2011 Yukon XL LT - Overland Build - Input Appreciated

[osb40000]

Helping my buddy build out his 2011 Yukon XL LT and doing all the research for him since he works 80hrs a week and has a wife and kids. I'm new to this whole GM arena but have been reading up on here as much as possible. Looking for input from those who have done similar and have learned what works and what doesn't.

He's not looking to do hard core rock crawling, but does want a decent ride and more ground clearance than he currently has. He has a wife and four kids and his boys are huge so between people and gear it'll be loaded heavy, my guess would be 900-1000lbs in people and then another 150-200lbs in gear. I wouldn't say this is a budget build at all, he's looking to go with coils instead of spacers.

Right now the only thing that he has set in stone is running LT285/75R17 Toyo AT3s. They balance easily, do well in the snow and measure in right at 33.9" and weigh 60lbs in E range. Should work well for his long 600+ mile trips in the south west. He's willing to trim so fitment shouldn't be a problem based off what I've seen in here.

Looking for suggestions on:

Wheels: Doesn't want them to stick out a bunch and make fitting them harder but also enough to clear the UCA, frame, etc. Thinking 17x8 or 17x8.5 but not sure on the perfect backspacing. Would love something lightweight to cut down on rotating and unsprung mass but I don't think he'd spring for forged stuff.

Suspension: Looking at the Cognito 3" they're using 2" Fox IFP Coilovers and then slapping a spacer on top. Anyone have a link for just the spacer? I don't see a way to get just that from Cognito or just the Front Fox setup with the spacer in a standalone.

For the rear, I'm guessing the Dobinson's C09-037 660-880lb constant load springs will be best (he doesn't want sag and he will tow a popup trailer here and there). Not sure what rear shocks to pair with those Dobinson springs. I'm also open to running something completely different than the Fox and Dobinson combo if it makes sense.

UCA: Open to input here. I and friends use ICON, SPC and JBA UCAs on Toyotas. No clue what to look at on GM stuff.

Axles: Not sure on what gearing he has or how to find out, need to look into that. Hoping it's at least 3.73. How do these rear ends hold up to tight limited slips with bigger tires? I don't think he's interested in doing a locker, but maybe.

I'll make him some rock sliders when I build mine. We'll use a mix of 2"x2" 3/16" tubing and 1.75" .120

What does he need to do to keep his trans happy? Are you guys running a big aftermarket trans cooler? If so what are you using and how's it working out?



What else should we be looking at? I don't know what I don't know and appreciate guidance from more knowledgeable people.

 

[B-train]

Wow! He's watched a lot of videos about it and caught the bug. LOL. Been there too.

My input won't be what you are looking for because I wanted as close to OEM as possible for ease of service and repair. I did 18" GM aftermarket wheels with Nitto Terra Grappler G3 tires - 265/65/18. They handled everything the CO, NM, and WY roads and passes had to offer

A few questions about gear. You said maybe 150-200lbs. I would ask are they just doing day trips? In order to REALLY get out there, you are talking a good 12v fridge, pots/pans, food, extra fuel, extra identical spare tire, extra water for food, water for cleaning, tools for recovery and repairs, extra vital fluids, etc........Then sleeping? Ground tents or RTT (which weigh 150lbs, require a good rack and air deflector).

Is he set on his ideas, or can there be wiggle room to use as a good base and then grow from there? If so, then maybe upgraded springs, good tires, etc. Also, if it has the air shocks, then maybe stiffer springs with those as an asset would work quite well.

Just my thoughts. Happy to help how I can. Overlanding is fun!!!

 

[osb40000]

Wow! He's watched a lot of videos about it and caught the bug. LOL. Been there too.

My input won't be what you are looking for because I wanted as close to OEM as possible for ease of service and repair. I did 18" GM aftermarket wheels with Nitto Terra Grappler G3 tires - 265/65/18. They handled everything the CO, NM, and WY roads and passes had to offer

A few questions about gear. You said maybe 150-200lbs. I would ask are they just doing day trips? In order to REALLY get out there, you are talking a good 12v fridge, pots/pans, food, extra fuel, extra identical spare tire, extra water for food, water for cleaning, tools for recovery and repairs, extra vital fluids, etc........Then sleeping? Ground tents or RTT (which weigh 150lbs, require a good rack and air deflector).

Is he set on his ideas, or can there be wiggle room to use as a good base and then grow from there? If so, then maybe upgraded springs, good tires, etc. Also, if it has the air shocks, then maybe stiffer springs with those as an asset would work quite well.

Just my thoughts. Happy to help how I can. Overlanding is fun!!!

Thanks for the reply! He just bought his wife a 2019 Suburban so the 2011 Yukon XL is going to be their camping/offroad beater. He brought his son on an overnighter where we did around 200 miles on dirt in two days. He was immediately hooked. It helps that we live in a meca for offroading/overlanding and have more trails available to us in a 5hr drive than we'll ever cover in a lifetime. I don't see him being out for longer than 4-5 days at a time and most trips will probably be 2-3 days. I'm the mechanical one that's built a few rigs for myself and buddies but I'm a fish out of water with GM stuff so looking for input on what works.

