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Hummer H3 Build

Been going to KOH for 11 years, I never got to watch too closely because I was doing recovery, volunteering, in the pits, fixing rigs, etc.

Missed this year and watched start to finish every race. Holy shit, between that and doing the OG course in December I’m hooked. I want to race but not in this H3. All my buddies are building family crawlers because their single cab Toyotas or little jeeps can’t haul the kids. We’re at that age where we are about to have kids or just had some. My H3 is perfect for that. It’s a luxury family crawler and I have said from day 1 I refuse to “ruin” it by racing it.

anyways, I am a dumbass and kinda wanna build another h3 for 4500 but it’s such a waste of money. I could also probably convince my brother to let me race his JK, I put 1 tons under it, coilovers up front. It needs a cage, and safety requirements. He hasn’t wheeled it in 3 years, I could work a deal with him. That makes the most sense financially because it requires the least amount of time/money.

My wife says I’m a hummer guy and should build an H3 to race.

Idk, just figured I’d see what IBB would say
 
06h3 said:
Been going to KOH for 11 years, I never got to watch too closely because I was doing recovery, volunteering, in the pits, fixing rigs, etc.

Missed this year and watched start to finish every race. Holy shit, between that and doing the OG course in December I’m hooked. I want to race but not in this H3. All my buddies are building family crawlers because their single cab Toyotas or little jeeps can’t haul the kids. We’re at that age where we are about to have kids or just had some. My H3 is perfect for that. It’s a luxury family crawler and I have said from day 1 I refuse to “ruin” it by racing it.

anyways, I am a dumbass and kinda wanna build another h3 for 4500 but it’s such a waste of money. I could also probably convince my brother to let me race his JK, I put 1 tons under it, coilovers up front. It needs a cage, and safety requirements. He hasn’t wheeled it in 3 years, I could work a deal with him. That makes the most sense financially because it requires the least amount of time/money.

My wife says I’m a hummer guy and should build an H3 to race.

Idk, just figured I’d see what IBB would say
Click to expand...

Depends on what your goal is. You trying to be somewhat competitive, or just go have a blast?

A full on 4500 build is a crazy undertaking. I havent looked at the rules in a long time, but seems like it's just "solid axles, no trailing arms, no full hydro and 37s" then you drape some skins over it to semi look like a rig.

I think the JK wouldn't meet 4600 class without some work.

4500 H3 would be kinda interesting, but could get expensive for a stock class with the ifs.

If it were me, I'd grab a jeep ZJ, put some decent axles under it and some type of better tcase or doubler and go run 4600 for fun, but also to get your feet wet and see what it's all about.
 
YotaAtieToo said:
Depends on what your goal is. You trying to be somewhat competitive, or just go have a blast?

A full on 4500 build is a crazy undertaking. I havent looked at the rules in a long time, but seems like it's just "solid axles, no trailing arms, no full hydro and 37s" then you drape some skins over it to semi look like a rig.

I think the JK wouldn't meet 4600 class without some work.

4500 H3 would be kinda interesting, but could get expensive for a stock class with the ifs.

If it were me, I'd grab a jeep ZJ, put some decent axles under it and some type of better tcase or doubler and go run 4600 for fun, but also to get your feet wet and see what it's all about.
Click to expand...
It’s more to have fun. Nothing competitive. I’d say I’d try to be competitive against the “true” 4500 cars IMO. There’s a Toyota Sequoia that’s SAS’d, a Nissan Xterra that’s SAS’d, a couple Jeep TJs that race, a few Samuaris that are linked and on Toyota axles. That’s the true 4500 class I’d want to compete against. Unfortunately rules have been twisted and there’s legit jimmy cars in the class that somehow are “stock mod”
 
Ok, time for an update.

I got my steering capable of 34-35* again. I built a new drag link and beefed up it to avoid it failing at the bend

Here is how much bend I needed.

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I cut out 3/16x 2x2 box tubing and cut one end off of it and made it follow the radius.

I also welded it a straight piece of plate at the center of the bend that butts up against the end of the 2x2 on the inside if that makes sense. So if it does try to bend it will transfer the load.

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So now I have 34-35* of steering I just have to get other crap out of the way now to actually get added angle.

I then did a quick mission to sand hollow. The hummer group is going to sand hollow instead of Moab this year and the leader has never been there so we ran some trails in a day. 9 hours of driving each way for 1 day of wheeling but that’s ok, I was helping out a friend!


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Overall I had a good time!

