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Old 05-10-2015, 05:34 AM   #1
bloodybigblock
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C20 8lug to C10 5lug!

1st off I'm not doing a crossmember swap. Can I pull the control arms,spindles, etc from my parts truck c10 and put them on my C20? I've also read the tie rod ends are diff lengths?? I'd guess I'd just need new brake lines since old ones will be old as dirt. I'm sure the rear axles just swap around easy. Thanks for any help. Really don't wanna pull two motors to swap crossmembers!
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Old 05-10-2015, 05:22 PM   #2
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Re: C20 8lug to C10 5lug!

I'm in the middle of doing that with mine. You don't have to change the crossmembers. Arms, spindles, rotors, and tie rods. The calipers are the same as long as you stick with the 1.25'' rotors.
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Old 05-10-2015, 07:59 PM   #3
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Re: C20 8lug to C10 5lug!

I believe the upper arms are different. The heavier truck has bigger studs sticking out of the side of the frame where the shims go. You may can just use the heavy arm with the 1/2 ton balljoint, but I have no firsthand experience swapping them.


Just a thought: You might be able to press the A-arm studs out and swap them.
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Old 05-10-2015, 08:15 PM   #4
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Re: C20 8lug to C10 5lug!

Quote:
Originally Posted by bdiamond View Post
I believe the upper arms are different. The heavier truck has bigger studs sticking out of the side of the frame where the shims go. You may can just use the heavy arm with the 1/2 ton balljoint, but I have no firsthand experience swapping them.


Just a thought: You might be able to press the A-arm studs out and swap them.
Correct.

The upper studs are larger so the shafts are different.
The C20 upper arms have the HD type bushings which are different vs C10's after 72.
1/2 ton BJ's will swap right over to the C20 arms.
Lower arms are different (larger OD ball joint) & again the HD bushings.
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Old 05-10-2015, 09:17 PM   #5
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Re: C20 8lug to C10 5lug!

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Originally Posted by tinydb84 View Post
I'm in the middle of doing that with mine. You don't have to change the crossmembers. Arms, spindles, rotors, and tie rods. The calipers are the same as long as you stick with the 1.25'' rotors.
Quote:
Originally Posted by SCOTI View Post
The upper studs are larger so the shafts are different.
The C20 upper arms have the HD type bushings which are different vs C10's after 72.
1/2 ton BJ's will swap right over to the C20 arms.
Lower arms are different (larger OD ball joint) & again the HD bushings.
I have read almost every thread that talks about this but, invariably, there are conflicting, or at best confusing, comments and none of them actually give a detailed account of what works, what has to be modified and how, what has to be purchased, or what will never work.

I do not mean to come across as critical, but for those of us looking at this kind of project, which posts up regularly because we can only find a clean C20 in our area, sometimes we come away more confused than when we started. Far too many threads have been started about this and died an ugly death without any clear and concise documented process as to how to go about it successfully or a clear refutation of its feasibility in the first place.

If the 1/2 ton ball joints swap right over to the C20 arms, but the lower arms are different with larger OD ball joints, and the C20 upper arms have the HD type bushings which are different vs C10's after 72... how then do the "1/2 ton ball joints swap right over?"

For the larger upper studs, can they be pressed out or can the shaft holes be enlarged... assuming there is enough material to do so safely?

Since the C20 upper arms have the HD type bushings which are different vs C10's after 72, does that mean the holes for the bushings are a different diameter, which means you can't use the upper arms and their specific shafts, or can they be modified and how?

I hope people can see how confused we become. It leaves you with the idea that the only way to accomplish this is to swap cross members and keep all the C10 components intact because they will never interchange with C20. I have even been told that the C20 frame has a taller cross-section and thicker material. If that is true, then how does that affect the fitment and geometry with a C10 cross member swap?

What is needed is someone who has done this successfully and in a safe manner. Lacking that, we need something with more clarity and details or someone with the trade knowledge to say it can not be done.

I for one can accept the finality that it can't be done. I just want to know that from an authority on the subject. I have a full C10 front frame clip and all the parts sand blasted and ready for powder coating, as well as the mating 12 Bolt 3rd member. If I can use components, fine; what and how? If I have to swap the cross member fine; will there be any fitment issues? If I have to graft on the frame clip, fine.

