ARP Stud gave up

TKB4 · **Posted:** Sun Aug 06, 2017 4:20 pm

I have always had trouble viewing and posting pics . I always attributed it to using a mac and safari browser so recently I spent some time trying to get it to work and ended up getting my sons to help me they recommended a site called IMGUR. It is free and they seem to believe it would be one of the last ones to start charging for their services. It seems to work well.

GordnadoCRD · **Posted:** Sun Aug 06, 2017 5:12 pm

TKB4 wrote:

I would like to point out that the instructions enclosed with the ARP studs is not clearly consistent with what the tech told you.

It states quote Lubricate the stud threads, nuts and washers with ARP end quote lube then install the washers and the nuts onto the studs and tighten them hand tight. I then says to tighten in 3 equal steps to 125 ft lbs in manufacture recommended sequence. But remember these are for the VW TDI.

I wonder if he told you 125 ft lbs because of that (VW TDI) even though originally outside bolts were rotated less degrees which would seem to end up with less torque on these.

Must confess being a good little boy, I read all the directions before installing and determined that first parts didn't apply to me so when later part said apply lube to threads I took it to mean both ends. Reading it a third time, since you could put loctite or permatex on coarse threads it would make sense not to put lubricate on the coarse end but it does not specify which threads but again looks like you would have already put coarse end in block before the lubricant step. They also do not make any mention whatsoever about making sure seat for washer is clean or dry or prepped in any way. They do not say don't put lube on any particular side of washer, or just a few threads of the fine end or no lube in the nut.
I am still not convinced that lube on bottom coarse threads will make much difference. The target torque whatever it is should still end up when the head to block pressure is the desired amount . Unless the lube would somehow let the whole bolt loosen by unscrewing. I doubt this since even the original tty bolts are oiled i believe.

What happened to ARP recommending 130ft lbs center and 120ft lbs outside bolts if this guy said 125ft lbs presumably on all bolts? I really think he just made an honest mistake on that. But if the rest of what he said is true they need to clearly state do not apply lube to the coarse thread end that will go into block and do not put lube on bottom surface of washer and make sure seat area for washer is clean dry and make some recommendation about how far to let the top of stud protrude from head.
I also may be mistaken but I believe ARP recommendation has always been 125 lbs-ft of torque, in 3 steps. This number was arrived at by measuring the clamping force of the OEM head bolts correctly installed. I don't remember who it was first, but it was someone from this forum that first tried the 130 lbs-ft figure, then found out that it caused significant compression-distortion of the aluminum head on the outer parts. From that came the 130 / 120 figure. I believe ARP's recommendation for this application has always been 125 lbs-ft done in three steps using their specific procedure for what is to be lubricated, and the final step of torquing is where you loosen the nut, set the stud height, and re-torque to 125 lbs-ft.

I though I read somewhere on forum to put washer and nut on tighten nut to flush with top of stud (fine end of course) and then put whole stud in hand tight. I could be wrong.
That is one of the steps, but not the whole procedure.

Enough of a rant

WHAT I WANT TO SEE is someone doing head dgasket replacement to install some or all of the factory head bolts according to FSM then check them with torque wrench to see what the actual torque values. This could even be done on the old head gasket or even moving one ARP at a time to check 2 or 3 with the new head gasket. Say start at 100ft lbs and increase 5 lb increments or so then may check another one or two 5lbs below that and increase 1 at a time. Do this on inner and outer bolts and see what torque the factory specs end up . This would at least give use a minimum for the ARP s and since the factory ones generally lasted a pretty long time before they stretched if the ARP s don't stretch even at this value they should last indefinitely. I saw up to 115ft lbs removing some original head bolts and as low as 75 to 80 ft lbs but I realize that isn't very accurate indication of original torque value whether stretched or not.

