1999 4Runner 4x4 Streamlining

[kach22i]

Originally Posted by aardvarcus

I have a relatively huge "wing" I built for the rear end this spring, that is the one I referenced as a kamm shell that I need to do more work to because the leading edge transitions are not smooth enough.

Dang that's a nice piece of kit.

Do you have a thread on it somewhere?

[aardvarcus]

Kach22i,

Its all in this thread, look at posts 9 through 20. Post 16 shows the under construction work the best.

https://ecomodder.com/forum/showthre...tml#post598593

It is Fiberglass over extruded polystyrene, built very similar to how I built my Aeroshell on my 05 Tacoma several years back.

Unfortunately I have been riding without it for a while, the transitions between the cab and the kamm did not turn out well, and I have been struggling with basically how to get it to come to a sharp thin point. Fiberglass over foam doesn't like sharp points. Initial attempts to span fiberglass by itself didn't fare well either. I need to either fix it or just put it back on as is.

[freebeard]

I was researching for this obscure little 4-post thread and found this:

Adhesion & Cohesion - adhesives.org
[Search domain http://www.adhesives.org/adhesives-s...sion-cohesion] https://www.adhesives.org/adhesives-...esion-cohesion
Chemical bonds, however, only form for very few substrate/adhesive combinations, e.g. between silicone and glass, polyurethane and glass, and epoxy resin and aluminum. For some of these bonded joints it has been demonstrated that chemical bonds account for up to 50% of all the interactions.

So maybe a mechanical bond between the polystyrene and an aluminum edge and then a chemical bond between the aluminum and fiberglass?

It could be as easy as doubled-over aluminum tape edging.

[aardvarcus]

Freebeard,

Using the aluminum tape is a great idea! I had been contemplating riveting some metal to the shell and fiberglassing over it, but the tape would work even better.

Really it should be ok even if the tape only was acting like a form, as once the fiberglass set up it should be rigid. I will try to give that a go this weekend.

[freebeard]

I was thinking rivets too, unlit after I'd already hit Post Quick Reply.

So it was a passing thought, I hope it works out.

[aardvarcus]

Over this past weekend I had a bit of time to work on something, so I finished ducting the upper grill of my 4Runner to the radiator. I used cardboard to make an accurate template, then copied it in black coroplast. The bottom is secured with fasteners; the sides are jammed into corners of the core support and held by the grill; and the top is held by tabs to the grill and down by the hood support bar. The bottom of the radiator was already sealed/ducted from when I did my belly pan work in this area.

Currently the upper grill opening is about 1/4 the size of the area of the radiator, so that is a bit more than the 1/6 rule of thumb, but this seems appropriate as the duct is not 100% air tight.

Temperatures are still running fine, but I did notice a marked increase in handling. I assume most of the air going through the upper grill before this mod was bypassing the radiator and running under the vehicle as it has with all my past vehicles. I am getting ready to do a "grill block" on the bottom grill opening, which will also include mounting fog lights in the grill location, having a removable cover/plug to access the front receiver hitch, and extending my belly pan/skid plate all the way to the nose of the vehicle.

[Tahoe_Hybrid]

Originally Posted by aardvarcus

Over this past weekend I had a bit of time to work on something, so I finished ducting the upper grill of my 4Runner to the radiator. I used cardboard to make an accurate template, then copied it in black coroplast. The bottom is secured with fasteners; the sides are jammed into corners of the core support and held by the grill; and the top is held by tabs to the grill and down by the hood support bar. The bottom of the radiator was already sealed/ducted from when I did my belly pan work in this area.

Currently the upper grill opening is about 1/4 the size of the area of the radiator, so that is a bit more than the 1/6 rule of thumb, but this seems appropriate as the duct is not 100% air tight.

Temperatures are still running fine, but I did notice a marked increase in handling. I assume most of the air going through the upper grill before this mod was bypassing the radiator and running under the vehicle as it has with all my past vehicles. I am getting ready to do a "grill block" on the bottom grill opening, which will also include mounting fog lights in the grill location, having a removable cover/plug to access the front receiver hitch, and extending my belly pan/skid plate all the way to the nose of the vehicle.

did u put a air dam?

[freebeard]

Julian Edgar's Writer seeking examples of tested DIY aero mods thread Permalink #183 suggests that if the front of the bellypan is curved it induces lift, but a step produces downforce, if I understand correctly.

[aardvarcus]

Tahoe Hybrid,

No, this vehicle is getting a complete belly pan not an air dam. The belly pan is presently over 50% completed made from bent ¼” aluminum, I have from the front crossmember all the way back to the rear axle under the center of the vehicle excluding under the exhaust. The nose, side steps, and rear diffuser are the parts that remain to finish. The only “air dam” I plan are the tire spats made from conveyor belt.

Freebeard,

I have and regularly read Julian’s book. You are correct, the S shaped step is the shape typically regarded for front belly pans generating downforce. I kind of tried to approximate it with how the front of my existing belly pan drops down to go under the front differential. I am balancing that with approach angle and trying to ensure I don’t hang up my front end while off-road as this vehicle does see rough terrain. The initial state of the vehicle allowed for almost all the air entering both grills to flow out the bottom of the bumper freely, so just having anything down there, even the improper shape, will be less lift than the factory state. The piece I am missing right now is the frontmost foot, extending from the first crossmember to the nose of the vehicle.

[aardvarcus]

To increase the utility of the vehicle, I drug home a 5x13 manual tilt trailer. This trailer will haul anything I would want to pull with the 4Runner. It will allow me to not have to use my 2500HD pickup truck as often, thus saving me some fuel.

I will be adding a trailer brake controller to the 4Runner prior to using the trailer. I will also be refreshing the trailer with new lights, RTMR fuse box, new wiring, etcetera. I am considering converting the trailer from manual tilt to hydraulic tilt, but I am undecided on that as of now. I will also convert the trailer to a ball hitch and add a receiver to be able to use my hitch mounted winch to load the trailer.

The biggest aero mod for this thing was holding out to buy a tilt trailer, not getting a gate or attached ramps to drag through the wind. Not planning to do many fuel saving mods to the trailer, but I might just do a coroplast belly pan for kicks.