Cascade Crew

[Alphius]

We had a productive weekend. Day 1 was an unqualified success, but day 2 proved challenging.

Day 1:
The transmission boogie


We started by swapping the second fuel tank out and plumbing/wiring the entire fuel system including tank vents and switching valve. Great big easy check on that one. It's easy to tell that GM designed the truck around the primary tank and the secondary was a massive afterthought. We did the primary this time, secondary last time.

We moved on to the trans pan, and while it was off swapped the internal wiring harness as the case connector was seeping a little fluid. The inside of this 4L80E is spotless, almost to the point where Aaron and I suspect it might be either a replacement or rebuilt trans. It is spotless for having a quarter million miles on it. We did not escape this part without spilling the red sea out on the floor, as you do.

The driveshaft was up next, so we swapped on two new U-joints including an adapter joint from Neapco to convert the 3R GM shaft to the 1350 yoke for the 4L80E... My planning (and luck) paid off and it turns out that the stock TH350 driveshaft was the perfect length. Couldn't have been any easier.

With the transmission nearly buttoned up, the final step was to shorten the auto shifter linkage an inch. The 4L80E is wider than a TH350, so the shifter ear was closer to the frame rail. A little cut and weld action and it fit perfectly. Now, here I thought I might need to swap my steering column out to get the correct sector gear to shift the 4-speed auto through all the gears, but apparently people on the internet are not as smart as they claim because my stock TH350 shifter successfully clicks the 4L80E into every gear. Just have to swap the 3-speed shift indicator in the cluster out for the 4-speed indicator and all will be well.

Final piece of the puzzle on day 1 was laying the engine harness out. Just a few wires to hook up (power, MIL, cruise module, VSS to cluster, OBD2 port) and the engine will be ready to fire.

As you can see, Day 1 was a screaming success.

Day 2


These goddamn control arm bushings can die in a fire.

I'll back up and start from the beginning. After a hearty breakfast and a little BSing, we blasted the front end apart. I have all new parts to solve the lowering "kit" of the previous owner, which consisted of cut springs alone for roughly 4-5" of drop. What is suspension travel anyway? On top of that, literally everything was still the original 200k mile OEM parts. Riveted balljoints, 100% original steering linkage, etc. and all of it was surprisingly still passable. However, I'm not one to let sleeping dogs lie, so I bought:

CPP 2.5" drop spindles
McGaughy's 2" drop springs
Moog control arm bushings and new bumpstops
Moog upper and lower balljoints
Moog steering parts (idler, pitman, inner and outer tie rods and sleeves)
KYB shocks
Energy Suspension swaybar bushings and brackets

Blasting everything apart with the impact proved easy, but we spent the next 8 hours just replacing control arm bushings. It took all of our redneck ingenuity and not-inconsiderable sledgehammer skills plus creative use of the 20-ton press and rental balljoint tool to free those bastards from their rusty 30-year old prisons. A common refrain heard in the shop was "GFB", or Get F---ed, Bushings.

8 hours later, with all new bushings pressed in, we called it a night. Now I'm reassembling the suspension bit by bit after work this week.

What's Left?
1. Reassemble front suspension
2. Finish up wiring harness
3. Swap cluster to 88-91 electronic Suburban cluster (delete cable speedo)
4. Weld up some exhaust from the headers to the existing pipes
5. Recover some interior (seats and doorpanels)
6. Reinstall core support to plumb up the cooling system and A/C
7. ???
8. Profit!

Stretch Goals:
Non-critical upgrades to take place after I'm on the road again
1. Detroit TrueTrac diff, potentially with new gears if I don't like the 3.08s anymore with the 4L80E.
2. Better exhaust. It's 2.5" duals with crappy "Xlerator" mufflers right now. I'd like to eventually H-pipe it with Magnaflow mufflers and hi-flow cats.

