One of the issues with the one-ton conversion is the one-ton knuckle's upper ball joint mount is 2" higher than the OEM knuckle.  This causes a camber
change with front end up/down motion.  Some find this disconcerting, but since I don't drive my coach like a rally car I don't notice it or at least
it doesn't bother me.

For those purists, here are a couple of YouTube videos of guys making their own knuckles so they can design them any way they want.  The first guy has
his pieces cut out by an on-line lazer cutting company.  His channel called SuperfastMatt is pretty good. He uses a lot of scanning/3D technology to
put a Tesla drive train into a 1950 Jaguar.

https://www.youtube.com/watch?v=dtH9C0yxo2I

This second guy is more back-yard mechanic type.  I haven't followed him, so I don't know how he came up with the downloadable files to make his.  I'm
sure he shows how in his earlier videos.

https://www.youtube.com/watch?v=YhbFEoPSf20

I'm not doing this, but just thought it was interesting how they did it.  By scanning the OEM and One-ton knuckles, one could come up with a hybrid
knuckle.  Getting it cast and milled would likely be very expensive for one-off copies.  I'm not sure at what quantity it would become economical.

--
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that

Richard RV told me of someone that made location jigs from a 1 ton 4 x4 truck, and moved the entire front suspension with control arms and mounting
perches. Truly keeping geometry OEM. Said it was magnificent work but the jigs were disposed after the project was built.  He can tell us more.

John Lebetski
Woodstock, IL
77 Eleganza II

I heard that as well.  I think there was some postings here, or on the photo site about it.

Having the knuckle redone with the mounting points to match the OEM knuckle and with correct taper holes would make the kit easier to install and
should correct the geometry complaints.  I heard Manny had some new one-ton knuckles cast because of a shortage of good  junkyard ones, but he did not
make any changes to the castings.

--
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that

Was that a guy named Roundtree?
I can see that fixing the camber gain, but
I wonder how he fixed the toe steer issue

From: John R.Lebetski gransport7087@gmail.com
Sent: Friday, April 8, 2022 5:54:11 AM
To: gmclist@list.gmcnet.org gmclist@list.gmcnet.org
Subject: [GMCnet] Re: Make a one-ton knuckle with the same mounting points as OEM

Richard RV told me of someone that made location jigs from a 1 ton 4 x4 truck, and moved the entire front suspension with control arms and mounting
perches. Truly keeping geometry OEM. Said it was magnificent work but the jigs were disposed after the project was built.  He can tell us more.

John Lebetski
Woodstock, IL
77 Eleganza II

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Found this on the GMC photosite.  Drawings of the OEM, One-ton and "Hybrid" knuckles.  The hybrid knuckle is what I am talking about.

Credit to A Hamilto for his drawing.

http://www.gmcmhphotos.com/photos/other/p58537-hybrid-knuckle.html

--
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that

Bolt on kits is one thing.  Relying on someone/others welding something on their frame is a whole other set of problems.

The only 1 l-ton I have been around was one that had welded on frame mounts for the control arms and I think supposedly had correct geometry.    For
some reason that coach seen some cv joint failures.

I just know it seems oem if done right(lenzi). Lasts forever.

Jon Roche
75 palm beach
EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
St. Cloud, MN
http://lqqkatjon.blogspot.com/

You summed it up better than I could, John.  Here's what I know so far:

A 1 ton donor vehicle ~10K# GVWR was sacrificed.  An expandable jig consisting of nesting square steel tubes was placed under the donor vehicle.
Locating arms/supports were attached to all of the components to be transferred over.  This included... well, everything.  Upper and lower control
arms and mounts, knuckles and hubs, shocks and mounts, front sway bar, linkage and mounts, etc.  The front end attachment points were then cut free
with a cutoff wheel to provide a clean edge and minimal heat distortion.

All front end components were removed from the GMC, the jig with the 1 ton front end was moved under the GMC, and the jig was expanded to match the
GMC front clip width.  The GMC's mounting points were cut off with a cutoff wheel to be either grafted onto or entirely replaced by the 1 ton mounts.
The 1 ton mounted jig was positioned and everything was welded into place.

The owner told me that after the installation was completed that he didn't have to touch the alignment.  He's a smart enough guy to realize that was
as much luck as anything as no one knows what the alignment situation is with a donor vehicle.  Point being, he got lucky with the donor vehicle
alignment being correct and he was precise in his surgery and reconstruction.

I've heard the argument about the issue with welding versus bolt-on solutions, often with the arguments concluding that welding is a much bigger
variable and therefore unworkable.  The kid working on your grandkid's school bus brakes is probably earning minimum wage.  There are plenty of
certified welders out there - hire one.  They won't be the cheapest, but they'll do it right and the next several owners of your GMC will be raising
glasses to your wisdom, so pop for the extra, what?, $300...?

I visited (read Blacklist) Jim Rountree and he showed me the GMC he was working on...at 88!  He'd taken the whole front clip from a 1 ton and grafted
it onto the GMC.  I couldn't spare the time to pay it the attention it deserved as it was Christmas Eve and I needed to be repaired and on the road.
I sorely regret not having seen more of his fabrication skills in detail.

I recall seeing some pictures ~10 years ago about someone who had made a 1 ton transfer/location jig.  It was outside, rusty and he'd fabricated new
extended upper control arm mounting ears, but I don't recall much more than that.

Richard

'77 Birchaven TZE...777;
'76 Palm Beach under construction;
‘76 Edgemonte waiting its turn

Honestly because the one ton uses a bolt in wheel bearing, fabricating a knuckle is not a huge deal [of course one needs to be a competent tig welder]
but there is no money in it...yes i understand for us it would be great but to create a jig and fab a few, maybe 50 sets, just doesn't cut it for what
they would cost to sell.  I think it would be easier to make upper and/or lower controls arms this way the jig could be tooled for one ton and/or
stock making it at least worth the time/effort for the money return.....just my opinion of course.

Who knows, if i get PO'd about the OEM suspension parts availability or an increase in prices i might just do it....lol.

Rich Mondor,

Brockville, ON

77 Hughes 2600