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Unread 08-06-2013, 04:28 PM
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Fair! Fair! is offline
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Join Date: Jul 2004
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Default Re: Vorshlag Shop Truck - 5.3L SWB GMT800

Continued from above


One of the many hideous "upgrades" done to this truck by a previous owner, something that I had to consciously overlook when I purchased it, were these nasty 20" chrome wheels. The wheels alone nearly made me walk away from this purchase, but I knew this would be "an easy fix", so I ignored them. I also knew these would be easy to sell when I was done with them too. The Sumitomo tires it had were looking pretty crusty, so I knew the wheel and tire package would be one of the first things we replaced. It didn't quite work out as quickly as I had planned though, as other repairs to our shop truck took precedence.

Over the past few months I've had a growing number of tire problems. First there was already a rear tire starting to go to cord before I purchased this thing. It was just starting to blister when I bought the truck, but quickly turned to steel belts. Then I had a recurring flat on the front, shown above. Luckily Ryan had some old 20" truck tires he gave me to use until I could find the right wheels. We eventually swapped on two of his tires to replace the old leaking and corded mess that was on this truck (the front tow was out - that was fixed early). Even after I had ordered the Forgestar wheels a third tire problem reared its ugly head! During the front Bilstein 5100 shock install, Kyle found that one more old Sumitomo tire had cords separate and it was now trapezoidal in shape when view from the front. On went the spare and I wore the Cone of Shame while driving.

The spare went on after tire number three failed on this truck - the old Sumitomo HTR is absolute junk.

From day one all I really wanted to use was a Forgestar wheel, as this is one of the two brands of wheels we work with and sell (D-Force being the other). Sure, we could get anything from our wholesale Discount Tire and TireRack accounts, but that wasn't the same thing as showing the wheels we custom design on a daily basis for our sports car customers. D-Force had nothing in a 6 x 5.5" bolt circle, and Forgestar told me the same thing. None of their 18", 19" or 20" wheels had enough meat on them to fit the large 6 lug bolt circle used by the 1/2 ton GMT800 trucks (the 3/4 and 1 ton trucks used an 8-lug pattern). But I kept bugging the Forgestar folks, and eventually one of their guys remembered a wheel they made for another 6-lug vehicle, only sold to the Japanese market. It was 20x9" wheel in an offset that could work for us, according to our calculations. It was an F14 fourteen spoke style wheel, just like on our TT3 Mustang, but they had never used it on a GMT800. Still, we were confident in our measurements and I was willing to give it a try, so we got the custom set on order.

The new wheels were much lighter, but that tall 20" diameter tire is one heavy mofo! (39.4 pounds)

They only had the wheels in raw aluminum form, so we got the set of four coming and powder coated them here, using our local powder coating shop that has done many sets of wheels for us. I liked the anthracite finish with the flat clear coat on the new 18x12" Mustang wheels so much that I had the GMC wheels done the same. I spec'd out a set of General Grabber tires in 275/55/20, which were a far cry from the Michelin tires I wanted, but also cost about half as much. Hey, we all have budgets, and most of mine goes into growing the company or building the handful of our sports car project test mules... so the "shop truck" is last in line. These General tires did have excellent reviews on TireRack though, and I made sure to avoid Sumitomo HTR's that kept falling apart before.

The tires were mounted and balanced (with stick on weights and aluminum tape - the only way we do it) and the finished weight for the wheel and tire was almost 6-1/2 pounds lighter per corner. They aren't super light, but they are a 20" wheel with a massive 40 pound tire. These new wheels and tires coupled with the newly installed Bilstein 5100s made for a world of difference in ride comfort, handling and traction. We still need to do something about that "one wheel peel" differential, but this was a big step in the right direction.

Current look of the truck with the new wheels, tires, shocks. Needs less chrome & MOAR LOW!

The wheels really look good, and Forgestar liked the image above so much they featured it on their Facebook page this week. Once we get a final price from those guys, we will feature this set of wheels as well as many of the other parts you've seen us add to our shop truck (ARH headers, Bilstein 5100s) to our website under a new "GMT800" section.