I know there is a C10 2.5" drop spindle conversion kit from Early Classic Enterprises that will use all the other C20 parts for those that can afford the $349 ( http://www.earlyclassic.com/catalog....ry=Drop%20Kits ). Barring any valid, documented example of using C10 parts, this may be the right choice for many of us and we can sell our C10 parts. (besides, we would have the benefit of a much more robust front suspension than a stock C10)

I apologize in advance if my frustration shows. I am by no means ignorant around vehicles and neither am I an expert. I am smart enough to recognize confusion and would like to get past that part and become educated.

If ever there was a need for a good sticky, this would be one. I challenge anyone with the expertise to document said swap and post it here. We will petition for a sticky and definitively answer this recurring question once and for all!!
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Last edited by Super_Dave; 05-10-2015 at 09:26 PM.
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Old 05-10-2015, 11:30 PM   #6
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Re: C20 8lug to C10 5lug!

We reamed some 1\2t spindles out to 1t ball joint diameter, and also the brakes hoses won't bolt to the 1\2t calipers.


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Old 05-10-2015, 11:42 PM   #7
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Re: C20 8lug to C10 5lug!

If the 1/2 ton ball joints swap right over to the C20 arms, but the lower arms are different with larger OD ball joints, and the C20 upper arms have the HD type bushings which are different vs C10's after 72... how then do the "1/2 ton ball joints swap right over?"



I was referring to bolting the 1/2 ton BJ into the existing 3/4 ton upper arm. I believe SCOTI was too. The entire 1/2 ton lower can be used in place of the 3/4 ton unit.
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Old 05-10-2015, 11:48 PM   #8
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Re: C20 8lug to C10 5lug!

The C10 upper arms bolted up to my C20 just fine. I had an issue with the bushings hitting the crossmember but a flap disc took care of that in a second.

The lower arms bolted right up as well
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Old 05-11-2015, 12:15 AM   #9
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Re: C20 8lug to C10 5lug!

Is a 3/4the use 1/2" upper bolts? The 1t we swapped used 9/16 studs.
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Old 05-11-2015, 12:17 AM   #10
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Re: C20 8lug to C10 5lug!

My bolts are 9/16". The c10 arms fit no problem.
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Old 05-11-2015, 12:23 AM   #11
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Re: C20 8lug to C10 5lug!

Nice.
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Old 05-11-2015, 01:10 AM   #12
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Re: C20 8lug to C10 5lug!

Quote:
Originally Posted by tinydb84 View Post
The C10 upper arms bolted up to my C20 just fine. I had an issue with the bushings hitting the crossmember but a flap disc took care of that in a second. The lower arms bolted right up as well.
tinydb84...

Just so I understand correctly... from a C10, you are using both the upper and lower control arms, cross shafts (or did you keep the C20's), ball joints, spindles, calipers for a 1.25" rotor and tie rods? What else are you swapping over?
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Old 05-11-2015, 01:17 AM   #13
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Re: C20 8lug to C10 5lug!

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Originally Posted by Super_Dave View Post
tinydb84...

Just so I understand correctly... from a C10, you are using both the upper and lower control arms, cross shafts (or did you keep the C20's), ball joints, spindles, calipers for a 1.25" rotor and tie rods? What else are you swapping over?
I am using C10: UCA, LCA, cross shafts, Ball joints, Spindles (1.25''), and tie rods.
I am using C20: Calipers, Center link, and steering box.

That's all I can think of as of now. I am still in the process of reassembling though. The only thing I haven't checked the fit on is the C10 inner tie rods to the C20 center link.
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Old 05-11-2015, 01:31 AM   #14
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Re: C20 8lug to C10 5lug!

We just changed the outer ends. Don't know about the inners
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Old 05-11-2015, 03:42 AM   #15
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Re: C20 8lug to C10 5lug!

Quote:
Originally Posted by tinydb84 View Post
I am using C10: UCA, LCA, cross shafts, Ball joints, Spindles (1.25''), and tie rods.
I am using C20: Calipers, Center link, and steering box.

