We wanted to take an opportunity to document the electric fan conversion on our '02 1500HD since we often see questions come up regarding what is involved in properly completing the conversion on the 99-04 GM Trucks. This write up will cover the basic of the install on the 99-02 platforms, but is relatively similar to the 03/04 installations as well (the only difference being in A/C trigger wiring).
There are several benefits to the electric fan conversion. Most people are looking for a few extra horsepower, but in addition to 10-20 hp gains, electric fans will provide better low speed and idle cooling as well as improved A/C performance at idle. Keep in mind that your truck will require a tune in order to enable the computer to control the electric fans!
We chose to complete the swap using 2005+ style dual fan assemblies, specifically the nine blade HD cooling variants found on the 2010+ trucks. Using this style fan is absolutely what we recommend if you truck is equipped with the larger 34" radiator. These fans bolt directly in place, as the 99-04 trucks already have all of the mounting provisions necessary for the later model fans. Even if your truck is equipped with the 28" radiator, it may be worth considering upgrading to the 34" for the additional cooling capacity. Another commonly selected option for the 28" radiator trucks are the 98-02 F-Body fans. However, those fans are considerably smaller than the 05+ truck fans and will require some modifications for installation such as OE fan mount trimming and custom mounting brackets.
There are a number of companies out there that offer the plug and play conversion harnesses, but we chose to use the harness from Nelson Performance.
The first step is, of course, gaining access to the OEM clutch fan for removal. The only things that need to come out of the way are the air inlet tube and the upper fan shroud. The upper fan shroud is held in place with two bolts to the core support and 4 push-clips connect it to the lower portion of the shroud. Once those are out of the way, you have access to the OEM clutch fan for removal. There are specialty tools out there for removing the clutch fan, but if you have access to an air compressor and and air hammer, nipping the side of the fan clutch nut with the air hammer is often the easiest way to break it loose from the water pump pulley. The fan clutch on the GM trucks has a standard thread orientation, and turning it to the left will loosen it.
With the OE fan out of the way, the lower fan shroud can then be removed as it simply slips into place. With everything out of the way, you can begin to prep the electric fan assembly for install. Remember to move all of the original retaining clips from the OE shroud over to the new electric fan assembly. In our case, we had one clip that retained the upper radiator hose and another that retained the oil cooler hard lines. Slipping the new fan assembly into place can be a bit of a geometric challenge, but with enough finesse and some careful prying, it will drop into place without removal of any other components. Remember to be sure that the tabs on the edge of the fan slip into the clips that are molded into the radiator end tanks. There are also several slots in the bottom of the fan assembly that are designed to rest on the lip of the lower radiator core support.
With the new fan bolted in place, we're able to now move onto wiring. On the 99-02 trucks the electric fan conversion harness has 6 total connections to make: one connection to each fan, constant power to the relays, ground, blue trigger wire to pin 42 on the ECM connector, and green trigger wire to the A/C clutch signal wire. You will need to determine which wire triggers the A/C compressor clutch. This wire runs in the OE wiring loom directly to the left of the red junction box near the alternator on the driver's side. Carefully remove a section of those wires from the loom and look for the green trigger wire. NOTE: there will likely be more than one green wire in this bundle. You will need to test for 12v power to the wire when the A/C clutch in engaged. Be careful here, as one wire will receive power under the same condition, but it will not be a full 12v. You will want to be sure that the wire you're testing sees a full 12v (or 13v/14v when engine is running) when pinned during A/C compressor clutch engagement. Once that wire is positively identified, use the included wire tap to tap into the OE A/C clutch signal wire.
After identifying and tapping into the A/C clutch signal wire, we moved onto installing the blue trigger wire to pin 42 on the ECM. Remove the ECM dust cover and then the connector closest to the engine. The connector uses a 7mm socket to unscrew the connection. Once the connection is loose, remove the wire cover from the outside of the connector. This cover uses several barb style connections to retain it, simply use a small screw driver or other device to carefully work the barbs loose. With the cover out of the way, find the pin labeled "42". This is usually on the lower side of the connector closest to the front of the truck and should be labeled with the number 42. The fan conversion harnesses come with a pin already crimped on that is designed to be inserted through this connector and into place in position 42. Lubricate the pin, and insert it through the back of the connector. Carefully work it into position until it becomes fully seated. This can sometimes be difficult to complete, so please take care when attempting to work the pin/wire through the connector. If the wire folds over and becomes kinked, it will be much harder to get the pin fully seated. Once fully inserted, the pin will snap into place - verify this by gently pulling back on the wire - it should remain in place.
