Matt's Yukon XL 2500 (Giant Silver Unicorn) Build

[Matt_]

It's kind of surprising what a little tune to the engine and changing up the trans a bit will do. It definitely makes these trucks more fun to drive.

That's the truth! Add to that all the aftermarket performance mods that are available for the L96.... Its going to be tough deciding what my next "phase" of the build will be once i'm done with all the suspension & steering updates (still need to beef up the steering and do UCA's, that's hopefully next year when parts start wearing).

 

[Matt_]

Ok so this is definitely NOT one of my proudest moments.... Every once in a while we're humbled by a lapse in critical thinking and reminded that we're human.

I could try to ignore this happened, but it wouldnt be right. So here I am putting my pride aside.

Remember those brake lines that didn't fit?

Before install I cracked all 4 fittings... all 4 used a 13mm line wrench.
The new hoses have the same diameter barrels (see where this is going yet).

I picked up the first line, put it in place... didnt fit.
I picked up the 2nd line, not choosing which side to hold up, and took the picture showing the mismatch.





So i'm on the phone with Crown Performance yesterday (cool peeps to talk to on the phone BTW) and the tech is looking up all different GM vehicle specs. Then, with a slight hesitation, he says "youuuuu didn't happen to try flipping the line around did you?" ... I thought he was nuts for a split second, thinking back to using the same wrench to crack the fittings, and the outer diameter of the new lines being the same. It was a complete paradigm shift to think the lines WERENT symmetric, and that both instances during the install I had a 50/50 chance and randomly chose the wrong side of the lines both times.

I walked downstairs, picked up one of the lines and looked at the threads [insert facepalm]. Had a good laugh with the dude on the phone. He tried to make me feel better and said "it happens all the time" which I replied with "I sure hope not!" lol

So yeah.... new lines installed! Next warm day i'll put the Airlift bags on and hopefully don't screw that up, like trying to inflate them with a vacuum or something

 

[Speck]

That could happen to anyone, and most definitely sounds like something I would do as well. At least you didn't have to send the lines back for others and they're installed! I love the build so far and look forward to seeing how the bags help the rear!

Joe

 

[Matt_]

@Burb2500
Got your PM but there's no "reply" option. Anyways glad my thread was able to help!

My wheels are also 9" wide with 5" backspace. Your tires are going to be wider than mine so expect similar (or more) trimming. I used a 3" rear block, so might want to consider swapping the 2" for a 4", and running the front end a bit higher than mine to help with tire clearance.

Honestly if I was to do it again I'd just make my own brackets instead of buying the procomp brackets. Some inch wide × 1/8" think aluminum from a hardware store would get the job done just as easily.

 

[Burb2500]

@Burb2500
Got your PM but there's no "reply" option. Anyways glad my thread was able to help!

My wheels are also 9" wide with 5" backspace. Your tires are going to be wider than mine so expect similar (or more) trimming. I used a 3" rear block, so might want to consider swapping the 2" for a 4", and running the front end a bit higher than mine to help with tire clearance.

Honestly if I was to do it again I'd just make my own brackets instead of buying the procomp brackets. Some inch wide × 1/8" think aluminum from a hardware store would get the job done just as easily.

 

[Burb2500]

I showed the performance shop your threat about the rear rake after installing the 2” and that we should go 3 or 4” but they said every vehicle is different and they want to follow Cognito install instructions and then set her down to access. Then make changes if necessary. I see $$ and would rather be aheadnof this instead of paying for multiple installs. Unfortunately I’m not as mechanically inclined as you nor do I have the right tools to pull an install off with this magnitude. I thought you were running 35x12.50s? You mentioned my tires would stick out more than yours. Are you pleased with the ride quality of the unicorn now since the lift? I’m hoping mine will still ride nice. Did it effect your pulling ability? I pull a 30ft travel trailer. Thanks again.

 

[Matt_]

@Burb2500
You're going to need to set that kit closer to 6" to fit 35x12.5. My tires are 35s, but 11.5" wide which help with the fit.... And as you saw I still trimmed a lot.

Rear block height is not hard to figure out.... every vehicle is different, so go measure yours. You know your front is going up around 6 inches, find out where that puts your fender heights then measure the rear. For a 2" block to provide a "level" look, your front will need to be sitting 4" lower than the rear stock.

If you're towing, the you know you'll want it like mine, an inch or two taller in the rear so it's level while loaded (and not relying on airbags to do all the work). You might also want to consider getting the 4" deaver leaf springs instead of blocks if you need taller than a 3" block. That's my personal limit on block height for a tow vehicle. No block is ideal, too tall and you'll get axle wrap. Not sure where the "too tall" line is, but gut feeling has me comfortable keepin it at 3"

Lifting will obviously effect towing. you'll definitely want to regear. From there pay attention to stability and handling characteristics

 

[Burb2500]

@Burb2500
You're going to need to set that kit closer to 6" to fit 35x12.5. My tires are 35s, but 11.5" wide which help with the fit.... And as you saw I still trimmed a lot.

Rear block height is not hard to figure out.... every vehicle is different, so go measure yours. You know your front is going up around 6 inches, find out where that puts your fender heights then measure the rear. For a 2" block to provide a "level" look, your front will need to be sitting 4" lower than the rear stock.

If you're towing, the you know you'll want it like mine, an inch or two taller in the rear so it's level while loaded (and not relying on airbags to do all the work). You might also want to consider getting the 4" deaver leaf springs instead of blocks if you need taller than a 3" block. That's my personal limit on block height for a tow vehicle. No block is ideal, too tall and you'll get axle wrap. Not sure where the "too tall" line is, but gut feeling has me comfortable keepin it at 3"

Lifting will obviously effect towing. you'll definitely want to regear. From there pay attention to stability and handling characteristics

 

[Matt_]

No real pics to show, but possibly one of the best and most functional mods is now complete.

4.56 Yukon Gears installed. Can't really get on the throttle yet.... It's going to be a looong 500 miles! But it already feels great. No downshifting on the highway and still pulling over 13mpg cruising at 70-73mph, and it's very peppy/light off the line (I'm easy on the throttle but it moves quick with little effort)

After 500 miles will do fluid change and inspection, and probably an aftermarket diff cover. Not sure which one I'm going with yet but these are my top 3:

I would paint this one body color, and like that it fits my heavy-duty-overlander theme.... but unless I go to MOAB, it's usefulness is questionable. I'll spend more time on beaches, and haven't heard of anyone busting a cover on a sand dune lol

http://www.ruffstuffspecialties.com/catalog/14COV.html

This one hits all the functional check boxes... increased fluid capacity, cooling fins, magnetic dipstick:

https://www.summitracing.com/parts/gta-40-2023mb

Then there's the standard "go to"...

http://mag-hytec.com/product/gm-14-10-5-a/

 

[PG01]

Check these
https://www.yourcovers.com/