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Okay, I waffled. A friend convinced me to swap out my drums for discs on the '66 F250 and to top it off, another friend is going to remove both sets of suspensions from both trucks for what I considered a reasonable price.
I've done some research on this forum and youTube and the primer on the Fordification website. I now believe my '74 F250 has the heavy duty suspension 7500 GVW which means I'll have bigger king pins to deal with. But my concern now is whether or not my larger calipers (2 pistons/caliper) will allow me to keep the original 16 inch rims? The '74 has 16.5 in rims, and I hate them. Almost impossible to find tires for them.
BTW, those calipers are huge in comparison to the ones i'm seeing on youtub videos. I guess the obvious answer it to just try one on for size. I'm almost afraid to see. I'm also hoping that the truck can be hauled away without a front suspension or whether a charity will take it like that?
I've donated two vehicles to a local radio station (KUOW / local NPR station), and they had a company that comes in and picks them up on a rollback flatbed. The flatbed hauls it to an auction house where it is sold to the highest bidder and then I get to take whatever it sold for as a tax write-off. Last one sold for $6,500 which was nice. Someone got a 1981 car for way too much money and I got a nice tax deduction for a car that I didn't want to deal with trying to sell privately. Maybe you could rig up the 2WD front axle under the 4WD truck enough to make it a roller if they require it.
I'll be interested to hear if original 16" wheels clear the calipers. I'd asked the question recently and someone said the two-piece 16" won't but I was wondering about the 16" 8-lug one-piece innies.
Well, I did the obvious task to answer my own question regarding rim fitment on the bigger '74 F250 disc brakes.
In short all tested rims fit with about 3/8 inch clearance between rim and caliper. It was obvious that Ford included a recess on the caliper casting for extra clearance. I tested original Ford rims, all 16in : 2-piece, innie, and outie rims. I fitted them up without bolting them in, and spun the tire listening for any contact; none heard. I got on my back to have a look-see and photoed clearances as best I could. Now that I think of it, I should have installed an original 16.5 in rim for comparison. Stay tuned.
As for clearance, what is the opinion of the group: Go for it or halt the transfer? I really want to stick with original rims; not a fan of the sporty rim look.
original 2-piece rim from '66 F250 Backside showing clearance at top Clearance at bottom 1-piece innie rim clearance at top clearance at bottom 1-piece outie rim clearance at bottom clearance at top
Did this upgrade to my 3/4 ton a few years ago. A huge improvement over drums. Would suggest you make things a bit easier by taking everything from the I beam to the radius arm. Don't forget the master cylinder, booster and distribution block as well. Even if any of those parts worn, at least you've got for replacements or cores. Especially if you've got everything sitting there for free.
I checked the clearance with the original 16.5in rims. The clearance was on the same order as the other rims so I have more confidence in being able to use any of the rims shown above. clearance with original 16.5in rims. It's just as close as the other rims. another angle
If I was going to do a disc brake conversion, I'd look at Wilwood to see what they have for master cylinders, proportioning valves etc.to fine tune your setup. And I'd consider finding a system that worked without using a brake booster. Seems to me most power assisted brakes require the power assist mechanism to work in order to have any kind of braking.
If you're going to do the work, might as well see what's out there that might be better than 1970's brakes.
Well, I hope you will keep at it, and keep us posted, as I will be searching for the same parts in a few weeks, and thanks for doing the mock up with the wheels, I too want to stay with 16" 8 lug steelies and will be on the lookout for a set of Innies as well.
Last edited by The Dassler; Apr 29, 2026 at 10:00 AM.
You will have no wheel fitment issues.
Do you know what truck the doner was besides a 74 F250? Extended cab, extended wheel base, camper special, etc. This will help you down the road when obtaining parts. I have the dual piston calipers (8800GVWR IIRC) and love them. I'm assuming you are also converting to a dual reservoir MC too? My doner was a 76 so I bought the MC and booster for that. I have a rear end from an '81 with ginormous drums on it that was also an option in 76, so it all works together as a system, as designed by Ford. Get all new brake hoses. Your 66 will have a brake distribution block which is for drum brakes and it not a proportioning valve. I made it work for years without one though. You will eventually want to add a proportion valve from Wilwood for installation in the rear brake line. It's adjustable and not very expensive. You will need to fab a mount and switch for the brake lights.
Update and questions:
I finally got the front suspension bits off yesterday. They are HEAVY and it was more of a challenge with these bigger rotors than I recall with my F100.
Question 1: Do I reuse my '66 F250 springs or the '74 F250 springs? The '74 springs appear to be a little longer and the ends look like the coil narrows more than the '66 springs. I ask because the upper spring perch differs between the two trucks.
I retrieved all the front brake lines and the one rear brake line up to the point where it has a connection about mid-truck length. With the exception of the left and right brake lines, all the smaller lines were kept intact so no guesswork as to how to reconnect them between the MC and proportioning valve is required.
Question 2: As I understand the process, I will be removing the original brass distribution block located below the steering box and installing the proportioning valve that came from the '74 that is located below the master cylinder. The brake lines from the '74 look in good shape so I hope to clean them up and reuse them. The only modification I need to do is shorten the rear brake line and join it to the existing rear line on the '66. Oh, and I will install the '74 brake line brackets and likely remove the existing '66 brackets.
