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vskid3 10-22-2015 08:59 PM

Fool's Errand (Aeromodding GMC 2500HD)
 
I finally ordered 10 sheets of coroplast from Home Depot to do some aeromods and seal the bottom of my trailer. (Only $110 and free shipping to store, not bad)

The canvas:
http://i.imgur.com/2BhzuPZl.jpg

First project was making wheel skirts for my truck, 2003 GMC 2500HD, 2WD, 6.0L gas, automatic. There's roughly a half inch gap between the fender flares and the actual fender. I cut 2 ~3" slots in the flares at the top of the wheel well for the coroplast to slide into and secure it up top. I folded in the sides and attached them inside the wheel well using the existing holes for attaching the flares to the fender. There should be plenty of clearance for the tire to move into the wheel well as the suspension is loaded and they're quick and easy to remove without any tools.

Now for the bad... They both bow out about an inch and they get flapping a bit at speed (50MPH is the fastest I've gone so far). Is this messing up whatever gains the skirts otherwise might provide? I'm thinking of putting a strip of metal on the outside of the skirt and riveting it to the flare to control the flapping while still making removal easy.

http://i.imgur.com/3khFVx5l.jpg
http://i.imgur.com/UIWEySDl.jpg
http://i.imgur.com/T4eCgHrl.jpg

I'm also thinking of adding a belly pan, but probably just partial because of the large exhaust. If I do an aerocap it'll have to be removable and collapsible in order to accommodate towing our fifth wheel, any ideas? I won't be blocking any of the cooling area of the grill because it's mainly used for towing, but I'll see if there's any nonessential aero-ugliness that can be fixed.

elhigh 10-23-2015 08:14 AM

EXCELLENT.

I've been wanting someone to do this for some time now. The open space above that wheel is just ridiculous. There have been a couple of other users here that went whole hog but I didn't catch them at the outset, so they were already well on their way when I noticed them. PLEASE make a garage page for your truck so everyone can see how it improves!

You could probably fab up some skirts to close off the huge gaps above the steering wheels. They don't need all that space either.

Absolutely add some metal to the loose edge of your rear skirts. You aren't the first guy to notice that flapping, and the others that did notice it were working on a MUCH smaller scale. I think a strip of aluminum will do.

NOTE: I think you could add more aluminum than you strictly need, and use that to splice in some more coverage. I bet you could bring your coverage further down over the wheel with no ill effects.

On my Honda I have a vinyl skirt over one wheel - mostly I'm just leaving it to see how long it lasts, over six months so far - and its clearance is about 1/4". Obviously your rear suspension is way different from mine but I doubt if it shifts around too much, you can probably get closer than you are and still be clear.

I wouldn't worry about the bowing. It's a long, smooth curve, so flow should stay nicely attached. It's one hell of a lot better than it was before, anyway.

Pan any part of the underside that you can. It's an aerodynamic mess under there, all kinds of crap just poking every whichaway. I think virtually anything you do has the capacity to make it better. Foremost and rearmost improvements will have the greatest effects, but the ones at the middle of the truck will likely be easiest to do.

Paint the coroplast black and no one will ever notice it. Or don't, your call obviously. Maybe you'd like more people to notice it, ask questions, maybe make improvements to their own rides.

I bet it comes out quieter.

SUBSCRIBED WITH A BULLET.

redneck 10-23-2015 09:12 AM

.

Looking good...:thumbup:

Instead of using a piece of metal to stiffen up the skirt, try adding another layer or strip of coroplast.

Just buy a spray can of permanent contact glue. Coat both surfaces, wait for it to tack up and press them together. Done.

Pay attention to the direction of the coroplast tubes. If you line up the tubes in each layer it will be easier to bend in one direction

If you alternate the direction of the tubes in the coroplast it will be much stronger but harder to bend. A example of that type of construction would be a sheet of plywood.

By using coroplast instead of metal, you lessen the chance of causing damage to your vehicle or another vehicle should it fly off. (tires, paint, glass)


>

elhigh 10-23-2015 02:42 PM

^^

Good point, that.

vskid3 10-23-2015 03:32 PM

Quote:

Originally Posted by elhigh (Post 497387)
PLEASE make a garage page for your truck so everyone can see how it improves!

