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Flywheel bolt torque


br549
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1 hour ago, Mack Technician said:

Torque to 44 ftlbs. In X-cross pattern.

angle tighten 120 degrees in X-pattern.

I understand what that means, but why to they give procedures like that and not just the final torque #?        Just curious that's all.    

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1 hour ago, Hobert62 said:

I understand what that means, but why to they give procedures like that and not just the final torque #?        Just curious that's all.    

Its the Volvo way complicate the simple. This final torque will likly end up at 180 like all other mack flywheels in the past  ITS a dam 5/8 bolt .However It seems they need to Tech shit to death! Torque to yield everything!🙄

Edited by fjh
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6 hours ago, Hobert62 said:

I understand what that means, but why to they give procedures like that and not just the final torque #?        Just curious that's all.    

What fjh said and they can also sell a cool digital angle meter to you also.

Anyone remember Mack E-tech flywheels, rod or main brgs coming loose in the abscence of torque-turn specs? I don’t. 

Edited by Mack Technician
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I'm sure there would be some valid excuse why they do the things they do We are just out of the loop on it🙄 ! Its not for us to wonder why , just blindly  do what the stupid instructions say! Its the same with the injector cup issue and the ever changing instructions to install  them to try and make them last thru the warranty period! 😫

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Ford started the degree torque in the late 70's early 80's on the bigger F- series. Much of the chassis and engine fasteners HAD to be angle torqued there was no foot pound values. In fact most fasteners on the heads and internals came with head sets and main and rod sets. 

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9 hours ago, 41chevy said:

Ford started the degree torque in the late 70's early 80's on the bigger F- series. Much of the chassis and engine fasteners HAD to be angle torqued there was no foot pound values. In fact most fasteners on the heads and internals came with head sets and main and rod sets. 

Torque to yield instead of torque turn? 

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25 minutes ago, keg1 said:

I know I'm not to bright but what is angle tightening?

Take a group of bolts to a low torque spec then turn each one a predetermined number of degrees of turn to get your load, instead of just torquing to a top spec. Like taking a 180 ft lb bolt to 50 ftlbs and then an additional 1/2 turn with a breaker bar to reach 180 instead of just using a torque wrench to full spec. If you stretch them (per manufacturer) its a torque to yield, you intentionally distort the bolt and have to replace them every time. Otherwise you can reuse them if not taken to the “stretched” dimension. 

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1 hour ago, Mack Technician said:

Take a group of bolts to a low torque spec then turn each one a predetermined number of degrees of turn to get your load, instead of just torquing to a top spec. Like taking a 180 ft lb bolt to 50 ftlbs and then an additional 1/2 turn with a breaker bar to reach 180 instead of just using a torque wrench to full spec. If you stretch them (per manufacturer) its a torque to yield, you intentionally distort the bolt and have to replace them every time. Otherwise you can reuse them if not taken to the “stretched” dimension. 

So could you take a bolt that requires 180 lbs of torque to 60 then 120 then 180 with a torque wrench and get the same results?    terry:MackLogo:

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1 hour ago, Mack Technician said:

Not according to many engineers. At this level we just say “sir, yes sir” and follow the established protocol. There are some interesting reads online explaining dynamics, they primarily do it on critical fasteners. 

Certain bolts used on the MP inierds  rockers / injectors  bla bla bla they recommend marking and are only to be   used  several times! Snap on sells a tecky digital torque wrench for this, pricey but if you doing lots of this kind of work worth having! I believe the Idea behind this is the tighter the bolt gets the more lost due to friction could impact the (eveness for lack of a better word)  of the bolt tightness. we could likley add this number in however its more techy and MAYBE More reliable bolt tightness! And if they reasonable they stick to even numbers 90 degees, 120 degrees ect it can be done with an impact wrench!

Edited by fjh
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Many fasteners list the proper lube to use to get the required torque.  Either dry, oil, or moly, they all give a different friction which changes the actual torque on the bolt.   I think the angular way eliminates that.

