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Car Forum / Honda Cars / October 2006head thread repair on aluminum block
We are working on a Honda 90 Accord, F22A4 open deck aluminum block. One of the head bolts pulled the threads out on removal. This was not noticed until the head was repaired and reassembly was attempted. The threads are recessed approximately 2 inches below the deck surface. The head bolts are not TTY and are 12mmx1.5. The gasket is MLS type. Torque is 3 stage, 26/52/78. (Note: ARP makes head studs that will fit. Timesert makes a repair kit [the kit for the Odyssey on their site], but charges $400 for the kit since it is intended for pro rebuilders.) The best we can come up with is to tap and helicoil the damaged hole. But the recessed threads make this difficult to manage, both in driving the tap and in breaking off the installation tang. Anyone with experience there? I can get a bare machined block for $100. What's the chances it will correctly seal up with the existing head, and what should I do about the rings? A new (used) motor is $500+freight, but I'm $250 in on the valve job and wasted head gasket already. Can anyone recommend a course of action? What was intended to be a quick valve & gasket job has quickly disintegrated. > We are working on a Honda 90 Accord, F22A4 open deck aluminum block. One of > the head bolts pulled the threads out on removal. This was not noticed until [quoted text clipped - 20 lines] > Can anyone recommend a course of action? What was intended to be a quick valve > & gasket job has quickly disintegrated. I have seen and used helicoils in an aluminum block, I don't think they will pose a problem with your Accord 2.2 block. The holes are blind so that no coolant is present in the bolt hole which could potentially leak past the threads. Breaking off the tang should be easy. Strike it with a long flatblade screwdriver and hammer in one quick tap. Pick up the tang with a greased stick of some sort. I can't remember if helicoils are "magnetic" since they are some stainless type of compound. I seem to remember getting tangs out with a pocket magnet in the past, but my memory sucks. You can thread further down into the block by modifying your 14 X 1.5 mm Helicoil tap. Cut off half of the square drive end of the tap and cut a matching half out of an old 3/8" extension or similar tool steel shaft. Assemble the two parts together, butting the lap joints you just made as tightly as possible, and weld the assembly together (or have a welding shop do this. Now grind down the thickness of the extension shank as necessary to get it to fit in the threaded holes. If welded properly, it will hold up and allow you to reach farther than the tap would normally allow. You will probably need to install two helicoils (stacked). Make sure the highest point of the top helicoil is slightly below the uppermost thread -- this is where the most stretching load is concentrated so this area needs to be sound. Toyota MDT in MO > You can thread further down into the block by modifying your 14 X 1.5 > mm Helicoil tap. Cut off half of the square drive end of the tap and [quoted text clipped - 10 lines] > > Toyota MDT in MO That sounds like a reasonable plan. How do I deal with the situation where the two stacked helicoils end up being higher than the uppermost thread? Use one instead? The helicoils are 18mm and the threaded part of the bolt is 1 inch (25.4mm). We do not know how deep the threads in the block are yet. >> You can thread further down into the block by modifying your 14 X 1.5 >> mm Helicoil tap. Cut off half of the square drive end of the tap and [quoted text clipped - 16 lines] > part of the bolt is 1 inch (25.4mm). We do not know how deep the > threads in the block are yet. 1" is more than enough to hold the bolt. [for stress analysis purposes, the load is only carried by the first 3 threads if any threaded bolt anyway.] as long as you can overcome the issue of the recessed hole to drill, tap and coil the new thread, it'll hold just fine. > > That sounds like a reasonable plan. How do I deal with the situation > > where the two stacked helicoils end up being higher than the uppermost [quoted text clipped - 6 lines] > anyway.] as long as you can overcome the issue of the recessed hole to > drill, tap and coil the new thread, it'll hold just fine. So a 1" bolt threads inside a single 18mm helicoil should be sufficient not only to hold the load but also to keep the bolt from backing out? Is there anything different about a helicoil tap from a normal tap? We are thinking of just buying a long normal tap of the correct dimension. If so, what tap goes with a 12mmx1.5 helicoil? I emailed the manufacturer to ask them but they didn't answer... >>>That sounds like a reasonable plan. How do I deal with the situation >>>where the two stacked helicoils end up being higher than the uppermost [quoted text clipped - 14 lines] > If so, what tap goes with a 12mmx1.5 helicoil? I emailed the > manufacturer to ask them but they didn't answer... no, a helicoil tap is NOT the same as a regular tap - you need the tap that comes with the specific inserts that you want to use. The helicoil tap is larger in diameter but still has a 1.5mm thread pitch because the outside of the insert is by necessity a mirror image of the inside. The same is true of pretty much any type of threaded insert such as Time-sert etc. nate  Signaturereplace "fly" with "com" to reply. http://home.comcast.net/~njnagel >>>> That sounds like a reasonable plan. How do I deal with the situation >>>> where the two stacked helicoils