What is the meaning of the following torque setting values

Can anyone here shed some ligh

Can anyone here shed some light on the meaning of the following torque setting values

I am just about to change the crankshaft damper on my 400hp Iveco diesel the workshop manual recommends to tighten the 6 bolts to the following torque settings

"270NM + 180 degrees + 180 degrees"

Does this mean I need to tighten each of the 6 bolts to 270nm then a half turn on each bolt then a second half turn (as in a whole turn but done in 2 parts to tighten the circle of bolts equally?)

Jim

"B Shark...
Thats exactly wha

"B Shark...
Thats exactly what that means. But...you may want to double check those numbers. 270 newtom meters is about 199 foot pounds when you do the conversion. Then when you give those bolts a half turn and then another half turn, I can't imagine that they won't start breaking bolt heads off. You should also be looking for new bolts to put in there before you start re-assy. The reason for the extra 1/2 turns is to stretch the bolts to the proper torque. The factory figures this all out and designs the bolts accordingly. The bolts are usually only to be stretched once. New bolts are required every time..... If the book says 270 though, then thats what you should go with. When tightening them down in the proper sequence, tell everyone around you to keep quiet and count the bolts out loud to yourself as you tighten them. It may sound stupid to do that out loud, but if you loose your way through that tightening sequence, you;ll miss a bolt, and do one of the other ones twice. Bad news.

Wrench"

"Wrench,

Thank you for clar

"Wrench,

Thank you for clarifying the extra 2 half turns.

I was also thinking like you 270nm sounds a lot and then a whole turn again. Most torque wrenches don't even tighten to 270nm. The print on my photocopied manual is not 100% legible so I e-mailed Iveco in England and they sent me those figures also, but to be safe I just e-mailed them again to double check it may well be a misprint in the workshop manual.

I have a new set of bolts because I am also adding a double pulley to drive a hydraulic pump so I needed longer bolts to allow for the pulley width. The bolts were difficult to source. They have a 1.25 fine metric thread M10 X 60mm in 10.9 strength.

Good advice on counting the bolts! I think I'll mark them and make a note of each as I tighten them too at that torque level

Jim"

"I've never seen torque in

"I've never seen torque insturctions like this before. Usually, torquing procedures include a tightening sequence and torquing in incremental stages to full torque. Often, a relaxation time is given, 30 min to an hour, to let the gasket seat in before a final tighening pass is applied.
Usually a specific bolt thread lubricant is named so that there is a known thread friction factor. Load generated on the bolt is in direct, but inversely, porportion to the thread friction, i.e. increasing the thread friction by 2 cuts the load applied to the bolt by 1/2 in theory."

"Mike...
I'm not sure abo

"Mike...
I'm not sure about the Marine industry, but in Automotive applications, it is quite common to torque head bolts to spec. and then stretch them with a final one or two, 1/2 turns.

Wrench"

"I understand torque to yield

"I understand torque to yield specs, but those values are incredibly high. if the bolt would take that kind of torque (which I doubt) it would almost certainly pull the threads out of the crankshaft. something not right about those numbers. be carefull."

"Well here is the latest updat

"Well here is the latest update. I doubled checked with Iveco UK and they told me the torque figures were correct and to go ahead and tighten the 6 bolts.

So I went ahead and "SNAP", two bolts sheared, I thought the first one was the wrench clicking but the second one was a clean break. Both left about an inch of the bolts inside.

I contacted Iveco UK again and it seems the workshop manual has an error after all. The torque figure of 270nm + 180deg + 180deg is in fact for the crankshaft bolt. arrrrrrh!!!

Next I tried to open the crank shaft bolt but failed to budge it with a 3.5 foot power bar. The bolts stick out about 5 mm at the back so would have been easy to remove if I could have opened the crankshaft bolt. Looks like no other option now only drill the bolts and use a screw extractor.

What a pain "

"Doon't you love translate

"Doon't you love translated Japanese instructions! You'd think they'd hire an American mech engineer to go over all that before publishing, but...

Good luck!

Jeff"

"Shark...
I feel your pain,

"Shark...
I feel your pain,
Been there myself when you're trying to do things by the book only to get screwed up by the people who are supposed to know what they are doing. Are these the bolts that hold the pulleys onto the crank dampener? If so, I don't think that I have ever worried about proper torque on those bolts. It maybe different if they are on a big diesel with more vibration, but other than that, I make sure that they are all good and tight and move on. Over the years I've had an incredible number of pulleys and dampeners off and on and have never had a problem. Have they come up with a more reasonable torque value for those bolts or are you just going to make them very tight with some red loc-tite on them? Even for the big crank bolt, that 270 + 1/2 + 1/2 seems over the top. Things don't need to be THAT tight.

Wrench"

"Hi Wrench..

Iveco recommen

"Hi Wrench..

Iveco recommends changing the damper every 1500 hours although I suspect this may be just an extra little money spinner for them.. The double pulley is a new addition as I am fitting a hydraulic pump to drive a capstan winch.

The big crankshaft bolt (36mm hex head) bolts on a flange for want of a better word, with 6 X 10mm fine pitch threaded holes which the damper bolts on to. You just need to replace the bolts with longer bolts to add the pulley option. The two broken bolts are sticking out about 5mm from the back of the flange but there is is only a few mm clearance behind the bolts. If I could open the big crankshaft bolt it would be a simple case of cutting a straight slot in the bolt ends and screw them back out. I could also grip them with a vice grips and screw them right through but I would be afraid that could damage the flange threads.

