Questions about 1965 C20 front end drum to disc

[nelson-ohio]

Ok, I have been posting on a different site for a few days now, thought to post the same questions here and maybe someone have the answers.

I recently bought a 65 C10, but believe it has a C20 frame. It has rear leaf spring, and all wheels are 8 lugs.

I want to convert the front from drum to disc, but have a few questions:
- 1 see there is a kit from Performance On Line (https://www.performanceonline.com/63...-deluxe-8-lug/) suppose to be a conversion kit. However, several posts I have read on different forums all say you can not simply convert a 65 front drum to disc, you have to swap out the whole front with a later year model, like a 70 or later. So I'm a little confused on this point. Has anyone used this conversion kit on a 65 C20 or C10? The price is not cheap, but if it really works well and a perfect fit, I would consider it.

- If I do need to do a front end swap, anyone knows how well a 1983 C20 front would work with a 1965? I found someone parting out his 83 C20. I believe it will fit, just wondering if anyone has done it and how many holes you will have to drill. Would the power steering link work the same as well?

Thanks for any help

[Palf70Step]

It can be easier with the whole front cross member (you get all the tie rods and etc that go with the spindles. Since the disk brakes spindles have large tierod holes, you'll need to get an adapter to convert the out tierods of the spindles/disks to the original stuff. Some just find it easier to swap out everything.

I kept my original A-arms and swapped out spindles/brakes...etc from a 78 C10 (new ball joints for the later model spindles). I imagine if you are trying to keep the 8 lug, you can do the same with the C20 stuff. The 83 sounds like a good deal. If you get the steering box from the 83, you'll need an adapter/tweaks to hook the o-ring style power steering to the older style power steering box. If you stay with the manual, no issies that I can remember. I even kept my stock pit-man arm.

[nelson-ohio]

I plan on changing the steering to PS instead of the current manual steering. If I get a new/rebuilt steering box for the 83 C20, then the linkage will work with the new 83 front end, right? Will the 83 C20 power steering box fit the current 65 C20 steering location, or do I need to drill new holes?

Where to get this adapter for the o-ring style to old style PS box?

1 more question: other than the 83 C20 I'm looking at, I believe all 71-87 C20/2500 will work in such a swap situation, correct? Is there a particular year that's easier too swap? (less new holes to drill)

Thanks.

[padresag]

the only difference in those years is around the early 80's they went to metric thread on the p/s pump and str box.
to do with your c10-20 query check the top of the frame by where the str box mounts; there should be a ser# stamped there which should correspond with the ser# on your vin plate. gmc did not have any nbrs stamped on the frame there.
someone may have put that cab on a c20 frame. gmc did use rear springs and someone could have changed the eng. a lot of things happen to these trucks over the years .
guys trying to make a quick buck can cobble these things together pretty quick.
here are also some frame measurements which don't vary much between a c10-20, but there are differences, the biggest is thickness of the frame material.
http://67-72chevytrucks.com/vboard/s...d.php?t=550856
ron

[Captainfab]

The best way to convert your '65 to power disc brakes is to use the entire front suspension and steering, crossmember and all, from a '71-'87 C20. However to do this it is much easier without the engine in place. It can be done wioth the engine in, but it is a bit more difficult. You will have to drill 1 hole on each side and elongate 1 hole on each side. You will need an adapter plate for the steering box.....I make and sell those. I would use the entire later model steering linkage. You will just have to drill the holes for the idler arm. Otherwise you will need special tierod adapter sleeves.

With ther '63-'6 C20/30's you can not just change the control arms as can be done on the C10's. There is a member here that claims that the ball joint hole in the lower control arms on the '63-'66 C20/30's can be enlarged with a flap wheel on a die grinder, to accept the disc brake ball joints. I have not verified that.

There are several threads on this disc brake conversion that can be found in the '60-'66 FAQ section under 'Brakes'. Most everything that applies to the C10, applies to the C20/30, except for what I stated above.

[gmcdeadhead]

i did the front end , power steering , and rear end conversion on my 66 c-20. i bought a 87 chevy 1 ton , single rear axle truck chassis from a guy who parted everything else out. i only paid 600 for the whole chassis. i bought all the adapter brackets from captain fab. the hole thing went rather smooth. i say that's the only way to go instead of buying those expensive conversion kits.

