C-10 v. C-20 frame - The 1947 - Present Chevrolet & GMC Truck Message Board Network

panhandler62 · 04-05-2010, 08:15 AM

Is there a difference in the shapes in the C-20 and C-10 frame in the rear axle area?

I bought bolt in c-notches a few months back (I really don't remember if I specified that I have a c-20 or not) and finaly got to working on that part of the restoration this weekend.

The things really don't fit well. I expected them to flush up to the outside of the frame (once the notch area was removed, of course) and they really didn't. There are some gaps and the bottom plate hangs outside the frame by about 1/2 an inch at the front. They are close enough that wanging on the one I have installed with a BFH got it mostly matched up but not close enough to make bolting it make sense. I welded it on where it does hit the frame and I'll be doing some trimming and making gussets and reinforcements to finish. With the peice not fitting flush; I didn't want to just bolt it up, leaving gaps for rust to sneak into between the peices.

Not a show-stopper in the end, just kind of wondering is "sort of" fits is normal here, if I bought c-10 parts when I should have bought c-20 parts or if I just got a set that wasn't quite right?

panhandler62 · 04-06-2010, 08:25 AM

Some veiws, no comments -- Either I made no sense or I posted such an "out there" issue that no one knew what to say! lol

Given the amount of rusted material I had to remove I'm thinking it would be a good idea to box in this section of the frame.

**N2TRUX** · 04-06-2010, 09:44 AM

Keith I am no 67-72 expert. but I can tell you this seems to be a common problem. I don't think it matters if it's C-10 or C-20, there was just a lot of variance in the rear frames. I'll take a guess and say it may have had something to do with the plant they were manufactured at, but that just a guess.

panhandler62 · 04-06-2010, 09:51 AM

At least my welding is improving as I work on it... lol

SCOTI · 04-06-2010, 12:53 PM

The main difference would be leaf frame vs. coil frame. The C20 3/4 ton coil frames should be shaped the same as C10 1/2 ton coil frames so that c-notch should fit w/minor tweaking.

I wonder if these bolt-in notches fit a lot worse vs. when I did mine back in 2000? Seems several have had similar complaints recently.

panhandler62 · 04-06-2010, 01:30 PM

I got them to work, with the help of a BFH and some gusseting, but I really had expected them to flush right up. If I had known that I would end up fabbing (my fancy word for the hack I'm doing! lol) them in I would have bouht the weld on plates to begin with. lol

Oh well.. it's just time, bulk plate and burned fingers. I'm just all tickled to have the rust gone!

04-05-2010, 08:15 AM	#1
panhandler62 Java Mechanic Join Date: Jun 2005 Location: Martinsburg, WV Posts: 6,764	C-10 v. C-20 frame Is there a difference in the shapes in the C-20 and C-10 frame in the rear axle area? I bought bolt in c-notches a few months back (I really don't remember if I specified that I have a c-20 or not) and finaly got to working on that part of the restoration this weekend. The things really don't fit well. I expected them to flush up to the outside of the frame (once the notch area was removed, of course) and they really didn't. There are some gaps and the bottom plate hangs outside the frame by about 1/2 an inch at the front. They are close enough that wanging on the one I have installed with a BFH got it mostly matched up but not close enough to make bolting it make sense. I welded it on where it does hit the frame and I'll be doing some trimming and making gussets and reinforcements to finish. With the peice not fitting flush; I didn't want to just bolt it up, leaving gaps for rust to sneak into between the peices. Not a show-stopper in the end, just kind of wondering is "sort of" fits is normal here, if I bought c-10 parts when I should have bought c-20 parts or if I just got a set that wasn't quite right? __________________ Keith 11 Lincoln MKT -- Momma's wagon 13 G37xS -- middle age crazy car 68 C20 Fleetside -- RIP Decorating the whole town up at a cost of $27 .... Last edited by panhandler62; 04-05-2010 at 08:16 AM.

04-06-2010, 08:25 AM	#2
panhandler62 Java Mechanic Join Date: Jun 2005 Location: Martinsburg, WV Posts: 6,764	Re: C-10 v. C-20 frame Some veiws, no comments -- Either I made no sense or I posted such an "out there" issue that no one knew what to say! lol Given the amount of rusted material I had to remove I'm thinking it would be a good idea to box in this section of the frame. __________________ Keith 11 Lincoln MKT -- Momma's wagon 13 G37xS -- middle age crazy car 68 C20 Fleetside -- RIP Decorating the whole town up at a cost of $27 ....

04-06-2010, 09:44 AM	#3
N2TRUX Happy to be here Join Date: Mar 2000 Location: Cypress, TX Posts: 39,023	Re: C-10 v. C-20 frame Keith I am no 67-72 expert. but I can tell you this seems to be a common problem. I don't think it matters if it's C-10 or C-20, there was just a lot of variance in the rear frames. I'll take a guess and say it may have had something to do with the plant they were manufactured at, but that just a guess. __________________ Follow me on Facebook and Instagram @N2trux.com Articles- "Jake" the 84 to 74 crewcab "Elwood" the77_Remix 85 GMC Sierra "Scarlett" "Refining Sierra"

04-06-2010, 09:51 AM	#4
panhandler62 Java Mechanic Join Date: Jun 2005 Location: Martinsburg, WV Posts: 6,764	Re: C-10 v. C-20 frame At least my welding is improving as I work on it... lol __________________ Keith 11 Lincoln MKT -- Momma's wagon 13 G37xS -- middle age crazy car 68 C20 Fleetside -- RIP Decorating the whole town up at a cost of $27 ....

04-06-2010, 12:53 PM	#5
SCOTI Registered User Join Date: Apr 2001 Location: DALLAS,TX Posts: 21,963	Re: C-10 v. C-20 frame The main difference would be leaf frame vs. coil frame. The C20 3/4 ton coil frames should be shaped the same as C10 1/2 ton coil frames so that c-notch should fit w/minor tweaking. I wonder if these bolt-in notches fit a lot worse vs. when I did mine back in 2000? Seems several have had similar complaints recently. __________________ 67SWB-B.B.RetroRod 64SWB-Recycle 89CCDually-Driver/Tow Truck 99CCSWB Driver All Fleetsides @rattlecankustoms in IG Building a small, high rpm engine with the perfect bore, stroke and rod ratio is very impressive. It's like a highly skilled Morrocan sword fighter with a Damascus Steel Scimitar..... *Cubic inches is like Indiana Jones with a cheap pistol.*

04-06-2010, 01:30 PM	#6
panhandler62 Java Mechanic Join Date: Jun 2005 Location: Martinsburg, WV Posts: 6,764	Re: C-10 v. C-20 frame I got them to work, with the help of a BFH and some gusseting, but I really had expected them to flush right up. If I had known that I would end up fabbing (my fancy word for the hack I'm doing! lol) them in I would have bouht the weld on plates to begin with. lol Oh well.. it's just time, bulk plate and burned fingers. I'm just all tickled to have the rust gone! __________________ Keith 11 Lincoln MKT -- Momma's wagon 13 G37xS -- middle age crazy car 68 C20 Fleetside -- RIP Decorating the whole town up at a cost of $27 ....



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