Hi all,

I went scrounging through a boneyard the other day and found a '67-'69 bumpside 1-ton dually. Now, me being who I am, I began thinking. I could tell this, because I smelled rubber burning.

My F250 is a Camper Special, with the front disks. The dually had drums, of course, on the front.

I'm thinking of putting the dually rear axle under my truck, but also want to keep the front end matching, so that I can rotate tires (and carry one kind of spare...)

A few questions:

1) Are the spring perches on the rear leaf springs the same distance apart on the tonner vs. the F250? Meaning, can I swap in the heavier rear springs along with the heavier rear axle, without having to chisel the spring perches off the frame and move them forward (or backward?)

2) Are there any dually disk brake hubs, rotors, calipers, etc. which will fit on the F250 I-Beams? Meaning, can I keep front disk brakes, and still use the dually wheels? Perhaps replacing studs on the F250 hubs with super-duper-holy-crap long studs, and use a spacer to push the wheel flanges out to dually-wheel width?

3) I understand that the '70 dually wheels are "keyed" together, to keep the valve stems 180* apart, and to locate the wheels positively on the axles. However, I also understand that 16.5" tires are getting pretty tough to find. Are there adapters that will allow me to use a more modern 17" dually wheel (maybe from a Dodge or GM, since I seem to remember that Ford changed their 8-lug bolt patterns?)

4) Is there a stock application using the same rear axle, which I can scavenge for rear disk brakes?

5) What hydroboost brake boosters can be bolted onto the F250 firewall? I realize I may have to use a different master cylinder/proportioning valve.

6) Is there a difference in the heavy-dutiness of the F250 frame vs. the F350 frame in the bumpsides? I'd like to know, since it'd be fun to get the truck inspected afterward and get the GVWR bumped up to F350 levels officially.

I'm sure there are more questions I have to ask, but those'll do for now.

Thanks. :-)

--Silly

 

You should be able to bolt the front dually adaptors onto you existing hubs, or use I-beams from a 73-79 dually.
I'm working on a Dana rear disk swap, but there are kits out there that use off the shelf parts with a custom bracket to mount 78-79 Cadillac rear calipers.
If both trucks have the flex-o-matic rear springs, then it should be a bolt-together swap. If not, then you will have to move perches.
Grab the rear half of the driveshaft as well, it'll be different since the axle is considerably chunkier and the yoke should be bigger.

 

How can I tell whether the springs are Flex-o-matic? I know they're both leaf spring setups. :-) I suppose I'll have to take a tape measure back to the boneyard and go to town.

Thanks for the tip about using my existing hubs with the dually standoffs... much easier.

How about the sturdiness of the frame?

And does anyone repop flareside fenders, for turning into more-or-less matching dually fenders?

Thanks!

--Silly

 

I just retrofitted my 70 F350 with a hydro boost. I took the hydro boost off about a 86 GMC 1 ton van. Built a stand off for it a bolted it in. Works great.

My leg got tired of the vacuum booster!

Steve

 

A 1 ton dually is an F350, not an F250.

Ford didn't offer an F250 with dual rear wheels till 1985.

The exact same disc brakes used on 1968/72 F250 2WD's were also used on like years F350's.

The discs were optional on all the F250 2WD's and F350's, they didn't come with the Camper Special package.

All dual wheel F350's were only sold as a Cab & Chassis till 1980, when Ford offered a Styleside pickup dually for the first time.

 

Never did I imply that an F250 was a dually in these years. What I said was, "I have an F250, that I'd like to investigate swapping a dually axle and rear suspension into. Will it fit?" I assumed that everyone would know that a 1-ton dually was an F350. Now, since you probably know as well as, or better than, anyone here (I've read many of your posts, and have until now had great respect for your contributions here,) can you tell me about the frame of the F350 vs. F250, and if the F250 frame specs out the same as the F350?

I wouldn't have thought they'd have offered an F250 dually at all. Go figure.

Cool. This, together with a previous reply, gives me hope for my little scheme working, at least on the front.

That's interesting. I'd never thought these trucks came with disks at all, until I looked under my Camper Special. Most of the posts I'd read here mentioned drums, unless someone also had "Camper Special" mentioned somewhere else in their post or profile. So, I figured that was a standard part of the CS package, and rarely optioned outside it.

Yep. That's why I was asking about flareside fenders, so that more-or-less matching dually fenders could be fashioned for the styleside bed.

 

Awesome. :-) Does the original master cylinder bolt on to the GM booster? Did you have to craft a different pushrod? What did you use to run the booster? Will the stock steering pump push enough pressure to run this and the power steering?

Thanks!

 

You have to use the GM master cylinder as the bolt pattern is a bit bigger than fords. Just used the same master cylender that would have came with the gm and two brass MC adaptors to get the MC fittings the same as existing. A guy could just reflair these.

No welding or other modification on the push rod as this was one of my objectives with the project as to ensure nothing fails. Also no welds are under tension. Really there are no welds used!

I used the original power steering pump… but just brazed in second return line into the back of the case.

The unit does work well although you can feel a bit of pulse which I think is from the aging pump. Other that that it took some pressure off the foot. I am stopping about a 10,000 lbs motor home.

Steve

 

So, do you have the pressure line teed to run both the brake booster and the power steering line, with returns coming from each of these?

Are there any kits that you know of which will adapt the GM pump to the FE motor?

Geez, I need to get a place to work, and get my welders and other tools out to Cali...

 

No.. the pressure line goes from the pump to the Hydro boost. Then there is a secondary line that goes from the hydro boost to the poser steering box. Both the hydro boost and the PS box have return lines.

I didn't look at changing over the pumps.. don't really see the need for the hassel of making brackets etc.

Steve

 

The topic in the title read "70 F250, Dually axles/brakes.."

Prolly 50% of the ppl here have no idea what is right and what isn't.

If someone said they had a 1985 F100 dually with a 3.8 V6 and a MX Cruise-o...someone else would chime in and say...yeah, that's correct.

 

Forgot to reply about the flex-o-matic- Basically, if you have a thing that looks like this:

Then you have flex-o-matic. If it just has a regular shackle at the rear of the leaf, then it's not-

 

Schweet. Thanks! I'll have to check out my truck tomorrow, and hit the boneyard after payday to check the other truck.

Do you know about the heaviness of the frame on the F250 vs F350? I.e., would it be worthwhile to do this, and would my truck then be as capable as an F350?

If I recall correctly, the cab&chassis dually rear will be narrower wheel-to-wheel than the single rear wheel. Would this mean, then, that the bed simply will not fit down over the tires, if this axle were on the truck? If so, are there later-model F350 dually rear axles (especially those with disk brakes) which have the spring perches the same distance apart, and which will essentially bolt on? Or will I need to grab a Dodge rear (to keep the same bolt pattern,) and get the spring perches welded on?

Hmm... if the dually wheels are keyed together for the rear, are there notches in the axle flange that these wheels "key" into? If so, do the front-end standoffs also have these same registers? Is there an adapter somewhere that "smooths" these registers out, to make the mounting more wheel-centric than hub-centric?

So many questions, but I'm still trying to learn. :-)

I'd really love to get some advice on a propane 390, too...

Thanks!!

--Silly