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Multipurpose Tahoe Build

adventr

tim_zr2 from the old forum
Joined
Nov 11, 2021
Member Number
4540
Messages
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A tahoe? Wtf
Other than they are my favorite shape ever for a vehicle. Proportions are just right. Old school "fullsize" is just the right size. :flipoff2:


Many years ago I had a '95 model K2500 Suburban that I 12v swapped. Loved that thing and had big plans, but I was broke and nothing ever came about. Have always wanted to build another, but this time the Tahoe version for the shorter rear overhang. Turns out, finding a NICE/CLEAN/STOCK OBS tahoe is really really difficult. Like for real difficult. Most are just ragged out junk by this point.

So, one evening last month (Sunday) I was sitting in my comfy chair browsing marketplace and BAM there it was. Just listed, decent price, checked off all my boxes...etc.
But it was 5hrs away. :shaking:

So I did what any normal person would do and hopped in the truck, grabbed the trailer and took off.



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Got there at like midnight, seller was cool enough to wait up for me. Didn't even test drive it, just loaded it up and went back home.



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Here she is. A real beauty. :smokin:

2000 Tahoe Z71
Just under 100k miles
2 owner
No body rust
No door dings
No scratches
Just in excellent condition. Like, even ALL of the factory radio backlighting works. :laughing:



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And I am gonna cut the ever loving shit out of it for this build.


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Starting off with your real basic upgrades. I like functionality, so if there are any factory-style upgrades out there, I like to do them to any vehicle I get.
Stock alternator was a little CS130. Puny little thing. The larger AD244 alternators found on the LS engines will bolt right up (using a slightly longer belt) and they put out nearly double what the CS130 did.
Picked one up from Napa along with their battery cable upgrade kit for the GMT400s. Did you know they even made such a thing??? Let alone kept it in stock at a local store.
Replaces the alternator-to-battery cable and includes a much larger fuse. Also new battery terminals, additional ground wire...etc. Nice kit.



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Also picked up a OEM dual battery tray. Will end up adding the 2nd battery and assorted wiring.



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So an axle swap is a given, but what kind? Could do something real practical like a dana 44, retain the 6 lug pattern, keep it real clean.

Maybe do 1 tons under it? That would be pretty sweet. I've seen some great looking OBS trucks with d60s under them.

But you know what would be really awesome? If I could air down my tires while driving. :idea:
 
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So I bought a few things.

12k CTIS portal boxes
Ruffstuff fab'd/armored housings (for toyota 8" thirds...i know....i'll explain)
Axle Cs
Rear axle adapters
High steer arms
Wheel brakes

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So glad you posted on here. I thoroughly enjoyed your dmax build and I’ve been wanting more details on this build since I saw you post it on Facebook.
 
The portal boxes were in good shape, but pretty dirty. Had one of the guys bead blast them and they cleaned up pretty good.




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Test fitting some of the parts for the wheel brakes




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Finding a wheel that met my needs was a bit of a challenge. I did NOT want to go any larger than a 17" wheel. I also needed as much positive offset as possible to try and keep scrub radius to a minimum. Most of the wheels out there have negative offset for all the bro trucks...
Oh, and on top of all that, they needed to clear the wheel brakes which are mounted just behind the wheel mounting surface. :homer:

Your typical H1 wheels are out. Wouldn't clear the brakes (14.5" discs + wilwood calipers). They only H1 wheel that MAY have cleared would be the hutchinson 17" double beadlock that they put on the Alphas. I wasn't able to verify with any certainty, and the only set I was able to find for sale just happened to be $6,000. Of course.

One of my friend's has some AEV wheels on his ram truck, which appeared to have decent offset (+30mm). So I sent an email to AEV asking for some inner dimensions or possibly even a CAD model of the wheel (knew that wasn't gonna happen). Surprisingly an engineer got back with me the next day with some pretty useful dimensions/screen shots. He said it would be REALLY close and he couldn't guarantee it was going to clear.
Took the chance anyway and picked up a set.




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In the end, I needed to massage the calipers a bit with a flap wheel, but it looks like it will work. Appears to be quite a lot of meat on the calipers around the edges that needed smoothed. And it's on the opposite side of the mounting points. Sooo.........maybe they won't break off there.






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So WHY did I go with toyota 8" centers? My thought was that with the nearly 2:1 gear reduction at the hubs, that 8" ring gear would hold up just fine.
Also, the H1 gearboxes reverse the rotation from axle to wheel. I'll need to flip the third members to account for that. It seemed there were a few people that have done some oiling mods to the toyota 3rd's and worked out. So that's my plan there.
The 8" center section will allow me to tuck this stuff up close to the frame. I don't want much lift height, so packaging is already gonna be a challenge.

