I have the 03 Cobra IRS that came out of my wrecked 99 mustang that I want to swap into my 96 mustang... Im just wondering if theres anything special that ill need to get this done or is it a direct swap. I keep hearing conflicting information, so I decided to come an ask in here since someone may have experience with this!
03 IRS on a Pre 99 SN95?
- Thread starter HitmanKB
- Start date
Common, Some one has an answer for me!!:coolman:
I've done this swap last summer on a 1995 Mustang GT. There is a bit of work that needs to be done. Here is a summary as I recall:
1. DRIVESHAFT
If using the stock drive shaft, you will have to shorten it by an inch. Also the companion flange on the 03 Cobra differential is larger, and will have to be changed out with one from an earlier car. Maybe it was unique to my installation, but you may want to ensure this doesn’t affect this lash on the ring and pinion. Mine got tighter and had to be adjusted (???).
2. FRONT SUB-FRAME MOUNTS
Front sub-frame mount requires a different bushing. The 03 Cobra has a 14mm, and earlier cars has a 12mm bolts for the lower control arm at the chassis. Either have to drill out the lower control arm mounting point, or use the Maximum Motorsports 12mm urethane bushing. I elected the latter method, as I wanted to change out all the sub-frame bushings anyway.
3. FUEL LINES
I elected to drop the fuel tank to provide better access during the installation (I’d recommend this). Note that the fuel line routing has to be slightly modified. This is fairly easy and can be accomplished with a bit bending. Good time to change the fuel filter, because it’s a pain when you finish the installation of the IRS.
4. REAR IRS BRACKET
On the 98 and earlier SN-95 cars, there are no threaded holes provided for the bottom of rear sub-frame mounting bracket (2 holes ea.). Additionally, this sub-frame mounting bracket also uses the existing 2 bolt holes provided for the kicker shocks.
To ensure the correct location of the IRS, I bolted (loosely) the IRS sub-frame into the front mounting holes and then swung the assembly up in place (this is relatively easy with no springs installed). This allowed me to mocked up the exact location for installation of the rear bracket. Once I had the brackets bolted in place using only the kicker shock bolts, I then drilled the lower bolt holes into the frame rail of the chassis.
Obviously, you will need to be able to install either a nut or a bolt into the frame rail. I choice to drill a hole (using an 1-1/2” hole saw) in the floor of the trunk directly above the holes drilled in the frame rail. To do this, I inserted a drift punch in this newly drilled hole and extended it up until it made contact with the trunk floor, then I smacked the punch with a hammer to mark the location in the truck floor. Using the punch marks as a guide, I center punched the trunk floor and then sawed the 4 access holes. I cleaned up all the locations where I had drilled/sawed the holes and painted them up with cold galvanizing paint.
Once I completed the installation of the IRS assembly, I then installed a pair of cover plates that I fabricated out of sheet metal, by gluing them in place using some 3M weather stripping adhesive.
5. FASTENERS
Although I had the factory fasteners for the rear bracket, on the bottom side of the rear IRS bracket I choose to use a slightly longer Grade 10.9 bolts with large heavy flat washer, and inserted from the trunk side I used a nylon lock nut combined a large heavy flat washer.
Once all the bolts and nuts were attached, I then torqued all the fasteners on the brackets, both the side and bottom, to values specified in Ford manual. I also used new factory nuts and bolts on the front sub-frame.
6. BRAKE LINES
The tubing for the pre-99 SN-95 cars only has a single line running to the rear. 99 and later cars have two separate lines. So you have to modify the existing single line. I elected to cut the existing brake tubing very close to where it bolted to the original flex line going to the differential. I then installed a new tube nut, and double flared this bit of tubing.
I then installed a new brass tee block which was mounted to the body using some existing holes provided for the original flex hose body-side mount.
I then fabricated two new brake lines using a double flare on the tee block end and an ISO / bubble flare on the sides that are connected to the factory 03 Cobra flex lines. A good quality tubing bender is a must for this job. Note that there is no provision to mount these flex lines to the chassis, so did a bit of work to modify the side of the frame rail so that I could attached these flex lines in a manner similar to the way they are installed on the 03 Cobra.
