My latest project, IRS into a fox body

[wheelhopper]

It is already under way, but I figured I would tell you guys about my latest project. I am currently in the process of installing an IRS, from an '03 Cobra, into my '90GT. Right now the entire rear suspension, exhaust, and fuel tank is out of the car. The IRS has been mocked in place and the next step is drilling a few holes for the rear IRS bracket. While the IRS is out Poly subframe bushing were installed.

I also installed 13" Cobra brakes on the front. Maximum Motorsports helped out with the proper adapters and info for this one.

This project started in my quest to have a less expensive track car. I had made modifications to my Cobra that increased the cost of brakes and tires to the point that I was looking at spending several thousand dollars a year just for those items. So I decided to blow the dust off my '90GT and put a 500lb lighter car on the track.

While I am doing a lot of work on the car myself Jason Roth, owner of Competition Speed and Sound, is doing a lot of work as well in addition to being kind enough to provide his shop space to do the work.

 

[DAVESVT2000]

Nice !!

Pics ?

 

[JamesHell]

I always think about this. Does the IRS line up with frame rails and CA pockets. In other words is the width the same in the Fox as the SN95? I know the track is different, but I assume you will just trim the fenders.

 

[NJ 03Mach1]

It pretty much slides right into place without to much hassle. I've not personally done it, but I have seen one done.

 

[wheelhopper]

It does not quit slide into place. The front mounts go right into the lower control arm mounting points. The rear mounting brackets can be bolted to the subframe where the quad shock was attached. However, there are some mounting holes that have to be drilled, and reinforced with metal sleeves, through the hatch floor. So far the most difficult hurdle is running new rear brake lines and how I am going to keep the e brake. As far as the width is concerned I am using '99 Cobra wheels, so am hoping that I will have enough room without a lot of metal work. I am prepared that I may have to roll the fenders. If need be I am going to try a set of '05 up GT wheels. I am going to use 255 rubber. I am keeping my fingers crossed.

Dave, I'll try to get some pics up soon. I believe you instructed me at my first SCMC event, and gave me my only ride to date in a GT500. You'll have to make it down this year so I can return the favor in my IRS fox so you can tell me what you think.

 

[BlackBolt9]

Or you can just weld the rear brackets into place if you don't plan to remove them. Which is what I am planning on doing. You are also going to want to remove the bump stops otherwise they will interfere with the upper arms. That's about all the further I have gotten on mine before I bought my house and ran out of money

 

[DAVESVT2000]

Dave, I'll try to get some pics up soon. I believe you instructed me at my first SCMC event, and gave me my only ride to date in a GT500. You'll have to make it down this year so I can return the favor in my IRS fox so you can tell me what you think.

Wasn't me, don't own a GT500 :shrug:

Still looking forward to pics though :coolman:

 

[Ryan]

Why'd you decide to go IRS? Just curious as this was a topic of discussion on the SVO board...

 

[wheelhopper]

Or you can just weld the rear brackets into place if you don't plan to remove them. Which is what I am planning on doing. You are also going to want to remove the bump stops otherwise they will interfere with the upper arms. That's about all the further I have gotten on mine before I bought my house and ran out of money

I thought about welding, but I figured if I ever decide to go back to straight axle bolting it in place would be simpler to reverse. Got this done today as a matter of fact. Bump stops and pinion snubber were pulled out when everything else back there was.

Wasn't me, don't own a GT500 :shrug:

Still looking forward to pics though :coolman:

You're right, it was Ken. I think you were scheduled to instruct me at my second event, but we never hooked up and I was comfortable going solo, so Tony let me go.

Why'd you decide to go IRS? Just curious as this was a topic of discussion on the SVO board...

It started with me looking at putting a disc brake conversion on my foxbody. All the ones I could find were over $500. I had a few IRS assemblies that I had purchased over the years for good prices, one that was complete with brake calipers and everything I needed to transplant it into a straight axle car, so the decision sort of made itself. Plus I like having something a little different than everyone else, you should be able to relate to that. An added benefit will be better weight distribution in the fox body.