end up being higher than the uppermost [quoted text clipped - 23 lines] > > nate True on Helicoils and other coiled spring inserts. However most of the sleeved style inserts use a different exterior thread. On the inserts I have here the thread profile is also different, it is almost a round profile. All of them require the specific tap for the insert though. If you buy an insert kit it will have the tap and various length inserts in it. As an aside helicoil inserts in aluminum make stronger threads than the bare threads in aluminum. Take a look at most military hardware and you will find inserts in the soft metal parts. SignatureSteve W. OK, so we helicoiled it. Used the suggestions of welding the tap to an extension it worked great. Then noticed the Honda factory book said the bolts were 12mm x1.25 not x1.5. had a WTF moment but then determined that the book is wrong. Used some zinc assembly lube (all I could find). Did a test torque with the old gasket. All of the holes are good up to 80 ft lbs but the bolt is jumping around in the helicoil hole past 50 lbs. Removed it, and relubed it a few times but no improvement. Think moly lube would be better? I'm not sure if it's jumping in the helicoil hole because of something we did wrong, or because it is steel on steel so it needs different/better lube. >OK, so we helicoiled it. Used the suggestions of welding the tap to an >extension it worked great. Then noticed the Honda factory book said [quoted text clipped - 6 lines] >jumping in the helicoil hole because of something we did wrong, or >because it is steel on steel so it needs different/better lube. I haven't been following this thread, but I'm going to make some presumptions: you are talking about steel and aluminum. The coefficients of thermal expansion are different, depending on the alloy. What you want to aim for is a fastener TIGHTENING in a hole as the assembly heats up. IOW, the fastener should have a larger coefficient of thermal expansion than the pieces being assembled with that fastener, to prevent the fastener from loosening in the hole as the assembly heats up. The hole gets bigger, the fastener better be able to keep up with it. I suspect in your case...the hole in the aluminum is getting larger, and the helicoil is -not- expanding along with it to keep a tight bond. Of course it is expanding somewhat, but it has to overcome or at least match the rate and dimensions of the expansion of the assembly metals. Just a thought from a guy in the peanut gallery, who has come to the game *late,* and doesn't know "who is on 2nd" Lg You could easily be describing the results of trying to put a bolt with the wrong threads into a helicoil.... Are you 'sure' the book is wrong??? Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590 (More Off Road album links at bottom of the view page) > OK, so we helicoiled it. Used the suggestions of welding the tap to an > extension it worked great. Then noticed the Honda factory book said [quoted text clipped - 6 lines] > jumping in the helicoil hole because of something we did wrong, or > because it is steel on steel so it needs different/better lube. > OK, so we helicoiled it. Used the suggestions of welding the tap to an > extension it worked great. Then noticed the Honda factory book said [quoted text clipped - 6 lines] > jumping in the helicoil hole because of something we did wrong, or > because it is steel on steel so it needs different/better lube. Jumping, as in the static friction in the threads is so great that you turn the bolt-head a little, and the threaded part is 'stuck', then the threaded part suddenly turns a bit in the threads? Or jumps, as in you put torque on the bolt head, and the bolt head doesn't move, then all of a sudden the bolt head turns a bit (large static friction where the bolt head meets the head). Or, as Mike R suggests, could the bolt actually be slipping out of the threads? Dave > OK, so we helicoiled it. Used the suggestions of welding the tap to an > extension it worked great. Then noticed the Honda factory book said [quoted text clipped - 6 lines] > jumping in the helicoil hole because of something we did wrong, or > because it is steel on steel so it needs different/better lube. i don't know what the thread is on a prelude, but i can tell you for sure that the head bolt thread pitch on the civic is 1.25mm - i've just checked a couple i have in my box of bits. but since you've already helicoiled the block and are committed at this point, and have screwed the bolt in, you'll have effectively re-threaded the bolt. i suggest you screw it in and out a few times to complete the cutting process, then leave it. you'll know better next time. you may want to up the torque a couple of notches too. the finer thread with give a higher bolt tension than the coarser thread at the same torque, so since you have a coarser thread, the torque needs to be a little higher to get the bolt tension. not sure exactly how much without looking it up, but you may be able to find it on the web somewhere. > i don't know what the thread is on a prelude, but i can tell you for > sure that the head bolt thread pitch on the civic is 1.25mm - i've just > checked a couple i have in my box of bits. That sucks, before ordering the Helicoil stuff we checked the bolt against a thread gauge at Napa (fit exactly 12mm x 1.5) but I guess something was wrong since there would be no other reason for the bolt to be jumping now. I thought if the threads were wrong it would start hanging up way before that point.... > but since you've already helicoiled the block and are