Why is silk thread used as gasket material

N801BH said:
Of course the "hot setup" would be to use a CNC, ball mill and machine a slot for a O ring...:yesnod::wink2:
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If you do that then you set up a secondary sealed airspace within the wheel and and as you climb you are adding pressure stress on the grease seal which shouldn't have pressure on it.
 
Henning said:
If you do that then you set up a secondary sealed airspace within the wheel and and as you climb you are adding pressure stress on the grease seal which shouldn't have pressure on it.
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I was referring to the engine case sealing, not wheel bearing seals... Those are perfectly sealed up with standard lip seals as used in 100's of millions of applications
 
N801BH said:
I was referring to the engine case sealing, not wheel bearing seals... Those are perfectly sealed up with standard lip seals as used in 100's of millions of applications
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As little issue as there is with using a silk thread in a case seal, I can't imagine the desire in changing it.

There comes a time in the evolution of every technology where you reach a point of diminishing returns, silk thread in this juncture attains an excellent result for a minimum cost. What is it that we are trying to improve here? The only time they leak is when the case needs work, if the case needs work not knowing about it because you had a seal that kept it from leaking isn't really doing you a favor, it's costing you extra in the long run.
 
Henning said:
Looks like a $5000 solution to a 10 cent problem
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Yep and it is going to be recut every time the cases are lapped and reline bored. With that profile how many times can that be done, without welding the surface and recutting the groove?

Ca-Ching ------ > add about 5k to the overhaul costs.
 
Tom-D said:
Yep and it is going to be recut every time the cases are lapped and reline bored. With that profile how many times can that be done, without welding the surface and recutting the groove?

Ca-Ching ------ > add about 5k to the overhaul costs.
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Personally I like the silk thread as I have NEVER had a case mating surface leak oil.:nonod:.....

But... if you lap it or machine it to reline bore the cases the case halves themselves are already on a milling machine so a company in the business that alignbores will have CNC stuff and that remachining of the O ring groove deeper will take maybe another 5 minutes... Not 5000 dollars... And what the heck are you welding up ?:dunno:
 
N801BH said:
Personally I like the silk thread as I have NEVER had a case mating surface leak oil.:nonod:.....

But... if you lap it or machine it to reline bore the cases the case halves themselves are already on a milling machine so a company in the business that alignbores will have CNC stuff and that remachining of the O ring groove deeper will take maybe another 5 minutes... Not 5000 dollars... And what the heck are you welding up ?:dunno:
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The profile is a dovetail, not a slot.

When the dovetail opens up, it will no longer retain the o-ring.
 
N801BH said:
Personally I like the silk thread as I have NEVER had a case mating surface leak oil.:nonod:.....

But... if you lap it or machine it to reline bore the cases the case halves themselves are already on a milling machine so a company in the business that alignbores will have CNC stuff and that remachining of the O ring groove deeper will take maybe another 5 minutes... Not 5000 dollars... And what the heck are you welding up ?:dunno:
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You might put them on a mill, us mere mortals use a deck surfacer...;):rofl:

As I said before, "Cool, a solution in search of a problem...":lol::lol::lol:
 
ElPaso Pilot said:
The profile is a dovetail, not a slot.

When the dovetail opens up, it will no longer retain the o-ring.
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On most applications it is a square slot or a half round profile.. I have never seen a dovetail profile used in an O ring sealing set up. Probably a million or so 53 and 71 series Detroit Diesels made with a square profile slot on the block deck surface for the rubber sealing ring. And I have resurfaced and counterbored a couple of thousand of them without having to remachine the slot depth that contains the sealing ring. To clarify things too,, the O ring is not really a O, but a square strand of rubber material.
 
N801BH said:
On most applications it is a square slot or a half round profile.. I have never seen a dovetail profile used in an O ring sealing set up. Probably a million or so 53 and 71 series Detroit Diesels made with a square profile slot on the block deck surface for the rubber sealing ring. And I have resurfaced and counterbored a couple of thousand of them without having to remachine the slot depth that contains the sealing ring. To clarify things too,, the O ring is not really a O, but a square strand of rubber material.
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You have been suspended from comment for 3 hours for uttering "53 series Detroit Diesel", off to the penalty box with you...:rofl::rofl::rofl:

Funny that WWI war spoils from the same enemy were so instrumental in winning WWII. Even funnier is tha the same people who gave up the design now own Detroit Diesel.
 
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N801BH said:
:redface::(:rolleyes2:
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Noisy slobbering shaking POSs that just can't be killed. The State of California finally paid to repower the workboat fleet that still had them! You needed to get a electronic engine and and you couldn't uprate more than 10%, but they paid the full bill including the yard bill.
 
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Tom-D said:
The new technology wheel seal on my Jeep are already leaking.
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Yeah, but that's a Chrysler product. My car is a Hyundai, with no leaks after six years and 125K km (78,000 miles) and the car before that was a 2001 Chev Cavalier that ran 280,000 km with no leaks anywhere, at which point another driver backed into it so hard he caused $6000 damage. Leaking seals are not the norm anymore.

