New Member 1986 XLT 4x4 5.0L

Hi,
I stumbled upon this site while searching for various F-150 topics and technical subjects. I appreciate the detailed info provided as well as the standards expected of forum participants and the basic decorum of the site. It is refreshing.

I am a dyed-in-the-wool car nut, now at the advanced age of 72. I presently have way too many vehicles for one person but they all "Evoke Joy". For me anyway. For Susan, not so much.

I am a dedicated troubleshooter and have bought many vehicles over the simply for the challenge of getting them back on the road. I tend to modify everything I buy but these days for me it is less about drag racing, road racing and autocross racing than about retrofitting and reverse-engineering advanced technology to older vehicles, especially when it comes to efficiency and enhanced emission control methods. I have a bunch of European and Asian vehicles as well as a smattering of hotrod Dodge motorhomes, a '73 Maverick, a '53 Studebaker, an '85 Eagle wagon, and several F-150's.

I'll buy a non-running vehicle that appeals to me for who knows why, transfer title to me and then have AAA tow it to my home after the fact.

I live on a very steep (paved) approach that becomes impassible with the snowstorms we sometimes get, not to mention the treacherous black-ice storms. I have capable 4WD SUV's ('98 Mazda MPV, '08 Kia Sorento) but I also needed an actual pick up truck to haul things around.

I have no interest in mudding, mechanical abuse of things I then have to repair, etc. I've grown weary of that approach. I have cars dedicated to that, to Solo I and II and Historic racing, but I am most interested in performance efficiency and reliability in the older cars that I upgrade to more modern technology.

Re the F-150's I have a '94 rwd long bed 5spd, an '89 extra cab long bed AOD, and an '86 long bed 4x4 (which is presently the problem child and reason I joined Bullnose).

wordy? Tolstoy has nothin' on me.

The '86 5.0L 4x4 is in relatively nice condition in general but had turned into the previous owner's diagnostic nightmare. I bought it as-is, disabled, with wire harnesses and components hanging down from the dash and a slew of new and used electrical components (ECU's, relays, switches) on the seats and floor as well as old and new electric fuel pumps, filters, etc...you get the picture...

I had to delay even looking at it for two years due to a back injury and subsequent major surgery but now I'm fixed so I dove into it. No fuel supply working, dual tanks whose lines/reservoir/etc had been hacked into badly. I decided to plumb just the front tank, eliminated the in-tank primer pump and inline pump and converted to a Walbro in-tank pump with three puck pick-ups (since the tank was of pre-baffle design). That resolved the physical plumbing, now on to the electrical situation. Nothing at the fuel pump relay on its own with ign/start but I could bridge the relay and activate the retrofit in-tank high pressure pump. The relay worked okay but it wasn't getting activated. I was tracing wires and circuits using electrical schematics and component location diagrams and I saw that there was an unplugged relay up under the dash, barely visible. Then I realized that one of the things hanging from the wiring harness was a new relay, of a different colored finish but with the same three colors of wires that would have plugged into the orphaned relay affixed but without attached connector way up under the dash.

Yep, you guessed it. The new ECC activating relay was just hanging there rather than being attached to a ground. One sheet metal screw to affix it to the under-dash metal; now an active relay; now ECC activation, which the fuel pump relay needs for its activation, and bingo: fuel supply.

But that wasn't the troubling issue that I am now faced with. I bought this truck without really scrutinizing it in detail, assuming it was okay except for the no-start issue.

While under there pulling the front fuel tank to clean it and convert to in-tank high pressure pump I noticed that horrible and unmistakable smell of axle oil. And the drip from the pinion flange. OK, so I put replace pinion seal on the to-do list and returned my attention to the fuel supply situation which I was resolving.

Today after reinstalling the fuel tank I reached over toward the differential, twisted the driveshaft back and forth, and discovered a Huge amount of lash. Plus I could wiggle the pinion yoke up and down. Whether the seal went out first and the po drove it low on fluid, or the pinion bearing failed and then the seal leaked is a mute point. Now what? It is an 8.8 3.55 open. Do I tear it down/rebuild it if it's not too far gone to do so? Or do I swap in a replacement rear axle assy? LSD and disc brakes would be nice accoutrements but I don't want to mess around with having to widen an 8.8 Explorer rear axle to fit.

So I'm wondering about just replacing the entire rear axle assy with something of the same width as mine. I see that '73-'86 F150's, E-250's and '78-'86 Broncos came with 9" rear axle assys the same width  as mine (65.25").