Finally, we connected the relay power and ground connections for the harness. The two ring terminals connected to the red wire and red wire/white wire on the harness are connected to the power stud in the red junction box near the alternator. The bottom of the box will require some minor trimming to allow the new wires to exit without becoming crimped. The ring terminal connected to the black ground wires are connected to one of the bolts that secure the junction box mounting bracket to the alternator bracket. The power stud in the junction block takes a 17mm wrench or socket and the grounding bolt will take a 10mm.
After that, it's just a matter of connecting the fan harness to the electric fans and mounting the relays to the outside of the ECM cover using the supplied screws. Remember, the truck will need to be tuned in order to enable electric fan control by the factory PCM. There are a number of companies that offer discounted tuning services to enable fan control only, but it is certainly worth the extra money to go ahead and have a full tune done to the truck. Even if the vehicle is stock, like ours, there are a number of gains to be had for both performance and fuel economy even when using regular 87 or 89 octane fuel.
Now that the fans are in, go ahead and load your new tune if needed and enjoy the extra HP and cooler A/C!
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Not only do the Viking Performance shocks look great, but they also offer us 361 potential valving combinations with 19 positions of adjustment for each compression and rebound independently. These shocks are available in a variety of lengths and mounting combinations and typically run around $388/pair. Each application differs so we currently do not have Viking shocks on our website. However, we are an authorized dealer and can assist in getting you set up after you take a few measurements on your vehicle.
The first step was removing the current shocks and cutting the factory shock mounts off of the rear axle and the rear crossmember.
We found that our Ingersoll-Rand 118 Max Air Hammer with a cutting chisel helped release the mounts after a relief cuts were made around the perimeter. This is what I would consider the worst part of the install, but the right tools can help make the job a little bit easier.
Next up, we needed to grind the remaining traces of the brackets smooth and flush with the axle tubes and crossmember in preparation for positioning the new shock relocation brackets. We chose to use the brackets that are offered from Atomic Fabrication and Performance. These brackets are laser cut to be dimensionally correct for the stock GM 8.625 inch 10-bolt rear end. These brackets also use the existing rear shock crossmember, so there is no need for additional cross bars or unnecessary weight.
After a few test fits and some modifications, we were finally ready to weld the shock relocation brackets in permanently. Our friend Bill Moore, from Bill's Auto Restoration, gave us a hand welding them in place with his heavy duty Miller welder.
After welding the brackets in place we gave any exposed metal a coat of paint to keep it from rusting. We chose to modify the angle and position of our lower shock brackets to allow us to run a slightly taller rear shock, given that our RCSB sits so low in the back. The change in angle allows us to have a bit more shock travel at the expense of slightly more lay-back angle.
The last step was installing the new Viking Performance shocks. We can't wait to get it back out to the track and see what improvement these changes result in.
]]>We have them available on our site for $329.99, check them out here!
We were impressed at how well the components were packaged to prevent damage during transit.
These kits feature all necessary hardware, as well as an instruction sheet to prep you for the install. Speed Engineering equips their bars with heim joints and the pivot assembly with urethane bump stops. This results in easy adjustment and a smoother ride even when the bars are pre-loaded. We chose the satin black powder coat option, but they are also available in red if preferred. The high quality powder coat finish will offer exceptional durability and easy clean-up.
The install went smoothly and can be completed in approximately 1.5-2 hours, perhaps faster depending on your tools and skill set. Speed Engineering highly recommends installing bolts through the leaf springs on the front pivot bracket assembly to prevent the bracket from sliding over time. The bracket is pre-drilled for the through-bolts and the hardware is already included in the kit. If you choose to install the through-bolts as recommended, it will require you to drill your leaf springs (5/16 hole). We suggest utilizing the highest quality drill bit available because the leaf springs are hardened steel and roughly 1/2" thick. If you attempt to do this with cheaper drill bits be prepared for it to increase the install time significantly.
Ground clearance with the Speed Engineering traction bars is excellent. This truck is lowered 6-1/2 inches in the rear, and the traction bars are installed in the lowest holes in both front and rear brackets.
Overall, we are extremely pleased with the Speed Engineering traction bars and have already noticed improvements and increased traction on the street. We're looking forward to some test time at the track to see how these have impacted our 60'!
Speed Engineering's 1999-2018 GM Truck Traction Bar Kit - $329.99!
]]>I bought this truck when I was living in Texas in 2016 from its second owner. It had spent the first 20 years of its life serving as a work truck for a cattle farm outside of Houston. With only 50,000 original miles it still had plenty of life left in it, but certainly needed a fair bit of TLC. The story below gives a brief overview of its transformation. If you have any questions, please don't hesitate to comment below!
