Who makes and where can I get a dually conversion for my 88 F250?
thanks guys!

 

get a dana 80 axle thats the dually by dana

 

Ford never produced a dually F250 you would have to use a F350 axle and the you have the problem that dually frame rails are closer together.. and different wheels front and rear.. there are several places that sell conversion kits JC Whittney comes to mind... I am sure there are more..

 

The second truck in my signature is a dually conversion. It has an F350 dually bed on it and and F350 rear axle under it - or so the PO told me. I was told by others that the frame rails were closer together, but I'm not so sure that is really the case. I have the original axle that came out of the truck and took a few measurements. The spring pads on both axles are 41.5" apart (measured inside to inside). This makes me think that the frame rails must be the same distance apart - unless the dually has some special shackle mounts on it to move the springs farther outboard of the frame rails.

The only measurement I found to be different between the two axles is the length. Measuring from brake backing-pad to brake backing pad, the SRW axle was just over 57" and the DRW axle was just over 61". A 4" difference to accomodate the deeper inset of the inner rear wheels for the duallys.

 

If the truck left the factory with a bed installed, the frame rails are 37.5" wide.
Dually rear axles are 4" wider than SRW axles.
If the truck left the factory as a cab and chassis, the rear frame rails are 34" wide, you can run duals on an axle that is the same length as what is under a SRW pickup.
The spring perches are different on the cab and chassis axles, but the backing plate to backing plate measurement is exactly the same as your SRW pickup axle.
You can get spacers that let you run duals on a SRW axle and they are fine if you are towing trailers and want extra stability.
But if you are going to carry weight in the truck, the spacers cause a wierd bearing loading that is not good. The weight is all carried on the outer bearing and the inner bearing always has pressure on the top of the bearing. Not a good deal.

 

Sweet, I will probably be towing with a trailer 95% of the time. I have always wanted a dually, but I came across my truck froma friend at work. He said he was tired of having a diesel. I looked at the truck and it is rust free, perfect interior, and an IDI that ran like a top. I knew that similar trucks here in kansas go for $4000 to $5000 easy. I asked him "how much"he said "$1500 and its yours, im tired of its cold starting B.S. i said "Ill have the cash tommorow. HEHE. If I can convert it to dually, itll be my dream truck. Im even up for buying a salvage f350 dually axle if I have to. Ill need to get a new box too, a dually box. But atleast its an achievabe goal!!

 

Actually the 88 just used fender flares, the box is the same.
You have to trim the wheel opening out larger for clearance though.

 

Is it 2WD or 4WD? If it is 4WD and 3.55 gears, BE WARNED that an F350 DRW axle with 3.55s is hard to find. I'm starting to think that they weren't even an option from the factory - or at least if they were, they were a very rare option.

If that is the case then you are looking at a gear swap. This is a dilemma that I am currently dealing with. Do I re-gear my rear axle to 3.55s or do I swap in a 4.10 front axle and start looking for a used OD unit to get back my fuel economy for 2WD driving on the highway and around town when not towing?

A re-gear of the rear axle seems to run about $750-$1000. Fortunately there is another guy locally who has just the opposite problem as mine - he has a 3.55 SRW rear and 4.10 front. We're looking at possibly doing a front axle swap to resolve both our gearing issues. This will be a very economical solution - just a lot of work.

But then I'm still going to need to find a reasonably priced OD unit. The good news is that I'll end up with the best of both worlds. The bad news is that the OD is going to be about the same cost as re-gearing or possibly even more.......

 

[QUOTE]
Exactly, Cab and chassis frames are narrower.

It seems like that around here rear ends out of regular duallies are not easy to find. Cab chassis aren't to hard.

 

My truck is a 2WD with 3.55 ratio. If an axle costs too much money, then I may go with what Dave is saying about getting fender flares, and the dually spacer kit. Since I wont be doing any heavy hauling on the truck itself, just on a trailer. which reminds me... on my lunch break tommorow I need to finish up my NC program to make me a new hub for my trailer. Screw buying one, Ill use some 15-5 stainless from the scrap bin...lol anyways, hey.. Dave, with that spacer kit for dualies, is it just an aluminum spacer plate to add space between the 2 tires? If thats all it is Ill just make a set of those at work, we got several Mori Seiki mills and several lathes as well, all I need is dimensions, and its on like donkey kong! LOL
Thanks guys!!!

 

To make the spacers you have to use steel.
The spacer bolts against the brake drum and the studs have to be cut off flush or below the face of the spacer.
The spacer also has 8 studs that are located between the factory studs.
The new studs are what you bolt your wheels on with.

The problem is the depth of the inner bud wheel. It puts the wheel and tire into the spring leaves. The clearance there is also one of the reasons you can't run wider tires on a dually. The other reason is the clearance between the tires.

I actually have seen several dually welding rigs here that have 4 spacers on the rear axle. Dually axle to start then 2 against the drums and 2 between the wheels. They were running 315 or 325 mud tires with that setup on a dually. Those boys usually only have about 4000 pounds on the truck, but the places they go with them are unreal on pipelines and drilling rigs.

 

I like the sound of that. Think I've got an idea of how I can use plate-type spacers, and maybe longer lug-studs to run 265/75/16s in the back.

Lessee, 30 mm wider tires with half of that width to the inside = 15 mm, just about .6" for the inside spacers. For in between the wheels it would be double that - 30 mm, just slightly less than 1.2".

So about 1.75"-2" worth of spacers total. IIRC the existing lug-studs are about an inch longer than they really need to be, so if I can find some that are an inch or so longer than stock.....

I'm thinking steel plate, cut into rings on a lathe to be a really snug fit around the hub with holes precision drilled to just barely slip over the existing studs.

What do you think Dave? Would it work AND be safe? Not for heavy hauling, just for towing. I'll probably never haul more than a couple of tons in the bed.

 

Actually the Ford wheel is hub centric.
The load and wheel centering is done by the hub, not the studs.

265/70-16 tires are shorter than 235/85-16 tires.

 

That's good - that means my idea would work just fine.

True, but if you read my post again, I said 265/75/16. By my calculations

265/75/16 = 31.65" diameter and
235/85/16 = 31.73" diameter

Right about 1/8" difference - not enough height difference to matter. But 1.2" wider tread on the ground - on all 4 rear wheels - that should matter enough to be worthwhile...

 

Arrowcraft makes a nice dually conversion kit. I bought and installed one on an 89 f350 7.3. These spacers are high quality "superduty" parts. You'll question the price until you see the parts. I've hauled a lot on this truck and never had any bearing issues.