That's all I can think of as of now. I am still in the process of reassembling though. The only thing I haven't checked the fit on is the C10 inner tie rods to the C20 center link.
tinydb84

Thanks, that's good info. Nice, concise and documented. Once it's complete and operating as expected, you have the platform for a "how-to" for those of us that will be following in your footsteps.

Take photos, document any issues, large or small, any insights that makes it easier or better, all parts from both C10 and C20, and we just might have the makings of a good sticky, as far as I am concerned and I don't think I am alone on that.

I will be following this intently, as I have all the parts either in hand or on my C20, but I am a ways behind you guys.

Again, thanks!
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Old 05-11-2015, 10:03 AM   #16
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Re: C20 8lug to C10 5lug!

I went through something similar 20+ years ago with my 69 C10 that I converted from 6-lug drum brakes to 5-lug disc brakes using 72, 73 and 86 components from the junkyard. Using all 71-72 parts would have been easier, but I couldn't find any used 71-72 calipers. As I recall, I paid around $25 for a pair of 86 calipers.

One of my most valuable resources was a Moog catalog with the various steering and suspension P/Ns. Who would have guessed a 71-72 C20 center link (which I got for free) is the same as a 73-87 C10 center link?

Of course, today there is probably 100x the info on the Internet and lots of sources for conversion parts (including Chinese imports of questionable quality).
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Old 09-04-2015, 05:56 PM   #17
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Re: C20 8lug to C10 5lug!

Tinydb84,

How is your reassembly project coming along? Any progress to report back on? I am being asked to "move" my 1977 C10 parts from my brothers shop, and have to decide what to keep and what to sell. Any additional information or a final recap would be great!
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Old 09-04-2015, 06:34 PM   #18
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Re: C20 8lug to C10 5lug!

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Tinydb84,

How is your reassembly project coming along? Any progress to report back on? I am being asked to "move" my 1977 C10 parts from my brothers shop, and have to decide what to keep and what to sell. Any additional information or a final recap would be great!
Havent done much with the front suspension (been working on other parts of the truck).

This is what I am using. C10 upper and lower control arms and shafts, C10 ball joints, C10 outer tie rods, C20 inner tie rods, C20 center link and steering. The spindles are 1.25'' rotor C10 and I am going to use the C20 brake calipers.

This is the only pic I have on hand. I have attached the ball joints and spindles since then.
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Old 01-04-2016, 08:22 PM   #19
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Re: C20 8lug to C10 5lug!

Tinydb84... how goes the project?

If all goes well on my end, I should be in a position this Spring to do the 8 to 5 conversion. Have you finished the suspension or hit any snags in the conversion since your last post?

Dave
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Old 01-04-2016, 08:32 PM   #20
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Re: C20 8lug to C10 5lug!

Just to add to this thread,... ECE (www.earlyclassic.com) sells a direct BOLT-ON spindle that will convert 8-lug trucks to 5-lug (or 6-lug) suspension.
No need to change anything other than the spindle, rotor, and caliper.
I have a set I bought years ago, waiting for the right 3/4-ton truck to come along.
These make the swap super easy.
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Old 01-04-2016, 11:05 PM   #21
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Re: C20 8lug to C10 5lug!

I know his truck isn't on the road yet, don't know where he is on suspension. He has a thread in the builds section, Used Parts Build I think is the name.
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Old 01-05-2016, 12:22 AM   #22
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Re: C20 8lug to C10 5lug!

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I know his truck isn't on the road yet, don't know where he is on suspension. He has a thread in the builds section, Used Parts Build I think is the name.
Yeah... just went through it and hitched onto it.
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Old 01-05-2016, 07:28 PM   #23
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Re: C20 8lug to C10 5lug!

Hey all. Yeah I do have a build thread that is kept up to date. I haven't gotten much further on the front. Been mostly focusing on the major fab stuff. I have the spindles in and center link attached now but nothing else.
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Old 01-06-2016, 01:44 AM   #24
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Re: C20 8lug to C10 5lug!

We just reamed the spindle for the ball joints.
Went 3500 to 1/2 ton stuff, used everything over. The flex brake hose different too.
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