Then for the first time in my life I saw an H3 in the junkyard. I knew it was coming to the yard but didn’t know when, so I checked the inventory daily. I grabbed as much as a could. 3 fenders, abs module/brake booster/master combo. Those damn things are like $500-$900 depending on what brand. I got it for wayyyy cheaper then that. A bunch of interior trim, grabbed a BCM, ac condenser, compressor, lines, etc. I grabbed a ton of crap.

I hope to give the H3 a “2nd lease of life” from an aesthetic perspective. I’m still running my original fenders, they are all hammered and fucked beyond repair. This can give new life to it. From a drivetrain perspective it’s on its 10th life and running well but the looks need some help.
 
Those fenders look good from away in the photos above. Except the massive dent in the driver side rear in front of the tire. 😂
 
I spent my past few weekends rummaging around an H3 in a junkyard. I grabbed what I could because parts are getting tougher to come by.

This is after I already took a bunch of stuff.
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I grabbed the grille, fenders, wiring harness, interior trim, the controls for the heated seats and electric seat controls, BCM, TCM, PCM, ac compressors, hoses, condenser, headlight buckets basically anything I could get my hands on.

I also did some snow wheeling

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I have collected some parts…my CSF brand aluminum radiator is now leaking. It seems anyone who puts one in an H3 they end up leaking so I grabbed an ECP radiator this time. It’s substantially thicker than stock or any other radiator on the market. To fit it you need to modify the core support to push it forward to work with a fan clutch or use e fans. I’ll modify the core support. The H3 radiator is undersized so I’m happy to have the extra capacity. My CSF did last in 120 degree heat on UA. I can’t say it ran at 190-210 the entire week but it held its own and we never had to pull over due to overheating but at times it got warm. I’m sure this ecp setup will make it so it can’t get hot under the worst of conditions.

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Other than that I have been prepping my DRZ400 bike for the so cal BDR and practicing riding.

So the hummer has been on the back burner until I get home from that trip but I have been researching my 6L80E swap. I’m not concerned about the physical install, I’m a t case input swap away, lengths of the 4L60 and 6L80 are virtually the same. I’m not concerned about the wiring to make the trans work in D. I’m more concerned about tap shift and making the trans do what I want in M (tap shift) mode and getting my reverse lights to work when I put it in reverse.
 
This should give you wiring info for resistor values to make the 6l80 tap shift. Love the build and continual improvements.
 
Midget said:
This should give you wiring info for resistor values to make the 6l80 tap shift. Love the build and continual improvements.
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Thanks! I appreciate the comments.

Did you mean to add a link? Wasn’t sure if you meant “they” as in a company or this as in a link
 
Yes, there should have been a .pdf attached with the corvette tap shifter schematic showing two resistors to add to the harness to enable tap shift on the 6l80. Let me try again.
 

Attachments

  • 08 Corvette Engine TCM Conns to do tap shifting.pdf
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Went wheeling this weekend. Logged about 100 road miles and then some more wheeling.

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We had 4 rigs with us, an XJ of 36in iroks, a Tj based buggy on 42s, a K30 on 40s, and myself.

I am continually impressed with the 43in mickeys. I was in a deep section that they just churned through at about 5 psi that a buddy with 40in nittos couldn’t get through. With that said, when it was time to winch him out, it wasn’t a straight pull and when I was getting slid around while he winched to me I debeaded the inner bead. This happened 3 times at or below 5 psi. Which was frustrating. I do have gorilla tape on the inner bead.

These are battleborn steel beadlocks and bought them on the pre buy years ago so they are a gen 1 (if they even made changes?) I can’t say anything bad about them as your price per performance is amazing but I think there are better options when pushing the limits of beadlocks. I’d like to find a set that can go down to 1-2 lbs and not have this issue. I’ll also say that under 5 psi there’s so much sidewall that when turning it can be pulling on the inner bead.

Anyways, it was a fun day.

We played a race to get to the top of a hill.


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I took the early lead, then the TJ got way ahead, then I caught back up. Then the TJ got up a try or two before I got up. The XJ got right up to the top before getting stuck and winched him over. In the end, we all were on the hook at some point.

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Every time someone posts a picture of me on social media snow wheeling I get a ton of comments. My signature wheeling attire 😂

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From there my buddy in the k30 broke a Dana 60 spicer u joint which wiped out the inner shaft.

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I had a spare set of shafts and a used Dana 60 spicer u joint….out came the premier power welder where we ran my angle grinder on it to cut the u joint out. We could have done it another way but with the additional tools we had it just made it quicker and easier. I only had 3 clips for the u joints and he lost the clips when it broke so we had to weld one cap in….it sucked but it was the only way. Premier power welder earning its keep again.