Dan
 
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Ted DuPuis said:
We're mostly flying airplanes that were built in the 70s and earlier. At that time, the technology was still better than what you find in most cars.
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Really? Magnetos and felt seals and air cooling and so on in 1970s cars? Don't think so. My Dad's 1959 Rambler American had a Continental industrial engine in it, with a magneto. That was the last car I know of that used a mag. And boy, was it troublesome and unreliable.

We're still flying with bias-ply tires on light aircraft, too. With tubes in them. Tires that cost more than a cheap car tire yet are more eccentric and imbalanced that the car tire.

At least our radios have caught up technology-wise. If we can afford them.

Dan
 
Dan Thomas said:
Really? Magnetos and felt seals and air cooling and so on in 1970s cars? Don't think so. My Dad's 1959 Rambler American had a Continental industrial engine in it, with a magneto. That was the last car I know of that used a mag. And boy, was it troublesome and unreliable.

We're still flying with bias-ply tires on light aircraft, too. With tubes in them. Tires that cost more than a cheap car tire yet are more eccentric and imbalanced that the car tire.

At least our radios have caught up technology-wise. If we can afford them.

Dan
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When I was running fuel in the late 70s/early 80s the only ignition systems we had that could produce the power required were magnetos. There's nothing inherently wrong with magnetos especially on a constant speed engine.
 
N801BH said:
Personally I like the silk thread as I have NEVER had a case mating surface leak oil.:nonod:.....
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I have a 0-300 apart now that you can lay a straight edge on the case seam and place a .020 feeler gauge under it in places.

N801BH said:
... if you lap it or machine it to reline bore the cases the case halves themselves are already on a milling machine so a company in the business that alignbores will have CNC stuff and that remachining of the O ring groove deeper will take maybe another 5 minutes... Not 5000 dollars... And what the heck are you welding up ?:dunno:
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Lapping and line boring are not done on a milling machine, the case thru studs are removed and the case is placed on a flat plate and moved in a figure 8 motion on lapping compound until the whole surface is flat, that includes the bearing clamp surfaces. after that is completed, the cases are bolted back together, torqued, and a adjustable hone of the proper size is placed in the bearing line, and the line is honed to the proper size for the bearings to be installed.
 
N801BH said:
On most applications it is a square slot or a half round profile.. I have never seen a dovetail profile used in an O ring sealing set up. Probably a million or so 53 and 71 series Detroit Diesels made with a square profile slot on the block deck surface for the rubber sealing ring. And I have resurfaced and counterbored a couple of thousand of them without having to remachine the slot depth that contains the sealing ring. To clarify things too,, the O ring is not really a O, but a square strand of rubber material.
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Nope. In the earlier link (http://hhh.gavilan.edu/hspenner/Main/Manuals/Ly-ConCaseORing.pdf) Ken Tunnell at Lycon truly is cutting a dovetail slot and using an o-ring. $648 for a Lyc.

Ken did my IO-360 (without the o-ring.) The shop has a good reputation.

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Dan Thomas said:
Yeah, but that's a Chrysler product. My car is a Hyundai, with no leaks after six years and 125K km (78,000 miles) and the car before that was a 2001 Chev Cavalier that ran 280,000 km with no leaks anywhere, at which point another driver backed into it so had he caused $6000 damage. Leaking seals are not the norm anymore.

Dan
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My FAirchild has nothing but a keyed washer on the inner bearing and a keyed washer under the axel nut, nothing leaks, nothing wears out and it has been running that way since 1937.
I don't see a problem.
 
I stand corrected... Lycon is known for great work.... The dovetail is basically done to retain the O ring during assembly, or that would be my guess anyway.. 600 and Change is not really a bad price for the job and far cheaper then 5000 bucks Uncle Tom thought it would cost...
 
N801BH said:
I stand corrected... Lycon is known for great work.... The dovetail is basically done to retain the O ring during assembly, or that would be my guess anyway.. 600 and Change is not really a bad price for the job and far cheaper then 5000 bucks Uncle Tom thought it would cost...
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My point was, how many times can you resurface that arrangement before you loose the dove tail and must weld the grove shut, and recut it.

that ain't going to be cheap.

Remember that surface is flat with the bearing clamp surface, it must be resurfaced each time the bearing clamp surface is.
Are you going to limit the case to 1 or maybe 2 overhauls before you throw it away?
 
N801BH said:
I stand corrected... Lycon is known for great work......
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I have 4 NEW ECI cylinders that went thru LY-Con facility the STC to use the cylinders on a 0-200 were thrown away.
The only paper work I got was the return to service 8030-3. I now have no permission from the STC holder to use these cylinders on this engine.

so now what do I do?

Ly-Con flow balanced these cylinder with out the intake elbows, so what good did that do?

that was money wasted.
 
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Tom-D said:
My point was, how many times can you resurface that arrangement before you loose the dove tail and must weld the grove shut, and recut it.

that ain't going to be cheap.

