An Aerostar gets upgrades to tow at the maximum combined weight of 8500 lbs.
The target is to pull a 4200 lb Airstream, total rear axle load at 550 lbs, in western US mountains at up to nine-thousand feet, at 65mph.

Usually, I do my projects and then announce because, I hate being told something can't be done or can only be done THIS way.
But in this case I need to pre-announce because I am seeking useful contributions from people who have been towing for a while.

What has changed recently is that I gained welding machinery. If you haven't figured it out already, I'm a degree'd engineer and my area is actually electronics and software.

Here is my built-to-tow shopping list:
Done...
* All maintence and repairs up to date. Done.
* Tranny rebuilt to xR55 specs. Done.
* Heavy duty gas shocks. Done.
* Rear sway bar. Done but may get obsoleted.
* 17" wheels with XL tires. Done.

ToDo...
* A trailer hitch, built anyway I want.
* Review of trailer harness, especially trailer brakes. Can't imagine an '89 harness patching properly into a 2013 trailer.
* Tranny cooler. Easy.
* Stronger rear springs. In the works now but I suspect we end up at around 200lbs/in.
* Larger front bar, just to balance out the stronger rear springs. Easy.
* Beefier rear axle. Targeting Explorer 8.8 3.73 LSD. Could be a slugfest with perches and parking brake. The Explorer rear is the larger 31 spline with larger bearings. The Aero 8.8 is the smaller 28 spline axle, same as the 7.5.
* Change of diff, requires change of tranny speedo gear.
* Rear disc conversion. Comes with Explorer axle. If the axle doesn't happen then I can hack in the conversion.
* If rear disc conversion happens, then we need to swap in the Explorer master cylinder to get the proper f/r balance.
* Larger front brakes. Out: 10.29 Aero. In: 11.28" Explorer/ Ranger4. Skipped for now: Cobra or Stoptech 13", but they fit under the new wheels. Alt solutions require the stock rotors to be cut off from the integral hubs.
* New 15" spare wheel to fit over the larger brakes, with 23" OD tire to fit into the spare tire location, and has an mbz bolt pattern. Use of any ford wheel requires me to remove the adapter before mounting.
* Beefier front axle. This may end up being a 95-97 Ranger2, modified (if required) to take the larger brakes. The slugfest has started and i've taken a couple punches already.
* Any new axle will force an update to the wheel adapter to accomodate the larger hub. Luckily, the front hub steps down beyond 22mm and still fits inside the new mbz wheels. Otherwise I have to mod the wheels.
* Out: 3L Vulcan. In: SOHC 4L with mods and a sky's-the-limit pcm. Hope to see 240 hp, 270 ftlb. Skipped: A wide dohc 90degree V8 from bmw. Two to choose from, 340hp/350ftlb and 300/310.
* SOHC requires new bellhousing for frankentranny. Easy and planned upgrade path.
* Larger exhaust. Out: 2.00 for 3L. In: 2.25 for 4L. Pieces are here now. A fun welding project.
* 8 ft mirrors, or is live video a legal sub?

Probably, no one has any opinion, but what do you think?

 

Ambitious project for sure. Your proposed modifications will certainly help. I used to tow a 2 horse bumper pull trailer with our Aero but mostly to local events. I once had to tow into Wyoming and it was a tough go for a 4.0L on the grades. I felt sorry for both the beast in the trailer and treating the Aero like a beast of burden. It was a very uneasy trip. So much so, we upgraded to an Expedition for towing the hayburners.

At different times I used air lift shocks (Gabriel) and air bag spring inserts. The air bags worked better but did not last very long before the springs wore through the side. Looking over your mods, with the larger diameter wheels and new rear end, you are still going to need the biggest tranny cooler you can find. There will be some massive heat being generated by the transmission pulling that setup.

Keep us posted on the progress.

 

The stock front spindles limit what kind of brakes you can get. What will you be replacing them with? Something from the Ranger front end?

Will you be cutting much metal in order to jam the SOHC engine under the hood? I would have preferred the 4.4 DOHC v8 if I had that sitting around. Of course, I would also install 2.5" full-dual exhaust with a v8.

I think the OD of stock Aerostar tires are closer to 26.5", not 23", so you get to use tires with a little more sidewall rubber.

 

I've got a spreadsheet going on spindles and brakes.
We are looking for 1.375" front spindles from the Ranger2 '95-'97 or any Explorer2. Aerostar and earlier Ranger2's had 1.250" front spindles.
However, the style of the Ranger2 knuckle is vastly different from the Aerostar and the brakes are same diameter as the Aero, only thicker.
The Explorer2 knuckle is similar to that of the Aero, but key a few key dimensions are different. It looks like its the best starting point for doing welding mods.