#1) This would not be accurate, as the only consistency is bolt STRETCH, not torque, and because torque has so many variables that effect it, the results would be meaningless.
#2) The OEM stretch bolts are tightened using the coarse block-bolt interface. The ARP studs only use the coarse block-bolt interface to regulate installed height. The torquing is done using the much finer Stud-nut thread interface. The finer thread gives much more clamping force per torque value, in such manner as a lower gear ratio gives more turning force to the affected axles with the same engine output.

flash7210 · **Posted:** Sun Aug 06, 2017 6:04 pm

ARP does not make head studs for a VM R428 engine.
But they do make head studs for a VW TDI engine and it just so happens that those TDI studs fit the R428.
ARP does not know the specifications for a R428, they only know the TDI.
Therefore, ARP is only going to recommend a torque value for the TDI.

The 130/120 torque values were recommended by a forum member who did all the research to find the correct studs and pioneered the use and installation of such studs.

There was long thread about it, but Im not going to search for it.

racertracer · **Posted:** Sun Aug 06, 2017 8:26 pm

Thanks TKB4 ... You've given me fuel for the fodder ... I will be calling ARP again tomorrow.

GordnadoCRD · **Posted:** Sun Aug 06, 2017 9:17 pm

flash7210 wrote:

ARP does not make head studs for a VM R428 engine.
But they do make head studs for a VW TDI engine and it just so happens that those TDI studs fit the R428.
ARP does not know the specifications for a R428, they only know the TDI.
Therefore, ARP is only going to recommend a torque value for the TDI.

The 130/120 torque values were recommended by a forum member who did all the research to find the correct studs and pioneered the use and installation of such studs.

There was long thread about it, but Im not going to search for it.

Flash, That's the same thread I was referring to. There was contact with ARP about this use. In the first communication with ARP about the torque spec they required sending them an OEM CRD head bolt to test. The 125 lbs-ft was the result.
I'm Aware of the 10 piece package for the VW. That's why the "CRD kit" has 2 extra.

tjkj2002 · **Posted:** Sun Aug 06, 2017 9:41 pm

GordnadoCRD wrote:

#2) The OEM stretch bolts are tightened using the coarse block-bolt interface. The ARP studs only use the coarse block-bolt interface to regulate installed height. The torquing is done using the much finer Stud-nut thread interface. The finer thread gives much more clamping force per torque value, in such manner as a lower gear ratio gives more turning force to the affected axles with the same engine output.[/color]

Finer threads does not mean more clamping force,finer threads can take more torque then coarse threads since finer threads have more surface area then coarse threads.

You torque a bolt/nut to 125lbs-ft you torque it to 125lbs-ft regardless if the bolt/nut is coarse or fine threads.

Without VM or ARP actually doing the research for the correct torque values for the studs and if the threads should be dry/lubricated I would not use them.Good way to ruin a very expensive and hard to get engine which I've seen many of you do with the ARP studs.

GordnadoCRD · **Posted:** Sun Aug 06, 2017 9:56 pm

tjkj2002 wrote:

GordnadoCRD wrote:

#2) The OEM stretch bolts are tightened using the coarse block-bolt interface. The ARP studs only use the coarse block-bolt interface to regulate installed height. The torquing is done using the much finer Stud-nut thread interface. The finer thread gives much more clamping force per torque value, in such manner as a lower gear ratio gives more turning force to the affected axles with the same engine output.[/color]

Finer threads does not mean more clamping force,finer threads can take more torque then coarse threads since finer threads have more surface area then coarse threads.

You torque a bolt/nut to 125lbs-ft you torque it to 125lbs-ft regardless if the bolt/nut is coarse or fine threads.

Without VM or ARP actually doing the research for the correct torque values for the studs and if the threads should be dry/lubricated I would not use them.Good way to ruin a very expensive and hard to get engine which I've seen many of you do with the ARP studs.

That only holds true if the thread pitch is the same, and fine threads almost always have more tpi than coarse. it's works just like pushing something up a hill. It requires less force (torque) to move something up a 5% grade, than the force required to move the same something up a 10% grade. Or more relevantly stated, the equal force @limit applied to something weighing 100 lbs pushing up a 5% grade, will only be capable of pushing 50 lbs up a 10% grade.
Bolt diameter, Friction and Torque being equal, fine threads exert more clamping force than coarse threads.

