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

[bird_dog0347]

Dave I'm sorry I derailed your thread... but kinda not sorry. The main question is what do you want the car to do BEST? You really have to decide what you want the car to be great at and compromise from there. Me? I wanted handling and compromised straight line performance and comfort. The IRS really makes up for a lot in the comfort department when you go full retard in the handling department. In my case, my 8.8 needed a full rebuild, I had crap stock suspension, and wanted great handling. To get great handling it does not matter if you can fit a 315 tire out back when you can't get over 255 up front... it will understeer like you won't believe.

I found my 04 IRS for $500 stock... already had the 3.55 gears I wanted and needed to rebuild in what I had so whatever, plus cobra rear brakes (don't forget about that), I went with poly bushings everywhere because street car and I'm happy. I've got a 275/35/18 tucked perfectly with NO rub or excessive camber in the rear and can match that up front once I get the right wheels and/or spacers. Either way I plan to stay 400 hp or less long term on the car so the IRS is perfect for me. If you're going over 500 HP an want to go FAST in a straight line then go PM3L with MM PHB and call it a day. I didn't want the PHB/TA setup 99% because I LOVE the look of a coupe with proper tail pipes and it's complicated with big tires and tailpipes with all the suspension in the way. It's dumb, I know, and admit it... BUT, I don't care cause it's my car just like you don't care cause you are painting a unicorn bugger green...

It's YOUR car (until you sell it to me) so you do whatever makes YOU happy! I'm an engineer... I NEED requirements before I can DO anything, it's my kryptonite. You on the other hand aren't building my car (yet) so feel free to ignore everything I've said!

 

[droopie85gt]

Dave can repaint his car 2 or 3 more times before he decides SRA or IRS.

 

[Davedacarpainter]

Dave can repaint his car 2 or 3 more times before he decides SRA or IRS.

Could, not gonna....

 

[NIKwoaC]

Dave I'm sorry I derailed your thread... but kinda not sorry. The main question is what do you want the car to do BEST? You really have to decide what you want the car to be great at and compromise from there. Me? I wanted handling and compromised straight line performance and comfort. The IRS really makes up for a lot in the comfort department when you go full retard in the handling department. In my case, my 8.8 needed a full rebuild, I had crap stock suspension, and wanted great handling. To get great handling it does not matter if you can fit a 315 tire out back when you can't get over 255 up front... it will understeer like you won't believe.

I found my 04 IRS for $500 stock... already had the 3.55 gears I wanted and needed to rebuild in what I had so whatever, plus cobra rear brakes (don't forget about that), I went with poly bushings everywhere because street car and I'm happy. I've got a 275/35/18 tucked perfectly with NO rub or excessive camber in the rear and can match that up front once I get the right wheels and/or spacers. Either way I plan to stay 400 hp or less long term on the car so the IRS is perfect for me. If you're going over 500 HP an want to go FAST in a straight line then go PM3L with MM PHB and call it a day. I didn't want the PHB/TA setup 99% because I LOVE the look of a coupe with proper tail pipes and it's complicated with big tires and tailpipes with all the suspension in the way. It's dumb, I know, and admit it... BUT, I don't care cause it's my car just like you don't care cause you are painting a unicorn bugger green...

It's YOUR car (until you sell it to me) so you do whatever makes YOU happy! I'm an engineer... I NEED requirements before I can DO anything, it's my kryptonite. You on the other hand aren't building my car (yet) so feel free to ignore everything I've said!

Are there any well documented examples of the "poor man's 3-link" out there for Foxes? I've never heard this term before and after some brief searching I wasn't coming up with much more than people saying "yea I ran it for a few seasons, worked OK".

 

[Mustang5L5]

Do it. IRS. Cmon....

 

[xecute]

Nice to see you here, bird_dog0347




Hey Davedacarpainter.


IMHO, Mini tubbing is just what an IRS needs. The shock mounts can be articluated back, and the horriable cradle, which is that way


1.to clear the exhausts and
2.fuel tank, and
3. Link to the quad shock brace of the later 84-1/2's

can be brought back inwards. The axles and geometery can stay.


No one is thinking this through CMA, Solid Back axle style.


We virtually ‘reverse-engineered’ the IRS from the known suspension hardpoints, and we had to keep everything inside the same box." At a time when conventional wisdom often insists corporate executives and engineers think "outside the box," thinking inside a box was precisely what Team Mustang creative thinkers were forced to do. "The box" was an imaginary packaging space Zinkosky drew under the Cobra’s rear end, incorporating all of the solid axle components and their range of movement. If the IRS was going to meet its cost and packaging requirements, it was inside "the box" that the new independent rear suspension would have to fit and operate.

The mods CMA did, should done, and the shocker units and cradle upper handel bars mounts moved inwards. I like coil over springs with adjustable spring perches. You can lay em inboard with a sectioned frame rail reinforced.The cradle is not a great design, but its okay if not rusted or busted. Making a new one in better quality tube with a desicant so it doesn't rust from inside out, thats a good idea.


