Building a dependable 1993 GMC k1500

So, since I am bored and the race season starts ramping up next week, I thought I'd do my budget build thread for my tow truck Many people feel the need to own a $50k diesel pickup to tow around 5000lbs of trailer and load, but I feel differently about the subject.

The purpose of this build is to highlight how, through the installation of appropriate parts and managing your load correctly, a 1/2 ton gas pickup can be a perfectly acceptable tow vehicle. I will have testing to back it up, as the truck will see 40,000kms of towing across Canada from next week until the end of the 2013 rally season

So, where to begin? As I posted elsewhere (see this thread for a discussion on TORQUES ) you can see the start of my machinations. But, just to take off from the beginning...

This is my 1993 GMC K1500:

It was free from a family friend. When I got it, it had 273,000kms on it (170k miles) and a blown transmission. My father knows a guy near where I live that has done a transfer case rebuild and front diff rebuild in his 2004 GMC k1500, so off the truck went to Craig. For $1500, he dropped the tranny, fixed everything with better than factory stuff (tranny is setup for towing now, firmer shifts, more clutch packs, etc), and reinstalled it. He charged me an extra $200 to install a tranny cooler, which is obviously more than it'd cost me, but hey, he gave me a screaming deal and I'm not the one covered in ATF now am I?

So, then what? Well, besides doing an oil change with Shell Rotella T6 full synthetic 5w40 diesel oil (my favourite oil ever because of it's high zinc/phosphorous content and inexpense price when on sale. Also ranks highly on BITOG), I added the biggest battery to it I possibly could for the cheapest I possibly could. $79 for a 770CCA battery? With two year no questions asked free replacement? Awww yea

The truck then sat for a while (moved some furniture), as I had written off the Talon, so there was no rally car to move around.

Fast forward to the beginning of September, and we hauled the new rally car back:

The truck handled it quite well. The trailer was obviously loaded improperly, a UHaul puts way too much of the weight on the tongue of the trailer, and doesn't allow you to adjust the position of the vehicle. That's the way she goes sometimes though. Towing 5500lbs down the highway at 105km/h, I got about 15L/100kms (aka 15.6USMPG). Not too shabby eh? That was mostly flat land driving though with some rolling hills. The nice thing about the older pickups (compared to the small bore new ones) is that they have tons of torques down low (300lb/ft @ 2800rpm). The torque converter would stay locked in 4th even when presented with a slight incline. It took an actual hill to get it to kick out (locked in 3rd).

So, where does that leave us? Well, I purchased this today:

20' long and only about 2000 pounds All for the low price of $2700 all in!

Now, remember how I mentioned I'd be towing 40,000kms next year with this truck? 16,000 of those kms will be in the middle of winter So, what are possibly the best winter LT (load range E) tires were purchased:

245/75R16 General Altimax Arctic tires. These, combined with the 4x4 and chains should make the truck unpossible to stop. I ALMOST ordered them with studs, but at the last minute I had an epiphany: STUDS AREN'T ALLOWED IN ALL PROVINCES That would have been a long, cold night pulling studs out of tires.

You may be wondering about the suspension but FEAR NOT! I have just what the doctor ordered. The truck has replacement bilstein HD's on it in good shape, so good to go there. Being able to stiffen the truck at will though sure would be nice...

Ordered these bad boys up on Amazon.com (actually, I ordered a billion things on Amazon for the coming race season/tow truck, but I digress). I only want them for when I am at the maximum capacity of the truck (7000 pounds of trailer, 500lbs in the truck), keeping a truck level is important (obviously) for a number of reasons such as tire wear, headlight aiming, and steering/braking performance.

Speaking of braking performance, that's probably an important part of the towing equation eh? Canadian Tire had an awesome sale on brake components, high quality ATE rotors and pads for 50% off. Who am I to pass on such a good deal?! I will have a review of these after the trip to Olympia, Washington on Sept 21 for the Olympus Rally.

And finally, lights. Glorious, glorious lights! GM pickups of this era have decent lighting, but the lenses tend to fog over really bad. I was thinking about busting out the wetsandpaper and some polish, but then stumbled across these:

While ricey, they were $77 shipped. Combine those with new 100w bulbs, and I think we'll be in business for light.

We're getting pretty close to rounding out this high performance towing package, but while we've taken care of the truck itself, what about the occupants of the truck?