committed at this > point, and have screwed the bolt in, you'll have effectively re-threaded > the bolt. Well, do you think it would be possible to find a 12mmx1.5 bolt to use in its place? The bolt is 6 3/8 inches and the threaded part is 1 inch. The head is 14mm. I don't know where to look for this kind of thing... the best I could think of is maybe some other Honda uses a similar bolt. > i suggest you screw it in and out a few times to complete the > cutting process, then leave it. you'll know better next time. Yeah, we sure will. > you may want to up the torque a couple of notches too. the finer thread with > give a higher bolt tension than the coarser thread at the same torque, > so since you have a coarser thread, the torque needs to be a little > higher to get the bolt tension. not sure exactly how much without > looking it up, but you may be able to find it on the web somewhere. http://www.futek.com/boltcalc.aspx?mode=metric I put in the following values for the original bolt: Application Data Major Bolt Diameter: 12.00 Bolt Pitch: 1.25 Bolt Proof Strength: 827 Recepticle Length: 25.4 Recepticle Strength: 414 Applied Tensile Load: 0 k Factor: 0.2 Recommended Torque 113.25 N-m (11.555 kg-m) (83.52 ft-lb) Resultant Tension:4811 Maximum Torque 151 N-m (15.407 kg-m) (111.36 ft-lb) Resultant Tension:6415 83 ft lbs is in the ballpark of the recommended torque from the manual (78 ft lbs) And then the following values for the current situation: Application Data Major Bolt Diameter: 12.00 Bolt Pitch: 1.50 Bolt Proof Strength: 827 Recepticle Length: 25.4 Recepticle Strength: 414 Applied Tensile Load: 0 k Factor: 0.2 Recommended Torque 108.19 N-m (11.039 kg-m) (79.79 ft-lb) Resultant Tension:4596 Maximum Torque 144.26 N-m (14.718 kg-m) (106.39 ft-lb) Resultant Tension:6128 What is strange is that it actually recommends less torque for the 1.5 pitch (79 ft lb) than for the 1.25 pitch (83 ft lb) with everything else constant. That doesn't really make any sense, does it? > What is strange is that it actually recommends less torque for the 1.5 > pitch (79 ft lb) than for the 1.25 pitch (83 ft lb) with everything > else constant. That doesn't really make any sense, does it? Actually that does make sense, on a coarse thread you have less surface contact per length of threaded area, so you are losing less of the torque reading to thread friction. >> What is strange is that it actually recommends less torque for the 1.5 >> pitch (79 ft lb) than for the 1.25 pitch (83 ft lb) with everything [quoted text clipped - 3 lines] > contact per length of threaded area, so you are losing less of the > torque reading to thread friction. to be honest, i haven't thought it through. i was under the impression that finer threads gave higher tension for a given torque based on geometry. it may be that a lower torque is specified because typically, coarser threads are in lower strength bolts. i'll think about it some more. >>> What is strange is that it actually recommends less torque for the >>> 1.5 pitch (79 ft lb) than for the 1.25 pitch (83 ft lb) with [quoted text clipped - 8 lines] > impression that finer threads gave higher tension for a given torque > based on geometry. Fine threads are used in instances where vibration is a concern. Consider that, mechanically, a screw thread is just a variation of a wedge. The shallower the slope of the wedge, the less the mechanical advantage of the opposing (loosening) force. And, conversely, the easier they are to strip... > it may be that a lower torque is specified because > typically, coarser threads are in lower strength bolts. Coarse threads are, in and of themselves, stronger, but are more susceptible to vibration and loosening on account of their steeper slope. There exist M12 bolts with coarse threads, and indeed, they are in certain circumstances easier to find than fine-thread fasteners. Correct stretch and the use of prevailing torque nuts can satisfactorily allow coarse-thread fasteners to substitute for fine-thread fasteners. SignatureTeGGeR® The Unofficial Honda/Acura FAQ www.tegger.com/hondafaq/ >> i don't know what the thread is on a prelude, but i can tell you for >> sure that the head bolt thread pitch on the civic is 1.25mm - i've just [quoted text clipped - 5 lines] > to be jumping now. I thought if the threads were wrong it would start > hanging up way before that point.... well, if you checked the bolt with a thread gauge and it was 1.5mm, then you got it right! that's good news. >> but since you've already helicoiled the block and are committed at this >> point, and have screwed the bolt in, you'll have effectively re-threaded [quoted text clipped - 5 lines] > thing... the best I could think of is maybe some other Honda uses a > similar bolt. best stick with the original bolt regardless. >> i suggest you screw it in and out a few times to complete the >> cutting process, then leave it. you'll know better next time. [quoted text clipped - 58 lines] > pitch (79 ft lb) than for the 1.25 pitch (83 ft lb) with everything > else constant. That doesn't really make any sense, does it? > > Well, do you think it would be possible to find a 12mmx1.5 bolt to use > > in its place? The bolt is 6 3/8 inches and the threaded part is 1 [quoted text clipped - 3 lines] > > best stick with the original bolt regardless. Is it possible that the bolt really was a 1.25 but was able to thread into the 1.5 gauge anyway? Of course, maybe their gauge was cross threaded by another customer. So what can be done about it jumping around? It'd be nice to get something approximating the correct torque