Good to know that your Terra Grapplers held up on your rig, gives me hope that his AT3s will do fine under such a big pig.

He doesn't have the air-ride adjustable suspension. For the rear the Dobinson springs appear to be as beefy as it gets for off the shelf with a 660-880lb constant load rating over stock in addition to providing 2" of lift. This page shows them handling plenty of weight so I think he'll be good with whatever the throws at them. https://baselineoverland.com/blogs/suburban-builds/baseline-overlands-gmc-yukon-xl-denali-walkaround

Won't be running a RTT, there are six of them so just a basic ground tent. I don't see him doing a fridge, he has a great cooler that stays cold for longer than he'll ever be out.

Good call on the extra gear, I could of course be off on 150-200lbs and wasn't including a ton of liquids which do weigh a lot, so I probably underestimated a bit. I also didn't factor extra spare tire and tools in that estimate. Anything specific/special you bring for tools that are GM specific?

I appreciate your time!

 

[B-train]

Nothing specific in the tool department. The LS motors are pretty easy to work on, as is the remainder of the mechanical stuff.

I bring:
1. Multimeter
2. 8,10,13,15,17,18,19,22mm sockets and wrenches. This covers most stuff under the hood, etc.
3. Hammer, vise grips, pliers assortment, screw drivers, etc.
4. Some spare trans cooler/oil cooler hose and clamps to make a repair if needed
5. Couple gallons of antifreeze concentrate
6. A few qts of oil.
7. (2) 1 gallon jugs of ATF
8. Replacement main belt
9. Misc silicone hose 5/8" & 3/4"
10. Zip ties, tape, silicone, tire kit, and 18v air compressor.

Just the basics that I'm sure you're aware of, plus extras as deemed necessary. My 2 totes of extra supplies and tools probably weigh in at 100lbs, but I'd rather be able to try and limp home vs being stranded.

 

[osb40000]

Nothing specific in the tool department. The LS motors are pretty easy to work on, as is the remainder of the mechanical stuff.

I bring:
1. Multimeter
2. 8,10,13,15,17,18,19,22mm sockets and wrenches. This covers most stuff under the hood, etc.
3. Hammer, vise grips, pliers assortment, screw drivers, etc.
4. Some spare trans cooler/oil cooler hose and clamps to make a repair if needed
5. Couple gallons of antifreeze concentrate
6. A few qts of oil.
7. (2) 1 gallon jugs of ATF
8. Replacement main belt
9. Misc silicone hose 5/8" & 3/4"
10. Zip ties, tape, silicone, tire kit, and 18v air compressor.

Just the basics that I'm sure you're aware of, plus extras as deemed necessary. My 2 totes of extra supplies and tools probably weigh in at 100lbs, but I'd rather be able to try and limp home vs being stranded.

That's an extremely helpful list. Thank you for taking the time to type that out, I'm going to share with my buddy and get him started on getting prepped.

On the zip ties, have you found a specific brand that works well and doesn't break? I've had terrible luck with zipties getting dried out and brittle.

 

[B-train]

I get them through work, but the ones from McMaster Carr have been quite decent on projects. It seems a though most supply house have better quality than any big box store. We use OEM mfg ones as well and they are tough as hell.

Edit: it seems as though the ones that have a shiny appearance are more flexible and don't break as easily new, or over time. I've used a lot of Caterpillar and Kohler OEM zip ties over the years and they are almost indestructible. Again, they are a shiny appearance, and a little thicker than the standard cheap ones.

 

[Swanbird11]

Trans cooler definitely helped my temps. I think Ive got a Hayden cooler but alot of people run trucool 40k cooler.
I ran AN line from my trans straight to the cooler, bypassing the radiator. My old radiator got a internal crack and mixed trans fluid with coolant... not fun.
ALSO I highly recommend replacing the trash plastic Tee's coming off the heater core. Better yet, get the stainless adapters and barbed tee's. trying to fix those on the trail can be a real pain.

 

[osb40000]

Trans cooler definitely helped my temps. I think Ive got a Hayden cooler but alot of people run trucool 40k cooler.
I ran AN line from my trans straight to the cooler, bypassing the radiator. My old radiator got a internal crack and mixed trans fluid with coolant... not fun.
ALSO I highly recommend replacing the trash plastic Tee's coming off the heater core. Better yet, get the stainless adapters and barbed tee's. trying to fix those on the trail can be a real pain.

Love it. This is the kind of first hand knowledge and experience I'm looking for. Is the Trucool 40k beefy enough to run solo without the radiator?

 

[Swanbird11]

I would imagine. Its larger than the cooler I run and im still below stock temps.

 

[Charlie207]

Love it. This is the kind of first hand knowledge and experience I'm looking for. Is the Trucool 40k beefy enough to run solo without the radiator?

