Thunderbird/MKVIII IRS in a panther...

[mrltd]

Well, I'm going to look into doing this. Looks pretty straightforward. The only part I'm debating is whether or not to build my own arms and mounts and just use the diff and spindles, or just bolt in a stock setup (with aftermarket bushings)

Also debating the use of an explorer diff because of the beefier mounting points.


This site gave me some good design ideas.

http://team321.com/321HotRodIRS/321HotRodIRShome.html

and this...http://forums.vintage-mustang.com/mo...-big-pics.html

[DuceAnAHalf]

the MN12 irs is notoriously weak. it needs to be reinforced. a new Edge cobra rear would be better, but the supply of those has probably dried up by now

[torquelover]

I like the FN10 aluminum components. Any other advantages over the MN12? It's really too bad you, or anyone else here, didn't snatch up my old low-mile MK8. I think it went for $300.

[Pirate]

the MN12 irs is notoriously weak. it needs to be reinforced. a new Edge cobra rear would be better, but the supply of those has probably dried up by now

Areas of weakness in the MN12 IRS, and how it compares to the Cobra piece:

1. Rear diff cover: This is the Achilles' Heel of this system, however, it's easily repairable via' a special bracket especially made for this problem (or build your own), as there isn't much of anything reinforcing the rearend cover, where it mounts to the IRS subframe. This affects both the MN12 and new edge Cobra, but is only a real problem with manual-transmission cars....Automatic cars really don't have any problems here, even with those that are drag or road-racing MN12's.

There are also some billet covers for Terminator Cobras that also work on the MN12 cars....once again, this is really only a problem for 5-or-6-speed cars, it's not really an issue with auto cars.

2. Bushings. The IRS subframe bushings allow some movement under acceleration and heavy braking, but if he solid-mounts the subframe....not a problem.

3. Axles. Once again, if he runs an automatic....it's not really a problem, but he can upgrade to Super Coupe axles, or buy a set of Raxles, which are beefed stockers, and can handle quite a bit of power.

4. Assorted 'reinforcement' brackets....there are two other brackets he might want to consider building/buying, and I'll mention what they are when he gets around to building it, as these can be bolted/welded in at any time. The best suggestion here is to fully weld all of the seams and brackets before the IRS is installed, to eliminate flex.

5. The MN12 piece would be a better fit for the wagon, methinks, as it's wider than the Mustang unit. In addition, the Mustang uses tie-rods to keep the wheels centered, the MN12 does not....stronger design.

Other than that....he's pretty much good to go, unless he switches to a 5-speed.

I like the FN10 aluminum components. Any other advantages over the MN12? It's really too bad you, or anyone else here, didn't snatch up my old low-mile MK8. I think it went for $300.

Yes, but to switch to coil springs with the aluminum lower control arms requires a custom-made spring pocket, as the coil just flops around in the space left behind where the airbag once rested....and yes, I know the aluminum arms reduce unsprung weight, I'm just not convinced yet that the aluminum LCA's are stronger than the cast-iron pieces in the Thunderbird/Cougar, as the LCA's in these cars have to stop wheel movement in a lot of different directions; the UCA in these cars doesn't do a whole lot other than restrict camber movement/adjustment.

However, to switch to the aluminum diff housing? By all means, yes, install that.

[mrltd]

LPW makes a diff cover for the IRS cars. I've got a non IRS LPW diff cover on the wagon. I haven't blown gears or a diff apart yet-from shock load like the other wagon guys have.

I'm definitely considering my own custom setup using just the diff and the spindles. I might actually need to make it a bit wider than the t-bird setup. The stock rear is ~63" axle to axle-without brakes. I actually want a wider than stock track width-like the later panthers (90+) which are 64" so I can run the mustang wheels without spacers. I might actually want to go even wider, because I might decide to run 10.5" wheels and 315/335's on the car.

I like this setup...

[mrltd]

Well, gotta love craigslist. Found a complete supercoupe IRS for 150 bucks. They have trac-loks and decent gearing.

[Pirate]

Well, gotta love craigslist. Found a complete supercoupe IRS for 150 bucks. They have trac-loks and decent gearing.

Score. 5-speed SC's got 3.55's, and Auto SC's got 3.73's....and both received upgraded axles.

[gadget73]

Can't beat that price. Can those be changed to a 5x4.5" bolt pattern instead of the 5x4.25 or whatever nonsense they had ?

[mrltd]

Yes, the hubs can be redrilled or you can just get cobra hubs.

Oh, and it's a 5 speed car! So a set of 3.55's and another TL for me.

[Pirate]

Yes, the hubs can be redrilled or you can just get cobra hubs.

Oh, and it's a 5 speed car! So a set of 3.55's and another TL for me.

There's also a simple 'Big Ed' bracket to allow for 11" Cobra rotors on the rear and stock T-bird calipers....which I will eventually purchase....

[torquelover]

Doubt if anyone will claim the IRS, so the price will probably drop:

http://www.chicagolandmustang.com/fo...ad.php?t=45896

No Trac-Lock, and probably not a 3.55. Someone should snag those Octastars, though!

[mrltd]

Damn nice car to be parting just for the block.

The guy that had the supercoupe IRS locally never emailed me back. So much for that. I'm going to keep my eyes open, but for now it's going to get a stock 95 panther rear.

[91waggin]

He said it got a good front end hit.

[mrltd]

Well, finally called the guy. He's gonna get it pulled and I'll be picking it up next weekend.


The car was in a hard ass end hit though. So I'm not sure how good the subframe will be. However, the 3.55 TL and the upgraded axles are worth what I'm paying for it. Good possibility I will be making my own subframe too.

[87gtVIC]

I recently watched an episode of Trucks on Spike TV where they were installing a Cobra Sub Frame IRS stuff into a Ranger chassied Mazda. Maybe if you need some sort direction you could look up those clips.