on it. > jim beam wrote: > [quoted text clipped - 11 lines] > > Is it possible that the bolt really was a 1.25 I would bet money the pitch is 1.25. The online factory service manual for this Accord says in two places it's a 1.25 pitch bolt. Plus, only one piece of evidence you have (your own measurement of the bolt pitch) suggests it's not 1.25. "Believe your indications." -- Rule from navy nuke program when analyzing problems with the plant. (Psychological studies show a basis for resisting believing one's indications. One has to 'resist the resistance,' blah blah when making electro-mechanical diagnoses.) > but was able to thread > into the 1.5 gauge anyway? Yup. Plus all that soft metal will rework itself without much difficulty, but not to the point where I would trust the holding power of the setup. Re-helicoil? I have never done a helicoil job, so I ask for my own edification as much as yours. The net's reports on the use of helicoil inserts to repair stripped threads certainly are promising. I would be checking the other, so far relatively untouched head bolts to see that they are 1.25 mm pitch. Get yourself to a True Value hardware or other store that has a bin of M12x1.25 etc. nuts, and confirm the pitch? > Of course, maybe their gauge was cross > threaded by another customer. > So what can be done about it jumping around? It'd be nice > to get > something approximating the correct torque on it. Isn't "correct torque" rather tangential to the main concern, namely, how tight the head is held onto the engine? I personally would not focus on "correct torque" prior to getting the factory specified male and female threads into good repair. Just an amateur here. That resistance thing is called "denial" in civilian psychology courses, and it is probably the most powerful force known to humans. You are quite right that "how tight the head is held onto the engine" depends on the thread pitch. Finer threads have more leverage, and therefore give you more tightness for the same torque. Earle > > jim beam wrote: > > [quoted text clipped - 53 lines] > > Just an amateur here. I suspect there's more going on here, like the OP is working in an independent or dealer shop (nothing wrong with either, of course); has given a quote to the customer; so the budget is a bit tight; and can't a proper helicoil kit run some serious change? I was googling on the costs of kits and am not clear on that. Seems like these poor folks have found themselves in a morass here. I am interested in the outcome but fear someone is going to end up paying through the nose. OTOH, next time I bet this is a piece of cake. > That resistance thing is called "denial" in civilian > psychology courses, and > it is probably the most powerful force known to humans. Probably too often discussion of the phenomenon is applied to "emotions" (e.g. denying that Jane could have messed over Paul by sleeping with Paul's best friend yada). Fact is the technically inclined have to remember it applies to cold hard science, too. > You are quite right > that "how tight the head is held onto the engine" depends [quoted text clipped - 73 lines] >> >> Just an amateur here. There is a product out there that is used on Nuclear subs, and industrial equipment that will fix this problem if you can get to it. I've used it, sold it, and gave it to others. One time I fixed a Cummins diesel head crack with it, and it's still running..... I'ts expensive, and I haven't seen any around in awhile. Google for Belzona products. It's possible someone will give you the little that you need. MM^^ > I suspect there's more going on here, like the OP is working > in an independent or dealer shop (nothing wrong with either, > of course); has given a quote to the customer; so the budget > is a bit tight; and can't a proper helicoil kit run some > serious change? I was googling on the costs of kits and am > not clear on that. Nope, just a backyard job that fell apart midstream (and had several cooks in the kitchen who I'm collectively speaking for). The helicoil kit cost $60 from Amazon. > Seems like these poor folks have found themselves in a > morass here. I am interested in the outcome but fear someone > is going to end up paying through the nose. In the end, the worst case is drop in a used motor. > OTOH, next time I bet this is a piece of cake. I hope there won't be a next time <G> > Nope, just a backyard job that fell apart midstream (and > had several > cooks in the kitchen who I'm collectively speaking for). > The helicoil > kit cost $60 from Amazon. Great on all points. (I mean, better than having a customer breathing down your neck!) If you are feeling wealthy enough, I hope you'll confirm the 1.25 pitch size, buy another kit (Ebay?), and see how that works. Er, maybe wait until others who have done helicoil jobs chime in on how successful a "re-do" is first, though. Thanks for the update. I am sure someone down the line is going to learn from this. There really aren't too many reports of helicoil jobs on head bolt threads for the Honda newsgroups. >> Nope, just a backyard job that fell apart midstream (and >> had several [quoted text clipped - 8 lines] > until others who have done helicoil jobs chime in on how > successful a "re-do" is first, though. i've not seen "double-oversize" options for helicoil. i think the op is best sticking with the original bolt and multiple re-insertions to get it as smooth as possible. using another bolt may have very different elasticity and fatigue properties. [fatigue may be compromised in this situation, but you gotta suck it and see.] > Thanks