The Stovebolt Site Forums The Parking Lot Tons 'o Fun '53-59 dual wheel front disk brakes

Several years ago I copied what another guy had done and put a set of Mopar disk brakes on a '55.2 GMC 3/4 ton set up for duals. The major problem with it was that the steering stop tab on the steering arms has to be removed for clearance. This then means that another way of limiting steering travel has to be made. Solid axle ('53-'62) Corvettes have a heavy bracket under the steering gear that limits the pitman arm swing and something similar needs to be built.

A '56 GMC 1-ton followed me home a while back and I decided to keep it all GM this time. I ended up using mid-80's GM 3/4 ton 4 wheel drive front rotors and calipers. After a number of "measure - draw - cut" cycles using 3/8" plywood to mock up and verify, I had the brackets cut out of 3/8 steel plate this week and I assembled everything on the axle yesterday and it looks like it will work.

Do it yourself disk brake kit.

Unless you have your own lathe or access to one, the simple looking spacers should be painted green for what it costs to have a machine shop make them.

Next step is to weld the lower tabs to the basic plate, clean & paint everything, have the kingpins fitted and put everything back together. I have a set of roller wheel bearings for this so everything should be ship shape.

Neat setup. I do see something that can be changed in the basic design to eliminate taking the steering stop off the arm, though. Most, if not all disk brake setups on vehicles with them as oe, position the caliper on the opposite side from the steering arms for clearance. The same can be done here by simply swapping the calipers/mount brackets side to side. Not saying how you did it wrong, only giving a suggestion for anyone who might wish to fabricate a similar setup.

Thanks for the feedback Bill.

Just to clarify, the problem with the steering stop interference was on this earlier project.

Earlier thread using Mopar brakes on same spindle.

I've never seen calipers mounted in front of the spindle but if the factory does it, then that's very good news. It means I'm done with the problem solving on the original conversion too!

John

You usually see front mounted calipers on rear steer type spindles, virtually all FWD vehicles are made that way, though there are some late model 2wd and 4x4 trucks with rear steer, too (Toyota Tundra, Trailblazer/Envoy).

Any updates OlBlue? Have you tested your disc brake set-up?

I have everything cleaned and painted and the front axle with spindles back under the truck but ran into a problem with the roller bearing conversion.

After finding you need a non-stock seal with the roller bearings (I have a good number for them) , I attempted to assemble the hubs to the spindles and the outer bearings won't pull up on the spindle. Best guess at the current time is that the spindles need to come back off and have the diameter where the outer bearing fits machined about another 1/4 inch inward.

Since removing and replacing the kingpins means the expansion plugs on both ends get destroyed, it looks like that route means a new set of king pins just to get the new expansion plugs.

I'll be addressing the bearing issue in a week or so. I have a new set of original style bearings ready to install if I decide to cut my losses on the roller upgrade.

Sounds good!

So you basiclaly have a workable solution for the brakes but you're trying to do a bearing upgrade at the same time right?

How much of a difference do you intend to see with the bearings? is this a matter of increased life, less rolling resistance or increased weight capacity?

I imagine any person thta chooses to follow this path could decide for themselves if they just want the disc upgrade or both the disc and bearings.

I'm sure you've already considered this but can't you just get a sealed bearing so you don't have to worry abuot the felt seals?

Tj

I finished putting the disk brakes on the truck yesterday.

To many issues with the roller bearing conversion. Went with stock ball bearings.

See the link in the first post for updated pictures and commentary.

I've completed final installation of the '71 - '78* GM 3/4 ton 4WD disk brakes on a freshly rebuilt front axle.

Follow the link in the first post to see pictures of the project at this stage.

It's taken over 18 months of fiddling around from the start of design to final install.

I can say without reservation that the roller bearing up grade is not worth the effort. I gave up when I discovered that I would have to machine the spindle to make them work. That was after installing new king pins. If you pull them, you need to find new end plugs which seem to be made of unobtanium unless you buy another king pin set.

I also ended up roaching a set of hubs installing the bearings but I'm pretty sure that was my problem, not the bearings.

The passenger side bracket fit with only minor file work. The drivers side required a trip back to the machine shop to have .050 milled off of the bracket in order to obtain the correct fit of the caliper on the rotor. The caliper should drop into the bracket and onto the rotor. The rotor should then spin with almost no drag in the caliper. There is also a clearance specification between the caliper housing and the bracket that needs attention. I left the brackets "long" and spent time with the file to get them in specification (.005 to .012).

I've started on the rear brakes and discovered that the rear drums had never been turned. (Almost makes up for all the problems on the front ones.) They've since been turned and all new shoes, springs and wheel cylinders are ready as soon as I get the cleaning done.


* Original post has the wrong year given for the parts used

Looks NICE!

I wonder how easily this would adapt to a 54...

What donor did you use for calipers and discs again?

Why did you have to take 0.050" off of one side and not the other? Shouldn't everything be symmetrical?

Are you at all concerned about the slider pins being exposed and not supported the same way as originally designed in an enclosed tube?

NAPA part numbers:

NB4885677 Rotor

The calipers are early ones that use US sized hoses vs metric hoses for the later ones.

SE-4597 Caliper
SE-4596 Caliper

Pads to fit calipers (can't find the box!)

36761 Hose
82698 Banjo Bolt

looks like the rotor is a good common part used for many years. what made you choose the 3/4 TON version over the 1 TON?

The 1-ton uses a Bendix brake which requires a more complicated mounting setup vs the simple plate for the 3/4 ton Delco brake.

The 3/4 ton brakes are rated for 7200 lbs GVW which is right in line with the '56 1-ton truck.

The first conversion I did, 1-ton Dodge disk brakes uses a Mopar version of the Bendix brake rated around 10,000 lbs GVW. Mopar uses a mount that works with a 1/2" plate but it has other problems as discussed in the other thread.

Great work! I tried a similar design on my 3600 truck. I ran into some clearance issues though. It wasn't necessarily the steering stops, but it was the steering arm actually hitting the axle. I suppose it has to do with the difference between the 3/4 and 1 ton axles.

Again, great job!

Chris

Oops!
I didn't catch it the first time I looked at it. I
thought you had a 1 piece bracket. You actually welded a small tab on the bottom. Simple, but elegant.

Chris

Looks like that parts combo will work on my 51 3600, rotors not even close to rubbing on any thing.
The trickiest part will be the bracket that will be very much like the one you made.
How did you attach the rotor to the hub?
Did You tap holes in the hub and just use bolts long enough to take the lug nuts?
Oh see it wasn't a problem on the 1 ton looks like will just have to figure it out

I used these Rotor Spacers to mount the rotors on the hubs.

Well that parts combo fits the 51 3600 perfect, just finished the machining need to do a roller bearing and seal upgrade, test fit on the Ford 8 bolt rims is perfect no clearance issues.
Been taking pictures as I finish the parts,
Not really a bad job if you have a lathe, would be a real breeze with a mill,
If you used stock bearings and seals less then a day of machining.