TKB4 · **Posted:** Sun Aug 06, 2017 10:20 pm

I think one of the first was LMWatbullrun. BTW i think he and geeordi both had previous experience with the VW TDI which is ironic that thats the bolts that ended up being used. I believe then I saw a value of 140ft lbs . Yes the bolts have never been made for the 2.8 because apparently when ARP was contacted about making some for the R428 they reviewed data provided to them that IIRC came from VM engineers and stated it would end up being much more expensive per set to produce some specifically for the R428 and they said the closest thing they had were he ones for the VW TDI . Later I believe Geordi talked with ARP and was told that the 130ftlb and 120ft lb lb would be appropriate but of course they did not make an official written declaration at least he posted that this is what came from ARP via someone. Since they did not design them for the r428 but knew they would be used in the r428 and probably wanted the results to be good to sell more of them I suppose they believed it was in their best interest to give an unofficial opinion.

Explained with the gear ratio analogy I understand the point basically more mechanical advantage for a given amount of torque applied.
Yes, I agree prior to point of deformation the finer threads would be result in more compression force at a given torque value but we still need to know the original factory bolt torque value to be able to figure the torque value to put on ARP to be similar. We just need the threads per inch for both but we still cannot account for tty bolt stretch we do not have a measurement for. We could also say go to the same ftlbs as factory I believe 22 then turn the finer threads an increased number of degrees in proportion to thread count to try to reach same distance from head of bolt/washer to block surface but this again would assume no stretch of either bolt but may be more accurate. Even after deformation to a point increase torque would still increase compressive force .

I wonder what the VW TDI and ford 6.0 head bolt torque instructions were from factory and the thread count and what the recs were from ARP in proportion to the original factory bolts.

I suppose its a best guess at this point but I do know 130 and 120 on ARP sealed a leaking head gasket on my first replacement with the one by one method. However, at this point I wonder if a little lower values may be more prudent if replacing head gasket and make sure head is flat first also. Maybe someone can find the actual data as to what the clamp force was from factory and what it is with the 130 and 120 from ARP

Either way I will be interested in what they say in relation to the instructions.

tjkj2002 · **Posted:** Sun Aug 06, 2017 10:23 pm

GordnadoCRD wrote:

That only holds true if the thread pitch is the same, and fine threads almost always have more tpi than coarse. it's works just like pushing something up a hill. It requires less force (torque) to move something up a 5% grade, than the force required to move the same something up a 10% grade. Or more relevantly stated, the equal force @limit applied to something weighing 100 lbs pushing up a 5% grade, will only be capable of pushing 50 lbs up a 10% grade.
Bolt diameter, Friction and Torque being equal, fine threads exert more clamping force than coarse threads.

IF you torque a 3/8 24 bolt(dry) to 30lbs-ft and torque a 3/8 16(dry) bolt to 30lbs-ft both are torqued to the exact same 30lbs-ft.Both have the same clamping force if both bolts have identical dimensions besides one being coarse thread and the other being fine thread.

What you are talking about is makes no sense when talking about bolts and torque.gearing for differentials your comments make sense but not torquing a bolt.

TKB4 · **Posted:** Sun Aug 06, 2017 10:38 pm

I thought the same at first but after I thought of the physics I had my doubts but now i am thinking i was right the first time . :banghead:

Guess I will have to think about it some more.

GordnadoCRD · **Posted:** Sun Aug 06, 2017 10:49 pm

tjkj2002 wrote:

GordnadoCRD wrote:

That only holds true if the thread pitch is the same, and fine threads almost always have more tpi than coarse. it's works just like pushing something up a hill. It requires less force (torque) to move something up a 5% grade, than the force required to move the same something up a 10% grade. Or more relevantly stated, the equal force @limit applied to something weighing 100 lbs pushing up a 5% grade, will only be capable of pushing 50 lbs up a 10% grade.
Bolt diameter, Friction and Torque being equal, fine threads exert more clamping force than coarse threads.