The bmw DOHC is the one that would require cutting into the doghouse, plus I have to round up another 5HP24 tranny, do a drive shaft, do a 8-cyl pcm, and worry about accessory connections.
I figure the ford SOHC should dimension not too much different than the OHV and therefore should not require cutting.
The SOHC should just bolt up to my Frankentranny with a bell housing swap.
And I expect a certain amount of compatibility with accessories.

The 23" OD pertains to the spare tire wedged into the fixed space between the rear axle and bumper.

 

I've probably towed longer and harder than anyone else here.

Most of your efforts seem to be headed in the right direction. A few things though.

If you can confirm the specific Explorer axle you have selected is actually heavier duty. Stronger spider gears and more splines is a good thing, but if the wheel bearings are still too light duty, they will repeatedly fail and cause other problems. All of my historic axle problems were related to wheel bearings, and not to the diff itself. For the kind of weight goals you are talking about, I would look into a half ton axle.

Larger brakes is a must. I always struggled with brakes roasting with the weights I hauled. It would be interesting to see what you come up with for the fronts.

Cooling the engine will be a problem. I would switch to electric fans and a thicker radiator. This has to be done properly or it won't be an upgrade. Do NOT run pusher fans, pushers seem to cause the airflow to cavitate and recirculate, plus they fight the airflow at highway speeds. I personally recommend the Permacool fans, Flex-A-Lites have too low CFM and draw way to much power. You must have a proper shroud, just attaching the fan to the radiator results in poor airflow.

On mine I custom built the radiator and fan shroud. Mine does have a Flex-A-Lite fan because I had access to a low cost one (a friend had it for a custom project and ended up finding a better one for his setup) I think I also used a Perma-cool controller, the Flex-A-Lite fan controllers caused issues for me.

Also a radiator based probe for controlling the fan is not ideal, if you can trigger the fan off the coolant temp and not the radiator temp, it works better. On my Tbird I hooked up a temperature switch to trigger the fan. Running the controller off a proper coolant temp sensor is the best option. Some aftermarket computers can directly control a fan.

The 4.0L can in no way handle 240 hp unless seriously modified. If you contract Morena and let him know what you are trying to do, he can build you a motor that can reach those goals. With the right bore, stroke, compression, and a good porting job, it is quite doable. This saves the trouble of trying to fit a 4.0L SOHC motor (won't fit without modifying the firewall) or some other motor (won't mate to your trans without adapters).

I would recommend Timbren air stops. They are a good suspension upgrade. Obviously you need to match them to whatever axle you decide to go with.

17" wheels are towing are not a good combo. Running a low enough profile to avoid rubbing reduces the reliable weight handling of the tire, even if they handle the weight, they will wear way prematurely. I was very satisfied running Explorer 15" wheels, slightly larger than stock, but no rubbing, better ride, better weight handling, and no adapters or spacers were needed, everything was a direct bolt up. If you increased the clearance to run a taller profile, you would increase the load on the engine and brakes. A 15" tire is the ideal setup due to low cost, availability, load handling, etc. while still allowing for brake upgrades.

I have pulled heavier loads that what you are targeting and for the most part was able to maintain highway speeds of 65 mph or more with a few steeper grades being the exceptions. So it is doable. Again, the biggest hurdles I had were brakes and cooling. I never really got good brake upgrades, I dealt with replacing the parts. I did run a trailer brake controller, which did help a lot. The cooling system was a learning curve. I upgraded stuff as I found that certain parts were repeatedly inadequate. Unless you can get an older stock radiator, all of the ones on the market now are downgrades to the factory unit. The stupid cap on the second nipple was a source of repeated problems. I would also recommend moving away from a water based coolant. Evans Waterless Coolant does cost more, but for extreme situations, it has enough benefits to make it worthwhile. Lastly, I'm not sure if there are good solutions to the wheel bearings. With some machining modifications, it might be possible to run a heavier duty bearing. I never looked into that in great detail, but I did think about if it was doable.

 

I'm far enough along on the evaluations to make a fearless prediction where this is going to end up.

Exp2 11.28" rotor/hub, on the stock Aero spindle sleeved out to 1.375 to match the Exp2 inner bearing.
Outer bearings are shared/unchanged.
Caliper mounting ears on the Aero spindle get chopped/welded/drilled to bolt up the Exp2 calipers.
Seems quite doable and a pair of Aero spindles are now inbound.

 

While I like to tinker as much as anyone else, I wonder if in this case it's not easier to just get a full size van? Certainly you can upgrade a bunch of parts (engine, transmission, axles, brakes...) but you still have a pseudo-frame chassis that's not as strong as that of the smallest Econoline van. It might be cheaper than making all those mods on an Aerostar.

 

That is a valid point. I stuck with Aerostars for the AWD, but if you are ok with 2WD, the E series does have its hauling advantages.

