Because ships and submarines were my primary background, I'll use that terminology. Safety wire will keep a fastener from loosening enough to fall into the bilges before someone notices that it is losing preload. It doesn't take much movement to cause a fastener to lose most of the preload applied when tightening it, and even the best safetywire job will not prevent enough rotation to prevent significant to total loss of preload, it will just prevent bigtime rotation, enough for the bolt to fall out or the nut to spin off. And that assumes other conditions in the operating environment don't cause the wire to break - then all bets are off. Also remember that there are approximately 76 items (that one comes from a research project funded by the Air Force lots of years ago) that effect the preload on a fastener, and a number of things that can cause it to lose preload have nothing to do do with fastener rotation; embedment phenomena are one group, and that area gets even worse when a gasket is used in the joint, and thermal cycling can be a big contributor even without the exteme cases that result from overtightening. In submarine design space and weight are at a premium and many high pressure components (in the 1000 to 2000 psi range, and higher, especially in hydraulic systems) are made of aluminum to save weight; at manufacture many are fitted with helicoils prior to first assembly, as discussed in post #18 above, both to allow higher initial preload on fasteners that are part of the pressure containing boundary of the component and to give better durability during disassembly and reassembly during life cycle maintenance (the expected life can be anywhere from 30-45 years or more).
Lo206, small header bolts and gummy aluminum?
- Thread starter rkcarguy
- Start date
Because ships and submarines were my primary background, I'll use that terminology. Safety wire will keep a fastener from loosening enough to fall into the bilges before someone notices that it is losing preload. It doesn't take much movement to cause a fastener to lose most of the preload applied when tightening it, and even the best safetywire job will not prevent enough rotation to prevent significant to total loss of preload, it will just prevent bigtime rotation, enough for the bolt to fall out or the nut to spin off. And that assumes other conditions in the operating environment don't cause the wire to break - then all bets are off. Also remember that there are approximately 76 items (that one comes from a research project funded by the Air Force lots of years ago) that effect the preload on a fastener, and a number of things that can cause it to lose preload have nothing to do do with fastener rotation; embedment phenomena are one group, and that area gets even worse when a gasket is used in the joint, and thermal cycling can be a big contributor even without the exteme cases that result from overtightening. In submarine design space and weight are at a premium and many high pressure components (in the 1000 to 2000 psi range, and higher, especially in hydraulic systems) are made of aluminum to save weight; at manufacture many are fitted with helicoils prior to first assembly, as discussed in post #18 above, both to allow higher initial preload on fasteners that are part of the pressure containing boundary of the component and to give better durability during disassembly and reassembly during life cycle maintenance (the expected life can be anywhere from 30-45 years or more).
Aircraft was mine (Navy) and if done right a nut or bolt can't turn. Over torqueing will cause the threads to start to strip especially in aluminum and bolts pulling out will be the results. Try a few cat shots and see.
Jimbo
You can fool some of the people some of the time
Steve's post #10 is right on.
Also the WF engine with it's HD pipe that extends into the head is extremely durable.
It also uses 6 mm studs and nuts and i virtually never see a problem with them coming loose.
It has a very good header brace system as well.
All is good.
Also the WF engine with it's HD pipe that extends into the head is extremely durable.
It also uses 6 mm studs and nuts and i virtually never see a problem with them coming loose.
It has a very good header brace system as well.
All is good.
Doesn't matter how well it's done, lockwire (and cotter pins for that matter, that's the other of the earliest methods for preventing self loosening of a fastener). They can very effectively prevent total loss of a screw or nut, which is important (and what they are intended for), but they are not very effective at preventing at significant loss of preload in a fastener. 2 degrees of rotation results in a preload loss of 27% in a hard joint (and we aren't dealing with a hard joint here, it has a gasket), 6 degrees in a loss of 42% - and these #s were specifically keyed to lockwired joints . See Bickford, Introduction to the Design and Behavior of Bolted Joints (chapter 14), and Junker, New Criteria for Self-Loosening of Fasteners under Vibration, Trans. SAE, Vol. 78, 1969 for some history. And discussion of lockwire on engines ignores the roles of embedment phenomena, shock, vibration and thermal cycling, all of which contribute to preload loss with or without fastener rotation.
