Engine Baffle Springs

[M20F-1968]

I am doing some work on my engine baffling, which includes remaking the part the air filter mounts to (J model configuration).  My baffling has extensions which reach down and around the cylinders, and twisted safety wire was used under the cylinders to hold these parts against the cylinders (to encourage air to travel past the fins rather than elsewhere).  

Mooney makes long spring-like parts to use to hold the baffle part against the cylinders.  I would like to see what those parts look like.  I want to be able to hook the rear baffle extensions from the front and then pull them forward and hook the front extension.  The ideal part would be a spring with long reach arms.  Apparently the Mooney parts are expensive.  Are there any generic parts that could do the job?  Any better way to think this through would be appreciated.

John Breda

[ArtVandelay]

They look like thin cheap hangar wire with a spring fabricated in the middle and 2 hooks. I guess you can make it yourself, just need to heat treat it to make it malleable, then harden it when done.

[Sabremech]

Hi John,

I can take a picture of mine as it’s modified Vans RV baffling. They use a small stainless steel rod that is bent into shape and then threaded on both ends. Works well. I have the drawing that calls out the dimensions I can get you if you’d like?

Thanks,

David

[carusoam]

@M20F-1968 Doc John, message in from David above...

-a-

[PT20J]

Here's a picture from LASAR which currently shows them sold out. But it should be easy to fabricate with a spring and some piano wire. The wire threads through the hole in one baffle with the spring outside the baffle and between the baffle and the loop on the wire. The other end with the hook catches the hole in the opposite baffle.

The safety wire is only good for a temporary fix. With no spring, the vibration eventually causes the safety wire to wear through the baffle. That's what happened to mine. I repaired the baffle with a doubler and installed the correct part.

 

Skip

[Guest]

A Tinnerman nut makes a good reinforcement for baffle spring holes.

Clarence

[EricJ]

That looks like another item that could be easily reproduced if some specs were available.   If there's one laying around somewhere it would be pretty easy to make a dimensional drawing of the rod.   The spring is likely off the shelf once the specs on it are known.

 

[Bartman]

I think I might have one that came off my engine. The old ones looked like owner fabricated, but similar to the picture above. I fabricated new ones from the leftover spring steel wire I got from McMaster that I used on my overhead vent. If I can find it I’ll take a picture beside a tape measure. Can’t do till Sunday. 

[Bartman]

The one with the spring came off the engine and looks like owner produced part. I produced my own made of leftover spring steel wire used on my overhead vent. 

[moosebreath]

Even though they are shown out of stock Lasar had two.  I bought one so ... they had one two days ago.

[N201MKTurbo]

Owner produced,

$5 for 4.

[larrynimmo]

Well done!   My AI made mine, but they didn’t look as good as yours
 

as to installation, if to tight to easily install, use temporary wire ties to take out the tension....and of course cut wire ties out once spring tensionizers are installed

[N201MKTurbo]

2 hours ago, larrynimmo said:

Well done!   My AI made mine, but they didn’t look as good as yours
 

as to installation, if to tight to easily install, use temporary wire ties to take out the tension....and of course cut wire ties out once spring tensionizers are installed

If they are too tight, I’ll make more that fit. I just wave the music wire over a touch and then wrap around a piece of 1/2 inch copper tubing in the vise.

[larrynimmo]

Please let me know the size of the wire in case I need to make some at some point...

[N201MKTurbo]

I used 1/16” music wire.

[dmevans]

On 3/3/2021 at 3:58 PM, N201MKTurbo said:

Owner produced,

$5 for 4.

What size springs or P/n?

[N201MKTurbo]

3 hours ago, dmevans said:

What size springs or P/n?

Oh, jeez, you should have asked me 2 years ago. I don’t remember. 

[PT20J]

4 hours ago, dmevans said:

What size springs or P/n?

They aren't very critical. I'd just remove one and take it to a hardware store and get the similar size piano wire and a spring.

[PT20J]

26 minutes ago, N201MKTurbo said:

Oh, jeez, you should have asked me 2 years ago. I don’t remember. 

And, next time you post an OPP, be sure to include a dimensioned drawing and a bill of materials. 

[Skyland]

I made up some tensioners out of 0.049" music wire which closely matched what I think were originals.  The curved aluminum air baffles were wearing against the cylinder fins.  My A&P applied a thin layer of RTV on the curved baffles to stick to and prevent movement against the fins.  The tensioner holes on the curved baffles required doublers as well.  Springs are 1.75L x .48OD x .055 wire.  McMaster 9657K372 but something similar would be fine.

[EricJ]

25 minutes ago, PT20J said:

And, next time you post an OPP, be sure to include a dimensioned drawing and a bill of materials. 

And the analysis showing that the materials are metallurgically identical.   Justify selection of Brinell, Rockwell, or Vickers hardness testing and results.

[N201MKTurbo]

I found the spring number from some Cessna forum, except I couldn’t find the correct spring anywhere. It was a Lee Spring number. The ones I used were from the same family, but were 1/4 inch shorter than specified, so I made the wires 1/4 inch shorter. They worked, but they would be easier if they were 1/4 inch longer…

[dmevans]

14 hours ago, PT20J said:

They aren't very critical. I'd just remove one and take it to a hardware store and get the similar size piano wire and a spring.

Thanks. I don’t have the springs on my plane, or I would have matched them. I have the threaded rods, and was thinking this is a much better solution. Thanks. 

[dmevans]

14 hours ago, Skyland said:

I made up some tensioners out of 0.049" music wire which closely matched what I think were originals.  The curved aluminum air baffles were wearing against the cylinder fins.  My A&P applied a thin layer of RTV on the curved baffles to stick to and prevent movement against the fins.  The tensioner holes on the curved baffles required doublers as well.  Springs are 1.75L x .48OD x .055 wire.  McMaster 9657K372 but something similar would be fine.

Perfect!! This is exactly what I was looking for! Thanks so much!