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Discussion Starter #1
Hey guys, I’m new here to the forum. I’ve got a ‘90 K1500 that my great grandpa bought new. I’m wanting to do an overlander build on it, and I’ve been doing research about upgrades for the truck. I’m in college right now studying for Engineering Technology, and I want to have a career in the off-road industry, either for a competition company or an aftermarket company. I’ve had this idea rattling around for a while after I was researching lifts for my truck, and happened to stumble upon a video showing the design for an H1 hummer, showing the IFS with portal knuckles and the brake calipers set up on the inner side of the cv axle. I’d like to eventually redesign the front of my truck for better travel and some extra height. I thought I could either use most of the components from an H1, and just design my own parts when needed, or just use the portal knuckles off the H1, and design a new IFS to use them, with possibly redesigning the 8.5” rear end in my truck as a new center box for the IFS, center axle disconnect and all. I know it kinda seems overkill for an overlander and I still want it to run down the road fine, but I’ve always liked the builds that people do, like Bebe’s H3 build, that go against the grain so to speak. I’m not wanting to go as much as Bebe did with his, but I did find it pretty cool. Would the H1 portals be fine for highway and light to medium off-road use, or should I just try to use some heavy duty normal knuckles? And what do y’all think about the 8.5” for a new IFS center unit? I’m open to any suggestions. Sorry for the long post :)
 

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Throw your 90 K1500 body on an H1 chassis...done.
I see plenty of military H1s running down the highway. The 8.5 center should be fine, the H1 used an AMC 20 IIRC....
 

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blatant asshole
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Portals are 2:1 ish reduction. H1 diffs are 3.08 or 2.73:1 x portal ratio. So your 3.42/3.73/4.10 are going to net you about 65mph tops.

Have you ever driven an h1? Because the brakes are at the diff, the gear lash and torsion action of the shafts they constantly rock at a stop light.

The cad in an 8.5 suck. Particularly the early versions.

Building a d44hp clone of the 8.5 would be awsome. Figure out how to cost effectively design some locking hub system for the ifs knuckles would be another notch on the bitchen list. As well as some arms/ball joints that have some actual fucking travle.
 

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Discussion Starter #5
Throw your 90 K1500 body on an H1 chassis...done.
I see plenty of military H1s running down the highway. The 8.5 center should be fine, the H1 used an AMC 20 IIRC....
Though that does sound neat, that’s really a little farther than I plan on going with it. If I can, I’d like to keep my frame at least mostly intact

Portals are 2:1 ish reduction. H1 diffs are 3.08 or 2.73:1 x portal ratio. So your 3.42/3.73/4.10 are going to net you about 65mph tops.

Have you ever driven an h1? Because the brakes are at the diff, the gear lash and torsion action of the shafts they constantly rock at a stop light.

The cad in an 8.5 suck. Particularly the early versions.

Building a d44hp clone of the 8.5 would be awsome. Figure out how to cost effectively design some locking hub system for the ifs knuckles would be another notch on the bitchen list. As well as some arms/ball joints that have some actual fucking travle.
The portals will be fine, the 8.5 is trash.
Ok, I figured the portals were either about a 1.7:1 or 2:1, some where in there, so I should be able to gear up the diff to make up that difference for the most part. What I meant about the 8.5” is actually use the rear axle and not my 8.25” IFS I have in the front now, cut the tubes and shafts down (of course off centered to clear my oil pan), make new ends for bearings and seals (might be able to reuse the stock ones), new hubs to attach my cv’s to, and cut into the passenger side tube and shaft and fabricate a new heavy duty cad, so all in all it works like the stock 8.25”, but it’s a 8.5” instead. Now the 10 bolt Chevy rear axles get a bad reputation, but from what I’ve heard that’s from the 7.5” and the 8.2”, while the 8.5” and the 8.6” are actually good. Of course I don’t know if that’s true or not, and I’m open to using a different axle to make into an IFS. I’ll have to look into the D44, thanks for the suggestion.
 

