Re: Sullii the 72 GMC 1500
 

Sounds like it was a fun day. Thanks for sharing.

That’s great your wife is supportive (and even encouraging), and that your kids are involved.
Just remember, to you it’s a truck you bought and worked on, to your kids it’s “dads truck” they remember working on with dad… ;)

Re: Sullii the 72 GMC 1500
 

I heard it was a great show...Truck looks great!

Re: Sullii the 72 GMC 1500
 

Looking good!
And congrats on a successful road trip.

Re: Sullii the 72 GMC 1500
 

Looks like fun, truck looks great.

Re: Sullii the 72 GMC 1500
 

Great looking truck nailed it 100%

Re: Sullii the 72 GMC 1500
 

Most excellent truck sir! :metal:

Re: Sullii the 72 GMC 1500
 

Truck came out great man. Really dig the drop on it as well. Really wish I made it to the Revival! This year I plan on going. Hope to see you there.
Speaking of the driveshaft, I run the poly bushing and its great (says my driveshaft shop) and I had a slip yoke added to the rear if I ever decide to run bags, but also for rear travel on the differential side of the carrier. I always thought it was crazy that the carrier took the brunt of the movement rather than an actual slip yoke. Id be willing to bet this would help your floor contact issues.

At any rate, great job, really enjoyed the build!

Re: Sullii the 72 GMC 1500
 

Nice work, just read through the complete thread.

I like your approach to building trucks, Rg

Re: Sullii the 72 GMC 1500
 

Thanks all! I have been kicking around ideas on where to go next with the truck. I even survived a strong urge to sell a few weeks ago when issues started arising with my other project, my 2004 VW R32. As much as I love the truck, the R is the most entertaining vehicle to drive that I've owned. It's currently at 208k miles and a slew of items needing attention have built up to the point where I had to stop driving it. My immediate bonehead idea was to just sell the truck and buy everything I need for the R (plus some upgrades), but ultimately I decided to be patient and take a year or so to work through the R methodically. This also forces me to pause extensive work on the truck while it is in a dependable and drivable state.

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I've been trying to drive the truck several times per week, for the fun of it and to keep building confidence in all the work I've done. So far, it has not let me down. Many trips to work, landfill, etc. I've also hauled a 600 lb load of metal to the scrapyard and the truck handled it like a champ!

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Before it got too cold here we also did a few landscaping projects around the house. I do have a Tacoma that would be useful for this as well, but it's so much more fun to put the GMC to work!

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In parallel with everything I've been doing with my GMC, my friend was inspired to get his own truck. I helped him pick up a local '78 C10 that was all original and running, albeit very rough. It is now completely blown apart and he has some big plans for it. Here's a sneak peak at what he's thinking. Hopefully he starts a build thread for it because I think it's going to be quite the original build.

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That's it for now. Back to the garage for the evening...

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Re: Sullii the 72 GMC 1500
 

When I was in the Navy I had a VW Corrado, very fun car. But I bet those kids don't smile as much around the vw.

Is your buddy going fwd in the square???

Re: Sullii the 72 GMC 1500
 

They do love riding in the VW, but if I ask which we should take a ride in it is the truck 100% of the time!

He's actually doing a stock car inspired setup. Wide five hubs with a quick change rear end. He's going to run those wheels/tires on all four corners.

Re: Sullii the 72 GMC 1500
 

Nice!

Re: Sullii the 72 GMC 1500
 

Seems as though I can't leave well enough alone. I've never been completely satisfied with the wheel/tire combo I ended up with. The 235/75 tires that I bought were good for the stock suspension setup, but they just don't look right on the 15x8 wheel. It is too stretched and tall compared to the front tire. Most times it looks fine, but there are some angles where it looks very awkward. Then I got to thinking, what if I put the 15x8 on the front and got some 15x10s for the rear? After test fitting the 15x8 on front, I knew I had to make this happen.

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While we had the 15x8 on front, we had to throw the 15x6 on the rear just to get the truck back on all four. Needless to say, I will NOT be running 15x6s on the rear!

