Belly Pan & Diff Guards
We were lucky when the guard fell off. The steering arm kept it from falling off and getting lost.
Using a vehicle off road exposes it to a wide variety of hazards that can cause damage, and even cripple it. The old saying of a "soft underbelly" is very apt for off-roaders. Front steering arms, the engine pan, transmission pan and differential housings are all vulnerable to damage from rock strikes. So it's important to anticipate this and provide armour where needed.
We bought a few pieces that were commercially available. The aluminum front steering plate and rear fuel tank pan were well made, but the first time we hit a rock with the front diff guard, it fell off. Not a very good design. So we modified it to make it better, and then made our own belly pans where needed.
You can look at the photos below individually with the descriptions, or open a "picture only" slideshow here.
Belly Pan & Diff Guard Build Sequence
The differential guards were the first things to tackle. We started with a few pieces of 1/4" steel flat bar, bent them as needed, and then tacked them together with the welder.
The front and back bits were made longer so we had room to add the sides and then scribe things to fit.
Once the sides were fitted, and tacked in place, all the joints were fully welded.
Since the bottom side of the guard would be visible, all the welds were ground and polished for appearance.
The front was now scribed for shape and looks.
The rear of the pan was drilled to match up with existing holes in the differential casing.
Our objective here was not only to protect the differential casing, but also to protect the universal joints where the driveshafts attach. To accomplish this we extended a re-enforced tang out the back and far enough to cover the universal joints.
The front diff guard ready to be bolted on for fitting up to the purchased guard we bought.
With the pieces we made, and the store bought pieces all attached to the differential, I had to get underneath and weld the two together.
Fortunately we had these car ramps to lift the vehicle up high enough to make it easier to get underneath with a welding helmet on and do the work.
The finished front and rear differential guards.
All dressed down and ready for the next step.
The benefit of the new design is that it captures the front dome of the differential and then spans underneath to the back of the housing. The only way it can come off is if the rear grade 8 bolts back out, which is not very likely.
A close up of the joinery.
The final step in the project was to take them to a plating shop to have them plated with gold coloured zinc.
The front guard bolted in place. You can see how the rear tang protects the universal joint.
With the new pan underneath, the front of the guard actually has a double layer of steel in front of the differential housing dome.
The rear guard had to be designed so that there was little chance of anything jamming in between the guard and the universal joint. The steep upward angle should do the job.
The double thick steel at the front should withstand any rock strikes.
One has to wonder just how the original rear guard was supposed to work. It might protect the dome if you are backing up quickly, but there was no protection for the bottom of the housing.
We also designed up skid plates to protect the air tank, transmission and transfer case.
We bought the 3/8" aluminum plate and laid out the shape and cut it, but then had to take it to a shop with a decent brake press to bend the shape. When we got it back we were able to start drilling in the required holds.
The holes were drilled in for aesthetic looks, as well as to allow air flow for cooling and places to get a hose nozzle in for washing.
The holes are in, but they are a bit ragged looking.
To dress off the holes and leave a professional looking result, a router with a carbide bit was used.
Aluminum machines beautifully with carbide cutters, and is very similar to working with very hard woods.
This is the actual finish left from the carbide cutter. No other operation was done to make it look this good. However, the cutters need to be really sharp.
When the metal is clamped in place, the machining of all these holes only took 5 or 8 minutes to complete.
All finished and bolted in place.
The end of the protection plate was left open to allow access to the compressed air system.
The belly pan for the transmission and transfer case was also 3/8" plate aluminum, and was bent on all four sides. The holes were put in to allow air to rise up past the exhaust pipes.
To give something for the belly pan to bolt to, we had to make several steel brackets that were bolted to the truck frame.
The front brackets were made to take advantage of the now unused anti-sway bar mounts.
The rear bracket had to be cut so it would not come in contact with the muffler pipe.
The belly pan from the front. Its cut away to miss the two catalytic converters.
The side of the pan also used the same bolting point as the air tank cover we made for the side.
The rear of the belly pan shaped to clear the muffler.
After using the belly pan for a year we ended up drilling a lot more holes in it for cooling. Before we did this, the pan held in way too much heat from the exhaust pipes, and this in turn made the inside floor really hot.