1961-1964 Sweptline W100 Early Rear Disc Brake Manual
Tread Tire Width and Stopping Power
1957-1968 trucks usually came with 5Ó wide rims. This width tire was adequate for transferring the relatively poor stopping power of the drum brakes to the road. If they are used with disc brakes these narrow tires can lock up and skid during rapid stops especially when the roads are wet or icy. This can cause loss of control particularly on short bed trucks with little weight on the rear axle. If your 5Ó tires are still good you can use them but make sure you upgrade to more modern 6.5Ó rims and tires when they need replacing.
Proportioning Valves
An adjustable proportioning valve must be used in the rear brake line if 4 wheel disc brakes are installed. One may not be needed if you have front discs with rear drums as the rear drums will not have enough stopping power to lock up. This is something that you will need to determine for your particular truck.
Rims That Can Be Used With This Brake Conversion
Between 1957 and 1971 there were a number of different rim styles that were made for these trucks, some are useable with disc brakes and some are not. Fortunately rims are cheap and easy to find in 15" 5 X 4.5". The following are some problems we have encountered.
Pictured below is an early 15" X 5" wide rim these were used from 1957-1968 and are of two types.
This one can be used with disc brakes, notice that the drop center portion goes straight from the bead area to the center web. This allows clearance for the caliper.
The rim pictured below is identical to the one above in every way except that the side of the drop center area has a curve in it before dropping straight down to the web. This one can't be used with discs as the caliper will hit the rim at the curve.
The photo below is of a more modern rim that measures 15" X 6.5"wide. Notice that the inside drops straight down from the bead area to the center web. This gives maximum clearance between the caliper and the inside of the rim. Care should be taken when mounting this rim on '57-'60 trucks as the tire might rub on the inside of the fender if the spring is compressed all the way. It will not be necessary to use the 1/4" thick wheel spacers with rims of this type.
Installation of Rear Brakes
1. Remove the old hubs, drums, shoes, wheel cylinders and backing plates from the spindles. Be sure to keep the bearing preload shims together with the side they came off of. This is a good time to pull your axle shafts and differential so that you can check their condition and replace seals and bearings if they need it and grease the axle bearings. At the end of this manual is information on doing this.
2. There are a couple of types of caliper sliders pictured below. The right one is from a Dodge Aspen, the left one is from a Chrysler 5th avenue. Either type will work.
3. You will need to grind an arc in the inner edge of the slider as shown below so that it will fit around the axle tube. This is done by drawing a line connecting the sides of the bolt bosses. This is the depth of the arc. Now cut out a 3.300" circle and lay it on the slider so that its edge touches the line and it is centered between the two holes.
4. Install the backing plate on the spindle as shown below with the slider bolt holes to the rear and making sure that all of the shims that came off are reinstalled. Use the 3/8" nuts and loc washers provided. There should be .005-.010" endplay in the axle shaft. Shims can be removed or installed to arrive at this, however you can probably assume that it was correct when you took it apart and if you didn't replace bearings then the end play should be the same as before.
5. Install the hub/rotor assembly on the axle shaft and tighten the nut.
6. Assemble the slider to the backing plate using the 1/2"NC bolts and lock washers.
7. Check the runout at the edge of the rotor as shown below. Ideally it should be .006" or less, you can however get away with .010" with no noticeable affects on braking. If the the runout is more than .006" a burr on the axle shaft or a bent axle shaft may be causing the problem. You can also switch the hubs from side to side to see if the runout is better.
8. Once the hub is installed you can install the caliper making sure that the bleeder nipple is up.
9. In the photo below the upper caliper keeper has been installed so you can see how its pieces fit together.
10. Next hook up the brake hoses as shown below using the banjo bolts provided along with the copper washers provided with your calipers.
11. Attach the other ends of the hoses to the frame and screw the metal lines into them.
Tools For Removing Hubs and Axle Shafts
Pictured below is the proper tool for removing stuborn rear hubs from the early tapered axle shafts. This one is made by OTC and its part number is 7208. It cost me $29. The largest lug pattern that it will work with is 4.5" with 1/2" studs. For larger trucks you will need a larger puller.
The tool in the photo below is a 5 lb slide hammer that uses 3/4" water pipe for a shaft. These can be found at such places as Harbor Freight and can be used for pulling the axle shafts. You will need to weld a 3/4"NF nut to the end of a 3/4" pipe coupler as shown below and screw it onto the end of the axle shaft. What comes next should be obvious!