 

The dream rig I fell in love with back in 96 when I bought this 96 lease back was a new diesel E350 4wdr loaded at the same lot.
But I already had a diesel Ford PU that I loved, the E350 diesel 4wdr also gave me sticker shock.

drove the Aero for years as a passenger/utility hauler, even pulled at 4,500 lb trailer with it for awhile.

moved on.

the Ford diesel PU is long gone, probably made into Kia's.
the old Aero still loves to go to Lowes and HD.

 

Trailer better have good brakes..450 lbs tongue weight seems enough to me. The frame isn't too stout back there. Timbrens. I would do it on the flat but not on hills. Big hills.

 

I finally caught on to what you mean. The trailer manufacturer specs a 660 lbs tongue on their 4200 lbs rig dry, but this is doesn't mean you have to tow at that spec. Moving back to the 10% rule gets us to 450 lbs. I will get back with the spring guys and modify the requirements downward.


I'm still thinking about it.
I'll study the mismatch again between a 90 degree dohc engine and a 60 degree ohv space, and try to guess at what's behind the sheet metal, etc.
It's a long shot but it would use up the engine.
The install would have to be reversable back to the Vulcan.
The dohc track is a little cheaper than the sohc. As mentioned, the dohc track requires me to buy another 5HP24 and the one I want is $2K.
So it's $2K versus about $4K for the sohc crate plus mods plus fresh accessories.
Highway economy would rise as high as 26mpg from the current 20.
There is either a cable operated throttle or an electronic throttle used on this engine. I have done some throttle controller designs but never ran them to completion.
Also electronic, is the 5HP24 tranny and I had not planned on getting involved with tranny control beyond overdrive and lockup TC.
So my EEC-IV pluggable is good for the A4LD but not the later trannys. Fyi, I do have a later electronic case and its possible to migrate Frankentranny forward.
This all means would have to do an EEC-V + throttle, which was not planned, but I suppose it would make '94+ owners happy.

Actual pic of the 340hp dohc v8 sitting in my garage. It all aluminum, so it probably doesn't weigh much more than the iron block Vulcan.
The base version goes onto the dyno tomorrow but common estimates are 300hp. (update: Dyno said it was about 280, the factory spec didn't lie.)
The 280/310 engine sends my 4200lbs bmw to 60 in 6.3 measured, so it should push a 3400lb aero there in <5.8, about half what it takes now.


Factory EEC-IV versus my pluggable retrofit.


Explorer brakes. Rebuild kit, fresh rotor, fresh inner bearing. Hawk LTS pads.


Edit: Not in the pic, the new outer bearing. And oops, forgot to procure the inner seal.

 

I guess if you have the motor anyway, but from a reliability or cost standpoint, not sure why you would want to put a BMW engine.

No way a 90 degree engine will fit, at that kind of width is not just about altering the firewall anymore. You will be intruding so much that you won't really have anywhere for the accelerator pedal or brake pedal anymore, really no leg room at all. Remember you need to leave enough room around the engine to get airflow.

This means in the space you are stuck with, you have to stick with pushrod engines, OHC just takes up too much width.

Or you could just do as I have proposed (and still plan to do when time and money permits) and that is to take a 2.3L Turbocharged 4 cylinder and fit it. There should be adequate room, though you will be relying heavily on the cooling system. The engine compartment however should end up being slightly less crowded, though I haven't done any serious measurements. The power of the 2.3L turbo is more than enough to get an Aerostar moving. If you did end up having to trim and modify the sheet metal to give clearance around the turbo, it would only need to be on that side, and it would be more accommodating than an OHC motor.

 

I checked again and the dohc v8 didn't shrink at all.
It's still 11 inches wider than the Vulcan and the sump is in the wrong place.
One would have to have a criminal obsession with V8's to spend time on it.
I can only gain about 3" on the drivers side.
Over on the passenger side, at a minium the entire hvac section would have to be gutted.
I just don't see another 8 to 10" over there and the engine would be too far off center.

The sohc V6 provides an adequate 210/255 out of the crate and lets me stay back on the EEC-IV.
I would rather spend time on cooling system and tow package.
Engine mods would be last priority.

 

But it is unlikely that the SOHC engine will actually fit, it is wider than an OHV engine.

 

I don't have access to a Cologne ohv or the sohc for measurements, but I'll find one before procuring anything.

Actually I do also have an extra 2.3L engine and a choice of compatible trannys just sitting around. (Update: negative on the tranny. It's a 722.4 and needs to be the bigger 722.3 for this app)
A turbo app would have to be developed because its rating is currently a peaky 170/165, just barely adequate for an empty Aero.
With enough boost it could look like the stock sohc.
The advantage would be that the turbo would maintain performance at altitude.
Sump is a problem again, AC is on the wrong side.



The Aero knuckles came in and the spindle sleave and bracket steel are inbound.