The 4th gen Chevy pickup is (IMO) one of the comfiest riding trucks around, even in Z71 offroad guise. However, being a 1993 truck, some options like, oh I don't know, a bluetooth equipped mp3/cd deck with iphone controls were missing. The worn out speakers also had to go. So, in goes this:

and these:

I've had really good luck with Pioneer's products. Decent sound quality for a decent price. The speakers were chosen because they fit in the factory locations without modifications required.

So whats next? Everybody always talks about gas mileage. Having done the math, if I gained 50kms per tank of fuel, that would only be around $700 worth of fuel savings over the course of 40,000kms Since I have recognized this, I came to the conclusion that I basically have $700 to work with in improving the efficiency and bottom end torque on the truck. To that end, sometime this winter (preferably before the mountains of Big White are tackled), I'll be installing a comp-cams top end kit onto my truck. New cam, valvesprings, and double roller timing chain/sprocket. I am fairly certain that this will be BY FAR the biggest torque gain the truck will see. At $400, it better be. With only $300 left in the budget, I'll then replace the factory crossover pipe (super restrictive) and that will leave JUST enough money in the budget for a tune to accommodate the camshaft.

By that point, I hope the truck is ready to rock completely. For summer tires, I'll be running Michelin LTX M/S2. A truck tire that is geared towards highway miles, it is smooth riding and lasts the longest out of virtually any truck tire on the road. People see 60k+ miles out of them while towing! I will probably go for an oddball size (225/75R16) as to help get the cruising rpm in locked OD up from around 1750 to 1950 (I figure the RPM differential is worth it if the truck holds 4th locked more often vs kicking into 3rd all of the time). My truck is a rarity, as it came equipped with 3.73's instead of 4.10's. Of course, this helps me get awesome mpg while towing on flat land!

So, stay tuned for a shenanigan filled adventure next week, where I go from Edmonton to Chilliwack, BC, pick up my trailer, go down to Olympia WA, crew at the Olympus Rally, drive to Corvallis OR Sunday evening, turn around and sleep in Portland for the evening, and then head back to Edmonton through the Montana/H89 crossing... oh, did I mention the 1700L in race fuel I'll be carrying? That's 3000 pounds of fuel, 2000 pound trailer, and probably a couple hundred pounds in stuff we've ordered down there (plus 400 pounds of Jeff and I). It should shake the truck down nicely, as we are avoiding the nastiness that is the TransCanada highway through the Rockies, but still going through the mountains.

Edit- Guess I should put down the monies invested eh?

• Transmission + cooler = $1700
• Tires = $700
• Airbag Kit = $250
• Battery = $80
• brakes = $170
• headlights = $100 (with bulbs)
• all stereo equipment = $200 (deck, install kit, 4 speakers)

So far, we are up to $3200 for a fine truck. Yes, it is rusty, but the frame is good and that is all that matters. I have to MAKE it to the east coast, I don't have to look good while doing it. $5 to $6k would get me into a newer truck at a similiar mileage, however, then I wouldn't know how the truck was treated all of it's prior life (75% highway mileage, 40 miles everyday). Our family friend also ran Amsoil synthetic and filters on it, so you know everything is in peachy keen shape. As with everything, as soon as you consider buying a used vehicle, some maintenance (such as tires) will be required. So, if you were to take out the consumables, I'd be pretty close to $2k still. Not so bad eh? Add another $700 for the torque upgrades, and this truck is sitting pretty (figuratively, not relatively ).

I like builds like this. Just simple upgrades to the DD or hauler.

mguar wrote: Hi! I have a 1997 with those lights on it (Sport version came with those and small mirrors) You're right $77 for a pair of them with shipping is a great deal where'd you find them? Don't go into the engine!!!!!!!!! Unless it's worn out from neglect.. Then buy a crate engine to dump in.. (it's cheaper than re machining and rebuilding if you shop aggressively) The cam you're looking at is going to hurt rather than help you.. For towing the absolute best cam is the stock cam.. I'll bore you to death with cylinder pressure, flame front propagation and etc.. or you can find those free programs on the net and do what if's to your hearts content.. The best improvements for mileage is headers.. (real ones, not block huggers or anything with different length exhaust tubbing.. For pulling primary length is critical 36 inch long primary pipes of 1.75 collector length of 25 inches.. Stock cast iron manifolds cost you 40hp @peak &41 torque at peak but the important numbers are.. off idle the headers give you 25 more ft.pounds torque and 3 more horsepower..average gain is 19hp&29T. If legal put a set of duals on it and delete the cats. If not legal go to high flow cats.. The cam you were thinking of costs you in both Horsepower and torque.. until about 2200RPM..