From there we continued on, and in about 100 yards the XJ lost a bolt for his ram assist. Luckily I had a big spare bolt that got him going again. I understand having like 500 lbs worth of crap isn’t helpful for performance but it is nice when shit goes south.

We headed down the hill and got to the little mtn town around 7:30, I aired up the tires, they loaded up their tow rigs and we stopped for dinner and then headed home.

Last night I started the tear down.

My radiator leaks and I’m going with an ECP radiator which is like double the capacity so it isn’t a bolt in deal unless you go with e fans. I like the fan clutch.

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Factory sized radiator is 2 7/8 in between fan blade and rad.

New radiator is 1 3/4 inches away from the fan blade

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These end mounts are removable, I will unbolt them, cut it off the mounts and section them 1 1/4in offset to get the distance I need. Then I will cut into the core support to get some more room to section it forward.

I am doing this because H3 radiators are undersized to begin with. Factory setups can keep up but the system must be fresh and in perfect condition. The oem radiators are plastic and the trans/coolant mix and ruin your trans, the CSF radiator I have does a good job cooling but is notorious for leaking. Everyone has issues with them. I have heard good things about ECP but most go to an e-fan, I only know of one guy who did a fan clutch and did the same thing I plan to do.


I haven’t welded aluminum but will probably pick up a spool gun today and learn.

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I will throw in the lines, ac condenser and ac compressor from the h3 I found in the junkyard, they are in better shape, especially the condenser.

Next I gotta pull the pcm off the firewall and the tcm from the 6l80e and ship them off for tuning so I can start the 6l80e project. The 32 spline input for my 205 doubler should be here this week. My 8 FK heims should be here this week too. I don’t know what orientation the 8 FK heims will be used but they will be used for a rear leaf spring delete.
 
Worked on the radiator more tonight.

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Long story short, the radiator used to have 2in between it and the fan clutch and 2 7/8 between it and the actual fan blades. After trimming the core support 1in and trimming in 2 other areas I have it to where it is 1 5/8 from the fan clutch and 2 1/2. I think that should be enough to keep the fan out of the radiator.

Now I have to trim one more section for the little reservoir on the ac condenser.

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Cutting out that spot is going to be structurally detrimental unfortunately so I plan to take a piece of tube, cut it in half so I have a half circle and weld it into that spot to give it rigidity back. In the end I always have something to worry about and now core support strength can be my new worry
 
Worked on the hummer more this weekend.

The radiator is in! I had to do more trimming, and more trimming and more trimming. Getting this big radiator in was a PITA but it’s basically done. All that I have left is the top mount. I’m going to take some 1x1 square tubing weld it to the core support and then tap it so the bolt will attach like factory. I still need to gusset the core support where I notched it but I need to gusset the front side so the bumper has to come off. I was going to take 1.75in tubing cut it in half and weld it in but there’s not enough room. It’s super thin material so I’ll just weld some 3/16 to it on the front side to give it strength back.

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I also pulled my old ac compressor, lines and condenser out and swapped it out for the newer stuff I got off the junkyard H3. I just need to charge it and I’ll be good to go.

Then I worked on the 6L80E.

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the seller told me there’s about 100k miles on the trans. The fluid wasn’t bright red but still red, just a little dark. No chunks or crap in the pan so I’d say it looks solid overall!

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Next step is to pull the pan, filter and valve body.

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Separated the valve body and tcm. Tomorrow I’ll ship out my PCM and TCM to the tuner so he get it all tuned up for the 6l80E.

Next weekend I’ll probably pull the t case and trans.

I have also been playing around with the new link calculator. It’s so cool I can see the load on the links. It’s helping me decide what I think I can get away with in terms of load and determine a 3 link or 4 link. That’s next, I’m trying to get the trans, bigger radiator and rear suspension projects done this year.

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Lastly, I’m looking into how to get a high idle switch for my premier power welder. I’ve been using rocks or sticks between the pedals for years to adjust my idle when using the welder and I’m tired of that method, it’s a pain in the ass. I looked at a diagram and wonder if I can use a 0-5v potentiometer with off (0 volts) and then a dial that goes up to 5 volts. I assume the pedal position sends a 5 bolt reference to the pcm?
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It’s just weird it’s got 2 5V references from the pedal. My buddy mentioned maybe it’s for a fail safe? If the pcm doesn’t read 2 identical inputs it goes into limp mode?
 