[nelson-ohio]

Thanks for the help. I have located a 1984 C20 front end, he will cut it off from the cab and I can have the whole thing for $150. I will rebuilt it while it's off and install it. My truck is just cab on frame right now, so it should be easy to work on.

I have also done more searching and found other member's posting about how they did it. Thanks for all the great info people contributed in the past.

Captain Fab, I will be in touch with you shortly.

[Captainfab]

Having everything from the cab forward will be great for a disc and power steering conversion. If the rear differential under that '84 C20 is available, I would suggest considering changing your differential for that one, unless your truck currently has a Dana 60.

[nelson-ohio]

I will check on the rear as well.

There is 1 thing I would like to confirm still. My title for the truck is for a C10, the serial number on the title and cab is C1445Nxxxxxx, but it has lead spring rear, and 8 lug wheels. So either someone changed the wheels/suspension/frame or some combination of these. Or this should be a C10, not C20.

There is no VIN on the frame. The front suspension does not appear to have any bushing in the shaft of the upper control arm, each end of the shaft as a zerk fitting as well. Not sure if that's unique to the C20 frame.

I have attached some pictures.

I also tried to take some measurement of the frame and compare to the measurement in 1 thread which says "½ ton 2WD: 6-1/32 x 2-1/2 x 5/32", but the frame has several different section with different height and width. Is there a specific place I need to measure?

Probably a good idea to confirm which frame I have before buying anything.

[nelson-ohio]

Delete

[Captainfab]

If the frame does not have the VIN stamped into the top flange just forward of the engine mount on the drivers side, it has either been removed, or it is a GMC frame. The GMC's didn't have the VIN's stamped into them. Also most '63-'72 GMC's had rear leaf springs. Is the frame a long wheel base or short? I see that your truck has some sort of non-original engine mounts.

[nelson-ohio]

IT's a LWB.

The PPO put a BBC in, so the engine mount was replaced. The PO whom I bought it from had it for 8 years, slowly working on it, but got tired of doing it.

So it is possible that it's a C10 frame even with the 8 lug wheels all the way around?

[nelson-ohio]

I just spoke to the PO, he said he is sure the frame is the original and should be a C10, but the PPO changed the suspension to a C20 setup so it sits higher.

Is it possible to install a 1965/66 C20 front on a C10 frame without drilling any holes or modifications?

[Palf70Step]

pretty sure they use the same holes

[Captainfab]

Yes

Originally Posted by nelson-ohio

I just spoke to the PO, he said he is sure the frame is the original and should be a C10, but the PPO changed the suspension to a C20 setup so it sits higher.

Is it possible to install a 1965/66 C20 front on a C10 frame without drilling any holes or modifications?

[nelson-ohio]

Ok, just to recap and see if this makes sense:

-Even thou my title and the cab VIN says it's a 1966 C10, the suspension as it is with 8 lugs, and from what's shown in these pictures, is definitely not a C10 suspension, more likely a C20. Am I correct?

-Is it possible someone could have used an 8 lug wheel set up on the C10 suspension? I mean are the parts not interchangeable?

Sorry if this is going on for too long, just trying to make sure before going ahead.

Most likely I will go ahead with the 1984 C20 front end swap, since it's confirmed it will fit anyways.

Also a few pictures of the driver side wheel with the tire removed.

PS - just saw the latest reply from Captain, so that question is answered.

[nelson-ohio]

more questions about the rear now. What is the advantage of the 84 rear other than it's a 12 bolt? Are they built different and easier to work on, cheaper parts, etc.?

Also, should they fit on my current spring set up as is or will I need to move the brackets and things?

I have not look into this at all, too focused on the front until this point.

[Chevy Fleetside]

I helped a friend with this kind of swap on his 3/4 ton. He has a detailed thread with alot of pictures but I just can't find it. his username on this site is Hilander. I hope I spelled it right.

OH look I found it... http://www.67-72chevytrucks.com/vboa...light=Hilander

[nelson-ohio]

Thanks for the info. I actually have the thread saved on my favorite, saw it on Persh's blog when I was searching like crazy.

