fat avid 912 engine mount

48 posts in this topic

Posted

Larry the short answer is that we don't know for sure.  Ronny Smith said that he suspected oil starvation sometime in the past.  Maybe that was the vibration that you were chasing in the past, the failing pushrod bearing in the process of failing.  But the case fretting was a known issue on engines 912S manufactured before August of 2006.  With the lower compression of our zippers it may not be an issue.  I suspect that Ronny is correct the Zipper had not been one the engine long enough for case fretting to do its work.  It is easy to check for fretting problems and I suggest you, I and others with the Zipper on older engine keep a weary eye on this.  The first sign to check for is a prop that turns harder after shutdown and then easier again after 10 minutes or so.  If that is the case confirmation is made by loosening the cylinder stud nuts right after shutdown, if the prop turns freely again the the fretting is confirmed.

https://www.rotax-owner.com/en/rotax-forum/3-4-stroke-technical-questions/2271-rotax-912-uls-fretted-crankcase

And to answer your earlier question about Dallas that I did not get to, the new engine is doing well, nothing that money can't be a help in massive quantities. About $20000 for a nice round figure.

Share this post


Link to post
Share on other sites

Posted

 

Looking good Leni!

Chris, Jack has a great little digital angle finder called an angle cube that allows you to place it on a surface and zero it and then place it on another surface the get the angle; It really is a great tool and he found it on the internet for not too much.  A great addition to any shop if someone is looking for a Christmas present!  Info on the clearances is appreciated since Leni and I were thinking about what it needs to clear the filters.  I should have sent my filters with him. To match CG of my Subie I calculated the 912 prop flange would be at 27", so 1.5" forward of yours.  I am probably used to flying with my CG that far forward but I have always kept my tool box in the very rear of my cargo area, and all my survival gear, food, tent, sleeping bag, etc. in the furthest rear bay of the cargo area so there is at least 40 lbs back there all the time.  It kind of comes down to what kind of hauling we use our planes for?  Anyway, this gives me a solid range between yours and my calculation to decide on.  What do you typically haul in yours in the cargo area when loaded heavy?

Paul, my SN is 6778594. Hal gave me the SN to check and this is a later model engine so I went with the 114 hp kit.  I have always run premium in my Subie anyway so no change for me.  Hal says he runs his at 6000+ rpm in cruise for long periods of time as well and seems to think it gets better fuel mileage at the higher rpm with no issues.  He said he has about 1000 hrs on his high hp kit now so it convinced me to go with that one.  It is just amazing how light the pistons and cylinders are.

Share this post


Link to post
Share on other sites

Posted

Alright, I think you will really like the Zipper setup and it is good to hear Hal steered you right as one would expect.  They are great folks to work with.

Share this post


Link to post
Share on other sites

Posted

Starting to look like a mount now.  should be finished up tomorrow.

As with anything else getting the jigs just right takes more time than anything else.

:BC:

20180102_155157.jpg

20180102_155144.jpg

1 person likes this

Share this post


Link to post
Share on other sites

Posted

Where did u get this engine mount?  I need one for 912 installation.

Thx

Share this post


Link to post
Share on other sites

Posted

Where did u get this engine mount?  I need one for 912 installation.

Thx

He's fabricating it himself...

Share this post


Link to post
Share on other sites

Posted

Im making the 912 mounts on an as needed basis.  I bought a tubing bender so i can make the rotax horse collar part of the mount as well.  Still getting the new tools dialed in and set up to make production go quicker. 

 

20180102_173949.jpg

1 person likes this

Share this post


Link to post
Share on other sites

Posted

Nice, that thing is built like a brick shit house with the additional lower attach stations! Any chance you could bend a curve in the lower left leg and add a couple mounting legs/tabs to relocate the oil tank? Maybe a couple ignition module mounting tabs on the upper mount legs while your at it?