I don't know exactly how its done with your computer. But some use a 0-5v and a 0-2.5v signal, and others use a 0-5v and a 5-0v signal. Yes, its a safety thing. If you only have one set of signals, and you get a short to ground or the pedal has an issue, it could send a full throttle signal, and of course it'd be at the worse time.
 
Someone on the hummer forum said it’s. 0-5v and 5-0v signal.

Not sure how I’ll get around that
 
Curious how the 6l80 will work for you. I think more people should use them!
 
CornCobb said:
Curious how the 6l80 will work for you. I think more people should use them!
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I will report back and I agree, more people should go that route. I think it will be amazing! My parents had a 6.2/6l80e Yukon XL Denali back in the day and that thing ripped and it was a heavy pig.

When snow wheeling I noticed in an “all out” hammer down approach I go from 1st, to 2nd and then 3rd to keep wheel spin up and 3rd just bogs, you go from redline in 2nd to bog.

On the highway 4th gear is bogging and 3rd gear is screaming. The RPM drops on 4 speed transmissions are too big. This is a complaint of mine in almost applications, whether it’s on a rock crawler or tow rig. The one exception may be the 4l80e as the ratios are closer together.

Anyways, I’m excited for the smaller rpm drops almost everywhere.
 
Got the wiring diagrams from the guy tuning the pcm and tcm. T case and trans is coming out today. Next will be cutting/splicing wires into the harness.

After much research and seeing other 3 link rigs and seeing how much load the rear will take I am going 3 link rear.

From people I have seen….like em, hate em, none of that matters. Lite brite is running a rear 3 link. They have 500+ hp. 4:1 t case and a deep 1st gear in the 8 speed trans. They wheel that JL pretty hard, and they wheel that thing ALOT, in just about every type of terrain this country has to offer all with an off the shelf rock crawler 3 link. I doubt it will have as much separation as I plan to have. From what I know they have had no issues. I will message them and hope for an answer.

I was able to calculate out my old front 3 link and it was estimated that the upper link took around 27k lbs of force at 1G before failing. My new setup is about 16k lbs of force and it’s been flawless. I have mocked up a rear 3 link in the computer with slightly less load than the front sees and that’s being conservative. Once I actually do it I can make changes to have the upper link see less load. I’d be happy if I can get it to about 12-13k lbs of load at 1G.

track bar, I have never had a track bar bracket failure in the front. I’m going to do beefier brackets and I’m going 1.25in FK heims, not cheap ruffstuff 7/8 heims. I’m going 2in .25wall tubing. I bent 1.5in .25wall but it had a bend in it. 2in with no bends should hold up….

And lastly, if it does fail, I can do a 4 link at that time. I’m laying the ground work if I end up 4 link.

#’s.

My buddy’s double triangulated 4 link works great. I have an old file of his 4 link and he’s about 75-80% anti squat. My brackets can allow me to be as low as 50% and up over 100%. I’ll probably mimic his 75-80%.

His roll axis is about 2*. I’m at 4.5* that doesn’t help in stability but I’ll argue my coilovers should be mounted farther out then my leafs/shocks currently and I can sway bar that. I run no sway bar off-road right now.

So that’s my plan. Tell me I’m an idiot…or not.:flipoff2:
 
There is absolutely no reason to go that large on the track bar. It only sees push and pull forces.

If you want to spend extra money on ends, go with rebuildable instead of huge 1 1/4" heims.
 
I'm also curious on the direct swap from a 4l80e( I believe? ) to 6l80e. Im.a big fan of the 6 speeds on paper, but don't have any real personal experience.

A lot of people don't realize how different a 2.3:1 to 4:1 1st gear makes, almost makes a crawl box unnecessary.
 
CDA 455 II said:
What kind of final drive ratio are you getting with your tranny/T-case set up?
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110:1 which is overkill for an auto.
YotaAtieToo said:
I'm also curious on the direct swap from a 4l80e( I believe? ) to 6l80e. Im.a big fan of the 6 speeds on paper, but don't have any real personal experience.

A lot of people don't realize how different a 2.3:1 to 4:1 1st gear makes, almost makes a crawl box unnecessary.
Click to expand...
I am super excited to report how it does. I don’t think the difference will be in the rocks but it will be a huge difference on the freeway, in the sand and snow. Way smaller rpm drops.

I agree, I doubt I’ll use first in double low much. Probably 2nd double low.
 
Have you asked your tuner about high idle? Doesn’t the AC compressor command a high idle somehow, could you tap into that?

It’s definitely a thing on the diesels, I can’t imagine why it would be much different on the gassers.
 
Yeah, I asked him. I still have AC though so I don’t think it will work
 
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