You could probably fab up some skirts to close off the huge gaps above the steering wheels. They don't need all that space either.

I bet you could bring your coverage further down over the wheel with no ill effects.

I prefer using Fuelly, I'll be sure to make notes on there when each mod is added.

I'm not sure how much I could skirt the front wheels without having to make it hinge. I might get around to it eventually after taking video of the suspension travel to see how low I can go.
http://i.imgur.com/4tntgNhl.jpg
(Prius looks very Dr. Seuss in the reflection on the flare)

The skirts are as low as they can go while being inside the fender and not rubbing the tire if the skirts were flat. I don't plan on going any lower unless I add side skirts.

Quote:

Originally Posted by elhigh (Post 497387)
Pan any part of the underside that you can. It's an aerodynamic mess under there, all kinds of crap just poking every whichaway. I think virtually anything you do has the capacity to make it better. Foremost and rearmost improvements will have the greatest effects, but the ones at the middle of the truck will likely be easiest to do.

Paint the coroplast black and no one will ever notice it. Or don't, your call obviously. Maybe you'd like more people to notice it, ask questions, maybe make improvements to their own rides.

I think front and rear pans might be easier on my truck. The exhaust is about even or below the frame rails. I should be able to at least cover from the rails to the running boards in the middle. Running boards probably hurt a little, but I'm short and I love the ones at the front of the bed. Makes it so much easier for me to access the bed. Here's some pictures of the belly of the beast. Links to full size images are below each.
http://i.imgur.com/xhJJtCil.jpg
http://i.imgur.com/xhJJtCi.jpg
http://i.imgur.com/D4rdHbMl.jpg
http://i.imgur.com/D4rdHbM.jpg
http://i.imgur.com/3BIidGrl.jpg
http://i.imgur.com/3BIidGr.jpg
http://i.imgur.com/wFmT2Bcl.jpg
http://i.imgur.com/wFmT2Bc.jpg
http://i.imgur.com/0pcvldNl.jpg
http://i.imgur.com/0pcvldN.jpg
http://i.imgur.com/M4JxzL9l.jpg
http://i.imgur.com/M4JxzL9.jpg

I was planning on painting the skirts flat black after I get them all sorted out. I don't want the mods to really stick out and I don't think this coroplast is UV stable.

redneck- I think I'll try gluing more coroplast before moving to the aluminium. Looks like super glue is one of the best ways to glue coroplast.

darcane 10-23-2015 04:33 PM

Quote:

Originally Posted by vskid3 (Post 497418)
I think front and rear pans might be easier on my truck. The exhaust is about even or below the frame rails. I should be able to at least cover from the rails to the running boards in the middle. Running boards probably hurt a little, but I'm short and I love the ones at the front of the bed. Makes it so much easier for me to access the bed. Here's some pictures of the belly of the beast. Links to full size images are below each.
http://i.imgur.com/xhJJtCil.jpg
http://i.imgur.com/xhJJtCi.jpg
http://i.imgur.com/D4rdHbMl.jpg
http://i.imgur.com/D4rdHbM.jpg

I was planning on painting the skirts flat black after I get them all sorted out. I don't want the mods to really stick out and I don't think this coroplast is UV stable.

You basically have the heavy duty version of my old truck. I stopped at the engine, but some of my belly pan construction techniques could be useful:
Pics
Description

The running boards are likely not as bad as you think. Some studies have shown that they behave similarly to having side skirts. Plus it gives you something to mount your belly pan on.

My black coroplast on my Civic has been installed three years now. While it's slightly faded, it's still pliable and not getting brittle. I'm not sure if all coroplast is like that.

aardvarcus 10-23-2015 05:21 PM

Your truck is very similar to my extra/hauling truck. (2001 Chevy 2500HD 8.1L Big Block, Allison Transmission, 4x4.)

Stick some thin metal or heavy wire through the cells of the coroplast and that will stiffen it up quite a bit.

I am sure you have noticed the exhaust on these trucks is big, everywhere, and in the way. I would focus on putting belly pans between the frame and the steps first as that would probably be the easiest. I would also look at doing wheel tire air deflectors in front of the treads.

Also you can see the transmission crossmember hangs down below the frame about 2" for no reason. That can't be good for airflow down there. There are aftermarket flush ones available, or it wouldn't be that bad to fabricate.