A live rear axle works best for start line launches, but an IRS is easy to track down, and you get to solid mount it with proper solid chassis mounts.



Time to have some spare ribs with the Mrs, Dave. Or Spare Ribs with the Spare Rib, as my pasta, um, Pastor, used to say. Shoulda slapped 'em for bein' sexist....

But its your bag, um, no, its your car, and you'll do it fine whatever you decide.


In can see through your efforts....and approve!

 

[bird_dog0347]

Are there any well documented examples of the "poor man's 3-link" out there for Foxes? I've never heard this term before and after some brief searching I wasn't coming up with much more than people saying "yea I ran it for a few seasons, worked OK".

There's plenty of examples in the road racing section of Corral.net but you gotta watch your upper TQ boxes and should reinforce that area first for sure. Essentially it's what my 2014 GT has (except it was designed as 3L from the get go) and it works pretty well.

 

[droopie85gt]

PM3L search that some stuff comes up. Especially on corral.net. Basically remove one upper control arm and install a panhard bar. As @bird_dog0347 said, the upper control arm mount must be reinforced. By removing one of the upper arm, you get rid of some of the binding that the stock 4 link has built in. Same thing with a torque arm. One thing everyone says on the rear control arms when you go to really hard or solid bushings is it tears up the torque boxes. Most of it is from the rear end is in a binding position because the upper and lower arms are different lengths and trying to swing the rear end in different arcs. I want a torque arm but I may buy the MM panhard bar and try the PM3L first.

 

[Davedacarpainter]

Nice to see you here, bird_dog0347




Hey Davedacarpainter.


IMHO, Mini tubbing is just what an IRS needs. The shock mounts can be articluated back, and the horriable cradle, which is that way


1.to clear the exhausts and
2.fuel tank, and
3. Link to the quad shock brace of the later 84-1/2's

can be brought back inwards. The axles and geometery can stay.


No one is thinking this through CMA, Solid Back axle style.


We virtually ‘reverse-engineered’ the IRS from the known suspension hardpoints, and we had to keep everything inside the same box." At a time when conventional wisdom often insists corporate executives and engineers think "outside the box," thinking inside a box was precisely what Team Mustang creative thinkers were forced to do. "The box" was an imaginary packaging space Zinkosky drew under the Cobra’s rear end, incorporating all of the solid axle components and their range of movement. If the IRS was going to meet its cost and packaging requirements, it was inside "the box" that the new independent rear suspension would have to fit and operate.

The mods CMA did, should done, and the shocker units and cradle upper handel bars mounts moved inwards. I like coil over springs with adjustable spring perches. You can lay em inboard with a sectioned frame rail reinforced.The cradle is not a great design, but its okay if not rusted or busted. Making a new one in better quality tube with a desicant so it doesn't rust from inside out, thats a good idea.


A live rear axle works best for start line launches, but an IRS is easy to track down, and you get to solid mount it with proper solid chassis mounts.



Time to have some spare ribs with the Mrs, Dave. Or Spare Ribs with the Spare Rib, as my pasta, um, Pastor, used to say. Shoulda slapped 'em for bein' sexist....

But its your bag, um, no, its your car, and you'll do it fine whatever you decide.


In can see through your efforts....and approve!

So, let me see if I’m understanding you Dean.

If I narrowed the upper ‘handle bars’ of the irs cradle, and shifted the upper shock mount back let’s say 1.5-2.0”, kind of similar with what I did to Doby with the mini tubbing, then I could have an irs with 315’s within the stock 1/4’s?

Now wouldn’t that be interesting......hummmmm.......

That would make me need to jump in an ice cold shower.

And if it would work, even in theory, I’ll do it.

@CarMichael Angelo @bird_dog0347 @90sickfox @Hoytster and any other IRS/fabricator guy, what do you think?

 

[Hoytster]

315’s within

So, let me see if I’m understanding you Dean.

If I narrowed the upper ‘handle bars’ of the irs cradle, and shifted the upper shock mount back let’s say 1.5-2.0”, kind of similar with what I did to Doby with the mini tubbing, then I could have an irs with 315’s within the stock 1/4’s?

Now wouldn’t that be interesting......hummmmm.......

That would make me need to jump in an ice cold shower.

And if it would work, even in theory, I’ll do it.

Anything's possible with enough time, skill, money, the right tools, and beer.

He's correct imo, you can modify the cradle enough to get 315's in there and mini-tub. I shouldn't have said it wasn't possible, just something I wouldn't expect anyone to go through the effort of doing. It would take quite a bit of work and thought, but was something I had figured out was technically possible when I was looking at my options. Bending a whole new cradle was something else I thought of, just thought I was crazy for even thinking about it. When I was looking at modifying the cradle like that, I had pretty much come to the conclusion I would have to run side exhaust, which I didn't want. Maybe I am missing something there @xecute could clarify. Both options were a ton more work for me and didn't benefit my goals at all.