In hindsight a disc conversion would have been cheaper. I have been getting nickel and dimed every time I work on this project. By the time it is done I will have easily a $1000 in misc. brake lines, adapters, sleeves, bolts, bushings, etc. It is going to be cool though.

 

[03 TOPLESSSVT]

I will be doing this to my newly aquired notch this year. The start of my Notch Terminator quest. Good luck with you project!

 

[grant007]

wow i am veryinterested, i took my IRS out of the cobra to put in my 90 convertble. my fox will never be a beastly fox just a nice DD with 280ish or 300ish hp. cant wait to see some pics.

 

[Ryan]

It started with me looking at putting a disc brake conversion on my foxbody. All the ones I could find were over $500. I had a few IRS assemblies that I had purchased over the years for good prices, one that was complete with brake calipers and everything I needed to transplant it into a straight axle car, so the decision sort of made itself. Plus I like having something a little different than everyone else, you should be able to relate to that. An added benefit will be better weight distribution in the fox body.

In hindsight a disc conversion would have been cheaper. I have been getting nickel and dimed every time I work on this project. By the time it is done I will have easily a $1000 in misc. brake lines, adapters, sleeves, bolts, bushings, etc. It is going to be cool though.

Just curious....that's basically the same conclusion I came to on the SVO boards. Its the cool factor, I've considered doing that to mine too, but I need some HP first. You takin' it out to the track this year?

 

[93vertirs]

e brake cables

I have a car that had the swap already done to it. It didn't have the emergency brake cables installed thought. I got a set of cables from an irs car. Will I have any problems routing them?

 

[wheelhopper]

Just curious....that's basically the same conclusion I came to on the SVO boards. Its the cool factor, I've considered doing that to mine too, but I need some HP first. You takin' it out to the track this year?

My first track event this year is the March NASA event at VIR. I plan on having it there. I am also signed up for the SCMC/SVTOA stangfest, I'll have it there as well. It is going to be a rare sight at the events, but nobody will even know I have it, no visual clues like an SVO. I guess I better improve my driving skills to where people have to come by and wonder why they are getting passed by a plain looking fox.

I have a car that had the swap already done to it. It didn't have the emergency brake cables installed thought. I got a set of cables from an irs car. Will I have any problems routing them?

I have not hooked my e-brake cables up yet. I am going to try to use the factory fox cables an see how they work . I do want to have the e-brake working, even though I don't need it for what I am using it for, I just would not feel like it is a complete and thourough install otherwise.

 

[BlackBolt9]

I have not hooked my e-brake cables up yet. I am going to try to use the factory fox cables an see how they work . I do want to have the e-brake working, even though I don't need it for what I am using it for, I just would not feel like it is a complete and thourough install otherwise.

I guess you could say that, but aren't you doing it for the track anyways? I'm not putting mine in but it will be a dedicated track car, not a street car at all.

I took the e-brake out of my Lightning but it has an automatic so I never used it anyways.

 

[gcassidy]

Doug, I'll just bring a brick to events for your parking brake. :idea:
Unless you want to show off with e-brake drifting. :nonono:

 

[Force4.6]

Sounds cool Doug, should be cool to see the next project running around the track at VIR.

 

[wheelhopper]

Got the rear brake lines run tonight, Jason did a great job. I will be installing all the calipers tomorrow and bleeding the system. The plan is to have this car moving under its own power by Thursday. I will get some pics for you all tomorrow.

 

[TRBO VNM]

almost done. Doug failed at bringing a camera. I can't talk too much though, mine is just inside the house. Maybe we will get some pics when it is on the lift or take the rear tires off again and snap a couple.

the gas tank went in last night and started the car up and set the timing. found a nice exhaust leak from the smog pump lines, so time to delete that setup. then it should run much better.

Doug, gotta redo those rear brake lines. I really don't like them, but for now it will do. I think we need to do a custom set so they are the correct length instead of having extra there and creating more bends to take up the slack.

other than that it wasn't a horrible install. just a lot more to do. Unlike putting one in a 99-04 gt. It wil definitely turn out to be a great upgrade for the car.

now, just replace the rest of the IRS bushings with bruce's kit and you will be set.

 

[SHOLANDO]

Pics!!!!