for the update. I am sure someone down the line is > going to learn from this. There really aren't too many > reports of helicoil jobs on head bolt threads for the Honda > newsgroups. > Nope, just a backyard job that fell apart midstream (and had several > cooks in the kitchen who I'm collectively speaking for). The helicoil > kit cost $60 from Amazon. I'm getting back to this thread late, but want to agree with the people who proposed that your head bolts are actually 12mm X 1.25mm pitch. You'll be hard pressed to find a 12mm X 1.5mm bolt on any (real) Honda product. That excludes the Passport, etc. At this point I think the engine is probably beyond saving, unless there is a double-oversized helicoil product out there I'm not aware of. It's too late now, but the answer to your "what size Helicoil tap" question is -- 2mm larger than the intended bolt size in the same pitch. i.e. repairing a 12mm X 1.25mm hole would require a 14mm X 1.25mm tap (and appropriate drill size). The Helicoil taps don't have their actual measurments listed on them, but I have measured and matched all of the common sized metric Helicoil taps to regular tool taps. Furthermore I have used standard taps in place of the Helicoil tool with total success. Toyota MDT in MO > That resistance thing is called "denial" in civilian psychology courses, and > it is probably the most powerful force known to humans. You are quite right > that "how tight the head is held onto the engine" depends on the thread > pitch. Finer threads have more leverage, and therefore give you more > tightness for the same torque. That makes no sense. If anything finer threads would lose more of the torque value to friction, the same friction that prevents a finer thread bolt from backing out under the same vibration that would back out a coarse thread bolt. So in the end you need a higher torque value to deliver the same clamping force. >> That resistance thing is called "denial" in civilian psychology courses, and >> it is probably the most powerful force known to humans. You are quite right [quoted text clipped - 7 lines] >out a coarse thread bolt. So in the end you need a higher torque value >to deliver the same clamping force. Not so. It is called Mechanical Advantage. With fine thread, you need 20 turns of wrench to say sink fastener 2 inches. With coarse thread, maybe 10 turns of wrench to sink fastener 2 inches. So you have a virtual 2 to 1 gear ratio with a fine thread in this example, and a 1:1 gear ratio with the coarse thread. Use your head. If you put the same torque on the fine thread that you put on the coarse thread, you will get TWO times the clamping force, friction losses notwithstanding. A mind is a terrible thing to waste. Lg > Not so. > It is called Mechanical Advantage. [quoted text clipped - 11 lines] > put on the coarse thread, you will get TWO times the clamping force, > friction losses notwithstanding. Then perhaps you can tell me why the online torque calculators disagree with that assessment. > A mind is a terrible thing to waste. Thanks, but you really have no idea what I do with my mind aside from my posts in this NG, so you can free yourself from feeling such pity for me. >> Not so. >> It is called Mechanical Advantage. [quoted text clipped - 20 lines] >my posts in this NG, so you can free yourself from feeling such pity >for me. Are you saying, that there is no mechanical advantage of a 20 thread per inch bolt over a 10 thread per inch bolt? That if 10 ft lbs of force is used to rotate them, that the clamping force will be exactly the same, although twice as many turns went into the 20 thread per inch bolt compared to the 10 thread per inch bolt? a screw is a gear. specifically, a *ball screw* is a gear, of the linear kind. It isn't different in how it works than a circular gear, in terms of mechanical advantage. I contend, that if I have a 2 to 1 thread advantage...with the same torque applied via a torque wrench, the fine thread will give more clamping power than the coarse thread. If I had a 1 thread per inch screw and a 10 thread per inch screw and a 20 thread per inch screw which one would give more clamping power, revolutions notwithstanding, with 10 ft lbs of torque applied to the screw head? You fill in the answer, and show me why you come to your conclusions: Take all the white space you want/need. Lg > >> Not so. > >> It is called Mechanical Advantage. [quoted text clipped - 26 lines] > the same, although twice as many turns went into the 20 thread per > inch bolt compared to the 10 thread per inch bolt? Lawrence, There is no point in arguing with this type. "Then noticed the Honda factory book said the bolts were 12mm x1.25 not x1.5. had a WTF moment but then determined that the book is wrong." The "book was wrong" because it did not agree with the heli-coil that he had just installed! And later, "All of the holes are good up to 80 ft lbs but the bolt is jumping around in the helicoil hole past 50 lbs." So far, no one reading this thread knows what "jumping around in the helicoil hole" means. It's obvious too that a coarse thread will provide more "clamping power", because the threads are bigger! I would have loc-tited the heli-coil in the hole, after test-threading it onto the head bolt. You can't be too careful. Cheers, Earle > a screw is a gear. specifically, a *ball screw* is a gear, of the > linear kind. It isn't different in how it works than a circular gear, [quoted text clipped - 16 lines] > > Lg > Are you saying, that there is no mechanical advantage of a 20 thread > per inch bolt over a 10 thread per inch bolt? I'm