Nice truck by the way, looks clean and taken care of.

spacemanspif 10-23-2015 05:49 PM

For the front wheels and the front of the rear wheels just make gap fillers out of coroplast to to encourage the air to pass over the wheel/tire and leave the rear open. This way there isn't interference with the turning wheels and your rear skirts don't have to look weird. For the front close up any gaps that exist that are not in front of the radiator like around the headlights and bumper. Belly pan would be nice but a huge ass air dam is easier. I can't see if the truck already has a dam, but it should have had one from the factory, I think. If you don't have one, get one, and then make it longer appoximately as low as your lowest piece (rear axle?) or a little lower.

Electric cooling fan of belt driven? Thought about a chip for the engine for eco and towing modes??

vskid3 10-23-2015 06:06 PM

Quote:

Originally Posted by aardvarcus (Post 497427)
Stick some thin metal or heavy wire through the cells of the coroplast and that will stiffen it up quite a bit.

Nice truck by the way, looks clean and taken care of.

Great minds think alike! I just got back from Lowe's with a couple pieces of 1/8" steel rod. Unfortunately, it still flaps with one rod a few flutes from the bottom. I made a little video of my test drive. You can see the skirt in the mirror. Is this too much flapping?
https://www.youtube.com/watch?v=F4hVTsNRK8E

Paid a little more than I wanted to for the truck, but there weren't many alternatives. It's lived its whole life in the El Paso area, so there's barely even any surface rust. I think the original owner mainly used it as a commuter and the people I bought it from only had it about a year and barely drove it. 118k miles on it now.

darcane- Nice belly pan! I'm going to try to get away with mainly using zip ties, but your way looks like a good option.

spacemanspif- No air dam on it now, not sure if it had one stock. There's really not too much that sticks out below the frame, so I would like to see how much I can cover with a belly pan without ending up with melted coroplast.
Cooling fan is belt driven. Last I looked into it, going electric was pretty spendy and probably wouldn't ever break even. I'll have to explore some junkyards and see if I can find some deals. I've thought about a tuner, but again, probably wouldn't be able to justify it off of gas savings alone. A nice thing about this truck is that the towing mode can be set up as a completely different tune from the regular, so I could have access to an eco and towing/power tune at the touch of a button.

redneck 10-23-2015 07:39 PM

.

This is what I use.
You can buy it at Lowes.

http://i536.photobucket.com/albums/f...psavbtihil.png



>

darcane 10-23-2015 07:55 PM

Quote:

Originally Posted by vskid3 (Post 497431)
darcane- Nice belly pan! I'm going to try to get away with mainly using zip ties, but your way looks like a good option.

Zip ties are adequate when the coroplast is supported and there are lots of places to attach to. Under the bumper, I found that it was just a lot of open space and I had to build some sort of frame. I was also concerned that if a zip tie or two in the wrong spot broke, it would act as a parachute and rip the remaining zip ties losing the whole belly pan. Using the screws and fender washers also makes it a very robust connection.

vskid3 10-23-2015 10:24 PM

I put the skirts on pause for now. What do you guys think about the amount of flapping I'm getting and what would be the best way to stop it if it's too much?

Started working on the belly pan. I did from the running boards under the cab on the driver's side to the frame. There's a bit of a lip under the outside of the running board that it's resting on and I cut out where the transmission brace is so it's kinda wedged up there. Zip tied it at 8 points to various brackets and holes. Tried to take a picture but it was too dark for it to show much with the flash, I'll post one tomorrow morning. I'll finish tightening the zip ties and take it for a test drive and hopefully return with it still attached.

I'm thinking of having the front piece rest on the bottom lip of the bumper so it can't get the parachute effect going if the front zip ties break. It'll be next after doing under the running boards on the passenger side.

I'm going to see about attaching smooth wheel covers to the center caps. Would a kammback on the back of the cab be helpful or would it hurt the existing air bubble that's formed in the bed? Kammback would be easier than a full aero cap to collapse and store for towing.

BabyDiesel 10-24-2015 08:10 AM

Quote:

Originally Posted by vskid3 (Post 497456)
I put the skirts on pause for now. What do you guys think about the amount of flapping I'm getting and what would be the best way to stop it if it's too much?

