Drum to disk brake conversion on 1967 C20

[Captain X]

So I have a 1967 Chevy 3/4 ton that I would like to convert to disk brakes all around if I can. I was wondering if any companies offered a kit conversion for this style of rear axle, and if anyone had any recommendations for front wheel conversion kits.

Failing any handy kits, does anyone know if Chevrolet ever made a HD 3/4 ton with a rear axle of this style that came with disk brakes and would work on a '67 C20?

[Big Kev-O]

If you have an Eaton or Dana 60 rear axle Lugnut4x4.com sells disc kits. It's is hard to tell which axle you have without seeing a picture of the differential cover.

https://lugnut4x4.com/product/eaton-...se-your-rotors


https://lugnut4x4.com/product/dana-6...oose-your-axle

[Captain X]

Well, it's like a 3 hour drive away from me, so I can't just stick my head under there and take a picture just now, but I know it's a posi-track rear end with a big round pumpkin.

Next time I'm there, what should I look for to tell me if it's an Eaton or Dana?

[Caddylackn]

The problem with rear disc brake kits is the parking brake. The rear disc swap kits usually use the cadillac eldorado type rear calipers with the cable operated rear parking brake. The cable disc parking brake arrangement is usually too weak to hold a truck with a load on any hill. Unless you have a manual with a granny gear this will be problematic if you have a camper or a load.

To overcome the weak rear parking brake, you can add a line lock on the hydraulic brake line or use the motorhome type turbo 400 which has the drum parking brake on the output shaft.

[Captain X]

I don't suppose there's a way to strengthen the parking brake on the kit, is there?

This is also part of why I was wondering about rear axles on later models that just came stock with disk brakes.

[Captain X]

So I managed to get out there this weekend, and here's the differential.

[Big Kev-O]

That is an Eaton rear axle.

According to Lugnut4x4:

"Our e-brake calipers are unique. While they're based on GM designed JB6 calipers made for the '76-78 Cadillac Eldorado, Lugnut4x4 e-brake calipers feature a much stronger parking brake lever arm that is better suited to heavy-duty applications."

[Madkidd007]

The aftermarket disc brakes using the eldarodo calipers are not ideal and I wouldn’t trust to hold a truck still on a hill. Being you have a trailing arm truck you can’t use an entire late model axle. Personally my c20 converted to disc on just the front with hydroboost will put you through the windshield. In a truck rear discs from a useful aspect aren’t worth it unless you have a lot of weight in the bed. But as far as the front goes, entire front end from a square body works

[dagnabbitt]

As others have noted, rear disc brakes can be more trouble than they are worth in trucks, especially 3/4 tons. But I know better than to try to talk someone out of what they want to do.

I don't think you have mentioned what transmission you have. It is a manual? You will be using that parking brake all the time.

[Captain X]

Yes, it's a four-speed manual.

I just like the idea of converting to disc brakes because I hate working on drum brakes, and they're more efficient anyway. The only real concern I have is the same one I've always had, which is the parking brake issue since I know how they work in drum brakes, but really nothing about how they work in disc brakes. And then there's the other concern of if they'll work for a 3/4 ton.

[dagnabbitt]

Well, one thing you could consider is a driveshaft brake, there is some precedent for these on our trucks. If you check out my 68 C20 build you will see that it was an actual option on mine: and if your trans is an SM 420 - it should be, if it is a 67- it might be easier than you might think if you collect the right parts. I complain a lot about mine of course because there is so little information on them, but I also think it is kind of cool and if it works, it works. I have yet to get mine assembled but it is pretty straightforward for me since it originally had one.

http://67-72chevytrucks.com/vboard/s...d.php?t=795405

There is always a way to get what you want, and if you really want discs in the rear you can have them and have a parking brake, too.

[67 twins]

Originally Posted by dagnabbitt

Well, one thing you could consider is a driveshaft brake, there is some precedent for these on our trucks. If you check out my 68 C20 build you will see that it was an actual option on mine: and if your trans is an SM 420 - it should be, if it is a 67- it might be easier than you might think if you collect the right parts. I complain a lot about mine of course because there is so little information on them, but I also think it is kind of cool and if it works, it works. I have yet to get mine assembled but it is pretty straightforward for me since it originally had one.

http://67-72chevytrucks.com/vboard/s...d.php?t=795405

There is always a way to get what you want, and if you really want discs in the rear you can have them and have a parking brake, too.

I actually have one of these driveline brakes on the back of an SM420 but it came out of a larger truck like C50 or C60. I think it would be neat to use it in something, just don't have a plan for it yet

[Madkidd007]

Originally Posted by dagnabbitt

As others have noted, rear disc brakes can be more trouble than they are worth in trucks, especially 3/4 tons. But I know better than to try to talk someone out of what they want to do.

I don't think you have mentioned what transmission you have. It is a manual? You will be using that parking brake all the time.

I forgot my 62 1 ton was setup that way, it worked great. More than once I forgot to take it off and stalled the truck

[dagnabbitt]

Originally Posted by 67 twins

I actually have one of these driveline brakes on the back of an SM420 but it came out of a larger truck like C50 or C60. I think it would be neat to use it in something, just don't have a plan for it yet

I'm hoping to get mine together this winter. I have yet to actually see one on a 67-72 so its going to be trial and error, but I also think it will be cool. I have always preferred a handbrake to that little pedal.

[RichardJ]

You're going to adapt your SM420, that dates from 1947, so that you can put more modern disc brakes on a '67 Eaton axle? Even at that, the calipers are going to be skimpy car calipers on a 3/4 truck.