saying you're living in a fantasy world where you can simply neglect losses due to dynamic friction, that you have exchanged for whatever mechanical advantage you have gained. > You fill in the answer, and show me why you come to your conclusions: Go to an online torque calculator. Fill out the clamping force and bolt characteristics. Calculate the torque for a fine and coarse thread bolt. Everything else held constant, the apparent torque required to obtain a given clamping force is less for the coarse thread bolt than for the fine thread one (in my case, 77 lb-ft vs 83 lb-ft). Something tells me the model used by an engineering firm takes a few more empirically obtained factors into account than your Aristotlean model does... > Take all the white space you want/need. Are you this pretentious in real life? >> Are you saying, that there is no mechanical advantage of a 20 thread >> per inch bolt over a 10 thread per inch bolt? > >I'm saying you're living in a fantasy world where you can simply >neglect losses due to dynamic friction, that you have exchanged for >whatever mechanical advantage you have gained. So, you ADMIT there is a gain in mechanical advantage, by using a fine thread over a coarse thread. Thank you very much. You can go back to your nap now. Lg > So, you ADMIT there is a gain in mechanical advantage, by using a fine > thread over a coarse thread. Thank you very much. You can go back to > your nap now. So tell me again how this new discovery refutes my earlier post that you jumped all over? The results from the torque calculator show that the whole thing cannot simply be dismissed in the two words "mechanical advantage". >> So, you ADMIT there is a gain in mechanical advantage, by using a fine >> thread over a coarse thread. Thank you very much. You can go back to [quoted text clipped - 4 lines] >the whole thing cannot simply be dismissed in the two words "mechanical >advantage". You apparently are having a problem with a bolt. I don't know how you got into this situation, and I don't know how you're going to get out of it. IIRC, you said the specs given by the manual/book were wrong, as you had a "WTF moment," and you went ahead with a procedure that contradicted the manual's instructions, if I interpret this all correctly. Now you're complaining that the bolt isn't holding like it should. I can't see your aluminum block, I can't see the hardware in question, I have no further comment, other than it appears you're in over your head, and it might be a good time to call in someone who knows what they're doing. Lg > IIRC, you said the specs given by the manual/book were wrong, as you > had a "WTF moment," and you went ahead with a procedure that > contradicted the manual's instructions, if I interpret this all > correctly. Now you're complaining that the bolt isn't holding like it > should. No, you interpret wrong. The bolt is holding. What the bolt is not doing is turning smoothly. That is a problem because the carefully calculated correlation between apparent torque and clamping force then dissolves. The bolt that came out was checked against a gauge. It was determined to be a 1.5. The book says 1.25. Ergo, the book is wrong. If the book is right, then the NAPA bolt gauge is wrong (and by wrong, I mean not even in the ballpark, and it's STILL wrong after a recheck). When "the book" is wrong, that's an automatic WTF moment, no? > I can't see your aluminum block, I can't see the hardware in question, > I have no further comment, other than it appears you're in over your > head, and it might be a good time to call in someone who knows what > they're doing. I'll dearly miss your comments, you know. The people who "know what they're doing" wouldn't even touch the helicoil job. That's because they want to stay in business and they can't stay in business doing repairs they can't guarantee. Helicoiling one hole in the block and assuming the others won't pull out in the same fashion that one did is not a repair they can guarantee. However, it's a risk we can live with. I'm now back to about 30 posts ago. We installed the correct helicoil using the correct procedure (drill, tap, etc). The bolt is now jumpy when torquing it. I thought it was a lube problem, because that's what it acted like. The respondents all thought it was a thread problem. But thread problems just don't act like lube problems. We are absolutely certain now that we measured the threads correctly and used the correct helicoil. The best idea I now have to approximate the original clamping force is to count turns from the torque where the bolt starts to jump to the final torque, using a reference bolt that doesn't jump. From jim beam's post. If nobody else has a better suggestion, that's what we'll go with. If the Honda motor becomes a steam engine, so be it. Can't win them all. > If nobody else has a better suggestion, that's what we'll go with. If > the Honda motor becomes a steam engine, so be it. Can't win them all. Here is what I would do - replace the bolt with a stud. Either buy a pre-made stud of the correct lenght or make one. Use loctite stud and bearing mount on the threaded portion that screws into the block. I'd screw it in as tight as I could with the stud and bearing mount applied (but not so tight that it "jumps"). I'd then I'd install a nut on the portion of the stud that extends from the head. I'll bet I would have no problem torquing the nut to the correct value. Ed >> If nobody else has a better suggestion, that's what we'll go with. If >> the Honda motor becomes a steam engine, so be it. Can't win them all. [quoted