Devils, Details and Weight Reduction



There are many things I could call this exercise. A party is not one of them.

I've spent three days crammed in the axle well of this 1989 Mustang with nothing to keep me company beyond a trouble light, a DeWalt drill on the very last of its legs and billion razor sharp, red hot slivers of metal with an affinity for my most sensitive of regions. My joints are raw from crawling around on the concrete. I'm half deaf from the shriek of the spot weld cutter and the boom of the cold chisel and hammer.

There are many things I could call this exercise. A party is not one of them. You see, after test-fitting the independent rear suspension from a 2004 Mustang Cobra into the old Fox Body I was left with the really challenging portion of the install: the details.

Technically, I could have simply plumbed some brake lines, said, "screw the emergency brake," dropped in a driveshaft and rolled, but I want this car to function in all the ways a road machine should, while still being able turn a decent lap on a road course. Combine that desire with a compulsion to scrape every ounce of unnecessary weight from the Mustang, and the result is me doing my best impression of a hammer-wielding Quasimodo, contorted into the void where the rear suspension should be.

Need to catch up on Project Ugly Horse? Take a look at the earlier posts here!
This all started logically enough. The old bump stops had to be removed to allow for proper suspension travel, so I sourced a cheap spot weld cutter and got to sending the old rubber bits to the scrap yard in the sky. Or, more precisely, to the scrap yard on Central Avenue. The parts came out with only the slightest bit of persuasion, which inevitably reintroduced me to a familiar old foe: unearned confidence.

Vestigial Brackets
Removing Brackets

Deleting the solid axle from the car had left me with a few bits of vestigial bracketry stuck to the floorboard with what appeared to be a haphazard smattering of spot welds. The backing plates for the old rear seat belts and the mounting points for the rear control arms sat there like a bunch of freeloaders. More importantly, they prevented me from cleanly routing new hard lines for the brake system. All told, the bits couldn't have weighed more than king size Snickers bar, but by glory, I wanted them gone.

Imagine sitting inside of a 50-gallon steel drum while an army of pipe-wielding toddlers wailed on the exterior.

After destroying every last tooth on my el cheapo spot weld cutter in the span of around six seconds, I broke down and purchased a quality tool from a local parts store. I also brought home a passel of extra cutting heads just in case, drew the shades and settled in for my new life as an axle well troll. I found that using a punch to set a center point in the weld itself did much to keep the cutter from walking, and all that remained was hours and hours of patient, diligent cutting. Wrapped as the control arm brackets were around the trunk pan of the car, some of the welds weren't accessible with the drill, which meant I was left to hammer the pieces off of the car with a cold chisel.

Imagine sitting inside of a 50-gallon steel drum while an army of pipe-wielding toddlers wailed on the exterior with all of the determination and persistence that particular age bracket is renowned for. Ear plugs can only do so much.

Still, I eventually succeeded without the neighbors setting fire to the house. I ground down what was left of the spot welds, cleaned up the 23 years of axle grease slung around the underside of the car and shot the whole thing with white industrial Rustoleum to keep the metal from going rusty. That just left me with sorting the brake lines. From the factory, the Mustang uses one hard line to supply the rear axle with hydraulic pressure. My new set up required two hard lines, so I picked up a brass T junction, mocked up my routing with some wire, picked up a few lengths of brake line and got to bending. Once I was satisfied with the way the lines looked and confident everything would fit in place without any interference, I mounted everything with a few plastic clips and self-tapping sheet metal screws. Another trip to Royal Brass and Hose served up a functional set of braided stainless brake hoses.

Finished Rear Brake Lines
Emergency Brake CablesBrake Line T-JunctionBraided Stainless Steel Brake Lines

Once done, I reinstalled the IRS cradle with only a modest amount of cursing and a more than a little help from a transmission jack. Let me just say right now that Harbor Freight makes an excellent example if you're low on cash. With the rear suspension resituated, I could turn my eye toward the emergency brake. Getting the more modern cables to cooperate with the ancient chassis was as simple as routing them up and away from the driveshaft. I used two of the old retainers to bolt the cables in place, and while the set up doesn't provide as much tension as the factory allowed, it will hold the car on a hill. Still, I'll probably leave the machine in gear as a safety precaution until I can come up with something better.

That left just one very crucial part of the recipe: the driveshaft. As you may recollect, I had been using an old salvage piece from a GT to pump power from the T5 transmission to the old solid axle, but the independent rear suspension meant the rear flange would no longer mate to the differential. Never one to pass up an excuse to upgrade, I turned my lust toward an aluminum Ford Racing driveshaft. Shut up, Freud. You don't know me.

Ford Mustang Driveshaft Comparison

Not only did the new piece weigh in at 15 pounds, but it also came with brand-new universal joints throughout. Now, I ordered a driveshaft that would fit Mustang GT models built between 1979 and 1995. The part offered the correct spline count for the transmission and was the correct length, but came with the foreboding warning that it would not under any circumstance work with a Cobra of any ilk. Under the presumption that, like Freud, the internet doesn't know me, I clicked buy and waited patiently for the UPS truck to show up at my door.

Once it did, I quickly found out why Cobra models were a no go. The companion flange on the IRS differential is simply too large to bolt to the flange on the driveshaft. One call to the Mustang salvage shop and $20 later, I had a GT flange that would party. In the photos below, the GT flange is on the left, the stock LX flange is in the center and the Cobra flange is on the right.

Installing the Driveshaft
Mustang Companion FlangesReverse Companion Flanges

Use too much or too little torque and you'll soon be picking bits of ring and pinon gear from your fancy 8.8 rear end.

