Bolt torque values

Hello guys. Been putting my 2606 back together and wonder what the correct torque values should be for 1/4" and on up to 5/8"? The table I pulled up on my phone and have been using is all over the place and different numbers for galvanized, plain, galv + wax. Been using most of the old bolts which I think are grade 5 but have replaced some with grade 2. Typically use anti-seize except the blue locktite on the 1/4" fan bolts and red on the flywheel. Been going with the higher values. The IH book has 90 for head, 60 for flywheel, and 25 for manifold screws but these are special applications. Think I was using 150 ft. lbs for the 5/8" bolts. I see now that I have to pull 2 head bolts to add the tank bracket and then tighten them back down. Thanks. Just trying to be consistent. Been replacing most of the lock washers as a lot of them are flatter than a pancake after 50+ years. Most are coarse thread but I see that the 1/4" fan bolts are fine thread and I used 12# on those.

Put the Grade 2 in the iron barrel.

There is a torque spec section/link on the left side of this page.However,If you are overhauling the engine,why are you not useing a manual? An overhaul is just to important to 'wing
it'.Guessing is a good way to have a premature catostrophic engine failure.Why would anyone spend several hundred dollars on an overhaul(or any other major repair) without a 40
dollar book that contains all the specs,clearances and other pertanant information?

Lock washers are always a single use fastener and shouldn't be reused. I always toss the old ones and replace with new if needed. I really think lock washers are over used and are sometimes used as a "chicken fastener" in some applications.

My opinion yours many vary...

OTJ

small bolt torques are in inch lbs. such as the 1/4 and 5/16 bolts. for these bolts i just use a 3/8 ratchet or wrench and go by feel thing.
i do not use silicone on any gasket . for example the pan gasket is cork on a lot of stuff. using that stupid silicone just makes the gasket
squeeze out cause it so slippery. i use high tack gasket spray on every gasket, it holds the gaskets in place and if you need to remove the
gasket it comes off easy. but any how you only tighten the pan gasket till you see it want to squeeze the gasket out. also go over it about 4
times little bits at a time. i dont even remember torquing a pan gasket ,other than may be class. torques are in dry and lubed threads and
in plated or black bolts, plus fine thread and course is different. yes always replace lock washers. i like the grade 8 washers. you dont
need red locktite on any engine bolt either.

I remember when machines started coming through in the 70's with no lock washers, where there always used to be one. I agree with your sentiment. Of course the advent of many types of locknuts has helped too.

Anything less than grade 5 should not be used on anything other than toys as far as I'm concerned.If there are no marks on the head of the bolt it's soft.3 slashs grade 5- 5 slashs grade 8 in most cases.

I used to tell people- if they wanted to use up grade 2 hardware- to build a hay rack.

Here is a link to the torque chart on YT. You have to be is Classic View to see it and if you are viewing from a
phone you need to select options at the top.
YT ..general use course thread.. torque chart

What does your overhaul manual say?

thanks. I found the torque tables on the side of classic plus plenty of other info is there. For the record, the shop did the rebuild of the engine itself, I'm just installing it back on the tractor plus all the extra stuff. I'd assume I can use grade 2 to bolt the gas tank down, the hood, and some of that stuff.

Now for a couple theory questions.

1. My review of the torque values both here and used by fastenal talks about the tensile strength/clamp down/proof load of a bolt. That I can understand but it appears that they are more worried about bolt thread stretch since grade 2 and grade 5 bolts of the same size have different torques. I also believe these torque values are based on using nuts of the same grade. To me that begs the question whether the torque value would be the same when threading into cast iron of the engine block, bell housing, and rear ends of a tractor as the tensile strength of cast iron would be different than the nut of each grade? I assume that is part of the reasoning behind using 25# for manifold bolts so you don't pull the threads out of the cast or break it off.

2. I would think that the strength of the steel used in grade 2, 5, and 8 would have the same clamp down values based on the same standard thread size and thread count would be same. For example, if you take two plates held together by a 1/2" bolt, stuck a jack between the plates, at some point the threads will stretch and the bolt will shear. Same deal if you hung something from a crane held by a bolt and keep adding weight it will finally break. Or say that you insert a hydraulic jack between a head and engine block, at some point the bolts will shear. Or if a crane tried to pick up a D10 bulldozer with a 1/4" chain, it will break.

So we are back to different torque values of different grade bolts based on their clamp down strength but it seems like it is a matter of getting the bolts tighten up enough so they don't come loose from vibration, etc. as opposed to a head or flywheel being pulled apart. So wouldn't a grade 2, 5, or 8 bolt with the same threads maintain the same hold down at the same torque when screwed into a cast iron block?

I may be off base here but I know there are some people here who know this stuff. And I know there are different safety factors here as well. Thanks.

different grades of bolts have different strength values and are not made of the same material. a grade 2 will stretch , while a grade 8 will
just snap off. plus the grade 8 bolt can be stronger than the thing being clamped. that is why you torque values are engineered into stuff.
but i am not am engineer , so maybe one can explain it better. you need to clarify what you mean or give some spec's as to the 2,5, and grade
8 bolts maintaining the same hold down with the same torque. guess i am not the only one wondering what you mean by the 1/4 " bolts at 12 #
?

