Smoothing the gap between pickup cab and bed

[mjboks]

Something that functioned like this:

but looked like this:

[aerohead]

Originally Posted by fourfa

the tall cap didn't seem to increase or decrease MPG. However I'm a tall guy, and I can sit up in the back comfortably - function trumps all else with this truck (I basically live in there like an RV all summer/climbing season).

There is a hitch receiver tiregate for around $600. Maybe I could add some storage for gear and gas cans and eliminate the need for the cartop box. Can you describe more what you were envisioning as a swing-away short boat tail? I'm all ears.

It would need a very tight fit to the receiver though. There are full bumper replacements which would be sturdier, but more like $1000. 4 mpg savings could be $4-500 a year for me so it's worth looking at...

also, being a double cab truck with 6 foot bed, it's already unreasonably long for maneuvering. Any length extension would have to not detract from departure angle, and allow other cars to park their front bumper underneath (street parking in San Francisco).

Looks like the length issue is going to scuttle any plans for the back.An inflatable cone works,but would require a full-scale rigid mock-up just for tailoring all the complicated panels for sewing.Not as big a challenge for a pickup tailgate as it would be for the cap and rear visibility.
I wrecked my trailer before I got more than 350-miles on it so I don't have much data to share with you there.It did prove that you can add 1,130 pounds,drive 8-mph faster,in winter conditions,and get close to 4-mpg better,than "naked."That's all I know so far.

[cfg83]

fourfa -

Try this. Go to Joanne's or Michaels and look for "magnetic sheets". You can get them in sizes up to 8.5"x11". They are very flexible. They will probably have adhesive on one side but you don't have to solve that right now (if it works, maybe just paint the adhesive side the same color as your truck?!?!?). In your example picture it looks like your roof is not flat. It looks like it has cargo slats/bumps/whatever. You can cut the magnetic sheets into strips that fit into the flat parts. Lay about 1/2 of the strip onto the cab roof and 1/2 of the strip onto the bed/cap.

A real picture of your truck, roof and side, with transition to bed/cap, would help a lot.

CarloSW2

[fourfa]

The cap is fiberglass, not metal. the top 'slats' are just minute depressions, the roof has some curve but would hold a magnetic sheet.

also, rear visibility is not an issue. I usually leave the rear window blacked out to conceal all the gear I store in there, and the shelf in front of the cab backlight is usually packed with crates anyway. It does mean there's not much I can do about the big side mirrors - I need them.

Pics of my truck:





looking down on the top:


here you can see the gentle radius on the back of the cab, and the scoop-like effect of the front of the cap. it just seems like it might pull some air into the low pressure zone under the truck.

[cfg83]

fourfa -

Originally Posted by fourfa

The cap is fiberglass, not metal. the top 'slats' are just minute depressions, the roof has some curve but would hold a magnetic sheet.

also, rear visibility is not an issue. I usually leave the rear window blacked out to conceal all the gear I store in there, and the shelf in front of the cab backlight is usually packed with crates anyway. It does mean there's not much I can do about the big side mirrors - I need them.

Pics of my truck:
...

looking down on the top:


here you can see the gentle radius on the back of the cab, and the scoop-like effect of the front of the cap. it just seems like it might pull some air into the low pressure zone under the truck.

Thanks! The top tells it all. You don't even have to cut the sheet, because you don't have the "metal bump/slat" thingies I was worried about. The cap shouldn't have to be metal, because you just lay the magnetic sheet to cover the gap and just rest on the cab. But, it may cost more.

Some sign shops also sell big magnetic sheets for putting ads on the doors of your car. They would have the biggest sheets, and probably no adhesive to deal with.

The sides don't lend themselves to magnetic sheeting as much because you don't get the benefit of gravity to "just lay" the sheet onto it. However, bed of the truck is metal, so you could use magnetic sheeting there.

You might try stuffing pipe insulation into the sides. However, you may not appreciate the aesthetics, and it may lead to moisture problems.

I have a small letter size piece at home. If I remember, I will put it on my wife's all-metal Civic and ask her to drive it around for the day.

CarloSW2

[cfg83]

fourfa -

Just for the record, aerohead is leading you in the right direction here. I am enthusiastic because I have thought about the "gap issue" in the past. In MPG races you will see drivers cover every possible gap in blue painter's tape because it is light and they are eager to "close the gap" between them and the best possible MPG they can get.

Originally Posted by aerohead

Not to sound curt,but in the grand scheme of things,I don't think the gap is an issue.
Air,while not very dense,does possess inertia,and once it is directed down the roof an flanks of the truck,it's momentum will just tend to carry it,skipping over the discontinuity.
Sure there's a little penalty but maybe not worth the energy to go after.
Uni-body pickups,as VW's and Honda's don't possess remarkable mpg in spite of their complete absence of a gap.

CarloSW2

[ECONORAM]

Originally Posted by TomO

Window Air Conditioner Foam @ Home Depot
OR

Garage Door Bottom Seal @ Home Depot

And

Outdoor Mounting Tape @ Home Depot

I've personally used the tape on a freshly painted front bumper (my VX) and when I removed it the paint was un-harmed.

I would shy away from using a tape running the gap between the bed and cab as the two will move independently of each other do to frame flex. This will cause the tape to distort and possibly tear.

I am using some of this very stuff to close the gap between my pickup bed and cab. I had to roll it out, stick 4 layers together one at a time, and then peel the final layer of paper tape off and apply it. Otherwise, it is much harder to get the layers lined up so it looks somewhat presentable. I had also planned to spread a thin layer of black RTV over the top, but have not done that yet. I noticed the 09 RAMs have a gap sealer there, and that convinced me I was on to something (maybe). Dave

[TomO]

Originally Posted by ECONORAM

I am using some of this very stuff to close the gap between my pickup bed and cab. I had to roll it out, stick 4 layers together one at a time, and then peel the final layer of paper tape off and apply it. Otherwise, it is much harder to get the layers lined up so it looks somewhat presentable. I had also planned to spread a thin layer of black RTV over the top, but have not done that yet. I noticed the 09 RAMs have a gap sealer there, and that convinced me I was on to something (maybe). Dave

Are you using the Window Ari Conditioner foam? That stuff is 1.5" thick and why I suggested it for his needs as it should fill the gap in one layer. how wide is the gap in your truck, ECONORAM?

[ECONORAM]

It is about 1.5". I used 4 strips of weatherstrip foam, which left me a small gap I can still use to clean the back of the cab. I didn't want to seal it off because I was worried about rubbing/scratching the paint...but I might stick some to the cab and make them compress in the middle with no adhesive.

[BamZipPow]

I covered my gap with some 4" baseboard that I only attached to the truck side only using the adhesive backing. I did this not fer the aero part but more to keep the rain from gitting on the back glass and making it just that much harder to see out the back.