My biggest problem is my Title and the truck seem to have some mismatch, and I'm still not 100% sure which frame I have, but it seems I have a C20 suspension for sure.

1 more questions: Does the stock C20 suspension sit higher than a stock C10? just curious.

[Palf70Step]

There are some differences between the C20 and C10 frame,. I know there is extar bracing in a few places, I just don't remember where. Also There is smoething about the cab mounts that are different. I think the sit lower, so the rubber cab mounts are thicker (or vice versa).

Swapping the parts are easy between the 2 are fairly easy, even redoing the axle mounts for the rear leafs. No far as I know, you cannot put C20 spindles on a C10 A-arm. so the probably sawpped the whole front end


What are you wanting from the truck? Do you need the 3/4 ton components?

If it were me, I'd find a later model 73-87 C10 rust bucket and swap all the 1/2 ton stuff over to you current frame so you'll have front disk brakes.

If you want the load carrying capacity, just rebuild what you need. I'd eventually look at upgrading the front to disks regardless.

Hopefullly some of the more smarter folks will chime in for you.

and yes...C20 sits higher than C10 by default.

[Captainfab]

The '84 C20 will not have a 12 bolt, it will be the 14 bolt, either a full floating or semi-floating. Assuming your '65 has the Eaton HO52 which would be typical, the 14 bolt should have better highway gears, plus better parts availability. The spring pads on the 14 bolt are a little farther apart than the '65 springs, but the springs may move side to side enough to bolt up. If not, the spring pads will need to be moved. Then you will have to move the shock mounts on either the differential or on the frame. Changing the differential from the Eaton HO52 to a 14 bolt is well worth the work IMO.

Originally Posted by nelson-ohio

more questions about the rear now. What is the advantage of the 84 rear other than it's a 12 bolt? Are they built different and easier to work on, cheaper parts, etc.?

Also, should they fit on my current spring set up as is or will I need to move the brackets and things?

I have not look into this at all, too focused on the front until this point.

[nelson-ohio]

Thanks Capitan for the info.

The guy told me his 84 C20 has a 12 bolt with a 4.10 gear, maybe it was replaced at 1 time. I will take some measurements off my current rear spring setup and compare with his setup when I get there.

Will see what kind condition it's in and how much work it maybe before deciding.

You know this is 1 of these "1 thing lead to another" deal, but I need to keep that in check. I wasn't even going to replace the current front end, it's in fairly good shape. I don't want to turn out like the PO who worked on it on and off for 5-6 years and just lost interest, I need to get it done in 6 months.

[66Submarine]

Certainly doesn't look like it's an Eaton rear from what I can see.

The 12 bolt would be a six lug or five lug rear; they made some light duty 3/4 ton trucks later on that were six lug, but '84 will all be eight lug AFAIK.

I'd bet you probably already have 4:10 gears; that seems to be by far the most common 3/4 ton ratio IME.

One thing that also stands out to me in your pictures is that the leaf spring hangers appear to be riveted on by the factory, which would be wrong for a C10.

[nelson-ohio]

Originally Posted by 66Submarine

One thing that also stands out to me in your pictures is that the leaf spring hangers appear to be riveted on by the factory, which would be wrong for a C10.

The rear I have is a 10 bolt, not even a 12. This is what I have bee trying to confirm. Now I'm wondering if the whole frame was swapped with a later model C something, and the rear axel was replaced again or something.

So it is possible that I go get this 84 C2 front, and it would not fit at all, since I have no idea what year the frame really is.

[66Submarine]

Originally Posted by nelson-ohio

The rear I have is a 10 bolt, not even a 12. This is what I have bee trying to confirm. Now I'm wondering if the whole frame was swapped with a later model C something, and the rear axel was replaced again or something.

So it is possible that I go get this 84 C2 front, and it would not fit at all, since I have no idea what year the frame really is.

Sounds like you probably have a Dana 60, which is a very common 3/4 ton rear end.

Can you post some more pictures of the frame? Might be a GMC 3/4 ton frame that someone swapped in. The drum brakes and coil springs put the front end as '63-'70.