IMO the flapping is better than it was, but is still less than optimal. To me, the flapping would still disrupt the airflow to a certain degree.

My design has had no flapping in over 6 months of being attached. I used 1/4" aluminum bar for a bottom frame, and 90* tabs drilled into the fender as attachment points.

http://s26.postimg.org/v052mqnix/0421151214.jpg

The tabs used. These are from Lowe's
http://s26.postimg.org/kospu2vtl/0421151127.jpg

I cut the coroplast to fit, and then painted black. Painting the coroplast helps it last longer when it is exposed to sunlight constantly.
http://s26.postimg.org/h90lkiyl5/0421151616a.jpg

They have been at speeds of up to and maybe past 80 mph with no signs of distress:thumbup:

Quote:

I'll finish tightening the zip ties and take it for a test drive and hopefully return with it still attached.
Zip ties will work. I have had my front and rear pans zip tied for around 6 months and they have held up great. Just make sure they are tight! Pic for reference.
http://s26.postimg.org/3rjfd6yzd/0415151306a.jpg

Quote:

I'm thinking of having the front piece rest on the bottom lip of the bumper so it can't get the parachute effect going if the front zip ties break.
Exactly what I did. I drilled a screw into the bottom of the front bumper through the coroplast, angled up towards the radiator. I have it rigged in such a way that when I tighten the zip ties down, it pulls and holds the coroplast down on this screw. The duct tape is no longer there FYI

Quote:

I'm going to see about attaching smooth wheel covers to the center caps. Would a kammback on the back of the cab be helpful or would it hurt the existing air bubble that's formed in the bed? Kammback would be easier than a full aero cap to collapse and store for towing.
Phil (aerohead) has data showing that a 2/3 bed cover (open space at the front) is a better choice than a full cover and it is much easier to design than a kammback. If it proves itself, you could remake a more permanent version that folds up and stores away in your bed for the instances you tow with your 5-th wheel. Easy on, easy off:)

kafer65 10-24-2015 10:02 AM

vskid3, the gap filler on the front wouldn't have to be much different that what you did in the back.
http://ecomodder.com/forum/member-ka...frontskirt.jpg

BabyDiesel here is what I used from Lowes to stop the flaps on my skirt.
http://ecomodder.com/forum/member-ka...way-wheels.jpg
Its slotted and you can see in the picture on it that its slightly folded which gives you the ability to bow it for clearance and retain rigidity. I mounted it on the bottom of the skirt so the folded part tapers back toward the tire. Everything is nice and tight and slender in its cross section.

vskid3 10-24-2015 01:03 PM

Probably won't be much belly pan progress today, it's pretty windy out and that doesn't go well with large sheets of plastic. :/

A little more about the truck. It has 4.10 gears out back, so the RPMs are high on the freeway. Just over 2k RPM at 60MPH and almost 3k at 75RPM. Not going to change them out as that would defeat the main purpose of this truck. On the trip to and from Home Depot to get the coroplast it averaged 16.5MPG doing 55-60MPH with the tailgate down on the return trip. At 75MPH it gets about 14MPG.

Here's some pictures of the belly pan so far. I also took a picture of the passenger side to give a better view of what was covered and the zip tie points.

http://i.imgur.com/xn5T5Kw.jpg
http://i.imgur.com/DwwrSsk.jpg
http://i.imgur.com/5wToDKc.jpg

BabyDiesel- I think I will just do a flat bed cover of some kind. Most of the gains while being easier to store.
http://i.kinja-img.com/gawker-media/...3749555240.jpg

kafer65- After looking at more gap fillers for the front wheel well, it looks like I should be able to cover more than I thought. I still need to do a video to see how far down I can go.

aerohead 10-24-2015 01:15 PM

tonneau cover
 
Quote:

Originally Posted by vskid3 (Post 497517)
Probably won't be much belly pan progress today, it's pretty windy out and that doesn't go well with large sheets of plastic. :/

A little more about the truck. It has 4.10 gears out back, so the RPMs are high on the freeway. Just over 2k RPM at 60MPH and almost 3k at 75RPM. Not going to change them out as that would defeat the main purpose of this truck. On the trip to and from Home Depot to get the coroplast it averaged 16.5MPG doing 55-60MPH with the tailgate down on the return trip. At 75MPH it gets about 14MPG.

