Inliners International Forums General Discussion Truck Talk '67 C20 drum to disc conversion

I've read on several different forums about converting my 2WD '67 C20 from front drum to discs. No two threads explain the conversion the same.

I've read that anything from a 2WD C20 3/4 ton '73 - '87 donor vehicle will go onto my '67 C20. Has anyone here done this? If so, then what will and won't work and what has to be changed?

p.s. - I know there are conversion kits available (alot of ???) I have access to several junkyards nearby - I'd like to do it with donor parts from another vehicle to save money. Obviously I'll be replacing any worn parts.

I'm open to all input. Thanks.

Jim, I updated my '65 Pickup drums to the 1972 discs. It was only a C10 but I think the same method will work. I kept the original arms and changed the ball joints and all of the steering linkages. The idler arm was the worst as we had to re-drill the chassis to get it to mount. I was told now that the easier way to do it would have been to undo the whole cross member on the '73 - '87 truck (8 bolts I believe) and then bolt it back into the earlier truck. One thing I remember hearing was that whatever year spindles you use, you have to use the same year ball joint. Take the power brake booster, brake proportioning valve and the power steering box off of the later truck as well. The junkyard hunt should work good for you.

I have a 63 and 68 C20 That I'm going to convert to disc. The 63 will be the first in hopefully a few weeks. IIRC if you stay with disc from a 72 or earlier it's a bolt for bolt change. If you get a later disc front end up to 86 there are a few bolt holes off by 1/8 to a 1/4 inch. Here's a thread from Chevytalk.org that has pictures, diagrams, a 128 post, should answer a lot of questions;

http://www.chevytalk.org/fusionbb/showtopic.php?tid/187532/

Larry

Thanks -
I didn't realize that all I need are the spindles! I can figure out the rest and it will be a bunch cheaper.

I looked at that thread-the a-arms, ball joints and spindle stuff seems straightforward enough, but what of the flipping of tie-rod ends and adjusters? I'd like to think that converting to disc on my 64 1/2 ton is that easy, but there's something to the tie rod part that seems like it's missing. Do you flip the tie rods end for end and use the stock inner as the outer now, but with a tapered adapter? If the shank of the inner tie rod is now too small to fit the taper of the spindle, wouldn't that mean the same where the outer tie rod now attaches to the center link? GM Dad, are you the man I bought a power steering box adapter from a couple years back? I'm in Edmonton, Alberta.

Basically, due to the diameter of the newer style tie rod end that goes into the new spindle, you have to use the current outer tie rod end in the inner position and then get an adapter to go between the two diffent size threads.

In the attached forum that L Griffin attached it is stated that you can get the tie rod adapters from Bob's Chevy parts, but that is not correct. I called Bob's and was directed to 4 different west coast old truck parts dealers before I told to contact Classic Performance. Classic Performance, I was told by the guy that answered the phone, actually manufactures the adapters to go between the different size tie rod ends. They are $50.

I'm getting close to getting mine down. I'll let you know how it works out.

Is the adapter that's being discussed just the toe adjusting sleeve with different size threads on each end?

Yup.

Huzzah! Clear at last. I imagined tapered sleeves of some sort that went into the spindle, then the tie rod shank went in and bolted down. A million thanks.

I called at least 10 machine shops about machinng the spindles to accept the original tie rod ends, but none of them wanted to do it. Probably a liability issue - steering component modification.

Liability would indeed be an issue. Called Classic Performance and got a really helpful guy on the other end. Unfortunately, they don't make the steel adjuster sleeves anymore, just the cheezy aluminum ones. Oh well, no one's gonna see them that low anyway. Price is up a bit, at $69. They also mentioned that the dual master to use is the 76 Corvette model. For junkyard parts and a $30 rebuilt master, you can't go wrong. Cheap discs, here I come. What power booster would one use, if I was so inclined? Would that mean a custom mounting bracket as well?

Does anybody know if the 72 and up spindles sit at the same height as the 63-66 ones? I noticed in the thread that there may be some change in caster, which I assume can be corrected by proper alignment.