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Discussion Starter #6
Oh and about the brakes on the H1. Yes I have seen that, and I thought it was neat enough that I might try to copy that for my truck. I have no idea how hard it’ll be to make sure they clear, but it shouldn’t be be that hard hopefully.
 

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The 8.5 will be geared high...so better tooth contact spread/strength...the H1 used the 9 7/8 Model 20..no?. Sounds like the pitfalls of a rear 8.5 will mostly be addressed. If concerned and space limited, possibly a 9.5 rear semi float or a fabbed HP 9". IMO a D44 is on par with the 8.5 anyway.
Why are you on love with your frame now...sounds easier to put the K1500 body onto that H1...get one with the 6.5L/4L80E and you have what you want..😆
 

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Discussion Starter #10
So overall I guess I need to look into different diff to use. It’s gonna be a while before I do this, so I have plenty of time to look. The reason I don’t want to swap my frame over is for one cost, but for another, for me the frame is a part of the vehicle. If you change out the frame, or even chop a big chunk of it off, it’s no longer really what it used to be, just like all these guys who take old trucks and swap the frames out for something newer, or cut the front off to weld a new car front end in its place. Lots of people do this to trucks like my other truck, which is a ‘59 Chevy. You see em all the time swapping frames for those custom ones or cutting the front end off to swap the old beam front axle for a Camaro front end. I’m of the sort “If you want it to drive like something else, go buy what you want it to drive like and sell yours to someone who likes it how it is.” Now yes I will be modifying my frame on the K1500, but hopefully all I’ll have to do is replace the mounting for the control arms and the center box, plus add some for some better shocks
 

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blatant asshole
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Got any other lies you want to tell yourself or the class?

Those parts get cut off because they suck.

Sell you truck and buy a 2500.
 

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The reason I don’t want to swap my frame over
Your not swapping the frame over, you're swapping the body over to the frame. But really to do it correctly, you'll first slice the body in half front to back, and then add sheet metal to essentially widen the body to match the Humvee width. As an overlanding vehicle that's a win because it gives you more interior space. Sounding pretty cool isn't it?
 

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Discussion Starter #13
Yes, I agree, putting a GMT400 body on a H1 frame and widening it to fit does sound cool, but I don’t want to be the one to do it. I literally just want to lift my truck 4-6” without dropping the front diff by changing the suspension/ driveline components, and I thought using the H1 knuckles would be a cool way of doing that.
 

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Rolling Mod
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Yes, I agree, putting a GMT400 body on a H1 frame and widening it to fit does sound cool, but I don’t want to be the one to do it. I literally just want to lift my truck 4-6” without dropping the front diff by changing the suspension/ driveline components, and I thought using the H1 knuckles would be a cool way of doing that.
😆 good luck
 

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For what you're talking about, just using the 9.25" gm front would be fine, no need to make it any harder. Check out Jesse Haines solid axle portal stuff mostly on FB, he has wheel brakes on them that would be more streetable than the inboards. His stuff may not be exactly what you need but maybe a close variation. H1 boxes are also set up around a H1 wheel with a ton of backspace so to have matching wheels you'll have to have a really wide rear axle which may not be on your radar yet.
 

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For what you're talking about, just using the 9.25" gm front would be fine, no need to make it any harder.
Was going to suggest that route as well. The 9.25" IFS diff is at least strong enough in stock form to run lockers in (unlike it's smaller/weaker 8.25" brother). It still will be some fab to fit as the 1500 frame clearances are not as generous as it's sibling the 2500 8lug/3500. But either way he's looking at some involved fab work. I would suggest running portals at the rear as well, it'll keep ratios in check (easier to match), and be bad ass. Beginning to sound easier to SAS with a D60 front and 14FF/Sterling rear with portals. Been done before and was a Ford F250/350(?) UA project not long ago if I recall, the project was in Petersens.

Edit, keep in mind the 1.92 H1 portal ratio combined with the highest 3.42 ratio for the 9.25 gives you a final of 6.57. As far as strength concerns, the H1 used essentially the "AMC 20" internals in an aluminum case diff did it not?
 
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