Here's some pictures of the belly pan so far. I also took a picture of the passenger side to give a better view of what was covered and the zip tie points.

http://i.imgur.com/xn5T5Kw.jpg
http://i.imgur.com/DwwrSsk.jpg
http://i.imgur.com/5wToDKc.jpg

BabyDiesel- I think I will just do a flat bed cover of some kind. Most of the gains while being easier to store.
http://i.kinja-img.com/gawker-media/...3749555240.jpg

kafer65- After looking at more gap fillers for the front wheel well, it looks like I should be able to cover more than I thought. I still need to do a video to see how far down I can go.

Here is GM's patent illustration for their patented half-tonneau,including the drag table for different length configurations.
It's for a circa 1985 GMC/Chevy,so it's not a 1:1 comparison with modern trucks.
http://i1271.photobucket.com/albums/...titled7_18.jpg

vskid3 10-24-2015 01:43 PM

Quote:

Originally Posted by aerohead (Post 497521)
Here is GM's patent illustration for their patented half-tonneau,including the drag table for different length configurations.
It's for a circa 1985 GMC/Chevy,so it's not a 1:1 comparison with modern trucks.
http://i1271.photobucket.com/albums/...titled7_18.jpg

Here's a link to the patent text. It says the vertical bulkhead only offers a slight increase vs the partial tonneau alone. It looks like that truck is a long bed, so I'll have to adjust some for my short bed. If my logic is correct, it's the size of the open area that's the money maker, so for my truck I would probably be best with a 30-40% cover to provide an optimal vortex size. If the image is to scale, it looks like the 50% opening is the same length as the height from the floor of the bed to the top of the cab, maybe I should try the same? Does that sound right, aerohead?

aerohead 10-24-2015 01:51 PM

sound right
 
Quote:

Originally Posted by vskid3 (Post 497526)
Here's a link to the patent text. It says the vertical bulkhead only offers a slight increase vs the partial tonneau alone. It looks like that truck is a long bed, so I'll have to adjust some for my short bed. If my logic is correct, it's the size of the open area that's the money maker, so for my truck I would probably be best with a 30-40% cover to provide an optimal vortex size. Does that sound right, aerohead?

I think it's a good guess,short of wind tunnel testing.
In a later article about pickup aero,it was mentioned that part of the performance criteria for the partial cover,was to have it open to the locked-vortex' low pressure core.
With the open cover,this low pressure was communicated under the cover to the inner face of the tailgate,where it increased the pressure differential across the gate.
It is this differential which is responsible for the drag reduction.:thumbup:

vskid3 10-24-2015 06:24 PM

Got the skirt flapping fixed. Put a piece of aluminum across and riveted it to the flare. Doesn't look the greatest, but it's high enough that it shouldn't interfere with changing the tires.

http://i.imgur.com/jJKnJ1d.jpg


Wind wasn't quite as bad as the weather forecast predicted, so I did the belly pan on the passenger side. Pretty much just a mirror image of the other.

http://i.imgur.com/1nXKiKG.jpg


Front pan is next on the list.

spacemanspif 10-24-2015 08:11 PM

Everything looks great!!! Can't wait to see what results you get out of that tank.

vskid3 10-25-2015 05:41 PM

Got part of the front pan done today. I cranked the wheels to one side and realized I couldn't go back very far before the tire would hit. I decided to split it into 3 sections, the middle (the width between the lower control arms) and the two sides in front of the wheels. I did the middle today because it can go back pretty far and it happened to be the same width as the left over coroplast from the passenger running board. :D

Took it for a test drive that included a few miles of 60MPH freeway and everything survived.:thumbup:

http://i.imgur.com/HBazcpD.jpg
http://i.imgur.com/vgKb5mE.jpg
http://i.imgur.com/ZNdoPR5.jpg


If anyone is curious how I go about sizing and installing the belly pan pieces, here's a quick rundown. First I figure out what area I want the piece to cover. Sounds obvious, but there are many things to consider such as how far the wheels move when turned, suspension travel, and accessibility for maintenance (I stopped this piece before the oil drain and filter). I then get a rough measurement of the area and cut the coroplast. Good ol' fashioned trial and error is used to get the piece cut to fit correctly, so lots of trips under the car.

