If you torqued them to the yield point, get new bolts. 
Question on torque to yield bolts
Guys,
I just torqued the main bolts on my ‘06 Ford 5.4 modular engine and used the torque angle gauge for the final tighten when I realized I forgot to oil the bolts. I realize you don’t want to reuse these bolts but is there a problem with removing them so I can lube them and then re-torque? Surely they can’t be so fragile as to not be able to be torqued twice, right?
Mike
I just torqued the main bolts on my ‘06 Ford 5.4 modular engine and used the torque angle gauge for the final tighten when I realized I forgot to oil the bolts. I realize you don’t want to reuse these bolts but is there a problem with removing them so I can lube them and then re-torque? Surely they can’t be so fragile as to not be able to be torqued twice, right?
Mike
1 - 20 of 43 Posts
I was afraid of that. That sucks. Think I’ll order ARP bolts. They’re cheaper too.
Mike
Mike
If you didn't use lubricant, there's a high probability that they didn't reach yield. Since friction in the threads is higher without lube, the angle will hit target before the threads screw all the way down into the hole. That typically means that the bolts don't elongate as much - you're using up torque and angle to twist the bolt elasically, not stretch it. The question is, do you feel lucky?
I hear ya. I'm thinking of just leaving it as is. When I got the block back from the machine shop I washed it thoroughly and soaked all the exposed unpainted surfaces down with an oil soaked rag. As I was preparing to place the caps I was surprised at how much oil got into the main bolt holes. It was basically dripping out to the point that I turned the engine over and let it sit a few minutes and "leak" onto the floor. Then I blotted the holes with paper towel. So while the bolts weren't soaked in oil like I usually do they weren't truly "dry". This is a stock rebuild on my '06 F150 that will only see limited daily driver duty. Given that the initial standard torque has a range of 27-32ftlbs and the torque angle is 85-95 what are the chances that a) these bolts aren't withing specs and b) this will lead to main bearing failure in this application? I'm guessing it's really low, no?
Yore in an iffy spot without thread lube maybe, or maybe not did you stretch them into yield. If you have one of these to measure length or can get the exact production length information then measure the bolts you used if they are a little bit longer after removal then they went into yield.
Bogie
Bogie
With the oil in the threads, I wouldn't worry about it.
I mean, really? It's not like they are made from glass, where a micro turn more would cause them to shatter.
Anyone know why manufacturers did something so ridiculous?
I mean, a hundred years or so of reusable bolts. What changed?
I mean, really? It's not like they are made from glass, where a micro turn more would cause them to shatter.
Anyone know why manufacturers did something so ridiculous?
I mean, a hundred years or so of reusable bolts. What changed?
TTY bolts installed using the torque-angle method eliminate the need to be concerned with thread friction---let it alone.
Sounds good that's the plan. gonna leave it as is. Thanks for all those who weighed in.
Mike
Mike
Sorry, but clearly some people posting here have no clue how TTY bolts work, based on the posts above.
The clamping force is designed to require a specific tension in the bolt. The way you get that is to use the threads as a micrometer - once the head of the bolt has contacted the clamping surface and you've taken out the slop in the joint, turning the bolt a specific angle causes the threads to stretch the shank of the bolt by a very specific amount. This is what provides the correct clamping force - it's exactly the same concept as using a stretch gauge on rod bolts. The lube on the threads ensures that you have taken out the slop in the joint BEFORE turning the fixed angle to provide the stretch and preload. If you didn't lube the bolts, you didn't take out all that slop and thus you did NOT get the correct stretch in the bolt when you applied the fixed angle. This is NOT a properly clamped joint and the head gaskets will likely leak at some point.
The whole point I was trying to make in my first post (which was apparently lost on people) is that the good news is that the friction in the threads means that you likely did not stretch the bolts past yield the first time, which means that you could probably remove them, lube them properly, and retorque correctly without having to buy new bolts. Doing nothing is a big mistake.