IF you torque a 3/8 24 bolt(dry) to 30lbs-ft and torque a 3/8 16(dry) bolt to 30lbs-ft both are torqued to the exact same 30lbs-ft.Both have the same clamping force if both bolts have identical dimensions besides one being coarse thread and the other being fine thread.

What you are talking about is makes no sense when talking about bolts and torque.gearing for differentials your comments make sense but not torquing a bolt.

I invite you to test that theory!
A couple pieces of reasonably thick UHMW drilled and tapped for each threading as you state. Sandwich A pressure sensor between them, and measure the force.
:twisted:

Prove to me that I'm wrong and I'll retract my statement. :twisted:

tjkj2002 · **Posted:** Sun Aug 06, 2017 11:13 pm

GordnadoCRD wrote:

tjkj2002 wrote:

GordnadoCRD wrote:

That only holds true if the thread pitch is the same, and fine threads almost always have more tpi than coarse. it's works just like pushing something up a hill. It requires less force (torque) to move something up a 5% grade, than the force required to move the same something up a 10% grade. Or more relevantly stated, the equal force @limit applied to something weighing 100 lbs pushing up a 5% grade, will only be capable of pushing 50 lbs up a 10% grade.
Bolt diameter, Friction and Torque being equal, fine threads exert more clamping force than coarse threads.

IF you torque a 3/8 24 bolt(dry) to 30lbs-ft and torque a 3/8 16(dry) bolt to 30lbs-ft both are torqued to the exact same 30lbs-ft.Both have the same clamping force if both bolts have identical dimensions besides one being coarse thread and the other being fine thread.

What you are talking about is makes no sense when talking about bolts and torque.gearing for differentials your comments make sense but not torquing a bolt.

I invite you to test that theory!
A couple pieces of reasonably thick UHMW drilled and tapped for each threading as you state. Sandwich A pressure sensor between them, and measure the force.
:twisted:

Prove to me that I'm wrong and I'll retract my statement. :twisted:

If the 2 bolts are the same dimensions besides the thread pitch they will have the same clamping force if both are torqued the same.

Quote:

Fine threaded bolts are stronger than the corresponding coarse threaded bolts of the same hardness. This is in both tension and shear due to the fine threaded bolts having a slightly larger tensile stress area and minor diameter.

Fine threads have less tendency to loosen under vibration due to their having a smaller helix angle than coarse threads. Fine thread Locking Insert grip coils are more flexible than coarse thread insert corresponding size grip coils, and are less likely to take a set under vibration conditions.

Fine threads because of their finer pitch allow for finer adjustments in those applications that need this characteristic.

Fine threads can be more easily tapped into difficult to tap materials, and thin walled sections.

Fine threads require less tightening torque to develop equivalent preloads to the corresponding coarse thread bolt sizes.

Last sentence,preload is not the same as clamping force.

Quote:

Negative sides of fine threaded fasteners:

Fine threads are more susceptible to galling than coarse threads.
They need longer thread engagements and are more prone to damage and thread fouling.
They are also less suitable for high speed assembly since they are more likely to seize when being tightened.

The potential benefits of fine threads are:

Size for size a fine thread is stronger than a coarse thread. This is both in tension (because of the larger stress area) and shear (because of their larger minor diameter).
Because of the smaller pitch they allow finer adjustments in applications that need such a feature.
Fine threads can be more easily tapped into hard materials and thin walled tubes.
Fine threads require less torque to develop equivalent bolt preloads.
Fine threads have less tendency to loosen since the thread incline is smaller and hence so is the off torque.

Again "preload",not the same as clamping force.

TKB4 · **Posted:** Sun Aug 06, 2017 11:24 pm

I am still on the fence but the more I think about it the more I believe it is the same force as I originally thought. As an analogy it takes the same amount of work to get that lower geared vehicle up a mountain to the same level you just go up less with each revolution.