For the zip tie locations, I look for existing holes or brackets I can loop over. You may have to add some framework. I measure and mark them on the coroplast like plotting points on a graph (over 6", up 12"). To make the holes I use a utility knife to cut one side, making sure it's oriented correctly, stick a small flat-head screwdriver through to open the hole, and press down to mark the other side. Then I flip the piece, cut through the marks, and use the screwdriver to open them. This gives me holes that are just big enough for the zip ties and avoid cutting the flutes.

To mount the piece of Ecomodder art, start at one edge and put its zip ties though. I started with the bumper lip and running board lips edge. I don't necessarily start zipping them, the just-big-enough holes grip the tie quite well and allow me to remove them if I need to later in the process. Then I work my way from that edge to the opposite edge, sticking zip ties up, wrapping them through the hole or around the designated holding object, and back through the coroplast. When all the ties are in their proper places, I begin zipping them a little bit at a time until they're as tight as they need to be. I used 8" and 11" UV resistant zip ties, occasionally doubling them up for additional length.

Here's a picture from halfway through the mounting process. None of the shown zip ties are zipped yet, it's just the bumper lip at the front and the tails of the two middle zip ties holding it up.

http://i.imgur.com/o32Gp2L.jpg


I'm done with working on the truck for the weekend, sliding around under the truck gets old after a while. The next things will be the sides of the front and the bottom of the control arms. I'll also start experimenting with the partial bed cover (then I don't have to lay under the truck).

elhigh 10-26-2015 08:32 AM

Your treatment of the running boards was exactly what I was going to suggest.

I had no idea the front wheels would intrude as far as that under the truck when turning.

The front pans really looks the business. Looking forward to the next Fuelly update!

ijames 10-27-2015 12:45 AM

2 Attachment(s)
I have the same shape truck, 2005 2500HD extended cab short bed, but Duramax diesel 2wd 5 speed allison auto. Logging about 100k miles on the highway I got about 22 mpg at 60 mph and then lost about 2 mpg for each 5 mph above that, so 20 at 65, 18 at 70, and 16ish at 75. I looked at the GM tonneau patent and decided that 44% was about the optimum and a convenient size so I could still reach into the bed with the cover on. Built it from plywood with a 2x4 frame so two big guys could sit on it in chairs. It is held down with ratchet straps and 1/4" line to the rear cargo hooks so it comes right out if needed, or I just lay it flat in the bed and put the cargo on top of it. It has never moved from wind, even on a short drive with the straps loose just to see. Here's a couple of pictures:

Attachment 18970

Attachment 18971

Did nothing below about 55 mph but added about 1.5 mpg at 60, 65, and 70 mph for sure, probably about the same at 75 and 80 but don't have good data. So basically it lets me drive almost 5 mph faster for the same mileage on the highway. It's been on for about a year and 15k miles so far with no issues. If you cut my plywood in half across the truck, added two more 2x4 cross pieces along the new edges, and then bolted them together with a couple of through bolts you would have the same thing for running empty but you could split it into two and lay each half out of the way down in the bed beside your 5th wheel hitch for towing. I bought some generic lug covers and pizza pans to make some wheel covers but never got around to that, and I was never ambitious enough to even consider your belly pan, but this was pretty simple.

vskid3 11-02-2015 08:45 PM

Nice cover, ijames! My dad has a 2002 2500HD crew cab, short bed with a Duramax and 4wd (I believe Allison tranny as well), he gets about 1MPG less than your stock numbers. He isn't interested in doing stuff like skirts and belly pan, but he likes your cover. It looks like it wouldn't be much trouble to add folding legs to it to make it pull double duty as a table.

I put a pan on the bottom of the lower control arm on the driver's side today. I have a picture of the bare passenger side for comparison. Passenger side is cut out, just needs installed.
http://i.imgur.com/AHOWsQe.jpg
http://i.imgur.com/2cIss1w.jpg


Took another trip to Home Depot, averaged 15.7MPG compared to 16.5 for the coroplast trip. Traffic was pretty bad (El Paso drivers are terrrrible), got stuck at a couple lights, and had AC on for the return leg, so really not that bad. Tank MPG so far is looking a bit better than I would usually expect.