Pros:
Small center section allows for easier packaging

Cons:
Gear ratio selection.... I guess I didn't quite think this part thru before pulling the trigger. I did a real quick search and saw that there was a 3.07 ratio offered in the 8" so thought that would be perfect for me. Upon further research, that's a unicorn. Only offered in the late-80s and early-90s 2wd manual trans trucks. I'm guessing the majority of those are in the scrap yard now. No aftermarket company ever manufactured the 3.07s.
Closest I can find is a 3.55 gear manufactured by Nitro. 3.55 x 1.96 = 6.96 effective gearing. Probably a bit steep, but not much choice.

4l60e overdrive of 0.70 would put me at ~2650rpm @ 65mph
Which is almost identical to running it in Drive (1:1) with the oem 3.73 gears and 265/75R16 tires
Essentially like running an older rig with a TH350/TH400
 
What am I going to do with all of this junk? There's a plan for that, I think.


Still ironing out a few details around the packaging and geometry before making finalized parts. It's gonna be a real snug fit.


I'm skipping all the BS this time and going straight to a 40x13.50R17 tire.



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Specs so far:

2.5" of suspension lift
3" front axle push
1.5" rear axle push
Radius arm suspension - inboarded on frame side
2.5x8" coilovers
Bump stopped at 3.5" up-travel
4.5" down-travel
Steering limited to 37 degrees
Less than 0.25" horizontal axle movement throughout suspension cycle


Ride height:

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Full bump:



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Full droop:



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Articulation:




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Steering angles:




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~19" of diff clearance
2.5" scrub radius - was really shooting for 0 on this one but couldn't get there
7 degrees caster
~74" WMS width
~85" overall width




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This one is going to be a challenge, and since OEM CAD data for the GMT400 platform just didn't exist, I'm left to do it all on my own. I feel that my measurements are pretty accurate BUT clearance around that trackbar is going to be the tightest area I believe.

Really needed another rig that I could just tear apart and do some measuring/mocking-up on before making parts and pulling the nice tahoe apart.
So back to marketplace for a parts truck! :flipoff2:


Picked this one up for $650. It actually runs and drives but its pretty rough overall. Will work fine for my needs though and I won't have to worry about being careful with it. Lol




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~19" of diff clearance
2.5" scrub radius - was really shooting for 0 on this one but couldn't get there
7 degrees caster
~74" WMS width
~85" overall width




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I pushed the front axle 4" forward on my old truck running 40" LTB's with an SAS that netted ~5" of total lift over stock. I had to make a lot of room at the bottom of the inner fender liner and the radiator mount to keep it low. I limited the steering angle as well. I ended up retiring the truck but my plan was to section a second inner fender that was about 3" forward and remove the small flat section on the bottom that transitions to the core support. Basically, move the inner fender liner all the way forward to the back of the turn signals. Second option was to remove the turn signals completely and trim the inner liner all the way up to the bottom of the headlights. I probably would have gone down the second path as it was mostly a dedicated wheeler at that time.

The radiator mounts are outboard of the frame rail in the stock configuration (not shown in your images). I removed them completely and mounted a body mount between the top of the frame rail and the radiator support. It worked for a few years but ended up cracking the radiator support around the mounts. If you go down this path you'll need to reinforce the radiator support.

You'll probably need to modify the passenger frame rail to clear your steering. The frame drops down right where your tie rod will want to be at full stuff. Those frames are paper thin anyway so you'll want to reinforce the front section anyway. It may be better just to cut the whole thing out forward of the motor mounts and rebuild it to clear. I cut the front cross member out anyway and fabbed a new cross member and integrated a winch mount under the radiator. Once you're there there isn't a lot more to remove.

On a 2 door tahoe I did a linked SAS on I had to trim the frame side motor mounts to get max uptravel. The leaf spring pad on a 79 hp 60 ended up sitting flush with the bottom of the frame rail at full stuff but the diff wouldn't clear the motor mount without a lot of trimming and a 1" motor mount spacer. With the Toy axle housings you may have a little more clearance but it will still be tight.

Looking forward to watching this come together.
 
I pushed the front axle 4" forward on my old truck running 40" LTB's with an SAS that netted ~5" of total lift over stock. I had to make a lot of room at the bottom of the inner fender liner and the radiator mount to keep it low. I limited the steering angle as well. I ended up retiring the truck but my plan was to section a second inner fender that was about 3" forward and remove the small flat section on the bottom that transitions to the core support. Basically, move the inner fender liner all the way forward to the back of the turn signals. Second option was to remove the turn signals completely and trim the inner liner all the way up to the bottom of the headlights. I probably would have gone down the second path as it was mostly a dedicated wheeler at that time.

The radiator mounts are outboard of the frame rail in the stock configuration (not shown in your images). I removed them completely and mounted a body mount between the top of the frame rail and the radiator support. It worked for a few years but ended up cracking the radiator support around the mounts. If you go down this path you'll need to reinforce the radiator support.

You'll probably need to modify the passenger frame rail to clear your steering. The frame drops down right where your tie rod will want to be at full stuff. Those frames are paper thin anyway so you'll want to reinforce the front section anyway. It may be better just to cut the whole thing out forward of the motor mounts and rebuild it to clear. I cut the front cross member out anyway and fabbed a new cross member and integrated a winch mount under the radiator. Once you're there there isn't a lot more to remove.