The clamping force is designed to require a specific tension in the bolt. The way you get that is to use the threads as a micrometer - once the head of the bolt has contacted the clamping surface and you've taken out the slop in the joint, turning the bolt a specific angle causes the threads to stretch the shank of the bolt by a very specific amount. This is what provides the correct clamping force - it's exactly the same concept as using a stretch gauge on rod bolts. The lube on the threads ensures that you have taken out the slop in the joint BEFORE turning the fixed angle to provide the stretch and preload. If you didn't lube the bolts, you didn't take out all that slop and thus you did NOT get the correct stretch in the bolt when you applied the fixed angle. This is NOT a properly clamped joint and the head gaskets will likely leak at some point.
The whole point I was trying to make in my first post (which was apparently lost on people) is that the good news is that the friction in the threads means that you likely did not stretch the bolts past yield the first time, which means that you could probably remove them, lube them properly, and retorque correctly without having to buy new bolts. Doing nothing is a big mistake.
Thanks Joe I get what your saying but my primary point in my reply was that the threads were in fact lubed and not dry. Just not the oil soaking I typically give these bolts, which I'm sure an engineer would say is way overkill. I'm satisfied that they were adequately oiled to technically satisfy the oiling requirement for proper torquing and bolt stretch. At this point I believe the likelihood of a problem is probably increased if I remove the bolts just to soak them in oil. Best approach is probably to replace them but I'm going to opt with sticking with what I got. If this were a race motor I might replace the bolts but this is a very low stress application so I'm satisfied.
Mike
Mike
the low torque of the initial step is to minimize the deviation caused by the thread friction component of the intended bolt torque.
LikeSorry, but clearly some people posting here have no clue how TTY bolts work, based on the posts above.
The clamping force is designed to require a specific tension in the bolt. The way you get that is to use the threads as a micrometer - once the head of the bolt has contacted the clamping surface and you've taken out the slop in the joint, turning the bolt a specific angle causes the threads to stretch the shank of the bolt by a very specific amount. This is what provides the correct clamping force - it's exactly the same concept as using a stretch gauge on rod bolts. The lube on the threads ensures that you have taken out the slop in the joint BEFORE turning the fixed angle to provide the stretch and preload. If you didn't lube the bolts, you didn't take out all that slop and thus you did NOT get the correct stretch in the bolt when you applied the fixed angle. This is NOT a properly clamped joint and the head gaskets will likely leak at some point.
The whole point I was trying to make in my first post (which was apparently lost on people) is that the good news is that the friction in the threads means that you likely did not stretch the bolts past yield the first time, which means that you could probably remove them, lube them properly, and retorque correctly without having to buy new bolts. Doing nothing is a big mistake.
Thank you for saving me the keystrokes. TTY doesn't mean they're a one-time-use, it simply means the way you achieve the proper bolt stretch uses angles, not torque.Sorry, but clearly some people posting here have no clue how TTY bolts work, based on the posts above.
The clamping force is designed to require a specific tension in the bolt. The way you get that is to use the threads as a micrometer - once the head of the bolt has contacted the clamping surface and you've taken out the slop in the joint, turning the bolt a specific angle causes the threads to stretch the shank of the bolt by a very specific amount. This is what provides the correct clamping force - it's exactly the same concept as using a stretch gauge on rod bolts. The lube on the threads ensures that you have taken out the slop in the joint BEFORE turning the fixed angle to provide the stretch and preload. If you didn't lube the bolts, you didn't take out all that slop and thus you did NOT get the correct stretch in the bolt when you applied the fixed angle. This is NOT a properly clamped joint and the head gaskets will likely leak at some point.
The whole point I was trying to make in my first post (which was apparently lost on people) is that the good news is that the friction in the threads means that you likely did not stretch the bolts past yield the first time, which means that you could probably remove them, lube them properly, and retorque correctly without having to buy new bolts. Doing nothing is a big mistake.