My wife has banned me from doing any more aeromods til I fix the climate control. It blows hot air out of the passenger side (dual zone system) regardless of the settings. This results in warm air seeping through the closed vents and the driver's side air being shared, which is why the AC was needed on today's trip. Pretty sure it's a bad blend door, only need to take apart most of the dash to get to it...

ijames 11-02-2015 11:08 PM

Thanks for the kind words, vskid3. You could add legs to make it a table, or sit on the tailgate with your legs under the cover as a quickie picnic table, and it's just long enough to be a very steep ramp from ground to tailgate if you need to partly slide and/or partly roll something up into the bed that you just can't quite lift by yourself :-). That 1 or so mpg difference between your dad's truck and mine is why I searched so long and hard for a nice 2 wd truck instead of settling for a 4 wd that I would only use in 4 wd maybe once a decade (automakers don't have to do the epa mpg test on 3/4 ton trucks but from all the 1/2 ton data I expected 1-2 mpg better).

darcane 11-03-2015 03:50 PM

Quote:

Originally Posted by vskid3 (Post 498305)
My wife has banned me from doing any more aeromods til I fix the climate control. It blows hot air out of the passenger side (dual zone system) regardless of the settings. This results in warm air seeping through the closed vents and the driver's side air being shared, which is why the AC was needed on today's trip. Pretty sure it's a bad blend door, only need to take apart most of the dash to get to it...

When you adjust the temperature settings on the climate control, do you hear a clicking sound under the dash? That's usually the telltale sign of the blend doors failing. I need to do it on our Tahoe and I'm not looking forward to it.

LousMX5 11-04-2015 07:02 PM

I've got the 2005 diesel version of that truck, watching with great interest!
You can remove those flares and likely get a little more aero advantage, likely only a little rubbing underneath that could have corrected with a little polishing compound.

Best of luck!

vskid3 11-21-2015 08:40 PM

I finally got the climate control situation figured out. Took the dash apart to get to the passenger side blend door actuator, it was toast. Went to Autozone and got the cheapest actuator, only had 3 pins instead of 5 like the old one, must be a redesign, I think to myself. Didn't work, so I figured it must be the control unit (part with the knobs and slides). Finally got that in, still no go. Realize I'd messed up the zeroing of the driver's actuator (which was good to start and used as my tester). Fixed that and it worked on the passenger door as well. Figured out that the new actuator was the wrong one, take it back and get the right one (not quite the cheapest) with 5 pins. And it works. So the controller might not have been bad, but I'll keep the new one because I already turned in the core ($200!?!). Now I just have to put the dash all back together and it should be good as new.

While waiting for parts to arrive, I put the pan on the passenger side lower control arm. No pics because it's the same as the driver's side. I think I'll finish the sides of the front pan and plug some holes in the front bumper next.

vskid3 11-22-2015 10:04 PM

Painted the wheel skirts black because I was painting something else. Looks much better than the white. I'll Plastidip the metal black, for easier clean up.

http://i.imgur.com/b2RJl7g.jpg

darcane 11-23-2015 03:09 PM

Quote:

Originally Posted by vskid3 (Post 500114)
I finally got the climate control situation figured out. Took the dash apart to get to the passenger side blend door actuator, it was toast. Went to Autozone and got the cheapest actuator, only had 3 pins instead of 5 like the old one, must be a redesign, I think to myself. Didn't work, so I figured it must be the control unit (part with the knobs and slides). Finally got that in, still no go. Realize I'd messed up the zeroing of the driver's actuator (which was good to start and used as my tester). Fixed that and it worked on the passenger door as well. Figured out that the new actuator was the wrong one, take it back and get the right one (not quite the cheapest) with 5 pins. And it works. So the controller might not have been bad, but I'll keep the new one because I already turned in the core ($200!?!). Now I just have to put the dash all back together and it should be good as new.

While waiting for parts to arrive, I put the pan on the passenger side lower control arm. No pics because it's the same as the driver's side. I think I'll finish the sides of the front pan and plug some holes in the front bumper next.

So, how bad of a job was this? Other than getting the wrong parts at least. How long did it take?

vskid3 11-23-2015 08:23 PM

Had to take the top and front of the dash apart. Not really difficult, just time consuming. This is the guide I used. How to remove driverside/passanger side temp controll actuators in 04 Chevy Siverado I think it took 3 or 4 hours to take it apart, haven't put it back together yet.

