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Unread 12-06-2013, 04:44 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

Project Update for Dec 6th, 2013: Long time without an update on Truck Norris, our single cab short bed "parts runner" and all-around Shop Truck. The little GMC has just been motoring along fairly well since August, with most maintenance items being minor or just ignored over that time period. We've put several thousand more miles on this truck, picking up parts from various suppliers and running things all over town. A few little cosmetic updates were done in the recent months but the brakes were getting worse. We finally did something about that in late November. In this series of posts I used pictures both that I had taken (which are generally pretty poor) plus pictures Brandon took (which look 10x better), in case you notice the difference. Anyway, let's get caught up on the GMT800 Vorshlag Shop Truck project.


This is the "Before" shot showing the old wheels, chrome side molding, "sun shade" rain deflectors and no window tint

COSMETIC UPDATES

We did a number of small cosmetic upgrades and repairs work on the truck, including: new window tint added, removed all of the chrome side molding and badges, and removed the adhesive residue from old trim and a new removed set of "sunshade" side window rain gutter shades. The chrome side molding looked ugly and always bugged me, so that had to go, as did the cheesy (and broken) drip rail sun shades around the doors.



Once the side trim and sunshades were yanked off there was some serious double-sided foam tape that had to be removed, too. This adhesive was strong and a total PITA to get off completely. We tried soaking the stuff with a number of chemicals ("Goof Off" worked the best) and then pushed the goo off with a plastic scraper, but had better luck with a heat gun. Once the adhesive got hot it was easier to remove, just messy. Be careful and don't concentrate too much heat near the paint or you could burn the finish. The "SIERRA" badge and some dealership badge came off of the tailgate and the "SLE" badges came off the sides of the cab, too. Lots of elbow grease later the adhesive residue was finally gone and the truck had a lot less chrome, and looks a lot better. I still cannot stand the ghetto grill, but that's a future fix we will have to tackle.


As of October the truck lost the chrome side molding, rain deflectors and got some window tint

Jason made a big, obnoxious "Vorshlag.com" windshield banner decal and we installed that right before the new windshield was cracked. Later we took the truck to our friends at Soundscape Car Audio in Plano, who installed new window tint on the side and rear glass. They use a CNC plotter to cut the tint perfectly and the installation was both fast and flawless. When it comes time for better speakers we will take it to these guys for that work as well.

BRAKE SYSTEM UPGRADE

The truck's brakes were one thing we couldn't keep ignoring, as they were pretty well shot by about September. Stopping briskly with four badly warped rotors on brake pads worn down below the "wear indicators" made for dash shaking, nervous stops in traffic, and this only got worse when the bed was loaded with hundreds of pounds of machined parts. We had to replace these old brake rotors and pads, but while we were at it I wanted to try to sneak in a brake upgrade, so I started some research.


The old brakes were worn out and a bit undersized. The picture above is of the old 12.00" front rotors

First I looked at the Baer "Eradispeed" GMT800 brake upgrade options. With their kit we could upgrade the front to a 14" rotor with just a spacer for the stock calipers and pay $505. Basically it was $500 for two rotors and two brackets, meh. The Baer rear kit is a 14" rotor as well, with what looks to be the same twin piston calipers we used below, for $1295. Ouch, that's $1800 for what amounts to little more than a rotor upgrade and the same twin pot calipers we eventually went to out back. Then it was time to look at what StopTech makes for this truck. Whoa, pretty... they have BBK for the front which uses 2-piece 15" rotors and their aftermarket 6-piston calipers, but it is a staggering $3595.... just for the fronts! I didn't find a Stoptech rear brake upgrade kit but at those prices I'm sure they make one. That's a little too rich for our parts runner.

So the aftermarket Big Brake Kits (BBK) out there were too blingy and too costly, so I did some research looking for more cost effective, OEM based brake upgrades. We thought about using Gen I CTS-V 4-piston Brembo calipers but that would have entailed a lot of fabrication and I couldn't find any decent 14" or larger 6-lug rotors that would work without major modification or expense, so we scrubbed that.

I was really hoping we could find a way to upgrade to the "Best of the GMT800" series brakes and do some quick and easy bolt-on parts swapping, which is what we did. I went to the GM truck forums to research... AHH! My eyes...!!! I cannot un-see some of the atrocities of bad taste that I saw there. So much noise, not much tech. After reading hundreds of posts mentioning brake upgrades (99% of which was garbage) I found a few potentially useful tidbits, then I poured through electronic parts catalogs where I found a pattern. I took some gambles and pulled the trigger on a number of OEM brake parts that should be better than what we have at both ends of the truck, yet not so expensive that they would break the bank. Once the new rotors and calipers arrived and we could then to test fit the various pieces and see if they really "bolted right on".



As you can imagine, the half ton GMT800 series of trucks was made in very large numbers. The trucks were produced from 1999-2006 and the SUV versions (GMT820) extended all the way until 2009 (Hummer H2). GM continued to develop this chassis during it's long model run and the brake system received several tweaks during that period. Since this chassis was produced in many wheelbases (short cab/short bed like ours + extended cab, and crew cab with two bed lengths) and formats (truck, Tahoe/Yukon, Surburban/Yukon XL, Denali, Avalanche) there was a variety of brake rotors and calipers used.

This GMT800 was the first GM 1/2 ton truck with 4 wheel disc brakes and 4 wheel ABS, which was a welcome addition. The 3/4 and 1 ton GMT800s had excellent brakes from the beginning but the 1/2 ton versions were a bit lacking from the start, with some improvements along the way. The major difference in the 1/2 ton and 3/4 + 1 ton trucks was the difference of 6 lug vs 8 lug hubs, so these 1/2 ton trucks cannot easily upgrade to the "big truck" 8-lug brakes. But we did some digging and found out what works.


Left: The old single piston rear caliper is shown next to the dual piston version. Right: Note rear rotor thickness changes

For the rear the later SUVs (Tahoe/Yukon) went to a thicker 13" diameter ventilated rear disc (from 20mm up to 29mm thick) and from a single piston sliding caliper to a twin piston sliding caliper. From what the interweb forums say this "all just bolts on", but as always I was very skeptical. Turns out it mostly did swap over, with some small tweaks and changes to the backing plate dust shields. We had to order new calipers and sliders to go with the correct thicker rotors, of course. The thicker discs and new calipers made for a tricky brake pad selection, though, as the pad shape is the wider and there were two thicknesses of the pads to choose from. It actually took ordering 3 different sets of pads before we got the right stuff, due to one mis-boxed set from one of our wholesale suppliers.



The front brakes were a bit trickier to upgrade, but we got it handled with a few extra parts deliveries and several pad test fits. From our catalog searches we noticed that there was a larger diameter front rotor available on the last 2 years of GMT800 truck production, going from 12.0" to 13.0" in diameter with the same 29mm thickness. This larger 13" rotor was only on the later trucks that had rear drum brakes, which GM reverted to for some unknown reason. We assume to make up for that rear drum brake "downgrade" they upgraded the front brake diameter - hey, it is fine by me, as it gave us a significant bolt-on front brake upgrade.

continued below

Last edited by Fair!; 07-03-2017 at 10:19 AM.
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