text clipped - 8 lines] > >Ed Sounds like an excellent suggestion, Ed. >> IIRC, you said the specs given by the manual/book were wrong, as you >> had a "WTF moment," and you went ahead with a procedure that [quoted text clipped - 48 lines] >If nobody else has a better suggestion, that's what we'll go with. If >the Honda motor becomes a steam engine, so be it. Can't win them all. "C.E. White" has what appears to be a solution to the problem. Sounds good to me. I would give it a try. I think the hard part would be finding a stud of the correct diameter and tensile strength. Other than that, I would give it a go. Like you say, what's to lose at this point? Lg > Are you saying, that there is no mechanical advantage of a 20 thread > per inch bolt over a 10 thread per inch bolt? I'm saying you're living in a fantasy world where you can simply neglect losses due to dynamic friction. That isn't the world I live in. > You fill in the answer, and show me why you come to your conclusions: Go to an online torque calculator. Fill out the clamping force and bolt characteristics. Calculate the torque for a fine and coarse thread bolt. Everything else held constant, the apparent torque required to obtain a given clamping force is less for the coarse thread bolt than for the fine thread one (in my case, 77 lb-ft vs 83 lb-ft). Something tells me the model used by an engineering firm takes a few more real world variables into account than your Aristotlean model does... > Take all the white space you want/need. Are you this pretentious in real life? >> That resistance thing is called "denial" in civilian psychology courses, and >> it is probably the most powerful force known to humans. You are quite right [quoted text clipped - 7 lines] > out a coarse thread bolt. So in the end you need a higher torque value > to deliver the same clamping force. for stress analysis purposes, loaded bolts only hold on the first 3 threads* regardless of thread depth/count, so friction on the non-loaded threads is minimal and can be ignored. * that may seem counter-intuitive, but it's true. tapered threads can have higher counts, but they're not practical for common fasteners. > Re-helicoil? I have never done a helicoil job, so I ask for > my own edification as much as yours. The net's reports on > the use of helicoil inserts to repair stripped threads > certainly are promising. Yeah, it's more a problem that the damage is already done and now what? > Isn't "correct torque" rather tangential to the main > concern, namely, how tight the head is held onto the engine? Yes. > I personally would not focus on "correct torque" prior to > getting the factory specified male and female threads into > good repair. If anyone has any suggestions on how to do that, I'm all ears. >> Re-helicoil? I have never done a helicoil job, so I ask for >> my own edification as much as yours. The net's reports on [quoted text clipped - 13 lines] > > If anyone has any suggestions on how to do that, I'm all ears. your threads are now as good as you're going to get them. there are no more "what if's" available to you. run with what you have. >>> Re-helicoil? I have never done a helicoil job, so I ask for >>> my own edification as much as yours. The net's reports on [quoted text clipped - 16 lines] > your threads are now as good as you're going to get them. there are no > more "what if's" available to you. run with what you have. What about a "big-sert?" http://www.timesert.com/html/bigsert.html They don't list a 12x1.25 big-sert, but it's worth an email. nate Signaturereplace "fly" with "com" to reply. http://home.comcast.net/~njnagel > >>> Re-helicoil? I have never done a helicoil job, so I ask for > >>> my own edification as much as yours. The net's reports on [quoted text clipped - 24 lines] > > nate There's always titanium putty and re-tapping to original size... JT > >>> Re-helicoil? I have never done a helicoil job, so I ask for > >>> my own edification as much as yours. The net's reports on [quoted text clipped - 22 lines] > > They don't list a 12x1.25 big-sert, but it's worth an email. http://www.timesert.com/html/honda.html I forgot to mention, another reason I went with the 12x1.5 is because I emailed Timesert and they recommended the Odyssey kit. The problem is that the kit costs $400. Just not practical unless you're a pro. But then that exchange didn't contradict the idea that it was a 12x1.5 either. > http://www.timesert.com/html/honda.html > I forgot to mention, another reason I went with the 12x1.5 is because I > emailed Timesert and they recommended the Odyssey kit. The problem is > that the kit costs $400. Just not practical unless you're a pro. But > then that exchange didn't contradict the idea that it was a 12x1.5 > either. Ok, so does the damn bolt spin out or just grab a bit when going in? If it is just jumpy, run with it until the last jump is close to the torque you want. If it spins out, you are screwed unless you can tap the hole and drill the rest out to fit a larger bolt. Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590 (More Off Road album links at bottom of the view page) > > http://www.timesert.com/html/honda.html > > I forgot to mention, another reason I went with the 12x1.5 is because I [quoted text clipped - 10 lines] > If it spins out, you are screwed unless you can tap the hole and drill > the rest out to fit a larger bolt. It doesn't spin out, like I said, it jumps around. The problem is that I think it is next to impossible to get accurate torque when that is happening. What do you think? I really have two options. Either it jumps and afterwards the pointer lands on 80, or it jumps only after I have applied enough force to put the pointer at 80. Which do you think is closer to where it needs to be? I am thinking it is the latter. > > > http://www.timesert.com/html/honda.html > > > I forgot to mention, another reason I went with the 12x1.5 is because [quoted text clipped - 15 lines] > I think it is next to impossible to get accurate torque when that is > happening. What do you think? Have you tried putting a washer under the bolt head, or lubricating the area where the bolt contacts the cylinder head? It could be that the bottom of the bolt head is just sticking to the aluminum of the cylinder head. Earle > I really have two options. Either it jumps and afterwards the pointer > lands on 80, or it jumps only after I have applied enough force to put > the pointer at 80. Which do you think is closer to where it needs to > be? I am thinking it is the latter. > Have you tried putting a washer under the bolt head, or lubricating the area > where the bolt contacts the cylinder head? It could be that the bottom of > the bolt head is just sticking to the aluminum of the cylinder head. It has a washer from the factory. We lubed both sides of the washer too. > > > http://www.timesert.com/html/honda.html > > > I forgot to mention, another reason I went with the 12x1.5 is because I [quoted text clipped - 19 lines] > the pointer at 80. Which do you think is closer to where it needs to > be? I am thinking it is the latter. I would do as Earle mentions and use a washer then bring it up as close to 80 as I could on break away torque trying to be as smooth as possible. You also should be aware that a lubricated torque is 'way' lower than a dry torque right? The fifty or 60 ft lb lubed up might be the same as your head calls for if it is the normal dry torque readings. Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590 (More Off Road album links at bottom of the view page) > You also should be aware that a lubricated torque is 'way' lower than a > dry torque right? The fifty or 60 ft lb lubed up might be the same as > your head calls for if it is the normal dry torque readings. It calls for 26/52/78 with engine oil lube. >>> http://www.timesert.com/html/honda.html >>> I forgot to mention, another reason I went with the 12x1.5 is because I [quoted text clipped - 19 lines] > the pointer at 80. Which do you think is closer to where it needs to > be? I am thinking it is the latter. does it tighten smooth to a given torque then start jumping? if so, you can count the turns [and fractions thereof] on an ok bolt from that torque to the required torque, then repeat the same number of turns on the problem bolt. that should get you close enough. > does it tighten smooth to a given torque then start jumping? if so, you > can count the turns [and fractions thereof] on an ok bolt from that > torque to the required torque, then repeat the same number of turns on > the problem bolt. that should get you close enough. Yes, that's exactly what it does. Your suggestion makes the most sense yet. I'll have a chance to look at it this weekend and that's what we will go with. >> does it tighten smooth to a given torque then start jumping? if so, you >> can count the turns [and fractions thereof] on an ok bolt from that [quoted text clipped - 5 lines] > Your suggestion makes the most sense yet. I'll have a chance to look > at it this weekend and that's what we will go with. Here is what I would do - replace the bolt with a stud. Either buy a pre-made stud of the correct lenght or make one. Use loctite stud and bearing mount on the threaded portion that screws into the block. I'd screw it in as tight as I could with the stud and bearing mount applied (but not so tight that it "jumps"). I'd then I'd install a nut on the portion of the stud that extends from the head. I'll bet I would have no problem torquing the nut to the correct value. Ed > > i don't know what the thread is on a prelude, but i can tell you for > > sure that the head bolt thread pitch on the civic is 1.25mm - i've just > > checked a couple i have in my box of bits. > > That sucks, before ordering the Helicoil stuff we checked the bolt > against a thread gauge at Napa (fit exactly 12mm x 1.5) I guess you now know why the hole was stripped..... Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590 (More Off Road album links at bottom of the view page) > We are working on a Honda 90 Accord, F22A4 open deck aluminum block. One > of [quoted text clipped - 19 lines] > and in > breaking off the installation tang. Anyone with experience there? Helicoil is the best way. A 12mm helicoil tap ought to be long enough for your needs. If not you can buy tap extensions, weld a bit more shaft on the end, cobble something together with a 1/4" drive female socket bar extension and grind the square on the tap down to fit. All sorts of ways with a bit of ingenuity. The tang is hardly an issue. You can knock that off with anything or just leave it in place if the bolt doesn't go that deep. The bit you ought to be worrying about is using the right length insert. Standard in most kits is 1.5 x D and they are usually fine. You might need a 2 x D for sufficient strength in aluminium but you can work that out by seeing how much thread is engaged on one of the other head bolts. SignatureDave Baker www.pumaracing.co.uk "Why," said Ford squatting down beside him and shivering, "are you lying face down in the dust?" "It's a very effective way of being wretched," said Marvin. |
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