalibrated twice a year . go to www.teamtorque.com they do all our wrenches and sponsor our ta/fc . normally a 72 hour turn-around and the prices aren't bad! or call 1-888-682-8675 and talk to cary .
     
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  16. Mike Canter

    Mike Canter Top Dragster

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    TOL as far as I know there appears to be two ways to make the rods we all use. Somebody else may want to amplify on this. The traditional forged rod such as Brooks, BME, C & A and the billet rod by GRP. The GRP rod is actually cut out of a sheet of aluminum. then machined to the correct finish. As far as which one is best is really more of a personal choice. If you get five racers together they will all have different stories on which rod has failed them and which one they swear by and nobody will switch from a rod that is not failing them. I believe most BAE motors now come with GRP rods.
     
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  17. TOL

    TOL Active Member

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    Thanks Mike. The billet rod deal confuses me, although as you say there are people having good luck with it. In the case of a forged rod, would there not be better grain structure/flow around the big end, for improved strength & stability? In the case of a rod made from billet, the machining would invariably have to cut across grains?........
     
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  18. Mike Canter

    Mike Canter Top Dragster

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    I am in total agreement with you. Since the rod is cut with the grain in the aluminum sheet probably running along the length of the beam it would make the grain in the shoulder area running across the shoulder making it the weak point and that is where we always broke our GRP rods.
     
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  19. Fuel Cars

    Fuel Cars AA/AM

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    Another fyi, you can get a billet that has been hammer-forged with directed grainflow, which is usually lengthwise to the billet. Traditional forgings are stronger and denser, but they are also prone to forging irregularities such as seperation, inclusions, voids, cracks, folds, etc.

    Billets come from either specially poured or normal bar stock, sheet is usually defined as less than 1/4" thick.

    I have seen forgings that when machined, large pockets of voids could easily be seen with the naked eye, not good. To avoid the forging problems, hammer-forged billets are usually ultrasonic/xray inspected before hammer-forging and have quite a bit of extra material to machine.

    The best way to detect forging problems is to penetrant/magnaflux followed by ultrasonic/xray the finished machined part.
     
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  20. Dave Germain

    Dave Germain New Member

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    Paul, I was referring to the amount the thread engages its opposing part rather than the length of the bolt. I don't know diddly about machining but I have read and seen bolts that didn't engage very well because the threads were cut with worn taps or dies. The paint turned out great but the clear coat went to hell. On the flat surfaces it just piled up and wouldn't run together, it looked like clear cottage cheese and on the vertical surfaces it ran like a big dog- all over. I had to sand it all off and now I will take it to a real painter to start over. I didn't put the strip down the side. I also changed the black on the roof to that chrysler electric blue. I thought after all it is an avenger body. I will put pictures on here when it is actually completely done.
     
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