Having spent my career on the ship/submarine side, years of it in resolving bolting problems and sharing info with the aircraft side of the house, I have noticed that one reason bolted joints, lockwired or not, perform well in aircraft is they receive a lot more maintenance attention during their life cycle. Only in aircraft will you find bolted joints designed around the fatigue life of the fasteners in the joint, with the planned maintenance program requiring fastener replacement every 6 months, 12 months, 18 months, or whetever translates to a bit over half of the predicted fatigue life of the fasteners in the joint; doing things like that is the only way you can fit it all into the space and weight envelope of a high performance combat aircraft, and it works fine. Even submarines are designed way farther from the ragged edge than that; there is no argument here that lockwired joints perform fine in aircraft, but it's not due to the lockwire, which is only part of a belt and suspenders approach to the specific joint designs, but because they are pushed to the limits of design, assembled with rigorous assembly procedures and then maintened even more rigorously and in more detail than ships, they do fine. It would appear that you are more than familiar with the tech manual procedures for lockwiring, so you are familiar with the sort of detail that goes into even the proper installation of lockwire (when was the last time you saw the exhaust header bolts on an Animal lockwired in accordance with, say, NSTM 075 if you didn't do it yourself?). Lockwire has it's place, but like Ronald Reagan said, "Trust, but verify." If all you do with lockwire is trust it, it will let you down if you are only looking for prevention of preload loss.
flatheadken
New member
Would studs be better? Are they allowed on a 206?
Clone_desire
Member
I've seen a few guys running studs for their exhaust pipe and they haven't had any issues. I think you would have to use a open ended wrench to Jimbo's point.
Jimbo,
I have never used metric ferrycap bolts or nuts.
Fastenal does not supply the nuts.
Your best bet is to call Jegs. They have or can get those nuts.
Again, tho, I cannot vouch for that hardware being available in metric sizes.
JR Race engines uses USS and SAE threaded fasteners.
I have never used metric ferrycap bolts or nuts.
Fastenal does not supply the nuts.
Your best bet is to call Jegs. They have or can get those nuts.
Again, tho, I cannot vouch for that hardware being available in metric sizes.
JR Race engines uses USS and SAE threaded fasteners.
Jimbo
You can fool some of the people some of the time
I know what JR uses for threads and i know that "ferry bolts" are common on after market karting aluminum connecting rods. I also know that ferry nuts can be found inside automotive engines on some connecting rods.
The original question is about the stock Animal header bolt issues that some people are having not the JR block.
There is no issue with the threads pulling out of JR block that i have ever seen. Maybe i'm just lucky.
However, my billet head has three 6 X 1 mm threaded holes to attach the header to the head.
I see no need to use any thing other than 6 X 1 mm socket head cap screws on my heads.
I will call Jegs and see it they have 6 X 1 "Ferry nuts" unless some one else already has the answer.
I will also try the 6 X 1 coupling nuts that has been suggested.
I'll be back with the answers.
The original question is about the stock Animal header bolt issues that some people are having not the JR block.
There is no issue with the threads pulling out of JR block that i have ever seen. Maybe i'm just lucky.
However, my billet head has three 6 X 1 mm threaded holes to attach the header to the head.
I see no need to use any thing other than 6 X 1 mm socket head cap screws on my heads.
I will call Jegs and see it they have 6 X 1 "Ferry nuts" unless some one else already has the answer.
I will also try the 6 X 1 coupling nuts that has been suggested.
I'll be back with the answers.
Jimbo
You can fool some of the people some of the time
Thank you Upman
PD
I will try to purchase some of these to try. I hope they don't have a minimum order.
But at a price of $3.79 each plus shipping, plus the cost of the studs i'm guessing the average LO 206 racer is going to go for the SHCS
You will also have to have a thin wall 1/4" drive socket to clear the OD of the pipe.
If the pipe curves over the top of bolt hole it may also present a problem getting the socket on.
We'll see.
I'll let y'all know.
PD
I will try to purchase some of these to try. I hope they don't have a minimum order.
But at a price of $3.79 each plus shipping, plus the cost of the studs i'm guessing the average LO 206 racer is going to go for the SHCS
You will also have to have a thin wall 1/4" drive socket to clear the OD of the pipe.
If the pipe curves over the top of bolt hole it may also present a problem getting the socket on.
We'll see.
I'll let y'all know.
I use studs on several different applications. If you have to repair the thread I prefer the thread sert or a solid insert.
If you use the 6x1mm coupling nut then you can get a wrench on the nut without issue.
They are easy to drill and safety wire.
Biggest thing I believe is the bracing of the pipe and silencer.
We use a brace and saddle for the silencer so it doesn't bounce around.
If you use the 6x1mm coupling nut then you can get a wrench on the nut without issue.
They are easy to drill and safety wire.
Biggest thing I believe is the bracing of the pipe and silencer.
We use a brace and saddle for the silencer so it doesn't bounce around.
And then a bolt into the nut to lock it up.....