I have searched this topic which is how I found the details above but I have not seen addressed the issue of the disparity between the 9" available ratio of 3.50 vs my OEM 8.8 ratio of 3.55, other than 'just live with it and use 4x4 only on gravel, mud or snow'.

Four questions: 1) what if I replaced my transfer case with a viscous-coupled AWD? Would that attenuate the F to R ratio mismatch? 2) why not run slightly smaller diameter rear tires in the rear to effectively increase the now rear 3.50 to more closely match the OEM 3.55 front ratio? 3) is the '96-'02 Expedition 8.8 rear axle the same narrow width (59.50") as the '91-'01 Explorer? 4) Where do I find spring perch spacings of the donor vehicles which I listed?

This is not a race truck or off-road purposed vehicle, just a truck with good ground clearance to get around in and haul things in foul weather. Drum brakes are fine and I can live without a locking rear diff, although that would be nice to have.

My least concern is a disparity between 5x5.5" PCD and 5x135 PCD bolt circles or wheel offsets. Those are easy. Welding up modified length axle tubes and relocating spring perches is probably not cost effective for this vehicle. I'll search the local JY's for a good condition bolt-in 3.55 direct replacement but if they are scarce I'd like to know of other practical options in advance.

wordy? Homer has nothin' either.

Welcome!  

You certainly get your point across...

1) Never considered this, though I've never heard of anyone else doing it.
2) 75 v/s 85 R15 tires might accomplish this. There's plenty of calculators or the RPMile is shown.
3) I can measure an Expy next weekend. I know the front half is F-150 all the way.
Those Expedition axles w/ disc brakes will prove challenging to get correct line pressure and parking brakes working.
4) I pointed another member to the bodybuilder's handbook the other day, which shows the spring centerline as 44.49"
Yes, E-series and pre-'80 frames have different widths, and therefore spring/shock perches, but I don't know who has the book for these vehicles.

Welcome.  Glad you joined, for a number of reasons - one of which is that there is now someone wordier than I.  

Seriously though, we don't get charged by the word, so it isn't an issue from that standpoint.  But some of the guys quit reading if the post is very long - DAHIK.

On the axle ratio difference, you should determine what front ratio you have via the info on our page at Documentation/Driveline/Axles & Differentials and then the Front Axle tab followed by the Application List tab.  And I think you'll find that you have a 3.50 ratio as the 3.54's came in D44HD's and yours should be a regular 44 from your description.

If that's the case I'd find either another 8.8" or a 9" axle from an F150 and slip it in.  That's because Ford didn't exactly match the front/rear axle ratios in all cases.

As for "retrofitting and reverse-engineering advanced technology to older vehicles", I wouldn't know anything about that.  

And concerning the 72 years of age, I have you by 4 and Bill has you by 5.  Strap in 'cause the ride gets rougher.  

Welcome!

RetroRockets wrote

...is the '96-'02 Expedition 8.8 rear axle the same narrow width (59.50") as the '91-'01 Explorer? 4) Where do I find spring perch spacings of the donor vehicles which I listed?

I don't think the spring perch distances will matter as the Explorer's have underslung springs, so the leaf spring pads are on the bottom off the axle tubes. I can't speak specifically about the Expeditions, but I did swap a 2001 Explorer 8.8 in to my 1952 pickup. I cut the old underslung leaf spring pads off (I left a tiny piece of each one intact as the caliper flex lines bolt to them). I welded new perches on top of the axles that fit my 1952 Chassis. I later added 1.25" spacers which also converted the 5x4.5 bolt pattern to the standard truck 5x5.5 pattern.

I'm a big fan of the 8.8 diff. It's very common, and you can find them pretty easily in the junkyards.

I'd personally look for one out of a 1987-1996 F150 or Bronco for ease of install.

Thank you all for the above replies.
 I'll be searching local JY's for the simplest bolt-in replacement swap above all. If I can't locate one of those in decent condition then I'll consider more involved options.

Something just occurred to me: what if the po had the pinion seal replaced but the yoke was mis-installed re sleeve crush and the result is a slightly floating pinion shaft (I can wiggle it a bit).

I'll drain the fluid and inspect it for bearing debris. But if it is clean maybe I could luck out, set the pinion bearing properly to eliminate slop, check the ring/pinion for undue wear, check/adjust lash and be able to use the present axle assy.

I'll report any progress in the technical/DIY subforums. TBC...