That's excellent info, thank you! When I plugged the cam combo into the online engine simulator, it showed there would be torque gains virtually off idle, but theoretical computer models and real world models are usually different.

I was quite skeptical about a cam helping that low down, but "everyone" on the internet seemed to say it would help. Your sizing suggestions on the headers will really help, as a full exhaust system (and I will delete the cats) is about the same price as the cam kit.

As for the lights, here is a link:

http://www.ebay.com/itm/88-02-Chevy-GMC-C-K-1500-2500-3500-Pickup-Composite-Type-Euro-Chrome-Headlights-/310393888655?pt=Motors_Car_Truck_Parts_Accessories&fits=Year%3A1997|Make%3AGMC&vxp=mtr&hash=item4844eadf8f

http://www.ebay.com/itm/OE-Style-Chrome-Headlights-Clear-Bumper-Lights-88-02-Chevy-GMC-C10-Truck-SUV-/310432736683?pt=Motors_Car_Truck_Parts_Accessories&fits=Year%3A1997|Make%3AGMC&vxp=mtr&hash=item48473ba5ab

I have a hard time believing performance cams will actually improve your fuel economy.

Thy do so by improving efficiency, and putting the power where you use it. Stock cams are a compromise to idle smooth, and last forever. In most applications, the stock cam is almost never a good choice.

You want whats called a RV cam, all grunt, all down low.

Sky_Render wrote: I have a hard time believing performance cams will actually *improve* your fuel economy.

If they are tuned for torque, they can improve real-world economy by not requiring you to use as much throttle to get moving. Stock cams are made to deliver good EPA numbers, not necessarily good real-world numbers.

Looks like you have the "oily bits" well sorted so that the truck will be able to give you many years more service. I assume that vehicles in the Great White North are like the ones here in Michigan, it's usually rust that kills them, not mechanical failure. Do you have any plans to address that by repairing it or at least trying to slow down what's there?

The 4-HI mod also helps lighting by giving you low and high beams when the highs are on: http://www.fullsizechevy.com/forum/general-discussion/tech-articles/191159-how-do-4hi-mod-obs.html

Here's the forum with the best signal-to-noise ratio: http://www.pacificp.com/forum/index.php This forum also has some really good information out there on the TBIs: http://www.fullsizechevy.com The cam of choice for the TBIs back in the day was the Crane 2030 (not sure if that's changed over the past 10 years)...

Tom_Spangler wrote: Do you have any plans to address that by repairing it or at least trying to slow down what's there?

Nope.

The truck already has 280,000kms on it. I figure if I am putting 40,000+kms on it per year (I expect to do the next two to three national seasons back to back at a minimum), she'll be pretty close to worn out at that point. Last one of these my family owned, we put over 550,000kms on it (1996 ext cab 2wd with the 5.7L vortec, stock tranny). It was used like a work truck it's whole life. I can patch the holes quite easily, but considering I have a full-time job and do all of my vehicle work (rally car and truck) myself, it just isn't a priority for something that is going to get abused and then thrown out.

Find another truck like it, stick the tranny in it, rinse and repeat

I think my game plan is changing (again) for the cam idea.

I am going to do an exhaust, as everyone universally says that it will be a major improvement. I am definitely down with the idea of dumping the exhaust in front of the rear wheels, that was my original plan.

As for long tube headers, I've only been able to find hookers so far, they are only 31" long. I don't think a 36" long primary is available due to how tight the 4x4 engine bay is. And finally, the hookers are almost double the cost of a set of "mid length", and they appear to actually be full length (which as I said with the hookers, is probably because of the 4x4). So...

These http://www.summitracing.com/parts/BIG-11504FLT/

With exhaust pipe ran to this http://www.jegs.com/i/Dynomax/289/17553/10002/-1?parentProductId=

And then dumped in front of the rear wheels. Should be inexpensive and the best bang for the buck.

Beyond that, I will probably forge ahead with a camshaft install at a later date if deemed necessary. The truck definitely needs some more jam to get to Big White, I'm hoping the exhaust and a TBICHIPS tune shall suffice...

