PAGE  [ 1 ]  -  [ 2 ]

If you're like most people, you like being able to come to a rapid and complete stop when you push down on the brake pedal. When the auto manufacturers began to discover the advantages of using brake discs on the front end instead of drums, the option quickly became a favorite for consumers, so much so that it didn't take long for most manufacturers to make front disc brakes standard on most of their vehicles. However, if you're the owner of an older Ford truck, more than likely it's still got the old tried-and-true four-wheel-drum setup.

Although Ford started installing disc brakes on the F-250 in 1968, they were not factory-installed on the F-100 until 1973...the first year they were standard equipment on all F-100 through F-350 trucks. However, the front disc brake setup on the '73-'79 trucks is a direct bolt-on for Twin I-beam-equipped trucks back to 1965...if the I-beams and spindles are swapped as a pair! (You CAN do some mixing/matching as detailed below, but it's always better to keep I-beams and spindles properly mated.)

While there ARE disc-brake conversion kits available, the easiest way to convert your truck to disc brakes is to simply find a '73-'79 donor truck and salvage all the brake hardware. If you've got an F-100, you'll need to find an F-100/F-150 to donate it's parts, as few F-250 disc brake spindles will fit your F-100 I-beams. (In addition, the F-250 calipers are a dual-piston design which is not as desirable and would give you an 8-lug setup on the front instead of 5-lug.)

FYI: The disc brake setup is nominally wider than the drum-brake versions, so your track width will marginally increase, but not enough to notice or for it to be an issue unless you're using wider wheels/tires that barely clear the fender as/is.

However, there IS a difference in some disc brake setups used on the F250/F350 trucks. Depending on the axle rating, some F250 disc brake setups use F-100 or even F-350 parts. And if that's not enough, the larger units also have 9/16" wheel studs vs. the 1/2" studs of the smaller units. Therefore, when performing this swap on an F250, be sure to check the GVW rating on the donor truck to be sure that you know what you're getting. Use this handy chart I put together after spending an entire evening researching kingpin diameters:

One other note: I spent some time comparing the F-100 I-beams from '67-'79 Ford trucks and have found a few interesting items. In addition to the differences in kingpin diameters and heights, there was also a change in the steering bump stop on the I-beams/spindles for certain years. You can read the entire article "Comparing I-beams and spindles" for more information, but basically it comes down to this:

• If you're using '75-'79 spindles, use '75-'79 I-beams and kingpins

• If you're using '68-'74 spindles, use '68-'74 I-beams and kingpins

• If you're using '67 I-beams, use '73-'74 I-beams and kingpins. However, the round pin used for the bump stop in the '67 I-beam may need to be trimmed or modified, as needed.

• 1965 has one-year-only kingpins, so if replacing spindle out and replacing kingpins, use 1965 kingpins.

NOTE: These recommendations are not based as much on kingpin size as they are by steering stop (bump stop) configurations between the different years of I-beams and spindles. You might find that by mixing/matching certain years of I-beams and spindles, your truck's turning radius could either be increased (meaning likely tire rub at full turn) or decreased.

You can now see why it's highly recommended to simply find yourself a '73-'79 donor truck and get ALL the brake parts from this truck for use in your project. It alleviates a LOT of headaches involved when attempting to mix and match parts.

Well, enough of the babble....let's get started! Follow along as I convert my '67 2WD SWB to disc brakes using all the parts from a '79 F-150 donor truck.

FRONT-END REMOVAL

The disc brake spindle is connected to each I-beam with a kingpin. While it's possible to drive the kingpin out manually while working on a parts truck in the field or salvage yard, it's going to require a LOT of effort. However, the ENTIRE front end can be dropped out as a unit in less than an hour with hand tools, so this is definitely recommended. You can then take your parts home and fight with the kingpin in your shop or garage, where you have access to tools and cool liquid refreshments. Here's what you need to do to drop the front end:

1) Remove two bolts holding the coil spring retaining strap at the top.
2) Loosen the upper shock absorber nut about 90%, but don't remove it completely.
3) Disconnect the tie rod from the steering box's Pitman arm and separate the drag link from the center link.
4) Disconnect the brake lines at the caliper.
5) Remove the large nuts holding the rear of the radius arms to the frame brackets.
6) Remove the I-beam pivot bolts and pry the I-beams out of the frame brackets.

At this point the suspension assembly should be hanging by the shock absorbers. Put a hydraulic jack under one side's brake assembly and jack it up a bit to relieve the tension, then lay on your back and give that side a couple good hard kicks forward to slide the radius arm out of the frame bracket. Then remove the shock absorber nut and lower to the ground. Repeat for the other side.

Other pieces you need to be sure to grab from the donor truck include:

• Brake hose frame brackets (see Fig. 4)
• Master cylinder/brake booster
• Brake proportioning valve - also snip the end off the valve's wiring, to splice into your existing harness so your brake warning light works properly. You'll also need the fittings going into the valve, so if you're planning on replacing all the lines, just snip them at the valve, leaving yourself several inches of line.
• Front steel brake lines (these probably need replacing, but grab 'em anyway to use as templates for bending your own lines)
• steering linkage (and possibly the Saginaw steering box's Pitman arm - more on this below)

Most of the brake components will be replaced with new parts, including the rotors, calipers, bearings, hoses and pads.

Fig. 1 - A quick before shot. The truck is setting on jackstands, but the front end loader is also supporting the truck, just as a backup.

Fig. 2 - It only took me about 30 minutes to drop the front end from this '70 F-150.

Fig. 3 - Here's the front end unit ready for it's new home.

Fig. 4 - I found that one of the brake line brackets was riveted to the frame, while the other was simply bolted. Since I didn't feel like messing with removing the factory rivet, I just grabbed another bolt-on bracket from a different truck.

ABOUT KINGPINS & BUSHINGS

     Once you get your parts home, you can start the disassembly. Remove the calipers, rotors, springs, radius arms and steering linkage. You should be left with the I-beams and spindles, held together with the kingpins. While it's possible to remove the kingpins in your shop, I'd highly suggest just dropping them off at your local machine shop and having them press them out with a hydraulic press...a 15-20 minute job for them that shouldn't cost you more than about $20-$30. If you're not planning on cleaning up and painting your I-beams prior to reinstallation, be sure to bring your new kingpin set for them to press in at the same time. The kingpin kit should only run you about $50 and it's installation will be another $50-$75...well worth it.

     Kingpin bushings are available in bronze and nylon versions. The bronze bushings are actually steel with a bronze inner lining and will need to be reamed (NOT honed!) by the machine shop after installation to properly fit the kingpin. The nylon bushings don't require reaming and can simply be installed by hand. However, while the bronze bushings will give you 100,000 miles or more of service, the nylon versions don't last nearly as long. Some users report having to replace these after 30,000-40,000 miles. And while they're easier to replace when they DO wear out, who wants to go through this again?? Just use the bronze bushings, keep 'em greased up and you'll probably never have to worry about them again.

     The bronze bushings are 'rolled' bushings...that is, they are manufactured from flat stock and then rolled around into a tube and secured with a connection which bears a resemblance to a jigsaw puzzle connector (See Fig. 7). Out of the box, they are not 'true', which is why it's mandatory to ream them to snugly fit the kingpin.

     Well, let's get those kingpins out!.....

PAGE  [ 1 ]  -  [ 2 ]