Another way to think of it is: If you tighten a torque wrench from one foot out on the wrench it will take exactly twice as much force to accomplish the same torque as it would from 2 feet out on the wrench. The torque will be exactly the same on the bolt. The mechanical advantage will allow you to get the same amount of work done with less force but it is still exactly the same amount of work.

I think I will put this question to a mechanical engineer i know and see what he says but all this is theoretical there is still going to be some difference from all kinds of variables.

GordnadoCRD · **Posted:** Sun Aug 06, 2017 11:39 pm

GordnadoCRD wrote:

tjkj2002 wrote:

GordnadoCRD wrote:

That only holds true if the thread pitch is the same, and fine threads almost always have more tpi than coarse. it's works just like pushing something up a hill. It requires less force (torque) to move something up a 5% grade, than the force required to move the same something up a 10% grade. Or more relevantly stated, the equal force @limit applied to something weighing 100 lbs pushing up a 5% grade, will only be capable of pushing 50 lbs up a 10% grade.
Bolt diameter, Friction and Torque being equal, fine threads exert more clamping force than coarse threads.

IF you torque a 3/8 24 bolt(dry) to 30lbs-ft and torque a 3/8 16(dry) bolt to 30lbs-ft both are torqued to the exact same 30lbs-ft.Both have the same clamping force if both bolts have identical dimensions besides one being coarse thread and the other being fine thread.

What you are talking about is makes no sense when talking about bolts and torque.gearing for differentials your comments make sense but not torquing a bolt.

I invite you to test that theory!
A couple pieces of reasonably thick UHMW drilled and tapped for each threading as you state. Sandwich A pressure sensor between them, and measure the force.
:twisted:

Prove to me that I'm wrong and I'll retract my statement. :twisted:

If the 2 bolts are the same dimensions besides the thread pitch they will have the same clamping force if both are torqued the same.

Fine threaded bolts are stronger than the corresponding coarse threaded bolts of the same hardness. This is in both tension and shear due to the fine threaded bolts having a slightly larger tensile stress area and minor diameter.

Fine threads have less tendency to loosen under vibration due to their having a smaller helix angle than coarse threads. Fine thread Locking Insert grip coils are more flexible than coarse thread insert corresponding size grip coils, and are less likely to take a set under vibration conditions.

Fine threads because of their finer pitch allow for finer adjustments in those applications that need this characteristic.

Fine threads can be more easily tapped into difficult to tap materials, and thin walled sections.

Fine threads require less tightening torque to develop equivalent preloads to the corresponding coarse thread bolt sizes.

Last sentence,preload is not the same as clamping force.

Quote:

Negative sides of fine threaded fasteners:

Fine threads are more susceptible to galling than coarse threads.
They need longer thread engagements and are more prone to damage and thread fouling.
They are also less suitable for high speed assembly since they are more likely to seize when being tightened.

The potential benefits of fine threads are:

Size for size a fine thread is stronger than a coarse thread. This is both in tension (because of the larger stress area) and shear (because of their larger minor diameter).
Because of the smaller pitch they allow finer adjustments in applications that need such a feature.
Fine threads can be more easily tapped into hard materials and thin walled tubes.
Fine threads require less torque to develop equivalent bolt preloads.
Fine threads have less tendency to loosen since the thread incline is smaller and hence so is the off torque.

Again "preload",not the same as clamping force.
True. All true. But because it's something different it answers a different question.

So get a pressure sensor and show me if the clamping force is the same. I know you've got precision torque wrenches and probably free access to strong enough materials to prove your claim. The bolt sizes are irrelevant, as long as they are the same size and fine thread vs coarse thread. The specific torque value is also irrelevant as long as it's the same for both. All can be adjusted to test within the force range of the sensor.
:twisted:

So show me. :twisted:

TKB4 · **Posted:** Mon Aug 07, 2017 1:33 am

Ok back to one of the former questions here is a link to where LMWatBullRun first replaced his deadbolts with ARP s and says 140 ft lbs is too much.

viewtopic.php?f=5&t=65524&hilit=Arp&start=80

That was about 12-4-2012.