Edit- A good article

http://www.carcraft.com/featuredvehicles/ccrp_0407_1993_gmc_350_pickup/viewall.html

I would also consider a good Y pipe and 2 into 1 exhaust. I did this on one of my 350 powered race cars, and it made a big difference in low RPM power. I went 2 X 2 1/2" to 3".

Zomby Woof wrote: I would also consider a good Y pipe and 2 into 1 exhaust. I did this on one of my 350 powered race cars, and it made a big difference in low RPM power. I went 2 X 2 1/2" to 3".

I've been doing a ton of reading on exhaust scavenging and what not today... oioioi!

Again, I believe I've changed my mind slightly... while long tubes would be nice, many people pointed out that at my operating range (off idle to 3k rpm) headers probably won't make much of a difference, partially because of low amounts of exhaust gas flow.

In order to get the most scavenging, you want the smallest, fastest flowing exhaust. Hedman has a set of headers that are long (31" primaries) that are only 1 1/2" diameter tube with a 2.5" collector, which is nearly perfect... buuuuut a friend pointed out that the great thing about stock exhaust manifolds (if they aren't cracked) is that nothing goes wrong with them. I really like that thinking, as the truck is supposed to be EASY to work on and cheap. Spending $300 on headers seems like a bit of a waste...

So the new idea is stock manifolds, 2 1/4" mandrel bent pipe from the manifolds to a really nice spintech muffler:

and then 2.5" single exhaust dumped in front of one of the rear wheels (probably the passenger side like stock).

2" inch from the manifolds to the muffler. 2 1/2" inch exit from the muffler

This is the stock sizing. I think it should be a legitimate idea to go to the 2 1/4" (I'd love to try 2", but I can't find a muffler that has dual 2" inlets with a 2.5" outlet, and I'd be worried about flow at that point).

So the new idea is stock manifolds,

BTDT, I would buy headers.

Zomby Woof wrote:

So the new idea is stock manifolds,

BTDT, I would buy headers.

See, if you were anybody else, I could probably just ignore you Mike

Having said that, after looking up some dyno plots, it would appear to me that smaller primary tube size is BETTER for low end torque than actual primary length. The longest length header that fits a 4x4 truck like this is the hookers at 31"... not that long. And they have 1 5/8" tube primaries/3" collectors. Flowmasters have 1 1/2" primaries/2.5" collectors... for a comparison, I present CHP's article which uses headers very similiar to what I would except for the engine (unfortunately, they don't start the dyno until 3k rpm):

http://www.chevyhiperformance.com/techarticles/148_0404_best_headers_shootout/viewall.html

The flowtechs are also $140 vs $250 for the hookers, and should be easier to install.

Hmm...

mguar wrote: But again you won't know until you have actual port flow numbers to confirm..

Which I will never have.

The science is great, and I do appreciate it, it's just that at some point the theory stops and reality hits. It is a cheap build. Stock exhaust manifolds are restrictive, even if their tube diameter is appropriate. Therefore, with a proper, free flowing, small diameter y, and tubing, plus the free flowing set of headers, I think I'll be ok. Maybe I will be wrong. But typically, (especially from that era), there were many reasons for going with equipment illsuited to making any form of power/torque (smog laws). Something has gotta be better than nothing.

I'm making due with what I have. And yes, the truck WILL get dyno'd to see if it was worth it, so at the very least, I can go "here are the facts, I'm either right or wrong".

Well, the first of a long line of trips the truck will be making is in the bag:

Write up to come soon. Long story short, more power is sorely needed. The truck overall was great, but it starts to wheeze really bad at 5500+ feet of elevation towing up hills.

Blurry picture aside, this was the start of my brake controller install. Bought one of the most highly rated brake controllers available, a Tekonsha P3. Also picked up a complete wiring kit and 4 way adapter from etrailers.com . The kit came with virtually everything I needed, all I had to purchase was some extra 14ga wire and a couple of extra butt connectors/ring terminals. Everything else was included.

I have it installed, but haven't been able to test it yet. Powers up fine, hasn't blowed up yet

Looking for updates on the exhaust? Well, I'll give you updates! I ignored Frenchy because, well, that's what I do is ignore people.