Remember that surface is flat with the bearing clamp surface, it must be resurfaced each time the bearing clamp surface is.
Are you going to limit the case to 1 or maybe 2 overhauls before you throw it away?
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Good question....................

On a normal align bore job you usually take .003 -.005 off each case half. If some idiot gets hold of the case and removed .050 then one align bore job will kill it... Most cases are trashed long before you can bore them 3 times anyway...
 
N801BH said:
Good question....................

On a normal align bore job you usually take .003 -.005 off each case half. If some idiot gets hold of the case and removed .050 then one align bore job will kill it... Most cases are trashed long before you can bore them 3 times anyway...
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Not true, many engines are overhauled many more times than that with out case replacements.

Remember the rods get shorter too when they are overhauled and reground, so the deck height remains the same.
 
Tom-D said:
Not true, many engines are overhauled many more times than that with out case replacements.

Remember the rods get shorter too when they are overhauled and reground, so the deck height remains the same.
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Hmmmm... Interesting...

Lets just take for instance each time a case is resurfaced they remove .010 from each half.. that makes the motor .020 thinner in width.. And that case gets rebuilt just 6 times... That makes it almost 1/8" or .120 thousands different that a new, stock motor

Then when you reduce the width of the engine cases through multiple alignboring, the pushrod length, valve train geometry, engine mount pick up points, exhaust system lining up on the cylinder exhaust port studs and various other critical dimensions that will change are not a factor ?:dunno:
 
N801BH said:
Hmmmm... Interesting...

Lets just take for instance each time a case is resurfaced they remove .010 from each half.. that makes the motor .020 thinner in width.. And that case gets rebuilt just 6 times... That makes it almost 1/8" or .120 thousands different that a new, stock motor

Then when you reduce the width of the engine cases through multiple alignboring, the pushrod length, valve train geometry, engine mount pick up points, exhaust system lining up on the cylinder exhaust port studs and various other critical dimensions that will change are not a factor ?:dunno:
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Pushrods come in assorted available lengths and the manifolds have slip joints. Way less hassel than when you angle deck or even take a flat .060 off each surface on a V-8, and that's not all that bad either.
 
Lapping case halves on a flat surface will remove only the tiniest amount of metal. It would take a long, long, long time to remove anywhere near .010". Normally, only the high spots around the case bolt holes and so forth are going to get ground off.

I spent 12 years as a foreman in an air brake component rebuilding facility. Lapping was a common technique use to get gasket surfaces flat, and in some units, an airtight metal-to-metal joint. Even on small parts it took a long time to get a couple of thousandths off the face.

Any serious metal removal will be done in a milling machine, then the faces lapped to finish them.

Dan
 
Dan Thomas said:
Lapping case halves on a flat surface will remove only the tiniest amount of metal. It would take a long, long, long time to remove anywhere near .010". Normally, only the high spots around the case bolt holes and so forth are going to get ground off.

I spent 12 years as a foreman in an air brake component rebuilding facility. Lapping was a common technique use to get gasket surfaces flat, and in some units, an airtight metal-to-metal joint. Even on small parts it took a long time to get a couple of thousandths off the face.

Any serious metal removal will be done in a milling machine, then the faces lapped to finish them.

Dan
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I think the issue is having to take off enough meat from the mating surfaces so that the main bearings can be line-bored round again.
 
N801BH said:
Hmmmm... Interesting...

Lets just take for instance each time a case is resurfaced they remove .010 from each half.. that makes the motor .020 thinner in width.. And that case gets rebuilt just 6 times... That makes it almost 1/8" or .120 thousands different that a new, stock motor

Then when you reduce the width of the engine cases through multiple alignboring, the pushrod length, valve train geometry, engine mount pick up points, exhaust system lining up on the cylinder exhaust port studs and various other critical dimensions that will change are not a factor ?:dunno:
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Yes they are, never said they weren't.

That is why we have new and service limits. you must do the measurements and make the proper adjustments as directed in the engine overhaul manual.
 
Dan Thomas said:
Lapping case halves on a flat surface will remove only the tiniest amount of metal. It would take a long, long, long time to remove anywhere near .010". Normally, only the high spots around the case bolt holes and so forth are going to get ground off.

I spent 12 years as a foreman in an air brake component rebuilding facility. Lapping was a common technique use to get gasket surfaces flat, and in some units, an airtight metal-to-metal joint. Even on small parts it took a long time to get a couple of thousandths off the face.

Any serious metal removal will be done in a milling machine, then the faces lapped to finish them.

Dan
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I have redecked hundreds of heads and blocks, not one on a milling machine. A decking machine as I'm used to uses a single large surfacing disc.
 
Henning said:
I have redecked hundreds of heads and blocks, not one on a milling machine. A decking machine as I'm used to uses a single large surfacing disc.
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Small block aluminum heads are done on the largest belt sander I've seen.
 
Henning said:
I have redecked hundreds of heads and blocks, not one on a milling machine. A decking machine as I'm used to uses a single large surfacing disc.
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There's that way, too. A surface grinder.

Dan
 
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