Question 3: I suppose I can tee off the pcv line for the brake booster vacuum? or is there another source? It's a 240 engine.
It appears that I will have to use tie-rods and drag links specific to the '74 F250 7500 GVW specs henceforth with this truck. Don't know how I can convey that to the next owner when that time comes; and we know it will someday in the future. I've also read, I believe in the fordification article that I will need to use the pitman arm off the steering box from the '74.
Question 4: Does it matter if I search for new shocks using the '66 or the '74 model years? I've heard KYB Gas-adjust are decent shocks and Monroe's don't last. Comments?
I have all the power steering bits off this truck and will set it aside for now. My recollection was that the steering on the '66 was fine without it with the six-cylinder engine. I removed the pulley from the crankshaft just in case it's specific to the power steering set-up.
It appears I'll be buying another Long Pilot adjustable reamer as the Kingpin is larger on the '74 as well, sigh!! I'm not looking forward to beating the snot out of it to remove it. Oxy-acetalyne helps. It took me the better part of today to merely disassemble one I-beam down to just the spindle.
That's all for now. I'm getting too old for this kind of effort but I need a functioning truck.
It appears I'll be buying another Long Pilot adjustable reamer as the Kingpin is larger on the '74 as well, sigh!! I'm not looking forward to beating the snot out of it to remove it. Oxy-acetalyne helps. It took me the better part of today to merely disassemble one I-beam down to just the spindle.
That's a lot of questions. You need to use the "I" beams from the donor truck that way the kingpins and the steering stops match the spindles. As far as the pitman arm you will just need to mock it up and see if it will work as the manual and power pitman arms were different in 74.
If you do install the power steering box pay close attention to the steering box coming in contact with the spring tower before it is tight against the frame. After Ford started using the Ford/ Saginaw box they started putting an indentation in the spring tower to give clearance for the bigger box the early trucks don't have that, and you may have to heat it and beat it for clearance.
It appears I'll be buying another Long Pilot adjustable reamer as the Kingpin is larger on the '74 as well, sigh!! I'm not looking forward to beating the snot out of it to remove it. Oxy-acetalyne helps. It took me the better part of today to merely disassemble one I-beam down to just the spindle.
That's a lot of questions. You need to use the "I" beams from the donor truck that way the kingpins and the steering stops match the spindles. As far as the pitman arm you will just need to mock it up and see if it will work as the manual and power pitman arms were different in 74.
If you do install the power steering box pay close attention to the steering box coming in contact with the spring tower before it is tight against the frame. After Ford started using the Ford/ Saginaw box they started putting an indentation in the spring tower to give clearance for the bigger box the early trucks don't have that, and you may have to heat it and beat it for clearance.
This is what is so great about this site, Thanks @Crop Duster for sharing your knowledge. I will be looking for parts to upgrade my '66, and all that you have written, is valuable information for this newby.
@jalls1 , don't give up, also, thanks for sharing, the fact that you are asking questions that make sense, shows you are on the right track. That and keeping record of what you swap for the "next caretaker" is right on the money. I have been reading a lot of older posts from 20 some odd years ago, and think I had seen more than one, where the OP had no idea of what parts were on his or her truck from previous owners. Wait a minute, that could also be me... So, smart thinking, maybe add the build plate information from the donor truck to your paperwork.
@jalls1 , so I have a question for you, and hope that you will be able to confirm something for me. Do the spindles from your '74 donor truck, have parts number "3105" on the right hand side, and "3106" on the left hand side? This might lead to some other questions, but I will start there for now.
I'll let him answer what his shows but in general 3105 and 3106 are the base numbers of the full part numbers for the left and right spindles. They are often stamped (cast) with base numbers 3107 and 3108 which are the engineering ID numbers
C5TA-8-B and C5TA-9-B which expand to C5TA-3008-B and C5TA-3009-B. These are part numbers C6TZ-3006-C and C6TZ-3007-C. The MPC should show all of this info, too, with more examples of stamped numbers as they changed. You wouldn't see a stock 1965/66 with the C7TA or C8TA, of course, since those are for newer trucks.
Oh, also for Matt. If yours is the typical 1966 F250 Camper Special yours likely has the newer design integrated spindle and steering arm so to do disk brakes you only need everything external of the spindles - the backing plates, rotors, calipers, brake hoses and their brackets and hardware. Your spindles are already the style most likely that accepts disk brakes without changing your axles or spindles.
Read this thread. What @Boss9F100 says should likely apply to your truck, too. In his post #9 second picture right hand side is the spindle with integrated steering arm. Only 1961-1966 F100 or F250 with them integrated, otherwise the steering arms bolts to the separate spindles.
That's why for the spindles with integrated steering arms there are two different part numbers instead of one. The steering arms on each side point rearward and no way you can do that with one part or part number.
If you have the upper brake size then you need newer spindles but if you have the lower brake size you can see the same setup is used for both drum fronts and disc fronts. Makes it much easier as you can use your existing axles, spindles and radius arms. People with 1965 F250 trucks and 1966 F250 trucks with the lesser surface area brakes have a lot more work to do.
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