Deezler 01-14-2016 09:55 AM

Nice thread and mods (thanks again for linking to it from my new thread) !

Quote:

Originally Posted by aardvarcus (Post 497427)
Also you can see the transmission crossmember hangs down below the frame about 2" for no reason. That can't be good for airflow down there. There are aftermarket flush ones available, or it wouldn't be that bad to fabricate.

I gotta agree here. The first time I got under my 2500HD I was shocked to see such lazy engineering by GM. $230 is a lot to swallow but I am now obsessed with this thing:

Transmission Cross Members By DJM At StylinTrucks.com

This is the only one I can find for a Chevy/GMC 2500. Anyone else know of other options?

Improved aero, better ground clearance, and "slightly moving the transmission, to correct driveshaft alignment" whatever that means. Is the factory alignment known to be poor?

With the low-pro crossmember it seems like you could get a nearly flat underside back to the rear axle, which hangs.... way down. Not sure if anything beneficial can really be done there to address/improve it and still allow for plenty of movement.

Deezler 01-14-2016 10:43 AM

Got it down to $218 with a coupon code on JC Whitney.... still too much.

http://www.jcwhitney.com/djm-suspens...545y2003g139j1

vskid3 01-14-2016 07:35 PM

I can buy a lot of gas for the price of that crossmember. I would consider it if I had a 4WD and took it wheeling, though. One way to reduce how much the rear axle sticks down is throwing a couple thousand pounds of whatever in the bed to squish the truck down a bit. ;)

I got the dash put back together a while ago. Took 1-1.5 hours using the instructions to work backwards. I now have heat and cold on demand for both sides. :)

My dad's truck ('02 2500HD Duramax 4WD 4 door) wasn't liking to get very hot when winter rolled around. He stuck a coroplast grille block between the radiator and grille and it's been doing much better. About the only aeromod he's interested in doing. Kinda hard to get a picture of it, he cut out a hole for the tranny cooler to keep the tranny happy.
http://i.imgur.com/trrFXTy.jpg

Deezler 01-17-2016 07:53 PM

Quote:

Originally Posted by vskid3 (Post 504755)
One way to reduce how much the rear axle sticks down is throwing a couple thousand pounds of whatever in the bed to squish the truck down a bit. ;)

I dunno man, I hauled ~2700 lbs of 12' drywall sheets and lumber for my buddy this morning and it barely squatted more than a couple inches! I was impressed.

Dunno if your dad has the allison or the 4L80 trans, but I've been monitoring my 4L80 temps on my scan gauge. It struggles to get above 100 deg F in calm driving when it's cold out, even with my grill block.

Snowman9000 02-11-2016 12:42 PM

lowering?
 
I have about the same truck. Have you considered lowering it? Not street rod low, but two or three inches?

vskid3 02-12-2016 02:24 PM

I haven't considered lowering it because its main use is doing truck things, like hauling heavy stuff that squishes it and driving over things. Also, the cheapest kit I found in a quick search was $350 to lower the front 2" and rear 4" (which would probably still give me plenty of clearance). Would be a very long time for it to pay off with how much I drive it, even if it helped quite a bit.

My current mod is working quite well; it's driving the truck as little as possible. :P I last filled up over 4 months ago and I still have about 1/3rd of a tank left. I've only put about 2600 miles on the truck since I bought it about a year ago. Clearly even my cheap aeromods are more a labor of love than investments.

vskid3 11-18-2016 01:05 PM

Update on the truck:

Moved back in June, loaded all our stuff into the fifth wheel (it was completely packed) and drove from El Paso to Idaho. My dad flew down to drive the truck, as he has much more experience towing. He said the truck did great, the best towing gas truck he'd driven. It did 70-75MPH quite well, except for the steep hills. Even at those speeds, it didn't do terrible on gas. I reset the dash MPG gauge a couple hundred miles in and it showed 8.5MPG over the rest of the trip (at 13-14MPG, it's about .5MPG optimistic, not sure how it translates for lower MPGs). Weighed the whole setup and it was a bit over 16k lbs, just about at the GCWR, so the performance was great considering that.

Now to the current state of the truck... I sold it a couple weeks ago. Didn't need it anymore and it was just making my insurance cost more. I miss its roar, but I like being done putting money in it.


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