7. ANTI-LOCK BRAKE CONNECTORS
I just had to reposition the grommet slightly and plug into the existing wiring connectors under the rear seat. I also was able to use the cable retaining brackets that attach to the body next to the wheel well.
8. EMERGENCY BRAKE CABLES
I found that I could not get the existing cables to fit up, as they were slightly short. I ended up re-routing the cables to get enough slack to get them in a position where I could attach them to the calipers. Although I have since bought 03 Cobra cables, as my original installation was not entirely to my liking.
9. EXHAUST
I reckon you could simply use an off the shelve 03 Cobra catback system. The only problems I see with using an 03 Cobra system is: A) the tail pipe tips on most these systems are large and therfore may look a bit out of place on the earlier car that have rear bumpers that don't have the semi-circular opening for the tail pipe. B). the 03 Cobra has a different rear hanger, and thus you'd have to modify the rear hanger on the 03 Cobra cat back for use on the earlier SN-95 car. What I did was used the Ford factory tailpipes, that were cut off at the polished tips. I expanded the tail pipes at both ends to allow a 2-1/2” pipe to fit snugly over the stock pipes. I then mocked up the exhaust system with a new set of Spin Tech mufflers and flow tubes. I had a set of DynoMax 2-1/2” tail pipes from my 93 Cobra sitting around. So I cut approximately 10” off the ends of the DynoMax tailpipes. I then welded everything up. Using these DynoMax allowed me to use the stock rear tailpipe hanger in conjunction with the stock 03 Cobra hangers on the other locations. The end result looks like a stock SN-95 Cobra with their 2-1/2” tail pipes.
My intention with this swap was to turn the 95 into a highway cruiser, rather than a Hot Rod (have one of those already). So at the same time as I did the IRS, I put the complete 03 Cobra suspension system on the car, including: new front lower control arms, spindles, hubs, tie rod ends, front & rear brakes w/Anniversary calipers, Bilstein struts & shocks, plus H&R Super Sport springs, etc, etc. I have to say this has greatly improved the driving dynamics to this car.
As a side note: this swap added 80 lbs, based on the weighing the car before and after the swap.
Good luck.
1. DRIVESHAFT
If using the stock drive shaft, you will have to shorten it by an inch. Also the companion flange on the 03 Cobra differential is larger, and will have to be changed out with one from an earlier car. Maybe it was unique to my installation, but you may want to ensure this doesn’t affect this lash on the ring and pinion. Mine got tighter and had to be adjusted (???).
2. FRONT SUB-FRAME MOUNTS
Front sub-frame mount requires a different bushing. The 03 Cobra has a 14mm, and earlier cars has a 12mm bolts for the lower control arm at the chassis. Either have to drill out the lower control arm mounting point, or use the Maximum Motorsports 12mm urethane bushing. I elected the latter method, as I wanted to change out all the sub-frame bushings anyway.
3. FUEL LINES
I elected to drop the fuel tank to provide better access during the installation (I’d recommend this). Note that the fuel line routing has to be slightly modified. This is fairly easy and can be accomplished with a bit bending. Good time to change the fuel filter, because it’s a pain when you finish the installation of the IRS.
4. REAR IRS BRACKET
On the 98 and earlier SN-95 cars, there are no threaded holes provided for the bottom of rear sub-frame mounting bracket (2 holes ea.). Additionally, this sub-frame mounting bracket also uses the existing 2 bolt holes provided for the kicker shocks.
To ensure the correct location of the IRS, I bolted (loosely) the IRS sub-frame into the front mounting holes and then swung the assembly up in place (this is relatively easy with no springs installed). This allowed me to mocked up the exact location for installation of the rear bracket. Once I had the brackets bolted in place using only the kicker shock bolts, I then drilled the lower bolt holes into the frame rail of the chassis.
