Home » Public Forums » GMCnet » Make a one-ton knuckle with the same mounting points as OEM
| Make a one-ton knuckle with the same mounting points as OEM [message #369412] |
Fri, 08 April 2022 06:17  |
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RF_Burns
Messages: 2276
Registered: June 2008
Location: S. Ontario, Canada
Karma: 3
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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
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| Re: Make a one-ton knuckle with the same mounting points as OEM [message #369413 is a reply to message #369412] |
Fri, 08 April 2022 07:54  |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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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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| [GMCnet] Re: Make a one-ton knuckle with the same mounting points as OEM [message #369421 is a reply to message #369413] |
Fri, 08 April 2022 21:58 |
Keith V
Messages: 2337
Registered: March 2008
Location: Mounds View,MN
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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
Sent: Friday, April 8, 2022 5:54:11 AM
To: 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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Keith Vasilakes
Mounds View. MN
75 ex Royale GMC
ask me about MicroLevel
Cell, 763-732-3419
My427v8@hotmail.com
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| [GMCnet] Re: Make a one-ton knuckle with the same mounting points as OEM [message #369422 is a reply to message #369421] |
Sat, 09 April 2022 00:23 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
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Dave Lenzi did one that is easier for most to do.
We have reservation of making the mod as it involves a part that is rather
touchy to modify without some reliability if not done really well.
On Fri, Apr 8, 2022 at 7:58 PM Keith V wrote:
> 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
> Sent: Friday, April 8, 2022 5:54:11 AM
> To: 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
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>
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Jim Kanomata ASE
Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.gmcrvparts.com
1-800-752-7502
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Jim Kanomata
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| Re: Make a one-ton knuckle with the same mounting points as OEM [message #369424 is a reply to message #369412] |
Sat, 09 April 2022 10:28 |
lqqkatjon
Messages: 2324
Registered: October 2010
Location: St. Cloud, MN
Karma: 5
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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/
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| Re: Make a one-ton knuckle with the same mounting points as OEM [message #369427 is a reply to message #369413] |
Sat, 09 April 2022 14:18 |
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Richard RV
Messages: 631
Registered: July 2012
Location: Full-timer for 12 years, ...
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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 Edgemont waiting its turn
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| Re: Make a one-ton knuckle with the same mounting points as OEM [message #369429 is a reply to message #369412] |
Sat, 09 April 2022 14:41 |
6cuda6
Messages: 975
Registered: June 2019
Karma: -6
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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
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| [GMCnet] Re: Make a one-ton knuckle with the same mounting points as OEM [message #369435 is a reply to message #369427] |
Sat, 09 April 2022 17:54 |
richshoop
Messages: 190
Registered: April 2017
Karma: 0
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Before you start something like this, a couple of things to keep in mind.
(1) You have to identify what kind of steel you are dealing with, both the coach frame material and the 'clip' parts. It is most unlikely to be just plain carbon steel.
(2) The weld joint design, yes I mean design, has to be done to minimize the local stresses. Take a look at how they originally did it.
(3) Preheat and post heat treatment will most likely be needed.
(4) The weldor you use beyond being certified, also has to have experience welding on truck frames.
> On 04/09/2022 12:18 PM Richard wrote:
>
>
> 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
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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| Re: Make a one-ton knuckle with the same mounting points as OEM [message #369437 is a reply to message #369412] |
Sat, 09 April 2022 19:17 |
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RF_Burns
Messages: 2276
Registered: June 2008
Location: S. Ontario, Canada
Karma: 3
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Senior Member |
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Sorry I wasn't clear, but I'm not planning nor talented enough to do this, but watching the the videos got me thinking. Could a knuckle be cast that uses the bolt-on hub, but has the mounting points of the OEM. I certainly don't think that welding them up from as those guys did would be viable for anyone except the talented people "because they can".
Then I found A Hamilto posted some drawings of a hybrid between the OEM and One-ton knuckle, so he had contemplated this long ago. Sorry, I don't know who A Hamilto is or whether he ever did any further work on this idea.
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
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| Re: [GMCnet] Re: Make a one-ton knuckle with the same mounting points as OEM [message #369467 is a reply to message #369435] |
Tue, 12 April 2022 19:50 |
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Richard RV
Messages: 631
Registered: July 2012
Location: Full-timer for 12 years, ...
Karma: -17
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Senior Member |
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Rich,
Certified was a poor word choice, I should have said qualified and vetted. An experienced welder has almost certainly worked on a truck, but point taken - experienced. The steel used in a 1970s GM chassis wasn't breaking new ground in metallurgy, but again, point taken. The general classification of steel can be identified by its spark pattern, which is also something any experienced welder would do if there was a question. https://en.m.wikipedia.org/wiki/Spark_testing
Judging from the quality of welding, or lack thereof, on the GMC front clip I tend to doubt any sort of heat treating was performed. The splatter and hanging welding wire remnants point to speed being the objective. Today's truck frames are a far cry from the bell-bottom days of the GMC.
Bruce,
Yours was the first one ton I saw on a GMC, and I'm in agreement - the change in camber due to the non-parallel control arms is not objectionable or noticeable to me. My coach drives and handles with ease...unless there's a steep curving incline! The custom hybrid knuckle is an interesting idea and has its benefits. After the improvements of the one ton's hub and brakes, the kludgey GMC control arms are still there. The GMC lower control arm and ball joint are particularly problematic. To me it's clear that grafting on a complete one ton front end is by far the superior way to go. Yes it will cost more, but you'll be doing it only once and _all_ of the parts will be available for decades. I've seen too many quality control issues with limited production parts, things that aren't readily apparent. Grafting on a complete OEM replacement front end would address most issues, the only questions are accurate measuring, jigging and welder competence. Well that and dollars.
Richard
'77 Birchaven TZE...777;
'76 Palm Beach under construction;
‘76 Edgemont waiting its turn
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