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Tube diamerter for 912 mount

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Posted

Hey guys, I am going to be making a jig and welding up a mount for a 912.  Does anyone know the tube diameter and the wall thickness of the tubes normally used?  I will be using the rotax mount and then filling in the blanks to the firewall.

Thanks

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Posted (edited)

Hey guys, I am going to be making a jig and welding up a mount for a 912.  Does anyone know the tube diameter and the wall thickness of the tubes normally used?  I will be using the rotax mount and then filling in the blanks to the firewall.

Thanks

well I have 5/8 .035  for my  Jabiru on the front of my kitfox

Edited by TJay
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Posted

Hey guys, I am going to be making a jig and welding up a mount for a 912.  Does anyone know the tube diameter and the wall thickness of the tubes normally used?  I will be using the rotax mount and then filling in the blanks to the firewall.

Thanks

Here is one for a 912 that I bought years ago with the intention to fill in the blanks to the firewall, the tubing on this one measures 3/4 and I would guess it is .035 to .049 I bought this one because I really like the rubber mounting system it uses,

100_1080.JPG

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Posted

I forgot to look at the Kitfox 4 912 mounts I have.  I think they are 1/2" tube, but don't know what the wall thickness is.  I'll try to remember tomorrow.  JImChuk

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Posted

Thanks guys.  found out that kf uses 1/2" .058" tubing for the mounts.   picked up most of the stuff today, will start facing the jig tomorrow and see how far I get with it. 

Added bonus is I will be able to use the same basic jig to make the mount for my 800 engine, this was just the push I needed!

 

:BC:

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Posted

Make a good jib that you can use over and over.  Maybe you can build and sell them if any one else needs a 912 mount for an Avid Flyer.  :-)  We need parts suppliers for these Avids, especially the more complicated parts.   Are you using the ring mount system for the engine side?  JImChuk

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Posted

Ok since no one will ask the question guess I better, Is this for you,  Are you doing away with 2 stroke and  going  4 stroke?

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Posted

No, this is for Jeff.  jig is made for the most part.  I am going to add a few more braces but the prop will always be in the sane spot as the 582 so no cowling mods should have to be made.

The jig will progress as I'm building the radiator mount and the exhaust, but those will be separate once the engine is in place.

Tomorrow I will be making a firewall with the "step" in it for the foot well so I can make sure everything will clear and be plug and play.

My goal will be to have everything fit the first time and be able to have Bolt on packages including exhaust and rad mount .

 

yes it will use the Rotax rear ring mount

 

Tjay, this is the kick I needed to make the mount for my 800 engine, they will all be able to use the same basic jig, 2 or 4 stroke to keep the prop in the same spot in relation to the firewall mount holes, just have to fill in the blanks for various engines. 

:BC:

 

 

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Posted

looking good leni

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Posted

I found a couple of photos of Dave's modified Airdale mount.  This is what he wound up with after modifying the Airdale unit when it didn't even come close to fitting.

Mount1.thumb.jpg.ab87ccb5e071fa250561784

 

Mount2.thumb.jpg.76984a005b6de0be0830b86

 

Mount3.thumb.jpg.023dea55cb609906ff3e47a

 

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Posted

I seem to remember reading some place that with the 912 install you end up moving the engine 2" forwards and having to add 2" to the cowling.  Unless of course you just hog out the front of the cowling and you stick the prop out further.

It looks like with the Rotax collar mount and the kf adapter / iso mount the tubes coming off the avid firewall will be damn near vertical.   that's one issue, the second issue is the starter will hit the firewall and cross tube unless I move the engine forrwards. 

Has anyone done a 582 to 912 conversion without having to modify the cowling?

 

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Posted

I can't add anything to help on this Leni, other than to say that perhaps someone who has a 912 in their Avid could get you the measurement from the prop hub to the firewall.  Also pictures if they have them would help.  JImChuk

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Posted

A friend of mine (JimS on TeamKitfox) did the conversion on his Kitfox IV 1050 and used the same cowl.  The #1 cylinder rocker box had to have some clearance cut in the cowl. 

I will see another friend today at my chapter meeting who went from a 582 to 618 to 670 to finally a 912 in his Avid mark4.  I'll ask him what he needed to do to the cowl. 

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Posted

Paul had to extend his cowl 2" to fit the 912. 

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Posted

I installed the 912 as the first engine in my plane and I had to extend the MK4 cowl to fit the 912. Also some of the 912 engine mounts from way back had the larger right side mount tube attached in the wrong location that interfered with the carb on that side. I believe Av8r3400's buddy had the same issue with his mount that he got from Airdale. The original fix was to add a 1/2" aluminum spacer to move the carb back so there was no interference and that is what I chose to do following the advice from some of the early 912 Avid builders from the Netherlands. You can see the spacer attached between the intake and carb boot.