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I got some Wheel Vintiques series 62 15x10s to match the 15x8s I already have. The only problem with these wheels is they only come in one backspace, 4.5". With the wider '72 rear end, this puts the wheels right at the fender lip with no room for tire. I will just have to make these work but cutting up these brand new wheels and changing the backspace. I have done this on several of my previous builds so it doesn't bother me. My current thinking is to change them to 5" BS. I will see once I cut them apart and test fit. For now, here they are with the 4.5" BS.

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Re: Sullii the 72 GMC 1500
 

Will be interesting to see how far the tire will bulge out past the rim ?

Re: Sullii the 72 GMC 1500
 

Yeah, that is the biggest unknown right now. I measured my current tires and the fronts are 1.25", rears are 0.85" (which also illustrates how my rears are a bit stretched). I've been working with the assumption it will be about 1". I've run 1/4" clearance between tire and fender on previous builds with success, so that's my current target. The 0.5" extra backspace should get me there.

Re: Sullii the 72 GMC 1500
 

What tire do you plan on using? a 275/60 will not bulge out too much, a 295/50 will...

Re: Sullii the 72 GMC 1500
 

I’m looking forward to seeing the new wheel and tire combo. Always preferred wider meats vs the stock pizza cutter look.

Re: Sullii the 72 GMC 1500
 

At the moment I am planning on using the 295/50. I've seen a 275/60 on a 10" rim and it has the same slightly stretched look that my current tire has, which I don't like. I know the 295/50 is a pretty short tire, but it will be tucked up several inches into the fender, so I think it will look fine. I did some further test fitting and I think I will need to go to a 5.25" BS to make this tire fit.

Re: Sullii the 72 GMC 1500
 

Truck looks awesome dude! I saw it down in the woods at FR on one of my bathroom break walks away from our booth lol

Re: Sullii the 72 GMC 1500
 

haha thanks! Yeah I got routed to the woods and most people seemed to not notice us over there. That's ok, it was a blast anyway. I'm definitely looking forward to going back this year. What booth were you running? There were sooo many trucks I didn't even have time to shop around.

Re: Sullii the 72 GMC 1500
 

Yeah it's one I look forward to every year. I work for AMD, I was the ginger in the straw hat lol. My truck was kinda in the back of our booth most of the weekend

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Re: Sullii the 72 GMC 1500
 

That's awesome! I'll have to stop by and say hi this year. I did check out the AMD booth briefly. You guys make some nice stuff! My friend and I were eyeing up the squarebody bed. He's building the truck I mentioned above and he needs a new bed for it.

Re: Sullii the 72 GMC 1500
 

Looking at your build timeline, you went from the chrome universal CAI, to this new black setup. Care to share the details? Looking for a similar drivers-side-intake, and like the black and simplicity. 😎

Re: Sullii the 72 GMC 1500
 

Sure! It's actually the same CAI in all photos, I just sanded and painted the main pipe flat black. I did not like the polished look. I got this universal kit from ls-swaps.com and for the price it is decent. It required a little work to fit like I wanted for this application, but in the end I like it. It has the correct adapters to work with a stock MAF sensor as well which is the main reason I went with this kit.

Re: Sullii the 72 GMC 1500
 

Yeah man, definitely do! His truck is gonna be killer, our bed setup would definitely be perfect for it

Re: Sullii the 72 GMC 1500
 

I've had a little set back with the truck this week. I drove the truck to work one day and upon walking out for the evening I was greeted with a puddle of coolant under the radiator. I was able to make it home, but the brand new Cold Case radiator was leaking from the core. Their customer service is actually quite good, however, and they are going to send me a new radiator thanks to their lifetime warranty.

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While I wait on the new radiator, I figured it was a good time to clean up the garage a bit and get the truck up on stands to work on my wheels. My son was quite enthusiastic about helping me on this particular day.

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The process is fairly simple for modifying the backspace of these wheels. Basically, I started by cutting the welds and knocking the centers out of the hoops so I could clean up all the old welds.

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Next, I made a quick tool to press the centers in to the 5.25" backspace I wanted. When the horizontal bar reached the back of the hoop I knew I was at my desired backspace. I thought this would press in my centers squarely, but it actually wasn't as close as it needed to be. So, I made another tool for checking backspace all around the wheel mounting surface. A little tapping here and there with a hammer until this feeler gauge was even across all points on the center of the wheel.

