Geoff's Cobra IRS Thread

[Geoff Chandler]

So it looks like the MM Torque arm (Or Griggs) will simply not work out with my oh-so-sweet side exit exhaust, so I am going to try something different. From what I can tell, the IRS can use the same Differentials as the 8.8, so I should be able to keep an Air-Locker in there, the only problem being that I will need to upgrade to the 31 spline unit, unless I use a '99 IRS.

http://www.fulltiltboogieracing.com/mystery_of_irs.htm

So much research to do, so little time.

[Geoff Chandler]

Preliminary Budget:

• $1200 - Stock '03 IRS
• $800 - Air Locker
• $429 - Coil-Over Kit
• $300 - Bilstein Shocks
• $800 - IRS Upgrades

That all works out to $3529, not cheap by any stretch of the imagination. IF I go with a 99-01 IRS that uses 28 spline axles, I will save about $1000 because I can use the Air Locker I have already, and the IRS units are cheaper. That may be the way to go, considering that I am not making nearly as much power as a Cobra.

[Jetsetter]

You're planning on spending 3500 dollars out of your way because of your side exit exhaust?

Tell me when you're selling your control arms.

[auto alchemist]

u know for 1200 bucks u could buy a complete running thunderbird which has the same irs setup as the cobra, it just doesnt have 31 spline axles, or find one in ajunkyard and get a rear dropout for dirt cheap

oh and btw lincoln mark 8s had irs also, but they came with an aluminum center pig that would lighter and take some weight off the ass end, trust me us tbird guys have looked into the simularities between the ford IRS units alot

[Geoff Chandler]

Originally Posted by auto alchemist

u know for 1200 bucks u could buy a complete running thunderbird which has the same irs setup as the cobra, it just doesnt have 31 spline axles, or find one in ajunkyard and get a rear dropout for dirt cheap

oh and btw lincoln mark 8s had irs also, but they came with an aluminum center pig that would lighter and take some weight off the ass end, trust me us tbird guys have looked into the simularities between the ford IRS units alot

I do not think that the Thunderbird is a Fox chassis, and the IRS does not interchange.

As for the $3500, remember, that is compared to the $2000 that it would take to get the torque arm setup properly. So, yeah, it is more, but if I can find a '99 unit, it should be about the same cost.

[Jetsetter]

Why such a high price for the correct torque arm? What install issues are you experiencing that require such modification to your car as to warrant 1500 additional dollars on top of the aquisition price?

[sergio91gt]

why would it take so much money for a torque arm if the maximum motorsports torque arm is only 450 and you pretty much have everything you need to install already in your car(panhard bar, subframe connectors, lower control arms, coilovers)

[Mars]

You need to shop around for an IRS. I know they go for a lot cheaper or traded out for upgraded 8.8 units. I coulda bought one locally myself for like $300 but didnt have the cash then :\

[Geoff Chandler]

Originally Posted by sergio91gt

why would it take so much money for a torque arm if the maximum motorsports torque arm is only 450 and you pretty much have everything you need to install already in your car(panhard bar, subframe connectors, lower control arms, coilovers)

I would need to get new springs and shocks, have a new exhaust built, and possibly buy the MM swaybar kit. The exhaust would be quite expensive, as keeping both pipes so that they exit on the passenger side, and retaining the catalytic converters would require some high quality custom work. With the IRS I keep the exhaust that I have now.

[Geoff Chandler]

Budget #2:

• $800 - Stock '99-01 IRS
• $429 - Coil-Over Kit
• $300 - Bilstein Shocks
• $800 - IRS Upgrades

Considering I should be able to sell my panhard and 5-lug rearend for some decent cash, I figure this IRS will not end up costing much more then the torque arm would at ~$2329.

[David Adams]

[Geoff Chandler]

owned!!!

http://forums.corral.net/forums/show...ox+irs+install

[David Adams]

Don't doubt it's very possible and quite feasible . . .just sayin . . .some of us get our IRS via different outlets . . .



>_>

<_<

[flyingboyfilms]

Originally Posted by Geoff Chandler

owned!!!

http://forums.corral.net/forums/show...ox+irs+install

Oh hell ya!

Dood! DO IT! Be a CHAMPION!

[Doug VDB]

Hey Geoff,

Should you get serious, I know where there's a complete new-in-the-create IRS setup sitting in So. Cal... I don't know what the guy wants for it but when you get your cash together give me a shout and I'll put in contact with him...

