brake swap advice wanted

[F-100Ranger]

Ok, so I've been following the old and new forum for half a year now. I've got my 68 Ranger engine and tranny out and am working on dissembling the drum brake set up. I found a 79' donor front end and have blasted the spindles.

I'm one of guys that can read forever, but need to have hands-on to understand the disc brake swap out. So here goes the question- can I simply just drop the 68' drum spindle and put in new king pins and the 79' disc spindle, or do I have to swap out the 79 I-beams too? Can I use the cast 68' radius arms with the 79' I-beams?

I also need to know what's the final consensus on what type of bushings? Poly, rubber etc. I'm keeping the truck street with small upgrades such as a 410FE, and variable rate coil springs

Thanks guys

Thanks

[willowbilly3]

Hi, welcome aboard. This is probably one of the two most popular mods for our old trucks. You might want to check with the tech articles for all the particulars. The spindles should interchange. I am not sure on the radius arms but I think they do too. This is also the time to add power steering if you don't already have it.

[FORDification]

Yes, the '79 disc brake spindle will fit onto the '68 I-beams. However, in the Technical section, I wrote an article called Comparing I-beams and Spindles in which I noticed that there ARE some differences in the steering bump stop in the various years of spindle/I-beam combinations. Mixing and matching certain years of spindles with I-beams will result in the turning radius either increasing or decreasing. An increase in turning radius sounds like a good thing, but you could also have problems with the tire rubbing on sheetmetal or the frame. Mating a '75-'79 spindle with a '68-'74 I-beam is one combination that will increase the turning radius. I haven't talked with anyone who had done this particular swap yet, so I'm not entirely sure how it would work out, so I'm not sure how the increase actually effects things.

I'd strongly suggest using the entire '79 front end, just to eliminate any future problems. It will bolt up perfectly to your truck, and you'll find that removing JUST the spindle from a truck in a salvage yard or in a field will be next to impossible. However, you can drop the entire front end in just a few minutes, remove the radius arms, springs and brake hardware, and have the local machine shop press out the kingpins. I dropped my '79 front end donor out in about 30 minutes using only hand tools and a hydraulic jack. The '67-'72 radius arms are the same dimensionally, so they interchange with the '73-'79.

When you get the kingpins replaced, I'd strongly suggest going with the bronze bushings and not the plastic. Granted the plastic bushings don't require a machine shop to ream them, but bronze bushings will last almost forever with proper maintenance, whereas I've heard the plastic versions won't even last 40,000-50,000 miles. My local machine shop charged me $20 to press out the kingpins, after which I had everything cleaned up and powdercoated the I-beams/radius arms and painted the spindles, then took everything back and was charged $40 to press in and ream the new bronze bushings.

Polyurethane and polygraphite suspension bushings will definitely stiffen up the feel of the truck. Polyurethane tends to squeek and be annoying, but polygraphite bushings are impregnated with graphite which acts as a lubricant to minimize the squeek. I'm using the polygraphite from PST. It'll be a while before I can give a first-hand account as to their performance, however.

One more note: the disc brake spindle's steering arm is thicker than the '67-'72 drum brake steering arm, so you'll be required to use the later steering linkage. Here's a pic I just took last weekend of the differences:



The '67-'72 steering linkage is on the left, the next generation is on the right. The earlier linkage, due to it being shorter, won't fit all the way up into the steering arm on the later spindle's steering arm.

[FORDification]

Well, I've spend the past few evenings working on a disc brake tutorial and have found out some more information on your question. The answer is: sort of. There was a .0001" difference in kingpin diameter between the '68 F100 kingpin and the '79 F-150 kingpin. This isn't a big thing, the machine shop who reams your bushings can fix the difference. However, there is also a difference in kingpin length between the two eras. The earlier trucks used a kingpin that was .8592" x 6.353" while the later trucks used one that was .8593" x 6.483". (We're talking 1/2-ton kingpins here....the 3/4-ton pieces are a whole new issue.) Therefore, you need to order the kingpin set for the '79 spindles and not the '68. Take a look at the new tutorial at http://www.fordification.com/discbrakes01.htm .

Bottom line: It's always easiest and the recommended route to swap in the I-beam and spindle as an assembly from the donor truck. Keeping the I-beams matched with the same-year spindle alleviates any headaches, and it's still a straight bolt-in.