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Next, I needed to really fine tune the center of the wheel by actually measuring runout. Unfortunately, I did not have a way to spin up the wheel because I was doing all this at work. I ended up checking for variations across a flat plate set on top of the mounting surface with the wheel face down on a surface plate. Max allowable runout at the outer hoop is 0.030", so I figured under 0.010" would be good enough where I was measuring. This was achievable with a little patience and a few more taps of the hammer.

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Once I was satisfied with the positioning of the center, it was simply a matter of welding them back in. All that work for 3/4" of difference!

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In the end, they don't really look much different, but it bought me the extra clearance I needed so I could tuck tire on a 10" rim. My son helped me check clearance with my tire gauge stick.

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Re: Sullii the 72 GMC 1500
 

Nice work on the wheels, I don't think I would ever try that!

You're son looks like he's a lot of help!

Rg

Re: Sullii the 72 GMC 1500
 

Very nice work...

Re: Sullii the 72 GMC 1500
 

So I have a few items to add resolution to before we get to the good stuff. First, I was able to install the replacement Cold Case radiator. This resolved my leaky radiator problem with the best possible solution: a new radiator. Cold Case was awesome to work with on the warranty replacement, and super fast shipping. I'm just hoping the new radiator doesn't leak as well! While I was investigating the leak, I also noticed that my serpentine belt was bouncing around quite a bit. I checked the tensioner and it was at full extension... not good. I decided to go with a 1" shorter belt, PN K060785. It was also at this point that I noticed the alignment marks on the tensioner. This belt ends up with the tensioner at the ideal location.

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Next up was my driveshaft vibration issue. After reviewing all my angles AGAIN, I decided to try adding a 2 degree shim to rotate the pinion downward. This put the pinion 1 degree below where I thought it should be in theory, but I was running out of adjustment at this point and wanted to try something. While I was checking angles, I also inspected the universal joints and noticed my front joint had radial play in both axes. Then I noticed that the cap faces were grinded down, I'm assuming in an attempt to get the retaining rings in. I was quite disappointed with this discovery since I specifically drove several towns over to go to a highly recommended drive shaft shop. I can only guess this is standard practice and someone just got a little over zealous on this particular u-joint. I decided to replace this ruined Moog joint with a Spicer that ended up fitting perfectly right out of the box. With the changes I made this time around, my driveshaft vibration is now gone!

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Now that those issues are resolved, it's on to the fun stuff. I debated on which tires to get for my new wheel setup and was stuck between a 275/60 or a 295/50 rear tire. I liked the height of the 275, but did not like that it would be a bit stretched like my 235 on the 8" wheel. The 295 fits a 10" wheel perfectly, but the 50 aspect ratio results in a very short tire for a truck at 26.6". Ultimately, I ended up going with the 295/50 rear and a 245/60 front to match. Coincidentally, this wheel/tire combo is the so-called "Squarebody Syndicate Formula" but I'm about to make it fit on a 67-72.

The first photo is the old 215/75 (left) and the 245/60 (right) that will replace it on the front. Second photo is the old 235/75 (left) and the meaty 295/50 (right) replacement! This tire definitely adds some depth to the rear of the truck compared to the skinny 235.

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I went with Cooper Cobra Radial G/T tires because they were the only decent tires in these sizes that I could find. BFG no longer makes the 295/50. You can get a BFG copy from Coker but I didn't want to drop that much change on tires. Besides, the Coopers are pretty darn nice tires anyway. The only thing I don't like about them is the ridiculous cobra emblazoned on the blackwall side of the tire, so white letters out it is.

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Re: Sullii the 72 GMC 1500
 

nice catch on the tensioner and U joints ...and look forward to seeing the new tires installed

Re: Sullii the 72 GMC 1500
 

With the tires mounted the only thing left to do was put them back on the truck. I may have mentioned already, but on the front I have to run a 1/4" spacer since the wheel hits the tierod arm. This was an easier solution instead of cutting these wheels up to reduce the backspace by one quarter inch. On the rear, it's a bit of a process to get the wheels on. I have to put the rear end on jackstands, then jack up the frame on one side to articulate the rear suspension, and then squeeze the tire inside the fender. I was worried I added too much backspacing to the wheel, but after installing them I am glad I went with 5.25". Another 1/4" less backspace and it would not have fit! With the shorter tires, I also had to double the height of my blocks that I use for getting the jack under the truck. Here it is after lowering it down for the first time.