Dent · **Joined:** Sat Aug 04, 2012 11:05 pm **Posts:** 275

racertracer wrote:

Here are links to pictures showing stretching and where the break occurred.

https://ibb.co/jobz4v

https://ibb.co/m6K5Ba

https://ibb.co/cmOqBa

Definately ductile overload in tension. Either you (your mechanic) over-torqued, and by a lot, or the heat treatment on the stud is wrong.

GordnadoCRD · **Posted:** Mon Aug 07, 2017 6:02 am

TKB4 wrote:

Ok back to one of the former questions here is a link to where LMWatBullRun first replaced his deadbolts with ARP s and says 140 ft lbs is too much.

viewtopic.php?f=5&t=65524&hilit=Arp&start=80

That was about 12-4-2012.

Yep, that's the one.
Dang I forgot how long it was too.
And yes, I remembered the details a bit off.

flash7210 · **Posted:** Mon Aug 07, 2017 8:39 am

This prompted me to do some research.
This is the best answer I could find.

http://www.thomasnet.com/articles/hardware/head-stud-bolts

Quote:

Torque Efficiency

During engine assembly or maintenance, a bolt must be installed by torquing it into place. Due to the head bolt’s design, it has to be rotated into its slot in order to engage the threads and secure it into place. This process creates both twisting force and a vertical clamping force, which means that when the cylinders within the engine’s combustion chamber begin accumulating load, the bolt will both stretch and twist. Because the bolt has to react to two different forces simultaneously, its capacity to secure the head is slightly reduced and it forms a less reliable seal in high-powered engines.

By contrast, a head stud can be tightened into place without any direct clamping force applied through the tightening. A stud can be threaded into a slot up to “finger tightness,” or the degree to which it would be tightened by hand. Afterward, the cylinder head is installed and a nut is torqued into place against the stud. The nut torque provides the clamping force, rather than the torque of the fastener itself, and the rotational force is avoided entirely. Because the stud is torqued from a relaxed state, the pressure from the nut will make it stretch only along the vertical axis without a concurrent twisting load. The result is a more evenly distributed and accurate torque load compared to that of the head bolt. This ultimately translates into higher reliability and a lower chance of head gasket failure.

In most cases, head bolts are "good enough."
But there have been lots of situations where factory head bolts were not good enough, especially with diesel engines.

flash7210 · **Posted:** Mon Aug 07, 2017 9:30 am

Regarding fine thread vs coarse thread torque values...

I can see how a fine thread will achieve the same clamping force with less input torque.
But I think that the difference between the two is relatively small.
I think the most important aspect of fine threads is this:

Quote:

Fine threads because of their finer pitch allow for finer adjustments in those applications that need this characteristic.

Which translates into a more evenly distributed clamping force across the entire head.

Lubrication of the threads is also important.
Whether it be a bolt or a nut on a stud, the force to be overcome when torquing is friction.
As is tightens, friction increases.
Conceivably, a oil of infinite lubricity could allow a bolt/nut to be tightened to the point of breaking before the prescribed torque value is achieved.

TKB4 · **Posted:** Mon Aug 07, 2017 10:26 am

That makes sense and is a good explanation. I found the other instructions from Geordi I referred to but I haven't gotten it in a form to post a link to or picture of it I have it on a screen shot and thought it would treated as a pic but it isn't at least for now am trying to get it in postable form.

It was apparently posted on Facebook which I don't use but I saw it via LOST because it is in Papadingos download in I believe the Tech section of his notes over the years and is about the fourth or so topic. Those notes are actually contained on the colorado four wheeling site where the factory service manuals are at bottom of list but he has a link to them and I believe the link to that site in NOOB guide probably goes to them also.. Geordi states clearly do not put lube on coarse threads and lube both sides of the washer the nut and the fine threads and the 130 / 120 torque values this was addressing replacing the studs one by one.

As usual Flash provides another thoughtful and researched opinion and help.

ARP Stud gave up

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