I bet anything is better than the factory non-K5L aux cooler. Even just getting one of those from a junkyard with it's brackets would be an upgrade.

 

[Tozan]

 

[osb40000]

View attachment 417132

I love your rig! Looks like an awesome setup!

 

[Marky Dissod]

Axles: Not sure on what gearing he has or how to find out, need to look into that.
Hoping it's at least 3.73. How do these rear ends hold up to tight limited slips with bigger tires?
I don't think he's interested in doing a locker, but maybe.

There are people who can tell if it's 2WD or 4WD merely by looking at the VIN.
Look under the front for axles and a differential, or just ask him.

If it has a 4L60E, 4.10 axle or axles minimum, with all the extra weight.
If it has a 6L80E, 3.45 or 3.73 minimum.
Ask him which transmission.

 

[Mondaytown]

I'm building a 2015 Yukon Xl into an overlander. I'm still getting advice on the suspension but the Motor and trans I know well. I did a Mishimoto Radiator and Trans cooler. The trans oil does not run through the radiator so its fully independent.

It works very well. Trans temps while towing never get over 150's even up the big mountain passes we have here in utah. I am also double the HP of the stock motor so that adds some heat and strain on the tranny. I would highly recommend mishimoto.

 

[Tozan]

There are people who can tell if it's 2WD or 4WD merely by looking at the VIN.
Look under the front for axles and a differential, or just ask him.

If it has a 4L60E, 4.10 axle or axles minimum, with all the extra weight.
If it has a 6L80E, 3.45 or 3.73 minimum.
Ask him which transmission.

One important factor is does he have a 2 speed tranfer case??? The following advice is based on having a two speed tranfer. With a single speed case it might be better to have the 4.11 gears.

The 2011 should have a 6L80E and running on 33's with a limited slip the 3.73 should work out fine. Even running 35's on mine I sometime wish I had 3.73 because my 4.11's are a little deeper than needed for light off road use but, I also have a two speed transfer.

 

[Marky Dissod]

"If it has a 4L60E, 4.10 axle or axles minimum, with all the extra weight."
"If it has a 6L80E, 3.45 or 3.73 minimum."

To be clear: by 'minimum', the above could very well be interpreted as follows:
"If it has a 4L60E, 4.10 axle or axles minimum, with all the extra weight.
4.30 or 4.56 or even 4.88 may be preffered depending on tire size and weight."

"If it has a 6L80E, 3.45 or 3.73 minimum.
4.10 or even 4.30 may be preferred ..."

 

[Tozan]

"If it has a 4L60E, 4.10 axle or axles minimum, with all the extra weight."
"If it has a 6L80E, 3.45 or 3.73 minimum."

To be clear: by 'minimum', the above could very well be interpreted as follows:
"If it has a 4L60E, 4.10 axle or axles minimum, with all the extra weight.
4.30 or 4.56 or even 4.88 may be preffered depending on tire size and weight."

"If it has a 6L80E, 3.45 or 3.73 minimum.
4.10 or even 4.30 may be preferred ..."

Most likely he has a 6L80E and with 33 tires anything over 4.10 will be horrible unless you plan on running 37's In my experience running 35's with 4.88 s they will get about 10 mpg highway tops and it will be a slug on acceleration it will also be shifting into 6th gear around 35 mph. It will be shifting into 3rd gear by 15 mph. with 35's and 4.11 gears it will get 16 mpg and with 33's and 3.73 you should be getting even better MPG and it should pull just fine.

I have a set of 4.88 gears in the garage they were a terrible choice even with my 35's Also at highway speeds the trans will be doing a lot of searching and shifting up and down.

Best choice 3.73 with a 6 speed running 33's should work great.

Pulling the weight... My rig weighs around 7200 pounds loaded out and has no problem pulling it's weight it still out accelerates a stock Tahoe.

 

[Marky Dissod]

No ecm-tcm tune?

 

[Tozan]

No ecm-tcm tune?

No I run a tuner on both trans and ecm... 4.88's even with 35s really sucks unless you want to rock crawl with it... But if you want to rock crawl with it then a solid axle will be necessary because the front diff is a weak point.

This is slightly exaggerated but, if you want to feel what 4.88 gearing will do just shift it into 4wd low and hammer it.. You go nowhere fast. Tons of torque lots of shifting but, very slow acceleration. The other downside is turning over 3000 rpm at 65 mph and that is a disaster on MPG.

If anyone wants to try 4.88s I am pretty sure mine are still in the garage send money for shipping and I will give you a set with less than 5000 miles on them..

 

[Tozan]

I do around 3000 miles a year off road with mine. It's been to Lake Tahoe, California, Oregon, Nevada, Utah, Colorado and Arizona. It's driven pretty hard sometime but, I try not to do too much body damage... lol

Catching a little air...

Black Rock Desert at the Burning man site when no one is there...