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#1 |
Registered User
Join Date: Jan 2017
Location: Larkspur, Colorado
Posts: 916
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69 C20 drums to discs from 74 C30-Is this doable?
I have a free ‘74 C30 donor that is a factory dual wheel truck. Can I purchase single wheel rotors and run everything else to put under my 69C 20? Is it best just to swap the entire crossmember with all the suspension components at the same time?
Steve weim55 Colorado |
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#2 |
Old member
Join Date: Jan 2002
Location: Liberty, & Garden City S.C. , U.S.
Posts: 19,936
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I'm having a whole 86 3500 put under my C-20 with disc brakes. The guy I hope will be done soon with it. I'm having him do the whole thing.
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1971 LWB Custom, 6.0LS & 4L80E, Speedhut.com GPS speedometer & gauges with A/C. 20" Boss 338's Grey wheels 4 wheel disc brakes. My Driver Seeing the USA in a 71 ![]() Upstate SC GM Truck Club 2013,14 and 2016 Hot Rod Pour Tour http://upstategmtrucks.com/ Get out and drive the truck this summer and have some fun! It sucks not being able to hear! LWB trucks rule, if you don't think so measure your SWB! After talking to tech support at Air Lift I have found out that the kit I need is 60811. Per the measurements I gave them. Ride height of truck inside spring and inside diameter of springs. |
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#3 |
Registered User
Join Date: Dec 1999
Location: Austin, TX, USA
Posts: 7,717
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Re: 69 C20 drums to discs from 74 C30-Is this doable?
Anything can be done. But MUCH easier to convert your C20 to C20 discs from a later truck rather than going C30. And parts should be cheaper.
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44 Willys MB 52 M38A1 64 Corvette Coupe 68 Camaro 'vert LT1 & TH700 69 Z/28 355 12.6's @110 69 Chevy Short Step 4 1/2"/7" drop 72 Jimmy 4WD 4spd 4" & 35's 02 GMC 2500HD 4x4 Duramax |
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#4 |
Registered User
Join Date: Jun 2011
Location: Central OR
Posts: 702
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Re: 69 C20 drums to discs from 74 C30-Is this doable?
I am not sure if the cross member will bolt up.
Will the spindles bolt up is a better question and can you run C20 hubs and rotors on C30 spindles. Bearing and ball joint part numbers will tell you. You may need to swap steering parts as well. Open up 3 rock auto pages and compare part numbers. I am going to try 80s spindles on my 71 because the rotors are NLA. I have the whole cross member dust cap to dust cap to play with.
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1955 GMC 250 8 Flatbed 1971 C30 157" 350 4spd 10' Flatbed 81 GMC K30 CnC 9' Flatbed 454 T400 89 GMC Jimmy Stock https://67-72chevytrucks.com/vboard/...d.php?t=810958 71 LT1 Convertible, 72 Coupe 69 CJ5, 75 CJ6, 67 M715, 72 M35A2 Bobbed, 95 XLC2 |
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#5 |
Registered User
Join Date: Apr 2010
Location: So Cal
Posts: 1,437
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Re: 69 C20 drums to discs from 74 C30-Is this doable?
I missed the DRW in the first post and assumed he is talking about a C30 SRW (single rear wheel).
I used a '76 C30 SRW as a donor for my '67 C20 (GMC 2500 actually). I disassembled both and selected individual parts. The C30 had a bigger sway bar. The C30 big block springs were too big for my C20 6cyl. I used all the brake lines, locating the combination valve under the radiator. Where the brake lines go through the frame, there is already a hole, but needs enlarged. The bolt holes for the crossmember to the frame are mostly the same. One hole on each side needs drilled and one hole needs slightly elongated.
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'67 GMC 2500, 292, 4spd, AC |
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#6 |
Registered User
Join Date: Jan 2017
Location: Larkspur, Colorado
Posts: 916
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Re: 69 C20 drums to discs from 74 C30-Is this doable?
Two specific things that I’m concerned about :
Is the spindle and caliper mount For DRW and SRW the same? Is The track width too wide for the 69 vs ‘74? In a perfect world I would like to swap out the entire front crossmember Complete with all of the suspension and brake components using the original C 20 springs in place of the much heavier C 30 springs. Steve weim55 Colorado |
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#7 | |
Registered User
Join Date: Apr 2001
Location: DALLAS,TX
Posts: 21,964
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Re: 69 C20 drums to discs from 74 C30-Is this doable?
Quote:
On Square body C30/1-tons, there are 2 different types of calipers depending on the SRW/DRW options so that's a difference that needs to be considered when mixing parts. The track width will increase going from drum to discs. Track width up front from a '69 to a '74 is minimal per side (.5-.75" greater).
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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. |
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#8 |
Registered User
Join Date: Jan 2017
Location: Larkspur, Colorado
Posts: 916
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Re: 69 C20 drums to discs from 74 C30-Is this doable?
Thanks for the information guys, exactly what I was seeking .
Steve weim55 Colorado |
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#9 | |
Registered User
Join Date: Jan 2017
Location: Larkspur, Colorado
Posts: 916
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Re: 69 C20 drums to discs from 74 C30-Is this doable?
Quote:
Assuming you used all of the suspension components from the C 30, Was there any change to the overall track width from the old suspension on the 67? Steve weim55 Colorado |
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#10 | |
Senior Member
![]() Join Date: Nov 2018
Location: Waterford California
Posts: 2,517
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Re: 69 C20 drums to discs from 74 C30-Is this doable?
Quote:
http://67-72chevytrucks.com/vboard/s...d.php?t=444823 |
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