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The rear fitment is exactly what I was hoping for. It's very aggressive but it fits without rubbing after all the clearancing work I did at an earlier stage.

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The front is close to where I want it, but it still needs some work. I had to remove 1/8" of camber shims to tuck the wheels in more because they were too close to the fenders. Even after this, my turning radius isn't very good. My limiter is tire rub on the outer fender. If I could narrow the control arms about 1/2" I think it would be perfect. For now, I will just have to be cognizant that anything resembling parking is going to take a wide arc or two attempts.

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Ground clearance has been reduced by 1" compared to where I was with the other tires. It is almost to the point of "stupid low", however, it is still higher than my R32 and I never have any issues driving that car. I realize I have crippled this trucks ability to do anything other than cruising around, but I knew that going in. I wanted to get the truck as low as I could static, and I think this is the absolute limit within my means. My goal was gringoloco levels of low. His photo of a can in front of his bumper was my reference for what low is :lol: He still has me beat by about 1/2" but I can live with that.

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Out on the road, I can definitely tell I have shorter sidewalls. The tires translate more road content, but in a good way. The ride is still very comfortable. I did not have any tire rub issues while driving with my other tires, and this remains the same with the new tires. Steering feels about the same. I was very happy with everything... until I hit 55 mph. Then the whole front of the truck got a case of the shimmies. If I went +/- 5 mph beyond 55 the shimmy went away. It was not tied to engine load since I could drop it in neutral and it would make no change to the shake.

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After this first ride I was a bit disheartened because these wheels/tires were fresh off the balancer. My intention at this point is to put the original front wheels back on and see if the shake goes away. If so, I will promptly pay a visit to the tire shop and demand in the nicest way possible that they recheck the balance of my tires. It will be a few days before I can get to this, so for now I stuck the caps on and will just enjoy looking at the truck.

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Re: Sullii the 72 GMC 1500
 

Nice work!
Hopefully you’ll get the shake figured out
At least you corrected the driveline vibration!

Re: Sullii the 72 GMC 1500
 

Dude, I love how that truck sits. In the end how much lower are you? 7-9? I think I will end up at 5-1/2 front and 7 rear.

Re: Sullii the 72 GMC 1500
 

I'm guessing the trailing arm mounting flip raises the nose of the rearend up? I have always mounted my shims fat end forward but have never flipped the trailing arm mounts.

Re: Sullii the 72 GMC 1500
 

Nominally, the truck is dropped 8/10 but with the short tires it's even lower. My rocker to ground clearance is 3.25".

Yeah, that is one of the benefits of flipping the trailing arm mounts. It was actually a negative for me since my rear is dropped so much, which is why my pinion shim is mounted large end to the rear. My driveshaft runs up hill on its way to the rearend, so my pinion needed to point down.

Re: Sullii the 72 GMC 1500
 

I made my mounts removable but didn't end up keeping them flipped. It made the rear pinion angle 9-10 degrees up.
https://67-72chevytrucks.com/vboard/...&postcount=280


I really like the new wheel/tire combo.
A re-balance will probably get you fixed up.

Re: Sullii the 72 GMC 1500
 

Thanks!

Sorry for the thread-jack! Rg

Re: Sullii the 72 GMC 1500
 

Duuuuuuuude. I fricken love this truck. I just read the whole thread and had a few “totally relate to that” moments.

If I can help you spend some money: Mike Losh just released an OE-style front wheel tub that might fit the bill.

Excellent read, great detail. Keep up the great work and updates, please.

Re: Sullii the 72 GMC 1500
 

Good golly miss molly! If it's ever possible I hope you and Gringo can do a photo shoot of the 2 coolest C10 rides in the world. The both of you fellas went to ridiculous effort to get EXACTLY what you envisioned and clearly ya'll have 20/20. Both trucks are just perfect in my humble opinion. :gmc2::chevy:

Re: Sullii the 72 GMC 1500
 

Thanks you guys!

gringoloco, I will definitely look into those wheel tubs. No inners is creating a mess under my hood.

cornerstone, you are too nice!

Here's a little before and after now that I am 3 years and 10 pages into this build. When I first got the truck I hated the white letter tires. Well look at me now. I guess grandpa was right!

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