Obviously, you will need to be able to install either a nut or a bolt into the frame rail. I choice to drill a hole (using an 1-1/2” hole saw) in the floor of the trunk directly above the holes drilled in the frame rail. To do this, I inserted a drift punch in this newly drilled hole and extended it up until it made contact with the trunk floor, then I smacked the punch with a hammer to mark the location in the truck floor. Using the punch marks as a guide, I center punched the trunk floor and then sawed the 4 access holes. I cleaned up all the locations where I had drilled/sawed the holes and painted them up with cold galvanizing paint.
Once I completed the installation of the IRS assembly, I then installed a pair of cover plates that I fabricated out of sheet metal, by gluing them in place using some 3M weather stripping adhesive.
5. FASTENERS
Although I had the factory fasteners for the rear bracket, on the bottom side of the rear IRS bracket I choose to use a slightly longer Grade 10.9 bolts with large heavy flat washer, and inserted from the trunk side I used a nylon lock nut combined a large heavy flat washer.
Once all the bolts and nuts were attached, I then torqued all the fasteners on the brackets, both the side and bottom, to values specified in Ford manual. I also used new factory nuts and bolts on the front sub-frame.
6. BRAKE LINES
The tubing for the pre-99 SN-95 cars only has a single line running to the rear. 99 and later cars have two separate lines. So you have to modify the existing single line. I elected to cut the existing brake tubing very close to where it bolted to the original flex line going to the differential. I then installed a new tube nut, and double flared this bit of tubing.
I then installed a new brass tee block which was mounted to the body using some existing holes provided for the original flex hose body-side mount.
I then fabricated two new brake lines using a double flare on the tee block end and an ISO / bubble flare on the sides that are connected to the factory 03 Cobra flex lines. A good quality tubing bender is a must for this job. Note that there is no provision to mount these flex lines to the chassis, so did a bit of work to modify the side of the frame rail so that I could attached these flex lines in a manner similar to the way they are installed on the 03 Cobra.
7. ANTI-LOCK BRAKE CONNECTORS
I just had to reposition the grommet slightly and plug into the existing wiring connectors under the rear seat. I also was able to use the cable retaining brackets that attach to the body next to the wheel well.
8. EMERGENCY BRAKE CABLES
I found that I could not get the existing cables to fit up, as they were slightly short. I ended up re-routing the cables to get enough slack to get them in a position where I could attach them to the calipers. Although I have since bought 03 Cobra cables, as my original installation was not entirely to my liking.
9. EXHAUST
I reckon you could simply use an off the shelve 03 Cobra catback system. The only problems I see with using an 03 Cobra system is: A) the tail pipe tips on most these systems are large and therfore may look a bit out of place on the earlier car that have rear bumpers that don't have the semi-circular opening for the tail pipe. B). the 03 Cobra has a different rear hanger, and thus you'd have to modify the rear hanger on the 03 Cobra cat back for use on the earlier SN-95 car. What I did was used the Ford factory tailpipes, that were cut off at the polished tips. I expanded the tail pipes at both ends to allow a 2-1/2” pipe to fit snugly over the stock pipes. I then mocked up the exhaust system with a new set of Spin Tech mufflers and flow tubes. I had a set of DynoMax 2-1/2” tail pipes from my 93 Cobra sitting around. So I cut approximately 10” off the ends of the DynoMax tailpipes. I then welded everything up. Using these DynoMax allowed me to use the stock rear tailpipe hanger in conjunction with the stock 03 Cobra hangers on the other locations. The end result looks like a stock SN-95 Cobra with their 2-1/2” tail pipes.
My intention with this swap was to turn the 95 into a highway cruiser, rather than a Hot Rod (have one of those already). So at the same time as I did the IRS, I put the complete 03 Cobra suspension system on the car, including: new front lower control arms, spindles, hubs, tie rod ends, front & rear brakes w/Anniversary calipers, Bilstein struts & shocks, plus H&R Super Sport springs, etc, etc. I have to say this has greatly improved the driving dynamics to this car.
As a side note: this swap added 80 lbs, based on the weighing the car before and after the swap.
Good luck.
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