1/2 VW case flange removal

[John Harmon]

Steve,

    What page are you referring too? I inserted the image here hopefully it shows up better, it's on my google+ hopefully I got the share right.
Hi all,

     I want to ask anyone if the regret removing the excess flange from the case. It looks to me as if the case could lose some strength near the mount holes.

     In the attached photo you can see the plugs I made for the unused pushrod holes. My buddy Jim was quick to tease me about their facile appearance. I couldn't get my calipers in to measure the hole size, and I didn't have a snap guage, so it took me 3 tries to sneak up on it! Then I spent an hour with three grades of sandpaper to remove the tool marks and achieve that shiny appearance.

     Insert teasing here....

John Harmon

[Steve]

Hi all,

     I want to ask anyone if the regret removing the excess flange from the case. It looks to me as if the case could lose some strength near the mount holes.

     In the attached photo you can see the plugs I made for the unused pushrod holes. My buddy Jim was quick to tease me about their facile appearance. I couldn't get my calipers in to measure the hole size, and I didn't have a snap guage, so it took me 3 tries to sneak up on it! Then I spent an hour with three grades of sandpaper to remove the tool marks and achieve that shiny appearance.

     Insert teasing here....

John Harmon

John:
Take a look at the photo attachment - I think there was an unexpected loading result... If you look in my Homepages "Fuselage Tab" there is a sub Tab to a Motor mount discussion on the full case - summary (some take off more case than others and some have had case breaks there - don't know if they are the same people)...
Steve

[Bob S.]

Yeah, I had a 'ear' break off of one of my engines...ruined a perfectly good case! 
I was about 25+ miles from home and 'felt' the increase in vibration so nursed her home to see this. I would also recommend that you do NOT attach anything else to the motor mount bolts.... THAT is probably why it really broke...a harmonic failure...

Bob

[Steve]

Steve,

    What page are you referring too? I inserted the image here hopefully it shows up better, it's on my google+ hopefully I got the share right.
Hi all,

     I want to ask anyone if the regret removing the excess flange from the case. It looks to me as if the case could lose some strength near the mount holes.

     In the attached photo you can see the plugs I made for the unused pushrod holes. My buddy Jim was quick to tease me about their facile appearance. I couldn't get my calipers in to measure the hole size, and I didn't have a snap guage, so it took me 3 tries to sneak up on it! Then I spent an hour with three grades of sandpaper to remove the tool marks and achieve that shiny appearance.

     Insert teasing here....

John Harmon

John:
I was hoping that there was a photo showing the plug out of the case - the reason I'm asking is there are a number of pushrod closing schemes and I want you to know that most of them "leak" - curious as the natural thought is not much going on back there with the crank cut off... Anyway, I drilled and tapped the pushrod holes and used alum elec box plugs bought from a elec supply house... I used aviation Permatex on the threads initially and then later carefully used Permatex Red RTV making sure no gobs were inside the case - I had to split my case at 15 hours to get the crank balanced properly and you can see that discussed in my webpages... Others may tell us their experience with the pushrod hole closing challenge...
Steve

[John Harmon]

Thanks Bob,
     I knew I'd seen a picture of this before. Is that the coil bracket on the motor mount bolt? I think I'll hold off on the hacksaw for now.

Thanks Steve,
     Those plugs are 0.250 thick (straight sides no taper) and chilled overnight in the freezer before being driven in. I will crap aluminum plugs if they leak. I can't fathom them leaking as they are as tight as the plugs in the oil galleries which are under pressure.

[Bob S.]

I made plugs for my 1/2 that were interference fit...or so I thought... I had put them in with a dab of gasket sealer on them as I drove them in... ONE was not quite as tight as the other (beginner lathe operator)... Thankgoodness there wasn't any pressure, only splashing and had to do a rudder turn to keep from draining my case!  Still only lost about 1/2 Qt.... Had oil pressure the whole way down...