[Alphius]

Got it back on the ground at the end of last week. Front seems a tad higher than the rear, but it is still minus core support in the front and the rear helper airbags don't have any air. They're supposed to always have a minimum of 10psi, so the rear end will come up a hair as well. I expect it to end up a little lower that it was pre-project and level out nicely when everything is properly put in.


Front suspension alignment is better in every way with drop spindles and lowering springs instead of cut factory springs. Firmer, better steering and balljoint angles, and more travel. Success!


On to the next stage!

[QwkTrip]

That will be nice when you're done.

[Alphius]

Let me learn you guys a thing.

81-87 cluster like I have in my truck with cable speedo and factory clock option. No tripmeter. 5-digit odometer. This one's more beat up than mine, but it'll work for illustration.


89-91 Suburban cluster with VSS speedo, no clock available so there's a blank spot. With tripmeter and 6-digit odometer. I wish it had two tripmeters so I could track both fuel tanks.


With my swap, I need to switch to the VSS cluster, but I want my mileage to match and I want to retain the factory clock. I set the mileage on my new cluster to match my best guess of the truck's current mileage: 199,733. Still have to mod the gauge bucket to stick the clock in, but that won't be too difficult. The newer cluster also nets me a "Service Engine Soon" light to hook up to my LS PCM. So fancy...


Bonus round: I know of a company making these to replace the big fuel gauge. I'd lose my seatbelt and e-brake reminder lights, but it'd be trick as hell. I can't decide...
A vanishingly rare number of these trucks had a factory tach there, but the max revcount was either 4k or 5k, and the fuel gauge would be displaced to the clock location which I don't like. Combining the two gauges into one is a novel and useful idea, along with a 7k tach.

[aaron_sK]

That combo gauge is pretty sweet and not priced badly for what you get.

[Alphius]

Yeah, similar price as an aftermarket gauge.

Looks great in the cluster too. Man, I'm convincing myself now.

[Dewey316]

I dig the combo gauge. DO IT

[Alphius]

Dangit, can't handle the peer pressure. It'll be awesome. Ordered one.

[Dewey316]

[Schultzy89GTA]

Truck looks good bud.

-Schultzy

[chevymad]

Only $200?? was thinking it would be expensive. I once tried to put a tach in the dash of my 70 the "cheap" way. In the end I still spent $350 for a 5k tach lol

[fiveoformula]

Nice! I don't think I've ever seen a square body truck with a factory tach. what is it with GM and the yellow line at 4500? lol

[aaron_sK]

They're realists.

The factory tach is rare as balls. I have never seen one in person. Funny thing is they have no redline or any coloration at all, the dial just ends at 5K!

[Alphius]

I saw one factory tach in person at the junkyard, but the face was super rusty.
Funnily enough, GM set the Express van to shift at 5200 at WOT, so the yellow/red on that tach is fairly accurate.
Silverado and Sierra with the 4.8 got a shift point of 5600; the 4.8 needs revs to make power. I'm going to run it on a bone stock van tune for a while before I start messing with things though.

I'm doing some wiring and other odds and ends this weekend. Tentative goal is to get enough done to start it.

Measuring for a serpentine belt since I'm running a junkyard kitbashed accessory drive:

[chevymad]

Dad's 1980 k30 4 speed truck has a tach. I've never checked redline though, but its been revved pretty good trying to move 20k#s with a 350.

[Alphius]

[Twilightoptics]

Shorter belt to pull the tensioner back/up.

[Alphius]

Tensioner is pretty much maxed out, if anything I'd try a longer belt. It points almost exactly downwards for all of it's travel so there isn't much if any help there anyway. The tape shot is with it fully relaxed. I walked the yard looking for an idler smaller than 3", there were plenty 3" ones but none smaller. I'll give it a shot as-is but if I have too much belt deflection I'll need to look harder for a smaller idler pulley.

[Alphius]

https://www.youtube.com/watch?v=vbFWFDHTLLw



Getting closer!

[chevymad]

That truck weighs 7500 empty, add a 7 ton backhoe and 3k trailer to that. Lots of high revs and long grinds.

Is both parts of the belt going the same direction there?