As you torque a traditional head bolt, the friction on the threads (lubed or not) becomes exponentially greater. The torque spec is a ballpark at best and assumes perfect threads, same coefficient of friction... etc. It's not very accurate to use torque as an indicator of bolt stretch and therefore tension.
If you instead use a lower torque value (before you get too deep into that exponential friction increase) and then use the angle method, you have used the ramp rate of the threads to provide a calculatable and far more accurate amount of tension than if you just torqued them to 80.
But the bolts themselves aren't made out of some special, one-time-use magical steel. They are still properly tensioned at the correct bolt stretch, regardless of the actual rotational torque. This is why I really hate the term "torque to yield" because it implies that you are torquing them to the absolute limit. It's basically saying "torqueing until they give up."
my understanding is that 'yield 'means the stress on the bolt as gone into the non-elastic region which causes permanent deformation of the bolt shank.
I get that TTY doesn’t have to mean disposable. The question is why use single use bolts on critical applications like these? I suspect the answer is it saved them 5 cents on every engine. ARP, the fastener experts, make their bolts reusable (as did all OEM for nearly a century as someone pointed out) and I have yet to encounter an application where they recommend a TTY installation protocol. If doing TTY was so much better and more accurate wouldn’t they adopt it for all their applications? I tried to get ARP main bolts but couldn’t find them for my application although I didn’t do an exhaustive search. I was able to get ARP rod bolts though thankfully and they of course are a straight up torque installation.
Mike
Mike
The OEMs have gone to TTY because it is far more accurate, which lets them shave materials in the block and heads to save weight. In older motors weight wasn't as important and the designers just make the deck surfaces thicker to spread out uneven clamping loads from torque variability. The point of a TTY fastener isn't that it's stronger. The point is that it produces a far more accurate and consistent clamping force.I get that TTY doesn’t have to mean disposable. The question is why use single use bolts on critical applications like these? I suspect the answer is it saved them 5 cents on every engine. ARP, the fastener experts, make their bolts reusable (as did all OEM for nearly a century as someone pointed out) and I have yet to encounter an application where they recommend a TTY installation protocol. If doing TTY was so much better and more accurate wouldn’t they adopt it for all their applications? I tried to get ARP main bolts but couldn’t find them for my application although I didn’t do an exhaustive search. I was able to get ARP rod bolts though thankfully and they of course are a straight up torque installation.
Mike
If you are asking why a company like ARP doesn't make TTY fasteners for older engines, it's because the block, heads, gaskets, and bolt pattern all need to be designed for TTY fasteners and the higher clamping force. Simply changing the fastener doesn't make the motor a TTY design.
I'd check them with a regular torque wrench at 65 and if they click off worry about something else.
What I’m saying is if that technique for tightening a bolt is far more accurate than why not adopt it for high performance applications like top fuel? I disagree that the system has to be designed for TTY. You can use TTY in any application if you study it to determine proper values. I think you have it backwards. Essentially, you first design the motor with “inferior” components, (the main bolts and head bolts are much thinner than old motors) but to get away with it you need very precise torque measurements. Again, comes back to saving a few dollars. I’ve lifted this block and crank it isn’t any lighter than any other sbf. Can’t believe there were any weight savings to justify this. My son is a student at one of the top engineering schools in the country and has helped me build several engines and is helping me on this one. He summed it up perfectly when he said “ I call BS”. This was not some major engineering advancement. It’s “experts” sitting around thinking too much IMHO. That’s how they came up with a disaster of an engine that the 5.4 Triton is. Look up “worst Ford engine ever” on you tube and you’ll get tons of hits on how badly this engine was designed. I usually am skeptical about everything the experts come up with. It’s sorta like “don’t wear a mask, wear a mask, you MUST wear a mask, you should wear two masks” BS. Or how about “use margarine it’s healthy!” Lol. Sorry for the semi rant. Just my 2 cents.
Mike
Mike
I give up. You're clearly much smarter than any of the engineers at the OEMs or at ARP. Knock yourself out.
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