I am no audiophile, but the old Alpine head unit in this truck had seen much better days. Half the printed text on the buttons were worn off so I had no idea what some of the buttons did. Half of the display's back lights were burned out too. Since it had no Aux input or USB ports, and lacked Bluetooth support, I was stuck with CD's (what are those?) and FM radio (crap). This old Alpine unit was at least 10 years old and needed to be replaced.

After doing some research I ordered another Alpine unit from Crutchfield, a 2013 model called the Alpine CDE-135BT. This model was made with a CD player (I almost bought the version w/o the CD), integral Bluetooth support (not an add-on module), and was made to work with Android based phones (perfect for my Galaxy S4; they also have one made for the iPhone/iPod). It also had native Pandora support, with buttons on the head unit for Thumbs Up/Thumbs Down, as well as Aux input port and a USB port on the front. I almost never listen to the radio, but stream music via Pandora channels most of the day. Kyle handled the new Alpine install and it works great now. We kept the small sub-woofer box mounted behind the seat as well as the aftermarket amp mounted to the floor under the passenger seat. I really like hands-free phone use in vehicles, especially with GPS based navigation working so well on the GS4. I've added a dash-mounted suction cup GS4 holder, too. Eventually I will mount this lower on the dash instead of up top - the phone gets really hot sitting up there in the Texas Summer sun.

Olof cleaned up the interior of the truck as well, and it looks 100 times better. The entire front bench seat was removed, the interior was vacuumed then the carpets were shampooed and vacuumed again. The plastics were all given a rub-down with Armor All and it all went back together clean. So much nicer inside now - no more coffee stains on the seats or carpet, the door panels are not covered in grunge, and I am a happy driver. The leather wrapped OEM steering wheel still needs to be replaced, so I am looking for a different OEM wheel unit from another GM truck to swap in.


With all of this round of updates, this little truck is now a LOT more fun to drive, and now I willingly choose the GMC over the 2013 Ford F-350. Before this round of mods that wasn't the case - the blown shocks, crappy tires, nappy interior, FM-only radio, leaking header, ghetto muffler, chrome wheels and iffy tires meant that it kind of sucked. I kept telling myself "Hey, it as a cheap "cash truck!", so it will have some rough edges", but that brand new F-350 dually sure was a lot nicer to driver.

Now the GMC rides smooth, doesn't shake-and-rattle from the crappy tires, I've got Bluetooth music and phone, real stainless full length headers, a quiet yet decent exhaust note, and it is finally less embarrassing to look at (wheels). Still needs a bit more cosmetic work, but the foundation is there. Now, when I have a choice between driving the F-350 and the GMC, I take the short wheelbase GMC (again - it is 6 feet shorter). Which is good as the GMT800 gets better fuel mileage with the 5.3L gas motor (running on 87 octane) than the crew cab dually diesel, driving this one keeps the miles off the new tow vehicle, and it is infinitely easier to park and navigate through drive-thrus than the big dually.

If you want to see more of the behind-the-scenes pictures of this work on our shop truck, go to the Project Gallery for this GMT800 and browse to your heart's content (link).


The ride height needs to come down a good bit more before I will be truly happy. Why? Vanity. I know, it is a "shop truck" but it still has to look good, to reflect the kind of work we do at Vorshlag, ya know? We aren't a "we work on boring stock trucks" kind of shop - we work on sports cars for a living. So we will make this at least look a bit sportier with an upcoming 4/6 drop. I've got the McGaughy's parts picked out (2" front drop spindles, 2" lowered front coil springs, 4" de-arched rear leaf, C-notch frame kit, etc), just need to let my budget recover. We will add helper air bags to the rear to help compensate for when I load up the bed with a pallet of parts, too.

And the brakes need to be replaced and maybe even upgraded too. If we can find an OEM 13-15" diameter 6-lug front rotor we will make a custom BBK, and might go with the bigger twin pot rear brakes from the Suburban. The newer '03-07 GMC front grill surround, headlights, fog lights, and bumper I mentioned in my previous post are still coming, eventually. Once the exterior is looking better we'll add some Vorshlag graphics in a classic "shop truck logo" kind of theme for the doors. All in good time.


Last edited by Fair!; 07-03-2017 at 09:11 AM.
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