[David Adams]

oh snap . . .

Shit just got real . . .

[Geoff Chandler]

Originally Posted by Doug VDB

Hey Geoff,

Should you get serious, I know where there's a complete new-in-the-create IRS setup sitting in So. Cal... I don't know what the guy wants for it but when you get your cash together give me a shout and I'll put in contact with him...

Do tell. Is it a 28 spline '99-01 setup or the newer 31 spline setup?

[Doug VDB]

Originally Posted by Geoff Chandler

Do tell. Is it a 28 spline '99-01 setup or the newer 31 spline setup?

I have no idea. I just remember seeing it in the create all wrapped-up. Like I said, when you're ready I'll hook Ya'll up and you can get the info straight from the horses mouth..

[Edward Thompson]

Sweet!!!!!! Yhat should help balance the car better as well putting slightly more weight in the rear very low.

[Geoff Chandler]

Originally Posted by Edward Thompson

Sweet!!!!!! Yhat should help balance the car better as well putting slightly more weight in the rear very low.

The car has decent balance already, but if I ever upgrade to gt40 heads, I don't have to worry about aluminum with all that extra weight out back.

[Edward Thompson]

Originally Posted by Geoff Chandler

The car has decent balance already, but if I ever upgrade to gt40 heads, I don't have to worry about aluminum with all that extra weight out back.

Hells yeah. LOL. I'm really excited to hear how this works out for ya. That tech link you posted was pretty cool. Might want to put it in tech as well. ROCK ON!

[sergio91gt]

whatever happened to your idea of making a parallel four link with hot rods to hell, wouldn't it be less expensive since you could keep all your current stuff.

[Geoff Chandler]

Originally Posted by sergio91gt

whatever happened to your idea of making a parallel four link with hot rods to hell, wouldn't it be less expensive since you could keep all your current stuff.

I don't know if he really wants to make a 4-link product, as his core business is the CenterDrive suspensions. I should probably post an update in that thread.

[Geoff Chandler]

Pulled the Mustang into the garage and got it up on jackstands to take a look at the condition of the rear suspension, and determine if I can maybe squeeze out another event this summer before getting down to IRS business.


The answer is a resounding NO!


With just my hands I was able to move the passenger side upper control arm mount about 1/2." No wonder my Mustang made such a loud creaking noise back there every-time I got on the brakes or gas.

I think at this point, I will recommend that anyone that's considering getting real serious with their Mustangs should consider a torque box reinforcement kit. Probably sooner then later. I can't imagine how much time and $$$ it would take to repair the stock suspension at this point. Remember, I am still running a pretty much stock engine combination.

[cbleslie]

When are you going to put the parts up for sale? So some lucky bastard can get custom Battle Version links?

[Geoff Chandler]

Originally Posted by cbleslie

When are you going to put the parts up for sale? So some lucky bastard can get custom Battle Version links?

Haha, it's true, the only set in existence. I think as soon as I get my hands on an IRS, I will be selling all this stuff. With all the damage to my chassis, it sure can't go back into the car.

[Jetsetter]

What custom parts are on it now? There's the Racecraft spindles, but I can't remember everything else.

[Geoff Chandler]

Originally Posted by Jetsetter

What custom parts are on it now? There's the Racecraft spindles, but I can't remember everything else.

My rear LCAs were made by battleversion. They are on the sides of the picture here.

[Geoff Chandler]

I managed to get the rearend and all the associated pieces out of the car last night. I also prepped the chassis for an IRS


Anyone is the market for a full 5-lug rear end with an Air Locker and fresh Axles, shoot me a PM. I also have the coilovers, panhard, and LCAs. I will cut a deal for the whole package, or simply part it out individually.


Here is the reason I am pulling all this stuff out. You can see the upper control arm attach point on the chassis is destroyed. It's had to see in an iPhone picture taken lit by a drop light, but damage extends all the way through to the floor boards. I guess that's what I get for doing 5 events after is started making creaking noises. I'm just glad I finally got in there and did something before swapping out my rear axle on the track.


Here is a shot of the drivers side of the car for comparison. This one was not damaged much, but had started to pull away from the chassis slightly on the inside of the mount.

[cbleslie]

Better pose as a team, because shit just got real!