Anybody still reading this?

Never heard of the problem.

Larry

I did the same swap, putting '76 parts in my '67 C20, about five years ago. There are a couple of differences you may want to look at before you start.

Some guys like to swap the entire crossmember, A-arms, tie rods and all. I took home the complete '76 suspension, but picked the pieces from both years that I liked the best.

There are slight differences in the '76 crossmember, but mainly just a couple of holes that can be drilled to line up. There is an angled piece on both sides, that the upper A- arms bolt to and this is bolted to the frame rails. The '67 is a large cast piece and the '76 is a lighter piece of pressed steel. They compensated by adding an extra piece on the inside of the frame rails. When bolted together, the frame rail is sandwiched between the two. Only one of those bolt holes line up, if I remember correctly. One has to be drilled and others elongated. The bolts through from the bottom do line up for both years.
I had taken both apart and picked the parts I wanted. I knew I wanted to keep the '67 springs, because the '76 was a big block. I kept the '67 cross member and added the '76 inside frame rail pieces for extra strength.

Either the upper or lower A-arm and ball joint is the same and fits both 67 drum and 76 disc spindle. The other arm ball joint fits only the '76. Sorry, can't remember which I used. If you were planing on using both upper and lower A-arms from the '76, you're good.

I don't recall that there was any difference in the tie rod ends. Someone correct me if I am wrong, but I thought that problem only came up on 1/2 ton conversions.

Be sure and get the sway bar. If you even have one, the '76 will be bigger.

The '67 brake line crosses to the passenger side on the back of the crossmember. The '76 lines go to the radiator crossmember, where the combination valve is located. The line to the rear of the truck from the combo valve, goes along the passenger side frame rail to a brass inline connector, just past the bellhousing. It's inside the frame rail. Your '67 has the exact same connector in the same spot. Unbolt all the lines from there forward and transfer to your truck. The flex lines go through the frame ahead of the A-arms, instead of behind as on the '67. I think there may have already been a hole there that had to be enlarged.
Be sure and check the lug sizes on the disc hubs. On the '76 I used, they were larger than the '67. I didn't want a mismatch or deal with getting new lug bolts for my aluminum wheels, so I replaced the studs in the disc hubs. Easier to change off the truck, before hand than dealing with it later.

Use the master cylinder and booster from the truck you take the suspension and brakes from. It would be stupid to use a Vette MC and have to fabricate parts for a mish-mash of parts. Using all parts from the same year truck will assure you that everything will work well together and make it easier to get replacement parts later on.

Take your time finding the right parts truck that is complete and the swap will be a lot easier. Either find a truck someone is getting ready to part out or keep visiting a pick-a-part till they pull one in that is complete and call in a buddy to give you a hand.
Hope that helps.

Richard,
What/how did you connect the brake pedal to the booster?

Also, I used the left brake line on the right side and vice versa and picked up some brackets from an '80's S10 do that the brake lines run on the rear side. But I used the original upper and lower 'a' frames.

I'm having an issue still and I think it has to do with brake pedal travel, but I haven't had the time to solve the problem due to workload, football pactice, etc!. That's why I'm really curious as to how you connected the brake pedal to the booster.

p.s. the ties rod end tapers are different. The 67 is too big. I had to purchase custom tie tube sleeves.

The brake conversion is done - FINALLY.

We had to buy a new booster, the free one that I had that was 40 yrs old leaked - imagine that! The new one is an 8" (7 1/2" actually) and left alot of clearance between the carb and booster. With the stock booster I had less 1 1/2" of clearance.

Works great! Had the alignment done today. The camber was WAY off, as I read it would be. The alignment stopped any shakes and vibrations and it stops like a new truck - I am truly amazed at how well it drives and stops now. Also put a bearing and synchro ring kit into the T5 while it was down.

Also downsized the jets in the Holley, hopefully for the last time. Drove it 116 miles back and forth to work. I'll update the other thread 'bout the Holley tuning after a couple of days of driving to check the mileage.