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Baffle Safety Wire Chaffing

J

JAT

Well Known Member
While doing my fifth annual, the safety wire holding the lower curved baffles together was found to have cut a deep groove in the #4 cylinder oil return tube. It originally had a supplied plastic tube over the safety wire, but that had melted onto the wire. It might be a good idea to check the clearance of the wire to prevent this from cutting through the return tube. The tube doesn't have high pressure oil in it, but would certainly make some smoke if cut. I made a new tube and bent it to have a bit more clearance.

JAT
 
I ran into the same problem a couple of months ago JAT - and since then, I have seen similar wear on a couple more airplanes. I suggested that everyone take a look to see if they have a problem - don't need a bunch of smoking airplanes....

Paul
 
As a possible "solution" consider an alternative to the standard safety wire technique on this portion of the baffles. I got a couple of lengths of stainless welding rod, cut them to an appropriate length, threaded one end with a 4-40 die (dye?), and put a 90 degree bend about 1/2 inch long at the other end. Two small holes drilled through the tabs at the end of the curves on the lower baffles will let you feed the threaded end of the rod through from back baffle to front. The 90 degree bend acts as the stop on the aft end, while a 4-40 nut is the stop on the threaded end. Tighten the nut down until it holds the curves in their proper place and you are done. Aside from being adjustable, removable, and re-usable, you can also add one or two joggle bends in the rod as necessary so that it does not interfere with oil return lines or any other obstructions. Get the length and joggle bends correct on a practice piece, then copy to final rod and cut the threads. Works for me.

While not always available, I was able to find a 4-40 die at the hardware store that was sold as a single piece. Some stores seem to only sell dies in kits with many different sizes, and those can get a bit pricey.

erich
 
Use two lengths per side...

If you drill a small hole in the flange of the inter-cylinder baffle, and use two springs (or twisted safety wire) on each side, then none of the stuff will be near the oil drain back tubes.

To clarify, connect the fore and aft sides of the inter-cylinder baffle to the nearest curved part of Vans baffles. No direct connection from forward curved baffle to aft curved baffle.

This is the way Grumman did it on the Tiger... and easy to copy...:)

gil A
 
The newer baffle kit is a vastly improved iteration compared to prior kits. Not only does the kit include comprehensive and very well written instructions and drawings, the most significant changes in the parts are major baffle components and an associated brace are now made of steel and obviously designed to beef up the oil cooler area.

The lower baffles are secured by enlarging the flange holes with a #27 drill bit. A length of (supplied) steel rod is cut to size, bent to shape, then threaded on both ends using a 6-32 die and finally secured with MS21042 nuts.

 
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When did the improved baffel kits come out?

I have had my baffel kit for at least a year. When did the improve kit come out? How can I tell if I have one or not?
 
I've had my kit about 2 months and it has the steel rods and Van's new style prints and instructions. Just look for the two steel rods. They sent me the wrong rear baffel bracket - it was for an RV-10 and wouldn't let the top cowl sit down.

Danny
RV-7A
 
Frank Smidler said:
I have had my baffel kit for at least a year. When did the improve kit come out? How can I tell if I have one or not?
Click to expand...
The areas circled represent the greatest improvement as the parts are now made of steel. The smaller circle encompasses an added part called an oil cooler brace and in addition to beefing up the area significantly the design also simplifies installation of the rubber baffle seals.

The DWGs are dated December 4-5, 2006.

 
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Improving the Improved

Rick6a said:
The newer baffle kit is a vastly improved iteration compared to prior kits.
Click to expand...

The new baffle setup is similiar to the way I made mine. One suggestion I have is to use a small sturdy compression spring under the 960 washer(s) to allow for expansion and contraction as cylinders heat and cool.
 
erich weaver said:
As a possible "solution" consider an alternative to the standard safety wire technique on this portion of the baffles. I got a couple of lengths of stainless welding rod, cut them to an appropriate length, threaded one end with a 4-40 die (dye?), and put a 90 degree bend about 1/2 inch long at the other end. Two small holes drilled through the tabs at the end of the curves on the lower baffles will let you feed the threaded end of the rod through from back baffle to front. The 90 degree bend acts as the stop on the aft end, while a 4-40 nut is the stop on the threaded end. Tighten the nut down until it holds the curves in their proper place and you are done. Aside from being adjustable, removable, and re-usable, you can also add one or two joggle bends in the rod as necessary so that it does not interfere with oil return lines or any other obstructions. Get the length and joggle bends correct on a practice piece, then copy to final rod and cut the threads. Works for me.

While not always available, I was able to find a 4-40 die at the hardware store that was sold as a single piece. Some stores seem to only sell dies in kits with many different sizes, and those can get a bit pricey.

erich
Click to expand...

I just used a peice of stainless steel All-Thread from my local Ace Aircraft Parts store. I joggled it to miss all tubes etc and covered it with high temp tubing to ensure it does not rub or wear anything.
 
Brace not shown?

Rick6a said:
The areas circled represent the greatest improvement as the parts are now made of steel. The smaller circle encompasses an added part called an oil cooler brace and in addition to beefing up the area significantly the design also simplifies installation of the rubber baffle seals.

The DWGs are dated December 4-5, 2006.
Click to expand...

Rick... what attaches to the nut/bolt that is above the rear cylinder in the picture (in the middle of part CB-10?4C stiffener)?

Is there a brace not shown in the picture?
If so, where does it's other end go to?

gil A
 
az_gila said:
Rick... what attaches to the nut/bolt that is above the rear cylinder in the picture (in the middle of part CB-10?4C stiffener)?

Is there a brace not shown in the picture?
If so, where does it's other end go to?

gil A
Click to expand...
Gil,

That is the one design feature that truly mystifies me. They left a gaping oblong hole that is to be filled with two #10 Tinnermann washers and an AN509 screw. The picture is a close up view of the subject hole in a scrapped part I am replacing and should receive today.....but that is another story. The important thing is both the baffle and stiffener (on both the left and right side) have that mysterious cutout in them. Anybody know what they are for?

 
Hey All,

Thanks for the help! I like the stainless rod fix and will do it right next oil change. For all of you who have the original safety wire dohickey, be sure to check to see if your oil return tubes are being cut in two.

Jim (JAT)
 
When I wired mine, I used soft AL tubing instead of plastic tubing for anti chafing. Seems to be doing just fine. I think the new setup with the compression spring will be the best setup. That's the way my Cherokee was rigged up.

Roberta
 
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