Tip: Budget Steel Firewall Shields

As the economy slows we all need to be little more creative on how to stretch our building dollars.

I thought I would pass along a good building tip I picked up from browsing Tony Bingellis's book Firewall Forward.

I am just about finishing up working on my FAB and needed to install two Bowden cables. One for the carb heat and one for the alternate air. One has a few options for passing cables through the firewall. You can purchase some fixtures from many of the aircraft supply web sites. They do the job nicely and prices range from $7 - $38, plus shipping. Or, not my recommendation, use a nylon grommet with some RTV .

Here are some directions on how to make a steel fixture for less than $.50.

1. Take a trip to your local hardware store and purchase some zinc plated 1/2 x 1 inch bolts, washers and nuts. Find a friend with a lathe and drill a #11 hole through the center of the bolt. Slightly countersink the hole on both ends.



2. Cut a 1/2 inch hole in your firewall with a unibit and test fit your cable run.



3. You can leave the fixture unpainted or you can give it a light coat of zinc chromate. Before tightening the bolt add a thin layer of high temperature RTV or firewall sealant behind the washers.



The cable is now secure and the firewall remains sealed. All for less than the price of a cup of coffee!



Best Regards,

Mike Draper
N468RV
RV-8 TMX O360
Finishing.....

Very nice! Would it be a good idea to use stainless bolts/nuts/washers?

Would it be a good idea to use stainless bolts/nuts/washers?

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You certainly could use stainless. You would be getting up there in price, probably a good additional $.85 per fixture . Stainless might take a bit more work on the lathe.

Mike Draper
N469RV
RV-8 TMX0360

Thanks for the tip Mike! Time to put the mini-lathe to good use...

Good idea. However, will this setup lock the cable in and prevent it from sliding forward or aft? If not, it would need to be secured with some sort of clamp just forward or aft of the firewall. Again, good idea.

Budget Steel Firewall Shields

A low cost way to lock the cable in place is to cut 1/2 of the way thru the threaded portion of the bolt near the end with a hacksaw. Lock the cable in place with a twist of safety wire. This method only works with cables, using it with wires will cause problems.

cut 1/2 of the way thru the threaded portion of the bolt near the end with a hacksaw. Lock the cable in place with a twist of safety wire.

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Great suggestion, I will add that to my installs.

tks,

Mike

Once you install the cable, you'll find it is not going to move and a dab of RTV will insure it will not move.

Ken