[John Harmon]

Bob and Steve,

     Thanks for sharing your experience. I really appreciate it. Losing that plug made an awful mess, how many hours did it hold on? I took some additional photos of the plugs I made. One pic from the outside and another from the inside. Ignore the metal chips, I haven't completely flushed out the case since it was align bored.

John Harmon

[leshoman]

I cut all the ears off. Had no problems

[John Harmon]

Thanks Les... Hey are my pictures showing up okay? They are on my Google+ and I've never shared them before.

JH

[Bob S.]

John, I think that one held for about 2-3 hours flying time....replaced it with another a little larger and is holding now very well...No leaks there!!

[John Harmon]

That's good to hear. I was debating if mine were going to work or not. They can be driven out from the inside but not if I wait until the motor is together!

[Dan_]

Thanks Les... Hey are my pictures showing up okay? They are on my Google+ and I've never shared them before.

JH

John, 
They are showing up great..!   

I assume they always will as long as you don't delete them from the Google account... Else, (I assume) they will go poof from your msg.

What you see is what we all should get, when you hit the "preview" button on the lower left. 

As an experiment, you could try a msg with a pic you don't mind deleting.  Post the msg with the pic in it and then go back and delete from Google+.  I'm curious as to what will show up here...  Maybe a little red x..?

[John Harmon]

Thanks Dan, 

     I meant to also thank you for the feed back omen my station one post. The picture of the plug from inside the case would not have been possible without the camera on my phone. I put it in macro mode and stuck it in the case where the back of them plugs reside. Couldn't have done it with a regular camera! I am going to post pics of my station one after welding for you to review. 

John Harmon

[Sparrow]

I appreciate all the information that is being shared on this site and I am currently going through everything I can on the old Yahoo site.  I hope they don’t close it before the information is absorbed.  My user name is Sparrow and I have received the LE XL plans about 2 weeks ago. 
 
Any of you that have been flying your LEs for a while with the Better ½ VW please chime in with pictures of your engine mounting and considerable experience regarding the personal manufacture of a flying ½ VW.  I would certainly appreciate any and all information.  I do pay attention and I try not to make errors that have already been hammered out by others.  I always believe that is one has the time and can do it, get informed and take notes then dive in.
 
I must admit I did have concerns regarding mounting the engine on the back flange.  The flange itself is seeing a bending stress loading which can lead to a fatigue failure if the stresses exceed about 65% of the materials yield strength for any length of time.  The down side of using nonferrous material is that the fatigue life of it is finite.  At some point in the future the cyclic loaded elements will eventually fail in fatigue if the stresses are high enough.  Steel is different in that a calculated infinite life can be made.  This is why I am interested in pictures from any and all that have high hour engine applications on the air frame and haven’t experienced any fatigue cracking.
 
I have noticed, when viewing aircraft standard engine mounting that successful mounts are made by securing the bolts to the engine so the bolts are in shear and not creating a flexing of a thin member.  Care in mounting the engine must certainly be taken to not introduce any additional stress into the flange caused by mounting.  Continuous compressive stresses are fine but anything that creates a bending load has to be considered an item that must be minimized.  Careful balancing to eliminate vibration is a must to help prevent the introduction of combined flexing and shearing loads at the flange.  The rubber mounting will allow for a way to snub some of the strains produced by the stress and help isolate them from the flange.  Just my 2 cents.
 
I would also be interested in prop specifications, RMP at WOT (wide open throttle), carb type and size, cylinder bore and stroke used and the engine case you stared out with.
 
Has anyone tapped out the holes with the appropriate pipe thread size tap and just screwed in a pipe plug with some Loctite® Threadlocker Red 271™ which is designed for the permanent locking and sealing of threaded fasteners?  I have considered doing this and assembling the pipe plug to case and marking the plug extension into the case and then removing it and cutting off all plug that is not actually with thread contact to the case. Just to keep some of the weight off.
 