Ya know we told ya NOT to use loc tite and you NEVER use a grade 2 inplace of a grade five . You will not takle the advice from us the ones that worked on them every day for a living and have decades of experience. So you seam to know more then we do soooooooo why keep asking when ya don't listen .

The whole goal of a threaded fastener is to provide a clamp load between the mating parts and, just as importantly, maintain this clamp load for the life
of the machine. This is accomplished by tightening the bolt until it is under a certain amount of tensile stress which directly relates to the amount that
the bolt is stretched. The allowable stress level is a function of the grade of the bolt - a Grade 2 bolt cannot handle near the amount of stress as a
Grade 8. When torquing a bolt you never want to exceed the yield stress since that would mean that the clamp load would not be maintained. At the same
time you don't want to under-torque a bolt - for example, torque a Gr8 bolt to Gr2 specs - since you won't achieve enough bolt stretch to properly maintain
the clamp load long-term. The bolt torque charts you typically see are figured at 75% of the yield stress.

Unfortunately the torque at which a fastener is tightened is a very imprecise way of determining exactly what kind of clamp load you'll end up with. But,
it is by far the simplest method so that is what is commonly used in all but the most critical applications. The cleanliness of the threads, hardness of
the bearing surface, type of finish, presence or lack of lubrication, and other factors all combine to alter the amount of torque that is actually turned
into the desired result which is bolt stretch. The torque that isn't converted into bolt stretch is just eaten up overcoming friction.

There might be some confusion to as to what happens to a bolt that is holding two pieces together that are getting pulled apart. Until the two parts begin
to separate the bolt won't even "feel" the force pulling them apart. For example, a 1/2-13 Gr8 bolt has a clamp load of 12750 lbs when torqued properly
which means that the two pieces being bolted together have a force of 12750 lbs holding them together. If you apply a "pull apart" force of 10000 lbs to
the two parts the bolt is still only seeing 12750 lbs of load but you're down to just 2750 lbs of clamping force between the two parts. Not until the
"pull apart" force exceeds the bolt's clamp load and the two parts start moving apart will the tension of the bolt start to increase. But, it would be
proper to say that the bolted joint had failed long before this occurs. The clamping force and resulting friction is what keeps the parts from moving
sideways relative to each other and so a minimum load must be maintained. In most bolted joint applications the bolts should never be subjected to shear
stress (a shear bolt being an obvious exception but this isn't really a "bolted joint") and if they do get loaded in this manner you'd say the joint has
failed due to loose or not enough bolts.

Tractor Vet ...... take a deep breath and count to ten ...... put yer feet up and relax before you have a hernia or a cardiac arrest. Good grief ......

I know. I just looked. The only grade 2 bolts I used was 2 of the 5/8" on the bolster as that is what I had on hand. I can replace those when I get to the store unless I find the originals in the pile. Thanks Vet for keeping me straight. You do a good job being the expert here. Read a ton of your posts.

Thanks Brendan. I get what you are saying. Now just wonder how the cast female threads compares to grade 5 and 8 as being stronger or weaker. Have a couple transmission cover bolts, 3/8" fine thread, that seem stripped as they don't tighten down so I will tap the threads. They were like that when I took them out.

you might be using a heli coil in those, not that i like them. and there is no fine threaded bolts in the trans cover, nor on the tractor.

the experienced guys post for a reason, then the proper advise gets side tracked with stuff thrown in from everybody else that thinks the way
it should be done. who uses red locktite on an engine??? dont even see it being used on shakers and such where vibration is present. have you
removed bolts with red locktite??? T.V. is correct ! if i was out in the wilderness i would not be scared to assemble an engine and put it to
work without a torque wrench! when i was about 14 years old i took the head off a 1959 chev and put it together without a torque wrench, i
did not have one! and yes it ran after that and drove it around then sold it . then the guy that bought it drove it also.

Agreed on the grade two as being junk . They are not allowed on our utility site .

(quoted from post at 18:49:32 03/12/21)

who uses red locktite on an engine??? dont even see it being used on shakers and such where vibration is present. have you
removed bolts with red locktite??.

Click to expand...

It was the engine rebuilder who told me to use red locktite on the flywheel bolts because some of the bolt holes were open to the oil passages. Asked them about getting them off and they said they take them off every day with an impact wrench. They would have been the ones to put that on if I would have taken that mounting plate to them. That's all I know about it as they have a warranty on the engine. Hopefully it will never need to come off. Not trying to ruffle any feathers here, just trying to learn a few things and maybe there are others interested in knowing.

(quoted from post at 18:34:55 03/12/21) you might be using a heli coil in those, not that i like them. and there is no fine threaded bolts in the trans cover, nor on the tractor.

Click to expand...

Yeah, I don't know. A couple of them I took out were fine threads. Maybe that was the problem. Looks like it is an inspection cover for the forward/reverser. The other bolts hold it tight. Might add some rtv to keep the water out.

I do know the 4 fan bolts that screw into the water pump were a fine thread. I assume because the round bushing on the end of the pump isn't very thick. Thanks.