DIY Cat Shield - Template/Write Up

Howdy all,

Since I wasn't able to find anything for how to make a cat shield, I am making a write up on how I made mine.

I went to a metal yard and bought two 30"x44" galvanized 14 gauge metal sheets for 40$.

I bolted them together to make a single 48"x44" metal plate, 48" being the width and 44" being the length. I could have also welded them, but I didn't want to breath in the galvanized metal coating.

I cut out two pieces off of the front to match the template.

I used my jack to put the shield into place, then marked and drilled holes to fit the front crossmember and the transmission crossmember. This is a lot easier said than done, especially if you are by yourself like I was. I used 4 inch bolts with very large washers to go through the pre-existing holes in the crossmembers.


There is still a small crack on the side, but nowhere near big enough to get your hand or a sawzall in. If I ever take it off, I will probably bend this portion upwards about an inch.

I also want to make brackets for the rear portion that covers the rear cats. Its pretty solidly in place but some brackets would add some peace of mind that it isn't flapping around in the wind.

I considered using security bolts but decided against it because realistically it is not necessary. Most people looking at it wouldn't even bother. Thieves aren't carrying wrenches or sockets around , and even if they were, the bolts are in awkward enough positions it would not be easy to access them (particularly those on the transmission crossmember). You have to grip both the top and bottom of the bolts to remove them, which requires quite a bit of finagling.

I also considered drilling a bunch of holes for airflow, but decided against it. The front oil pan area is very open and air should tunnel through that area. I may revisit the idea later if necessary.

An extremely determined theif might be able to get the driver side cat out. There is just enough space in the front oil pan area to reach in there, and just enough space in the back to reach the exhaust hanger. I might have to do something about that later. I haven't seen any shields on the market that cover up that area either.

It took me an hour to go and get the metal, plus another 4 hours on a separate day to cut and install it. Bolting the plates together and cutting was quite easy, only took an hour and 15. 45 minutes was running to the hardware store and 2 hours were spent aligning it, trying to determine the right locations to drill holes, and wrapping my arms around to fit and tighten the bolts under the car all by myself. That part was certainly the hardest.

I spent 40$ on the metal, 10$ on gas, and another 10$ on bolts, totalling about 60$. The cheapest I have seen a cat shield is 325$ from Apex offroad, and that one doesn't cover the rear cats. 325 doesn't include install either. Miller cat/valhalla does have rear cat covers but those are more in the 500 range.

I will admit those shields are far more refined, but this does the same job and no one will be seeing it (except for maybe thieves). Overall im pretty happy with it.

Template:

 

Very cool

 

Looks like that will work as intended and for a fraction of the cost!!!!

I know you didn't solicit any input... But, just in case you didn't think about it, what about heat dissipation? I believe most, if not all, commercial designs have several vent holes in the shields. I'm assuming that's to dissipate the heat that's coming off the CATs ...

I'd hate to see something, such as wiring, hoses, brake lines, etc. get burnt up between the undercarriage and shield if too much heats gets trapped in there. Just something to consider...

 

I thought about that. ANY metal plate you stick on your undercarriage is going to radiate back heat. Heat is a worry for me regardless of DIY or pre-made.

The sides of the shield have that gap between the frame and the plate. That will help to dissipate heat and keep air circulated. I also personally believe that the tiny holes/slits in many designs don't do a whole lot to dissipate heat. The millercat shields in particular seem to have very tiny slits that would be practically useless.

The front crossmember/oil pan area is also very open. Air will flow through the front crossmember/oil pan area past the undercarriage and out the back. This is likely how most heat is dissipated on all shield designs. I don't think I am explaining it very well, I will have to take a picture to show what I mean. I also don't have a 4wd so that will allow for a bit more airflow to the area without the front drive shaft/transfer case in the way.


(yes I have a tiny leak at the output shaft)

I do plan on keeping an eye on it, particularly transmission temps as that is the only thing that would really be affected.

 

Makes sense.... Keep us posted!!!

 

Very nice!!!

You also don't have the bended up sides, so I am guessing that helps with the heat dissipation. It may actually help that your shield can scoop/channel air to the cats.

I made this out of $200 in parts from HomeDepot because they have a 36x36". Lowes and Tractor Supply have a 24x48" that follows more along the lines of your design for those that don't have a handy scrapyard nearby, lol

I may decide to cut the sections out for the heat dissipation...

And, this is installed.

 

If I read you write up correctly you have approximately 9 hours into the build. If you factor your time in, I used $68 an hour as that is our entry level employee rate cost, you are looking at $612 in labor. I know it's not money out of your pocket but the cost ends up similar to a Valhalla or an RCI without wait and cost of shipping. All in all not a bad deal and it looks decent also.

 

Good point, but you are missing 2 other important factors: 1. The design/prototype build will always take much longer than subsequent builds. 2. Time is much more important when you are trying to run a profitable business over doing something as a hobby.

When I take on DIY projects, I also position the purchase of new tools. If I can do all three: 1. Save money, 2. Get a tool, and 3. Still have my wife be happy, then it is worth the time. Of course, I don't have a lot of drywall tools, because I don't really like doing that, lol.

 

But you can always use your "free" time to generate income. LOL

 

Touché

 

Fun to do little projects and buy some tools in the process! That's how I got most my tools that collect dust most of the time but I have them when needed.

Been trying to justify getting into welding, learning how do it and buying the equipment ... but it hasn't happened yet. I need to be using it more than just once or twice to justify the cost and lack of garage space!