Iveco UK said if I get the crankshaft bolt out to tighten it back to 270nm but not to bother with the two half turns "just give it what you can" they said. The six bolts on the damper they now say to tighten as tight as you can by hand and just give one or two "taps of a hammer" That is exactly what I had done before they said to tighten them to 270nm + 180 + 180 deg


I was going to drill the bolts today but the boat is afloat on a swinging mooring and its blowing a gale here, a rocking boat would make the drilling too difficult so I hope to get it done on Saturday.

The M10(mm) bolts are H.T strength 10.9 I need to drill a 4.5mm hole for the No. #3 screw extractor (EZ out). I bought a few new HSS drill bits and a bottle of cutting oil for the task.

Do you have any experience of drilling 10.9 strength bolts? Any tips or advice would be appreciated


Jim"

"Hi Jim,
I've got a few t

"Hi Jim,
I've got a few thoughts.
1) is there any chance that the big bolt (36 mm head) is left hand thread and you've been tightening it? Try putting that 3 1/2 footer back on it and going the other way.
2) I looked for a 10.9 bolt in my tool box and was going to drill it to see what is was like. I only have 8.8 bolts in there, so that didn't pan out. I really don't think it should be too hard to drill though. Make sure to use a slow drill, my air drill is 500 rpm. Don't go in with a 2500 rpm drill as it will burn out that drill bit in seconds. Use lots of pressure and oil on that drill bit and it should cut right in.
3) If you want to see how your drill bits stand up to the bolt, go out and buy a couple of 10.9 bolts at the hardware store and give 'em a try at home in a vise. If the bits don't stand up very well, go and get a good Cobalt bit. That should eat right through the hardness of that bolt.
Let me know how it goes.

Wrench"

"Hi Wrench,

I drilled one b

"Hi Wrench,

I drilled one bolt out last week. I first drilled a 2.5mm pilot hole then using TiN plated HSS 4.5mm drill bits I drilled it no problem. I had to use a few bits. The easy out removed the bolt with ease, it took about 20 minutes.

But the second bolt is a different story. It is much much harder it just melted the TiN plated bits so I then tried drilling a 3 mm pilot hole with a cobalt bit which melted away too, so I increased up to a 4mm cobalt bit that too went blunt in no time. I now have the second bolt drilled to a depth of about 5mm. I had to go and buy a few more cobalt bits but I didn't get a chance to continue the job today with the weather and it looks unlikely I will be able to with the weather over the next few days.

I used a heavy duty 110volt slow drill and plenty of cutting oil. I should get it sorted now that I am armed with a few more cobalt bits.

Any idea why one bolt would be much harder? Would it have anything to do with the way it snapped or is it just my luck it was a harder bolt


Jim"

"frankly, I'm surprised th

"frankly, I'm surprised the first one went that easy. are you aware of, and have you checked into left handed drill bits? in a situation where the bolts are not badly siezed, sometimes they will back out while drilling. the drawback- hard, or impossible to sharpen. good luck, S."

"Jim...
Scott is right about

"Jim...
Scott is right about those left hand drill bits backing out a bolt as you're drilling into it. I don't know what to tell you about one bolt being that much harder than the other one. Just luck of the draw I guess. It can become very frustrating trying to get out broken bolts, but if you're in about 5 mm by now, the easy-out should be pretty close to being able to grab a hold of something soon. Keep your fingers crossed.
Lucky to have some weather there to get some things done. We have two feet of snow on the ground and minus 15 degrees C today. Its a good day to stay inside and watch movies with the kids.

Wrench"

"Good news both bolts are now

"Good news both bolts are now out

It wasn't easy! The second bolt was a nightmare the easy out broke in the bolt

The crankshaft bolt failed to budge on a second attempt with an electric impact wrench. This however was a stroke of good luck as the bolt does not hold on the pulley and its flange at all, even though the engine manufactures told me it does I discovered this after trying the crankshaft bolt with the impact wrench, I noticed the pulley seemed to have a little play on it.

So I moved to "Plan C"... I drilled out the bolt and the broken easy out, this took a couple of hours over 2 days as the drill needed to be charged. It took several drill bits of various sizes and lots of em, a centre punch, a small chisel, and a hammer. Believe it or not the best drill of the few I had was my cheap n trusty little 12v cordless Draper with lots of pressure applied (many have laughed at this drill but it has quietened many with much more expensive toys!!)

I used cobalt, TiN plated and the normal black and bright HSS bits. To be honest there wasn't much difference between them only the price. I couldn't source left hand drill bits at all here they need to specially order them in for you!

Finally got it out today I bought a tap and re threaded the hole and its good as new!

Thank you for all your help and ideas!

Jim"

Hi Jim...
I have been wonderi

Hi Jim...
I have been wondering how the whole pulley job was going on over there. Glad to hear that you finally got the bolts out. I know about those broken easy-outs. You come up with a whole bunch of new words when you realize that one of those things breaks off inside the hole. Keep working at it and let us know how the hydraulics work when its all finished.

Wrench