As an additional side note, we are dealing with dissimilar material and the coefficient of thermal expansion is different, or could be if using different materials.  This link takes you to the page that has the listing of thermal coefficients:  http://www.repairengineering.com/coefficient-of-thermal-expansion.html
 
If the case is magnesium and the temperature change is 200 Degrees F then the case will grow 0.00276” /”. If you had a piece of Magnesium and it was 2” long then it would grow or shrink 0.00552” in a 200 degree F change in temperature.  Aluminum is 0.00256”/” in a 200 degree change and steel is 0.00145”/” in a 200 degree F change in temperature.  I only bring this up because the forum thread talked about plug loosening up and the thermal change from room temperature to operating temperature will change the press fit to a no interference fit if the proper materials and proper press fit levels were not achieved at room temperature.  It gets loose when it heats up if you are not using a magnesium plug. Someone said they used electrical plugs to close the lifter rod tube holes in the case.  Most of the electrical plugs are Zinc plugs that have been injection molded.  This is actually a better choice because the thermal expansion coefficient of Zinc is 0.00336”/” in 200 degrees F.  If you use a Zinc plug it will get tighter in the Magnesium case as the temperature changes upward.  If it happens to go down it will lose the initial fit and the clearances will get larger. Do all your fitting of Zinc plugs to the case when it is cold and the operating temperature will be higher than the assembly temperature.  Just a side note, the SR-71 leaks fuel on the ground at ambient temperature and the tanks don’t seal up until it reaches the thermal operating envelope it was designed to play in.
 
Another thermal compensation, by way of engineering, in the VW engine happens to be
the thermal characteristic changes do require the main bearings in a magnesium cased engine to be kept from spinning by use of a dowel pin because the temperature increase causes loss of compressed fit.  In regular cast iron blocks the bearings are held in place by a calculated crush height of the ½ shell bearings as the main cap is torqued down.  The normal automotive crush height is between 0.0004” and 0.0008” interference fit.  Another piece of trivia just falls onto the page.  If you work in automotive engineering for over 40 years, stuff rubs off.
 
 
 
Many thanks to the group in advance.
 
Kind regards,
 
John Leake
1409 Briarwood Dr.
Blacksburg, VA 24060-2663
Cell # 540 641 5056
Retired since 2007

[Steve]

I appreciate all the information that is being shared on this site and I am currently going through everything I can on the old Yahoo site.  I hope they don’t close it before the information is absorbed.  My user name is Sparrow and I have received the LE XL plans about 2 weeks ago.  
 
Any of you that have been flying your LEs for a while with the Better ½ VW please chime in with pictures of your engine mounting and considerable experience regarding the personal manufacture of a flying ½ VW.  I would certainly appreciate any and all information.  I do pay attention and I try not to make errors that have already been hammered out by others.  I always believe that is one has the time and can do it, get informed and take notes then dive in.
 
I must admit I did have concerns regarding mounting the engine on the back flange.  The flange itself is seeing a bending stress loading which can lead to a fatigue failure if the stresses exceed about 65% of the materials yield strength for any length of time.  The down side of using nonferrous material is that the fatigue life of it is finite.  At some point in the future the cyclic loaded elements will eventually fail in fatigue if the stresses are high enough.  Steel is different in that a calculated infinite life can be made.  This is why I am interested in pictures from any and all that have high hour engine applications on the air frame and haven’t experienced any fatigue cracking.
 
I have noticed, when viewing aircraft standard engine mounting that successful mounts are made by securing the bolts to the engine so the bolts are in shear and not creating a flexing of a thin member.  Care in mounting the engine must certainly be taken to not introduce any additional stress into the flange caused by mounting.  Continuous compressive stresses are fine but anything that creates a bending load has to be considered an item that must be minimized.  Careful balancing to eliminate vibration is a must to help prevent the introduction of combined flexing and shearing loads at the flange.  The rubber mounting will allow for a way to snub some of the strains produced by the stress and help isolate them from the flange.  Just my 2 cents.
 