All that was left was the tightening, as they say. Or so I thought. As it turns out, the companion flange is held on with the pinion nut. Smart mechanics mark where the nut lies in relation to the pinion itself because there is one very important crush sleeve in there. Stick things back together with too much or too little torque and you'll soon be picking bits of ring and pinon gear from your fancy 8.8 rear end. Of course, I only remembered this the second the air gun stopped spinning the pinion nut off the differential, leaving me with no way to know where everything was situated from the factory. Sweet.

Some internet sleuthing served up the correct preload for the pinion, though there's still some possibility that the whole set up is borked. I may be forced to retrace my steps to make sure everything is sitting pretty before putting any real miles on the machine.

Complete Driveline

With the driveline complete from stem to stern, I had planned on focusing my efforts on getting the suspension settled. But projects like this have a knack for taking your plans, balling them up and setting them on fire with boundless glee – in the best way possible. Somehow, Ford Racing had gotten wind of what I was cooking up with Ugly Horse, and they wanted to know if I needed help finding something to put in the engine bay.

Why, yes. Yes I did.

Need to catch up on Project Ugly Horse? Take a look at the earlier posts here!


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    • 1 Second Ago
  • 63 Comments
      artandcolour2010
      • 1 Year Ago
      quite a cool project!
      Proghog
      • 1 Year Ago
      Would the new 3.5 ecoboost be too big for the engin compartment on this? Hopefully you keep a turbo in it to keep some forms of the SVO alive.
      Riley C.
      • 1 Year Ago
      3.5L TT Ecoboost? That would make that little car scoot.
      cdwrx
      • 1 Year Ago
      Is the next installment the one where we depart from reality? I'm pretty sure if I did this project, Ford Racing wouldn't be so interested.
        Brodz
        • 1 Year Ago
        @cdwrx
        Hopefully they just offer some suggestions. But Prince Harry has to fit the bill, or autoblog does. I just want more project ugly horse.
      Sanchez
      • 1 Year Ago
      Great stuff yet again! I have to say I was looking forward to the 2.3L turbo, but realized it was a compromise.
      groksf
      • 1 Year Ago
      Nah, he's got to do something simple for the engine. How about the I5 from the Europe only last gen Focus ST?
        Proghog
        • 1 Year Ago
        @groksf
        But the Focus ST was FWD.
          Stuka
          • 1 Year Ago
          @Proghog
          Ford does have a RWD version of the zetec. Don't think they have any duratecs though. And the 5cyl is FWD only.
      CharlesM
      • 1 Year Ago
      I was wondering why you were going to all this trouble building a G machine only to use the unreliable and peaky 2.3T powerplant, but now I understand. It\'s because you\'re a kid and you don\'t know any better.
        Sheldon
        • 1 Year Ago
        @CharlesM
        Yeah, right Charles? He should just throw a 350* in there and be done with it..... ugghhh *Yes I know that's a chevy engine, that's part of the joke.
        imag
        • 1 Year Ago
        @CharlesM
        I was just reminded of a great quote by Teddy Roosevelt: "It is not the critic who counts: not the man who points out how the strong man stumbles or where the doer of deeds could have done better. The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood, who strives valiantly, who errs and comes up short again and again, because there is no effort without error or shortcoming, but who knows the great enthusiasms, the great devotions, who spends himself for a worthy cause; who, at the best, knows, in the end, the triumph of high achievement, and who, at the worst, if he fails, at least he fails while daring greatly, so that his place shall never be with those cold and timid souls who knew neither victory nor defeat."
        Zach Bowman
        • 1 Year Ago
        @CharlesM
        I suppose it's better to not know any better now rather than later...
          • 1 Year Ago
          @Zach Bowman
          Why do we fall, Zach?
        Zach Bowman
        • 1 Year Ago
        @CharlesM
        I think that's the first time a TR quote has ever been levied at a beater Fox Body.
          imag
          • 1 Year Ago
          @Zach Bowman
          Hah! Probably true... :)
          carguy1701
          • 1 Year Ago
          @Zach Bowman
          First time for everything.
        imag
        • 1 Year Ago
        @CharlesM
        What a nasty comment. Did you have a dad who said things like this to you?
        • 1 Year Ago
        @CharlesM
        [blocked]
          Zach Bowman
          • 1 Year Ago
          I'd say I was sorry this thing makes you sick, Rob, but I'd be lying I made out like half the point wasn't to rile a few corners of the enthusiast world. Hang in there. It's going to get fun.
          domingorobusto
          • 1 Year Ago
          You are a boring person Rob. I bet you've watched the same 4 movies in rotation your whole life. Come on man, broaden your horizons a little.
      bke599
      • 1 Year Ago
      I love these posts. Props to my favorite autoblog podcaster (no offense, Dan).
      carguy1701
      • 1 Year Ago
      "Somehow, Ford Racing had gotten wind of what I was cooking up with Ugly Horse, and they wanted to know if I needed help finding something to put in the engine bay." WE CRATE MOTOR NOW
      SPcamert
      • 1 Year Ago
      I started giggling like a little school-girl when I read that last sentence. Can't wait to see what Ford Racing can come up with for you.
      telkinsjr
      • 1 Year Ago
      I really hope that the word "coyote" is in the next update. Either way, nice of Ford to call on you.
      The Other Bob
      • 1 Year Ago
      Of please tell me they will let you experiment with an Ecoboost 2.0. That would rock it and be unique. I want to put one in an old \'66 Mustang.
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