HW Engine mount 1.jpg

HW Engine mount 2.jpg

HW Engine mount 3.jpg

HW Engine mount 4.jpg

HW Engine mount 5.jpg

3 people like this

Share this post


Link to post
Share on other sites

Posted

Doug, i can do anything thats asked.  The tubing bender finally shipped today so i will have that capability next hitch home.

Im planning a mount much like the rotax horse shoe collar so i can ship out complete fwf mount packages.

:BC:

20180105_121534.jpg

20180105_121520.jpg

1 person likes this

Share this post


Link to post
Share on other sites

Posted

What is cost of this mount?   

Share this post


Link to post
Share on other sites

Posted (edited)

What is cost of this mount?   

For comparison for I paid 700 shipped to my door from Australia for a Jabiru mount  Gives you an Idea at least

Edited by TJay

Share this post


Link to post
Share on other sites

Posted

Jabiru mount is way easier to build though then this 912 mount.  JImChuk

Photo0833.jpg

Share this post


Link to post
Share on other sites

Posted

I would also consider the jabiru; cant find much concrete info on its reliability.

Share this post


Link to post
Share on other sites

Posted

Are those YELLOW parts a KITFOX mount?  I have a couple of parts that look like they may be part of one.  EDMO

Share this post


Link to post
Share on other sites

Posted

Which parts in particular do you mean Ed?  Got any pictures of your parts? JImChuk

Share this post


Link to post
Share on other sites

Posted

Hi Ed. The yellow parts in the pics I just posted were all custom fabricated by Lowell Fitt over on the TKF forums. The fuselage is his Kitfox 4-1200, engine is a 912ul.

Share this post


Link to post
Share on other sites

Posted (edited)

Which parts in particular do you mean Ed?  Got any pictures of your parts? JImChuk

Jim,  If you go back up to (I think) Doug's photos of a mount painted yellow - I got some yellow parts that look like they could be small parts of a 912 mount - Cant verify that and don't have photos yet.  Thanks for the reply Doug.  Guess I could ship them to Leni or someone making mounts?  EDMO

Edited by EDMO

Share this post


Link to post
Share on other sites

Posted

I would also consider the jabiru; cant find much concrete info on its reliability.

We have a couple of guys who are using them.  1avidflyer probably knows as much about them as anyone on here.  EDMO

Share this post


Link to post
Share on other sites

Posted

What is cost of this mount?   

i have not nailed down a firm price yet.  Im pretty sure i can produce both parts of the mount for what rotax wants for just half of it... it takes some time to make, im hoping the new bender and tubing notcher will cut my time drastically on the fabrication.

Share this post


Link to post
Share on other sites

Posted

K, let know.  I have a machine shop and can  make parts also.

1 person likes this

Share this post


Link to post
Share on other sites

Posted

What kind of tubing bender you getting Leni ?  I have a JD2 and lots of dies.    In regard to Fireball tools.  I got one of their laser cut do it yourself kits for christmas. It was a fun project putting those accurate cut parts together. Now I have three more useful tools to work with.

1 person likes this

Share this post


Link to post
Share on other sites

Posted

What kind of tubing bender you getting Leni ?  I have a JD2 and lots of dies.    In regard to Fireball tools.  I got one of their laser cut do it yourself kits for christmas. It was a fun project putting those accurate cut parts together. Now I have three more useful tools to work with.

I went with the rouge fab bender with the thin wall attachment and back stop.  I used a JD2 on a boat hand rail project over the summer and while it works, I like just hitting the air button to bend the tube instead of the manual ratchet.  I am getting lazy in my old age :lol:

I took the fireball tools idea and made them smaller as well.  I have 4" squares and I made a few magic squares that are 1 1/2" tall for holding the smaller tubing and getting into tight places.  They are awesome for positioning parts like these mount tubes.

:BC:

 

Share this post


Link to post
Share on other sites

Posted

That's a nice bender.  I don't use mine often enough to worry about power assist. All my dies are 1 1/4" and smaller down to 1/2"    I used to have bigger dies but was able to sell them to the off road jeep guys on pirate 4x4.  That's a good site to troll for any metal fabricator. 

1 person likes this

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now