Most of the TTY bolts I've seen, have thin shanks on them.  Unlike a common fastener you just tighten.  Once that shank is stretched, it is junk.  I don't think you can just pull it tight and be accurate.  Maybe you can?  Not sure I would trust it for something critical(like main or rod cap) where lots of bad things happen when they fail.  A headbolt isn't so tragic, but still costly.

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Larry

1959 B61 Liv'n Large......................

Charter member of the "MACK PACK"

 

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Kind of have the same thinking .and it does take some of the grunt work out of it as well on the higher torque sets has its place I suppose!

however as mentioned the Same bolt size same job and you change the proceeder for it ? Worked before!

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I'm sure the ONLY reason for TTY bolts is cost in manufacturing.  Or at least repeat ability/accuracy on the assy line at lower cost?  Something along those lines.  Nothing to do with being "Better",  just cheaper.   The OEM doesn't build it for ease of repair.  They just want to sell you another one.

I watched International build the 7.3 PSD at the plant in Indianapolis back in like 2002ish.  Very cool to see the whole shortblock assembled by a robot.  Pistons, rods, crank, all put in and torqued by robot.

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Larry

1959 B61 Liv'n Large......................

Charter member of the "MACK PACK"

 

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When I went to the Mack MP engine class in Atlanta they showed us why they use angle torque method. First they showed us why “not” to use the new modern angle tourque wrenches.  They had a new Snap on angle torque wrench and fooled it many times by turning the wrench slowly. Then they showed us why angle torque is more accurate. During  torquing say a head bolt to 150 ft pounds . That if you stop while turning the bolt  ( stopping at say 130 ft pounds) due to the wrench hitting the fire wall then back the wrench back up to start pulling on it. To get the bolt started turning again while it at 130 ft pounds will probably require more than 150 ft pounds of tourque . So the Tech hears the click and thinks thes at 150 when really he’s at 130-135. Kinda hard to explain but they showed us right there in the shop and I saw what they were talking about. 

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6 minutes ago, Mackpro said:

When I went to the Mack MP engine class in Atlanta they showed us why they use angle torque method. First they showed us why “not” to use the new modern angle tourque wrenches.  They had a new Snap on angle torque wrench and fooled it many times by turning the wrench slowly. Then they showed us why angle torque is more accurate. During  torquing say a head bolt to 150 ft pounds . That if you stop while turning the bolt  ( stopping at say 130 ft pounds) due to the wrench hitting the fire wall then back the wrench back up to start pulling on it. To get the bolt started turning again while it at 130 ft pounds will probably require more than 150 ft pounds of tourque . So the Tech hears the click and thinks thes at 150 when really he’s at 130-135. Kinda hard to explain but they showed us right there in the shop and I saw what they were talking about. 

Good to see you Pro. and good info ! so did they have anything bad to say finishing out the angle turn by impact? This here kind of makes sense ! How ever.....

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Proper torque has to done with a very smooth, even motion to completion.  Any variation can lead to changes of final torque.  Luckily most things aren't that sensitive to it. 

Most of my racing engines, the rods are measured for stretch using a dial indicator.  Measure the bolt at rest, then pull it til it stretches like .006.  That usually equates to about 60 ft/lb.  But sometimes, due to metallurgy of the bolt it might take 65-70 to get it to actually pull the .006.  The torque isn't as critical, but gets you in the ballpark for stretch.   If you are short, just give it a slight pull and recheck the stretch.

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Larry

1959 B61 Liv'n Large......................

Charter member of the "MACK PACK"

 

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12 hours ago, Mack Technician said:

Take a group of bolts to a low torque spec then turn each one a predetermined number of degrees of turn to get your load, instead of just torquing to a top spec. Like taking a 180 ft lb bolt to 50 ftlbs and then an additional 1/2 turn with a breaker bar to reach 180 instead of just using a torque wrench to full spec. If you stretch them (per manufacturer) its a torque to yield, you intentionally distort the bolt and have to replace them every time. Otherwise you can reuse them if not taken to the “stretched” dimension. 

Thought that's what it meant wasn't sure. Thanks

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