Build Thread '83 T-top Coupe - Welding Holes in My Rear

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I'll keep an eye out for an IRS down here in DFW... if you're going to do it you really should only look for an 03/04 as it's stronger/better than the 99/01.

You definitely want an 03/04 unit, mostly because the 31 spline axles are stronger. The brace is also another benefit, but that can be purchased aftermarket. IMO, you will definitely want to upgrade the diff. cover to the ford motorsports version for the additional support it provides to the carrier/bearings and the extra strength in the diff. mount.
 
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Yeah, I got to try to get through to him. Good idea.


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Blend and Bend the two....Just do eeet without damage to limb. Thou shalt not maime thyself for a rightoeus IRS mit 315 mmKing of Tyre.


See Page 5 https://www.stangnet.com/mustang-fo...a-build-finally-im-moving-again.871263/page-5
And Post #271 to#277 , Page 14. https://www.stangnet.com/mustang-fo...-build-finally-im-moving-again.871263/page-14


More stuff:

It's funny how my "plan", and reality are so far apart. I expected to get a whole bunch of stuff done today, but after spending the entire day down there feel I have little to show for it.

The plan was to mock the rear end up using the old stock control arms, to be sure that it was properly located. Once that was done I intended to build the upper and lower shock mounts, and finish the wheel tubs after that.

Ha!

I did get the rear end located.
Starting on the driver side, I "eyeballed" where I wanted to hang the shock, and marked the frame rail. The shock needed to be moved inboard to the extent that I was gonna have to notch the frame rail.
I just happened to have some 3.5" .125 wall tubing from some other past project, and decided to cut it in half, and use it to build a tunnel in the frame.
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The tunnel ended up being so deep, that it compromised the integrity of the frame rail. I used the other half of the tubing to build a backer, to restore the section I cut out.
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I still plan on fabbing some additional "out riggers" made out of .125" plate, and weld them to the inner semi-circle, to add additional width to the frame rail. I'll add one in front, and one in back. When done, it should just look like a bend in the frame there.
I bought single adjustable aluminum QA-1's. The adjustment knob has 18 positions. I've used these shocks on two other cars, including the last fox mustang. This time I opted for the street shock. The only real difference is how it's bushed. The race shocks, use a heim type end, these use some sort of hard rubber to house the eye for the bolt. The shock is supposed to be installed at a "ride height" of 13.75." Locating the bottom mount in the stock location would require that I lean the shock in pretty dramatically, and I did not want to do that. Instead, I built a lower shock mount inboard of the stock location.
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I built a 3/16" end cap, and welded the short piece of 1.25" .125 wall tubing to a piece of plate I welded on top of the frame rail. I added a front support that is welded to the frame rail. I know that there is now significant added stress at that mount point due to it becoming a part of the support system for the rear of the vehicle. When the tub is re-installed, I intend to add additional reinforcement after that.
After I got it all welded up, I assembled the shock, and mounted the shock.

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Then I loaded the chassis (as much as you can load a completely stripped chassis)
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This is all I got done. I worked on it from 9 AM till 5 PM to get to this point.

Oh,....I did manage to do one, other, thing................
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hand slipped up the angle grinder while I was cutting some of the stuff today. Cut has to be 1/16 deep. Because it was a cutoff wheel, the cut actually self cauterized, and didn't bleed.

Weird.:shrug:



Do thou likewise.....
 
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God bless you, Dave.

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General consensus is the IRS weights about 145 pounds more than a SRA, and reduces unsprung weight by about 125 pounds.

Ya just took a dump in my cheerios with that one. I had no idea it was that heavy. I could have sworn I heard 40-60 lbs weight difference.
 
Those KB lower arms are expensive.... so are the custom coil overs that have to go with them. Guess it would all be under $1500. Not bad to get a 335 back there.

If i saw one spec of rust in the back off my car it would be tubbed quicker than a cat can go through an e fan....

Right now, it's all clean metal, so no cutting off anything.
 
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So much room is liberated with coil overs and combined adjustable spring perches.....


Even stock racing Mustangs from 1983-1987 gain room for bigger "meats"




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Anti roll bar doesn't have to go where FoMoCo decreed it should, nor do the IRS exhaust, the gas tank, and you don't have to hog out the frame rails as much as CMA did.

Bottom hanger exhaust systems are a traditional method of getting pipes out, Jag IRS style. But you can have it done Live axle style if you pancake the dual pipes, and shift the Anti roll bar and the blessed Cats Cradle of Cobra-doom.

Doing it this way is easier with a custom cats cradle.


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MM like the concept of do minimum changes that add integrity to Fords original engineering game plan. A hard tail IRS is what works, and the coil damper units don't need a whole heap of gas axe work to make room for the so called 315's.

I'd say 335 or 345's would fit without flares if you used angled in spring damper units, you could even run quad dampers, IRS Jag style.
 
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Ya just took a dump in my cheerios with that one. I had no idea it was that heavy. I could have sworn I heard 40-60 lbs weight difference.

I also had heard anywhere from 60-80 pounds when I first started researching. Once you actually weight the entire setup and compare it to a fully fitted SRA it becomes pretty obvious. That 145lb number comes from guys that have swapped the IRS out of their cobra for a SRA, and weighed the entire car before and after with no other changes. Seems the lower numbers comes from people not taking into account everything that is removed and/or added.
 
I also had heard anywhere from 60-80 pounds when I first started researching. Once you actually weight the entire setup and compare it to a fully fitted SRA it becomes pretty obvious. That 145lb number comes from guys that have swapped the IRS out of their cobra for a SRA, and weighed the entire car before and after with no other changes. Seems the lower numbers comes from people not taking into account everything that is removed and/or added.

Ah, I see... So I wasn't just imagining things. Thanks.
 
Waaaaaaaaaay back when, I joined both. For whatever reason this place grew on me where that one didn't. When it stopped being supported (after it changed from private hands) it went completely to hell IMO. It actually better now being neglected than it was at the height of lunacy after it was sold.
 
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