 

[bird_dog0347]

With the IRS the exhaust goes under the pumpkin so nothing to modify there... As long as you do not modify the control arm mount points or try to narrow the axles (which would necessitate shorter control arms to bring the hubs in) then I think it's doable. You'd have to cant the upper shock mount inwards as it attaches to the lower control arm as seen below. You'd also have to completely redo the rear of the cradle and assume the front of the cradle is ok where it's at (like if it were an SRA). I don't know what effect it will have on handling to move the upper shock mount point, that's a better question for someone like Jack at MM.

 

[Davedacarpainter]

Anything's possible with enough time, skill, money, the right tools, and beer.

He's correct imo, you can modify the cradle enough to get 315's in there and mini-tub. I shouldn't have said it wasn't possible, just something I wouldn't expect anyone to go through the effort of doing. It would take quite a bit of work and thought, but was something I had figured out was technically possible when I was looking at my options. Bending a whole new cradle was something else I thought of, just thought I was crazy for even thinking about it. When I was looking at modifying the cradle like that, I had pretty much come to the conclusion I would have to run side exhaust, which I didn't want. Maybe I am missing something there @xecute could clarify. Both options were a ton more work for me and didn't benefit my goals at all.

Wouldn’t the exhaust routing be the same? No changes down there.

 

[Davedacarpainter]

With the IRS the exhaust goes under the pumpkin so nothing to modify there... As long as you do not modify the control arm mount points or try to narrow the axles (which would necessitate shorter control arms to bring the hubs in) then I think it's doable. You'd have to cant the upper shock mount inwards as it attaches to the lower control arm as seen below. You'd also have to completely redo the rear of the cradle and assume the front of the cradle is ok where it's at (like if it were an SRA). I don't know what effect it will have on handling to move the upper shock mount point, that's a better question for someone like Jack at MM.

Yeah, I got to try to get through to him. Good idea.

 

[Hoytster]

Wouldn’t the exhaust routing be the same? No changes down there.

Yeah, not where the exhaust comes underneath the pumpkin, but where it comes up between the gas tank and tire. I'd have to look through my notes, but it might have been something specific to my setup that I wasn't going to be able to squeeze a 3" or 3 1/2" exhaust tube between the tire and stock tank location if I moved the whole tire assembly inboard by modifying the IRS.

 

[Davedacarpainter]

Yeah, not where the exhaust comes underneath the pumpkin, but where it comes up between the gas tank and tire. I'd have to look through my notes, but it might have been something specific to my setup that I wasn't going to be able to squeeze a 3" or 3 1/2" exhaust tube between the tire and stock tank location if I moved the whole tire assembly inboard by modifying the IRS.

Ah! I get it. That is something to think about.

 

[bird_dog0347]

As you can see from the previous pic as well as this one, there's lot of clearance (that's a 275/35/18) and you'd likely hit the top/front of the gas tank if you hit the exhaust pipe.

 

[Noobz347]

I've always wanted to see someone cut into the back seat/hatch/trunk area and still put the exhaust [over] the axle on an IRS swap. Tank would probably have to be modified along with the back seat area. To this day, I don't think I've seen anything like that.


Edit: Maybe cut sections out of the floor panels and weld in half-pipe to accommodate exhaust.

 

[95BlueStallion]

I've always wanted to see someone cut into the back seat/hatch/trunk area and still put the exhaust [over] the axle on an IRS swap. Tank would probably have to be modified along with the back seat area. To this day, I don't think I've seen anything like that.


Edit: Maybe cut sections out of the floor panels and weld in half-pipe to accommodate exhaust.

I was considering routing my exhaust up over my axle, through the spare wheel well (enclosed), and out the rear bumper with dual center exit. Still considering it.

 

[Noobz347]

I was considering routing my exhaust up over my axle, through the spare wheel well (enclosed), and out the rear bumper with dual center exit. Still considering it.

I'm not sure I would completely enclose it but I'd def have some sort of channel to hug the exhaust into. It would probably need custom hangers and insulators or drone like there was no tomorrow.

 

[Davedacarpainter]

I've always wanted to see someone cut into the back seat/hatch/trunk area and still put the exhaust [over] the axle on an IRS swap. Tank would probably have to be modified along with the back seat area. To this day, I don't think I've seen anything like that.


Edit: Maybe cut sections out of the floor panels and weld in half-pipe to accommodate exhaust.

I was considering routing my exhaust up over my axle, through the spare wheel well (enclosed), and out the rear bumper with dual center exit. Still considering it.

I'm not sure I would completely enclose it but I'd def have some sort of channel to hug the exhaust into. It would probably need custom hangers and insulators or drone like there was no tomorrow.