New to this site so I hope this works but I was looking to convert my 2wd 81 f100 to a 4x4. I have found an 81 f150 for sale cheap. Could I buy a 81 f150 4x4 and use it's parts it's to make mine 4wd? If so, would I have to make any modifications to make the parts work? I don't know if there is any differences in the body or anything that would need to be changed. And if not an f150 would parts from a 4x4 f100 interchange? Any info would be valuable. Thanks.

 

Extracted this post from a pre-existing thread and crated its own (on its own topic).

 

There was no such thing as a 4x4 F100 from 1980-83, so that's out. The major difference between the 100's and 150's was a 5x4.5 lug pattern vs 5x5.5 and brake size. If I were you, I'd find a set of F150 4x4 axles from 1980-1996, they'll bolt right in. Then you'll need to find a transmission, transfer case, and driveshafts for the 4x4, which could come from the donor truck if it is the correct setup for an '81.

Somebody who knows the specifics of a 4x4 swap will hopefully help with the other details, just wanted to throw that bit of info between 100's and 150's in the open.

 

My '83 F100 2wd has 5x5.5 bolt pattern but it has steel axle beams instead of the cast ones of F150s. The donor truck should give you everything you need to do the swap.

Heres a good thread on the conversion.
https://www.ford-trucks.com/forums/8...er-lariat.html

 

yes it can be done whats wrong with the 4x4 doner it would be so much easier just to get that one running

 

SAVE for the select few F100's that have manual brakes or a high GVWR, but in general they are 5x4.5.

 

INAZ - Welcome to FTE. Yes, what these guys have said about the swap and the diff between an F100 and F150 is right. But you are on the right track by buying a complete truck to do the conversion. It will be both less expensive as well as less of a pain - assuming you get the donor cheaply.

Since you have to have matched front and read differential ratios you will be stuck with whatever the donor has - unless you have deep pockets to buy new diffs. And that will typically be 3.50:1 in most 4x4's, although it does vary. That could hurt your MPG but it is probably better than what your F100 has as they tend to be high geared. And if you swap the whole axle assemblies you will get the larger 5.5" bolt pattern as well as the larger brakes.

 

Your only problem may be the engine/tranny combo. If you get the donor, everything is a bolt in, no problem there. The f150 4x4 will have 3 inch wide rear springs, your f100 and the 2x4 f150's have 2.5 inch wide springs. No problem there, just bolt in the 4x4 rearend on your 2.5 inch springs, unless you want to drill and bolt the 3 inch wide springs hangers on your frame and use the 3 inch wide springs.

Back to your engine/tranny. You will need to use the 4x4 tranny from the donor. It's the only tranny you will have that will let the transfer case bolt up. But what engine do you have in the f100 and what engine does the donor have? For instance if the f150 has a 351m, and your f100 has a 302 or 300 six, it's a no go on the tranny. But everything else will work, just the tranny in that scenario would not bolt up to your engine. But if the donor has a different engine and a good tranny, you may be golden.

One more thing; The trucks need to be the same wheelbase. If they are not, everything will still work except the driveshafts.

 

>> I bought a 1985 Ford F250 4X4 for 500 dollars from a farmer in Western North Dakota. The body on it was beat up beyond all recognition. But the chassis was good and the gear boxes and axels were good. It had a 460 V8
in it, got rid of that....

>> Then I bought a 1986 Ford F150, the body was nice shape , absolutely
rust free. And it had a 300 6 in it.

>> I took the beat up body and threw that away. Then I installed the 300 6
into the F-250 chassis. Then I set the good rust free cab and box on that chassis.

>> To me this is the easiest way to change over to a 4X4.. And as a bonus, I had some scrap metal left over to sell to the scrap yard. And some extra
parts.

>> The only issues I have now are a leaky steering sector, 2 dirty fuel tanks,
and the doors need new seals. I am close to being done with my Ford, I hope to have it done this summer.

>> Good Luck to you and your Ford, don't give up on it. If you get frustrated, just let it sit for awhile and go back to it refreshed with a
clear head.

LeRoy

 

The above is one of the problems I was talking about. One of his trucks had a 460 and the other had a 300. If the tranny was a 4 speed, he had to source another bellhousing. If it had a automatic, he had to get another tranny. He did not mention that part.

 

That is one of the problems with Fords - they changed the bolt pattern on the bell housing with most engine series. So, INAZ, here are the ones that match:

• Small-block pattern: Includes 300 six, 302, and 351W - and the 351W appeared in 82 on these trucks
• 335 Series: Includes 351M and 400, which were used through 81. Technically this is the same pattern as the 385 Series, but the flywheel is in a different place so it isn't always an easy swap
• 385 Series: 460
• Diesel

On top of that, the engine perches, which are bolted and riveted to the frame, changed between engines, not series. So the perches for a 300 are different than those for a W, which are different than those for an M, which are .......

 

Both trucks had a manual transmission.

I hired my cousin to do this work, and trust me, if there were any extra
work involved, he would have let me know about it .. My cousin has an
auto wrecking yard full of Fords.

 

Well he forgot to tell you he went out and got a different bell for it.

 

And, as you've already pointed out, that only works with some manual transmissions. The automatics have an integral bell, as do some manual transmissions, so can't be swapped.

 

Maybe because he kept that 460 V8 for himself, he didn't mind going out in
the yard and finding a bell housing.

I did some of the work myself. I took out all the bolts to remove 2 truck boxes. And I removed 2 front clips.