I don't see it?

My '67 3/4 has disc/drum and a SM365 (original 3spd). If i considered any change, it would be one that proved real improvement to the truck such as a NV4500 5 spd.

The NV4500 was available with a tail housing mounted driveshaft brake. Might be easier to find than a SM 420 brake

I'd be so excited about having the 5spd, I wouldn't want to ruin that thought by thinking about car calipers on the rear. I'd keep the drums and use a regular NV4500.

[jarrodblake]

Have you priced out a Lugnut4x4 disk brake conversion with the E brake option? It may be cheaper to swap the axle for a newer disk brake axle. I was going to use the Lugnut4x4 conversion but for the price it was cheaper to swap axles.

[Captain X]

Originally Posted by jarrodblake

Have you priced out a Lugnut4x4 disk brake conversion with the E brake option? It may be cheaper to swap the axle for a newer disk brake axle. I was going to use the Lugnut4x4 conversion but for the price it was cheaper to swap axles.

What would be a good axle to use for it?

[Madkidd007]

Originally Posted by Captain X

What would be a good axle to use for it?

There isn’t one, all of the late model axles with disc brakes are too big. It’s the axle tube diameter that’s too big, leaf spring trucks can do it but not a trailing arm truck

[Captain X]

Originally Posted by Madkidd007

But as far as the front goes, entire front end from a square body works

Would this keep the front tires in line with the rears (I noticed the conversion kit says it will move the tires out 1/4 inch)? And would I be able to just swap spindles, or would I have to swap the A-arms and steering and everything?

As far as the rears, would I maybe be able to pick out a vehicle with beefier rotors and calipers and custom make any parts I might need? Would a such a set also have a stronger parking brake set-up? I'd kind of like to keep the hand brake. Or is that no good for any disc brakes?

[mcmlxix]

I swapped a late model AAM 14BFF with factory disc brakes under my 1972 K5 Blazer. It came out of a 2005 GMC 2500HD truck. There are two versions, one with a 10.5" Ring Gear and an 11.5" Ring Gear identified by if it has a weighted ring on the input yoke. The new axel is wider than original and will use metric brake line fittings and wheel studs. I had to remove and replace spring perches and shock mounts on the axle tube. I used aftermarket E-brake cables.

www.car-part.com

[BigBird05]

Why do you want to go to rear disc brakes? A good brake job and a properly adjusted parking brake will work just fine on your truck. The rear brakes only provide between 20 to 30 percent in stopping power. The factory went to rear disc for weight savings. Every once counts.

[Captain X]

Originally Posted by mcmlxix

I swapped a late model AAM 14BFF with factory disc brakes under my 1972 K5 Blazer. It came out of a 2005 GMC 2500HD truck. There are two versions, one with a 10.5" Ring Gear and an 11.5" Ring Gear identified by if it has a weighted ring on the input yoke. The new axel is wider than original and will use metric brake line fittings and wheel studs. I had to remove and replace spring perches and shock mounts on the axle tube. I used aftermarket E-brake cables.

www.car-part.com

I'm hoping not to have to do anything that drastic, but thanks for the info.

Originally Posted by BigBird05

Why do you want to go to rear disc brakes? A good brake job and a properly adjusted parking brake will work just fine on your truck. The rear brakes only provide between 20 to 30 percent in stopping power. The factory went to rear disc for weight savings. Every once counts.

Because disc brakes are easier to work with. They are also more efficient.

[Mts67C10K20]

Here is an article from 4 wheel magazine it will answer several of your 4
Good wrenching

http://www.fourwheeler.com/how-to/su...o-disc-brakes/

I seem to remember hearing that the 14 bolt kit will work with an Eaton 052
You'll have to confirm for yourself

[Captain X]

Originally Posted by Mts67C10K20

Here is an article from 4 wheel magazine it will answer several of your 4
Good wrenching

http://www.fourwheeler.com/how-to/su...o-disc-brakes/

I seem to remember hearing that the 14 bolt kit will work with an Eaton 052
You'll have to confirm for yourself

Thanks, that kind of gives me some ideas. I'm kind of thinking all I might have to do is get the rotors and calipers off a newer model of Chevy 3/4 ton and get the brackets this guy got, or maybe even have a machine shop make me some based on measurements I'd make. The driveline brake this guy uses is more appealing than the stock one other people were mentioning, but I'd still love to use one that just engages the rear calipers mechanically just so I don't have yet another brake to worry about. Though, I found a video about the kit that Big Kev-O brought up, and it looks plenty heavy for what I'd need, and the only downside to it is that since the rotor fits along the outside of the old hub, it moves the tire out 1/4" from where it is stock. I guess that wouldn't matter as long as I got the kit for all four wheels, and you probably wouldn't be able to tell looking at it that way, but part of me likes the idea of what this guy did better.

I'm wondering what exactly is the problem with the kit's e-brake as far as it not being strong enough. Is it just a problem with that particular design, or is it fundamental to disc brakes in general?

[mcmlxix]

Electronic Parking Brake Rear Retrofit Brake Kit Description
Wilwood’s Electronic Parking Brake kits provides a complete parking brake solution for 0.81" and 1.10" rotor width rear brake kits. The Black or Red powder coat external electronic parking brake provides superior static holding power and a simplified installation with the included controller, harness and switch assembly. Installation would require custom bracket assemblies to fit to most application

WILWOOD WEBSITE HERE