On a 2 door tahoe I did a linked SAS on I had to trim the frame side motor mounts to get max uptravel. The leaf spring pad on a 79 hp 60 ended up sitting flush with the bottom of the frame rail at full stuff but the diff wouldn't clear the motor mount without a lot of trimming and a 1" motor mount spacer. With the Toy axle housings you may have a little more clearance but it will still be tight.

Looking forward to watching this come together.

Great info man. That's a big part of my reasoning for purchasing the 2nd Tahoe. There are still parts that I need to model up and measurements I need to take.

Sectioning the inner fender and extending is a good idea. I'll look into that.
I figure there's gonna be quite a bit of "wing it" when making these tires stuff up in the fenders. Lol

Your comment about the motor mount is good as well. I don't know exactly where those land in relation to my front axle placement. And the only way I was able to make the track bar clear was to put the axle-side mount on the diff. Hoping that's in front of the motor mounts. Also hoping that will clear the crank pull and oil pan.
Again, I don't really know where any of that sits just yet.

Plan for this weekend is to get the parts Tahoe into the garage and start taking the front clip apart. Will be able to get some good measurements and data that way
 
I take that back, I believe I do have some data on the motor mount location.
This is a snippet of the drawing I used to model the front frame rail section. It's an original 1:1 GM print. I have the opposite frame rail as well.

Looks like I will be able to pop back open my frame rail model and overlay the drawing to see where the axle is gonna land.
If it only had engine location on there I'd be set. Lol




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Here we go. Hoping someone that's chopped into one of these can take a look at these next few images and provide some insight on how much of a shit show this is gonna be.

Overlaying the 1:1 GM print into my model, it looks like my trackbar mount is gonna be just in front of the motor mounts at full bump. It does look like I'll need to trim the stock front diff mounting tabs off of the motor mounts, but that's not a big deal.

My main concern at this point is..... am I ALL up in the oil pan/crank pulley/important shit??? Or will it clear.... Lol



Pics are shown with axle at full stuff. I put a line to show the leading edge of the motor mounts.

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It looks to me like the trackbar mount is gonna land where i've circled in this next pic. Just inside the frame rail, just in front of the motor mount.
Trackbar will run at a downward angle to the opposite side of the chassis.






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dude this thing is going to be fucking cool as hell! cant wait to see more progress!
 
Man that looks sweet! Good to see some GMT400s getting the full build treatment. Nice score on the z71 too, not many of those around. When you decide to get rid of the stock bumper, make sure you save and sell the fog light buckets. They haven't been made for 20 years and guys that need them are hurting for them bad. You should be able to sell the lights and buckets for $100-$150, and make another GMT400 guy really happy.

Also smart move on moving the axle so far forward. I have a 6" lift kit and 37's on my '98 K1500 and even then I wish I could have pushed it all forward an inch or two for clearance, but it was a bolt on kit, not a SAS. You'll scrub tire on the rear corner of the front wheel well first and hardest. Don't be afraid to cut! What I did was pull a line with masking tape starting at the bottom of the impact strip, then down and back to the mounting bolt on the underside of the fender. That seems to be the cleanest looking cut and makes a lot of room for tires. I had some trial and error to figure this out but if I had to do it again I'd go straight for the full cut, not just for clearance but because it also looks right. Inner fender is another trouble spot... that's going to need some work from the big rubber persuader.

I know this is small potatoes compared to some of the work you are doing, but you got a nice one, you should keep it nice. :flipoff2:



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Man that looks sweet! Good to see some GMT400s getting the full build treatment. Nice score on the z71 too, not many of those around. When you decide to get rid of the stock bumper, make sure you save and sell the fog light buckets. They haven't been made for 20 years and guys that need them are hurting for them bad. You should be able to sell the lights and buckets for $100-$150, and make another GMT400 guy really happy.

Also smart move on moving the axle so far forward. I have a 6" lift kit and 37's on my '98 K1500 and even then I wish I could have pushed it all forward an inch or two for clearance, but it was a bolt on kit, not a SAS. You'll scrub tire on the rear corner of the front wheel well first and hardest. Don't be afraid to cut! What I did was pull a line with masking tape starting at the bottom of the impact strip, then down and back to the mounting bolt on the underside of the fender. That seems to be the cleanest looking cut and makes a lot of room for tires. I had some trial and error to figure this out but if I had to do it again I'd go straight for the full cut, not just for clearance but because it also looks right. Inner fender is another trouble spot... that's going to need some work from the big rubber persuader.

I know this is small potatoes compared to some of the work you are doing, but you got a nice one, you should keep it nice. :flipoff2:


I definitely plan on making all the cuts look as nice as possible. Not trying to hack anything. I will need minor work on the back edge of the fender when fully compressed and wheels turned. Looks like it will be pretty doable without getting into the cab or anything.
Thanks!





Whats your plans for attaching the rear portals to the tube?



A guy in Utah makes these rear adapters. Pretty beefy:



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