I would also be interested in prop specifications, RMP at WOT (wide open throttle), carb type and size, cylinder bore and stroke used and the engine case you stared out with.
 
Has anyone tapped out the holes with the appropriate pipe thread size tap and just screwed in a pipe plug with some Loctite® Threadlocker Red 271™ which is designed for the permanent locking and sealing of threaded fasteners?  I have considered doing this and assembling the pipe plug to case and marking the plug extension into the case and then removing it and cutting off all plug that is not actually with thread contact to the case. Just to keep some of the weight off.
 
As an additional side note, we are dealing with dissimilar material and the coefficient of thermal expansion is different, or could be if using different materials.  This link takes you to the page that has the listing of thermal coefficients:  http://www.repairengineering.com/coefficient-of-thermal-expansion.html
 
If the case is magnesium and the temperature change is 200 Degrees F then the case will grow 0.00276” /”. If you had a piece of Magnesium and it was 2” long then it would grow or shrink 0.00552” in a 200 degree F change in temperature.  Aluminum is 0.00256”/” in a 200 degree change and steel is 0.00145”/” in a 200 degree F change in temperature.  I only bring this up because the forum thread talked about plug loosening up and the thermal change from room temperature to operating temperature will change the press fit to a no interference fit if the proper materials and proper press fit levels were not achieved at room temperature.  It gets loose when it heats up if you are not using a magnesium plug. Someone said they used electrical plugs to close the lifter rod tube holes in the case.  Most of the electrical plugs are Zinc plugs that have been injection molded.  This is actually a better choice because the thermal expansion coefficient of Zinc is 0.00336”/” in 200 degrees F.  If you use a Zinc plug it will get tighter in the Magnesium case as the temperature changes upward.  If it happens to go down it will lose the initial fit and the clearances will get larger. Do all your fitting of Zinc plugs to the case when it is cold and the operating temperature will be higher than the assembly temperature.  Just a side note, the SR-71 leaks fuel on the ground at ambient temperature and the tanks don’t seal up until it reaches the thermal operating envelope it was designed to play in.
 
Another thermal compensation, by way of engineering, in the VW engine happens to be
the thermal characteristic changes do require the main bearings in a magnesium cased engine to be kept from spinning by use of a dowel pin because the temperature increase causes loss of compressed fit.  In regular cast iron blocks the bearings are held in place by a calculated crush height of the ½ shell bearings as the main cap is torqued down.  The normal automotive crush height is between 0.0004” and 0.0008” interference fit.  Another piece of trivia just falls onto the page.  If you work in automotive engineering for over 40 years, stuff rubs off.
 
 
 
Many thanks to the group in advance.
 
Kind regards,
John Leake
1409 Briarwood Dr.
Blacksburg, VA 24060-2663
Cell # 540 641 5056
Retired since 2007

John:
You will find the two Links provided next informative:
http://www.angoraaffaire.com/leu/id74.htm
http://www.angoraaffaire.com/leu/id52.htm

Here in short form are useful practices to understanding the engine case as used in this application:

-Use grade 5 metric bolts as sold at NAPA to attach the case to Fus 1... (There is a stainless customized lower 2 bolts suggested by Joe Engelman)- Pull the shop drawings from the Joe Engelman File directory in the yahoo group files
-The mount inner spools must move freely sandwiched between the Continental rubber bushings
-When tightening the mount bolts squeeze the bushings 1/8" and stop tightening
-To see if the 4 bolts are equally tight grab the prop extension and rack the engine in the mount while watching the movement in the 4 mounting bolts - it should move around some but equally
-The engine was designed to run with cooling tin and as you observe the magnesium grows with heat and in the uncovered state there is rapid expansion and contraction - you get leaks where the sealant used will not accommodate flanges shifting around some - covered in the second Link above...
Steve