I did end up purchasing the mid-length, 1.5" primary tube flowtech headers. These have 2.5" collectors on them. From there, they'll be stepped down with proper flanged 2.5"-2.25" collector reducers. Each header will have said 2.25" pipe ran from it as short as functionally possible to a flowmaster collector "y", which is dual 2.25" inlets into a single 3" outlet. From there, it will flow into this magnaflow muffler:

http://www.summitracing.com/parts/MPE-11249/

This is a big bastard of a muffler, so hopefully it keeps things down to a dull roar. Many people had good things to say flow-wise about magnaflow vs flowmaster which helped sway my decision.

And finally, as I mentioned earlier, the truck is in serious need of more power. I am trying to build a similiar setup (if not even more torque) than this:

http://www.tbichips.com/bluewhale.htm

300wtq @ 1800rpm, sounds like my kind of thinking.

HiTempguy wrote: Blurry picture aside, this was the start of my brake controller install. Bought one of the most highly rated brake controllers available, a Tekonsha P3.

I have the first generation of that controller and love it. Ive had a few different controllers through the years and in my opinion none can hold a candle to it. Its just a nice smooth application of the trailer brakes. You will be very happy.

Even a cheap set of headers is better than the stock manifolds. As far as flow of those mufflers, Almost everybody says FM sounds great, but are lousy for performance. Dyno testing proves otherwise. They sound good, and flow well also. Nonetheless, quiet with flow should be your priority, and that system looks like an excellent choice.

Are you going to be at Tall pines?

Zomby Woof wrote: Even a cheap set of headers is better than the stock manifolds. As far as flow of those mufflers, Almost everybody says FM sounds great, but are lousy for performance. Dyno testing proves otherwise. They sound good, and flow well also. Nonetheless, quiet with flow should be your priority, and that system looks like an excellent choice. Are you going to be at Tall pines?

Thanks Mike, I am currently soaking the manifold bolts in wd40 every night, hoping to do the headers on the long weekend

I wanted to be at Tall pines, even just spectating, but it's not going to happen this year The budget to do the whole 2013 season next year dictates I already miss a regional event in Alberta. It's the way she goes sometimes.

Well that was easy!

About two hours later, air bags installed on the truck. Even though it is rated to tow 7000 pounds (around 600-800 pound tongue weight max as well), it tends to sag quite bad when fully loaded. The bags are only going to be aired up about 10-15psi max at anytime. Supposedly, you are supposed to keep a minimum of 5 pounds in them even unloaded, and if anything, in doing so the ride of the truck may have even improved? Weird!

May I suggest an equalizer hitch set-up.

allen_m wrote: May I suggest an equalizer hitch set-up.

Sure, if you explain why I need it (seriously, as I don't know why I would).

We just towed 7000 pounds through the rockies (3000kms) no problem. Since they are really teenie bags, we went up to 35psi. Tire wear was perfect, truck handled and RODE like a boss, I was seriously impressed. All of my previous working with bags involved trucks riding like ass and me not being happy. 35psi in those bags equates to around 250# of extra spring rate on each side of the truck.

I never swayed once towing at 110km/h (sometimes up to 130 downhill if I was coasting).

In reply to HiTempguy: Sorry, Just a thought. Everything worked well so like I said, just a thought.

What's your current hitch setup?

allen_m wrote: In reply to HiTempguy: Sorry, Just a thought. Everything worked well so like I said, just a thought.

No apology required, I just was curious as to why? I sort of understand the theory behind an equalizer, but rallying makes things complicated. I'm a "if it ain't broken, don't fix it" kind of guy

What's your current hitch setup?

Um, a class IV hitch (reese brand IIRC) with 2" ball on it? Nothing special, basically what is standard on any half ton sold the past 2 decades.

With the 7K tow rating (350,700R4, 3.73s), Chevy recommends a weight distributing hitch (along with some other things you have, like the transmission cooler). The air bags increase your rear spring rate, but don't reduce the trailer's tongue weight on the rear end of the truck. An equalizer hitch would lessen the weight on the back of the truck and would give you the option of adding sway control. A general recommendation is to use an equalizer hitch when the trailer weighs more than 50% of the tow vehicle's weight. A good part of stability issues with trailers are due to improper loading of the trailer itself, and it sounds like you're in good shape in that respect.

It sounds like you're not chasing stability issues with your current setup, but it might be something to consider if you ever run into stability issues in the future.