After addressing some mechanical issues and general maintenance, the first order of business was prepping the truck for paint. I chose to use professional grade liner due to its near indestructible finish. The pictures below show some of the paint prep process. Every square inch of the truck, including even the finest details of inside the bed, were sanded to ensure long-lasting proper adhesion.
After paint prep, the truck was final disassembled, masked, and sprayed in two stages. I chose to use Monstaliner for the tan and Raptor Liner for the black. The Monstaliner flows a bit smoother, so it was used for the majority of the truck to allow for easier cleaning and reduced roughness on the areas touched the most. Both products are two-part, catalyzed, professional grade liners that are tintable with various color options.
After paint, the truck was reassembled and all trim, weather stripping, and lights were replaced. Shortly thereafter, the wheel and tire package arrived. 17 inch Method Race Wheels and 34 inch Toyo Open Country M/T tires were chosen. The wheel wells and inner bed sides were restored and painted before the wheel and tire package was mounted.
The truck spent roughly a year in Texas after it's transformation before making the 1,200-mile haul back to Florida. It never skipped a beat, even in the heat of summer, hauling 12,000 pounds for 20 hours straight.
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The Sierra 1500HD that will be pictured in this thread.
The truck began showing obvious signs of rust propagating from the backside of the sheet metal surrounding the third brake light. Chevrolet trucks are notorious for issues with water intrusion from under or through the third brake light assembly. This particular example was caused by water intrusion through the driver side mounting screw due to a poor seal and a very small fracture underneath the screw. The screws pass internal to the light seal and allow a direct path to the interior sheet metal. Evidence of moisture intrusion may also be present on the headliner inside the vehicle during severe cases. I would strongly recommend periodically checking the condition of both your light assembly as well as the condition of the seal underneath.
This photo shows the condition of the metal after putting light pressure on the affected areas. As you can see, many sections fell right through to the interior compartment.
Realizing that the damage was significant, I went ahead and Roloc'd the damaged areas back until clean metal was exposed.Unfortunately, the back side of the sheet metal showed even more extreme rust scaling. It was at this point that I realized the damaged areas would need to be cut out and a patch panel would need to be grafted in place.
I measured and marked the area that I chose to cut out. Notice the tape line in the center of the third brake light opening. This would be my reference point for centering the new panel.
No turning back now! As my dad stated, "cutting the roof open on your girlfriend's truck is not for the faint of heart." No fear here though, I wanted the repair done right. Which meant removing any and all damaged metal.
The extent of the rust damage was obvious once the original panel was removed.
The existing roof structure was panel flanged and a patch panel from a donor vehicle was sized and cut to fit.
The flanged area was ground to bare metal and the surface was prepared with a 40 grit Roloc at low speed to leave the proper tooth for the panel bond adhesive to bond to.
Both the roof and the patch panel were coated with high-grade professional panel bond adhesive. It's important to be sure that all bare metal surfaces are 100% coated with the panel bond to ensure proper corrosion prevention.
The panels were joined and clamped in place for the full 24 hour cure time of the adhesive. Some of you may be wondering why I chose to bond a patch panel in place, rather than weld. Panel bonding technology has become the industry standard because of its superior corrosion prevention. It also eliminates sheet metal distortion from the heat generated from welding.
After cured, the excess panel bond was ground flush and the area around the joint was ground to bare metal to allow the first stage of filler to properly adhere to the repair.
I chose to fill the immediate area around the joint with fiberglass reinforced filler. This will add strength to the joint as well as helping to prevent repair mapping in the final finish.
The first round of filler was blocked down with 80 grit sandpaper until the repair was relatively flush.
A coat of high-grade polyester filler, that was tech sheet approved for use over cured OEM paint substrates, was laid over the repair area and beyond. This will be block sanded smooth and straight to level any inconsistencies in the sheet metal caused by the repair and further prevent repair mapping.
This photo shows the final layer of filler after block sanding. This step was finished with 180 grit sandpaper to prepare for primer.
Several chips on the roof had begun showing signs of surface rust. While we were repairing the rear portion of the roof, we wanted to ensure that none of the other areas were left to worsen in the future. So they were Roloc'd down to clean metal and prepared to fill.
There were 10+ areas that needed to be addressed. This image shows them after they were filled and blocked level in preparation for primer.
All repair areas were covered with three coats of 2K urethane primer. They are now ready for the next round of block sanding.
Here's the roof, ready for paint, after several more coats of primer and a few rounds of body work.
Here's the finish after several coats of clear.
A quick snap shot of the project start to finish.
The roof was refinished using PPG Deltron base coat and PPG JC60 clear coat. It's a relief to have the roof rust-free and back to factory finish! On to the next project!
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