Travis

cowl 6 [800x600].JPG

engine 4 [800x600].JPG

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Posted

Fabrication  101... make sure the nice new welding table you purchased is level and plumb.... stupid stupid.. after I cut the jig loose from the table "level" on everything changed as I twisted it around the table.. sumbeyatch.. off to the hardware store for 3/4" bolts, blow holes in the bottom of the legs and weld the nuts on.  Get pissed off at the hot slag that just burned your arm and foot.  Make a captn n coke and contemplate blowing up the whole damn garage with torch in it to make yourself feel better.  then you realise it was your fault not the torches.. damn, insult to injury!  look at jig and cut it 98% apart, make sure everything is square and level prior to welding.  carefully tack things in place and slowly weld it out to make sure you don't pull anything with too much heat.  After cooling make another drink and figure out where your diamond heat patterns have to go to pull everything back to square and plumb.  Heat the areas and watch the magic happen and walla, we not have jig v.2.0. 

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Posted

Pick up the torch, put down the glass Leni.  You'll get there!  ;-)  Still think if someone would give you a dimention from firewall to face of prop hub, it would help to start off in the right place.   Although, relooking at the pictures with the starter touching the firewall, that  should locate things as well.  I'm guessing that the further back you can keep the engine, the better for the CG.  JImChuk

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Posted

Moved the engine forwards 2".  now things will fit better but damn, the mounts from the firewall won't have much angle to them.  a couple extra triangles should work.tmp_13844-20161009_2116251166383632.thum

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Posted

I know most builders take some liberty when they make the firewalls, Jeff's has a full width "foot well" in it, mine came with a flat firewall and I built a foot well so I could get full rudder and brake deflection but it's just on the pilots side.

Question for the masses.. would you rather make a new firewall or modify your existing firewall when doing a 912 upgrade, or would you rather move the engine forwards another inch or so to clear what you have now.  I know I don't want to move the weight any further forwards no matter what, but I'm not the one looking at upgrading to a 912.  looking at options to keep yall happy should you want a new mount made for the conversion.

:BC:

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Posted

With the rebuild of my Avid MK IV, I built the new firewall for several reasons.  Changed it to stainless from galvanized steel, got rid of a bunch of patches and holes in the wrong place, being that it originally had a 582 engine before I changed to the Jabiru.  At least now, I'm starting with a clean slate so to speak.  Other things to think about with how far forward the engine is, room for carbs and airfilters?  Where are you planning to put the oil tank?  I'm sure you've thought about those things, but I'm mentioning questions that would come to my mind if I was doing this.  JImChuk

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Posted

Leni - been watching this unfold with interest. This is the reason I said in another thread that I would not use the Rotax ring mount, and instead make my own engine mount mimicking the 'vertical isolators against the firewall' style 912 mount used in my Aerotrek. It certainly would reduce your CG and cowl extension issues as it keeps the engine closer to the firewall than the ring mount without the crazy acute leg angles from the ring to firewall. The other viable option for my wider A+ was to use the KF 5/6 912 engine mount (no ring) and cowl set, but that was equally important for the mount/minimal fitment issues of the cowl to the air frame which you are not concerned with.

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Posted

Getting a few tubes in place.  it's not as bad of an angle as I originally thought, it's going to work just fine   :BC:

 

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Posted

Looks great Leni.  In my research I saw a lot of 912 mounts in different aircraft that had steep angles just like that.  Good work.  Your IVO prop awaits.  LOL.

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Posted

I should have gone and looked at my Kitfox 4 with 912 project before I started posting on this subject.  Now granted, it's not on an Avid, and Kitfoxes don't have quite as much of an issue with nose heaviness.  Here is what I had forgot when I looked at my Kitfox 4.   My mount does use a ring mount.  It was actually a Kitfox 5 mount that a guy remodeled to fit a Kitfox 4.  Looks like firewall to face of prop flange is 28 3/4"  Distance from firewall to back of ring mount is 6 1/2".  Tubing is 1/2" diameter, don't know the wall thickness.  Oil tank is mounted on side of engine, which is better for not having oil run down into the engine when it sits for a long time and filling up the bottom of the engine with oil.  It does stick out to where I may have to put a small bulge into the cowl to cover it.  That's ok with me though.  Anyway, if I can help answer any questions, fire away.  JImChuk

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Posted

Can we see where you put the radiator and how it attached to engine and or firewall.

Thanks

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