This is topic Rearend swap. Trying to put an 03' cobra in my 93 in forum Tech Talk at Northern California Ford Owners  .


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Posted by 93HYWAY (Member # 6617) on :
 
trying to install an 03' cobra rearend in my 93' coupe. Just wondering what it would take & trying to see if there is any advice.
 
Posted by lambonotch (Member # 5758) on :
 
from what ive been told altho an irs in a fox might be a good idea on paper. in real life its suck, lots of wheel hop, and other issues.
 
Posted by 85gtcarbro8du-up (Member # 5169) on :
 
why would you wanna do that? i could see maybe the opposite, but independant rear in a fox would probly not be a good idea.
 
Posted by 93ReefBlue5.0 (Member # 5780) on :
 
why do you guys knock the idea? the IRS is better for a driver, increases track, smoother ride and disk brakes...

to the OP.. its not too hard mounting the IRS. the front subframe brackets bolt into the stock lower control arm mounts and the the rear subframe mount (i believe) uses the quad shock mounting holes.. i would also recommend having someone weld the rear subframe brackets to the frame and not rely on the bolts to keep it in the car...
 
Posted by 85gtcarbro8du-up (Member # 5169) on :
 
sorry not trying to 'KNOCK' the irs. it depends on what you want it for. i've just seen too many of them fail. maybe thats why it sounded like i was knocking them.
 
Posted by 93ReefBlue5.0 (Member # 5780) on :
 
You are right about it depending on what the car will be used for.. The fact thats it hops real bad sucks. The only way to stop it is to get all the rubber bushings out and replaces with delrin/aluminum and a set of sticky tires..And ya, the halfshafts are the weak spot in the IRS.

to the OP, make sure you put a brace on the rear cover at the minimum.
 
Posted by GOT 50 (Member # 1960) on :
 
There is a post on the coral about a guy doing a 03 cobra IRS into a fox. Everything bolts up exept one location where you have to weld new mounting tabs. If I remember correctly for teh rear part of the frame that is directly over the housing. Sick swap let me know how it comes out. Should handle the twisites a million times better than a solid axel.

Eric
 
Posted by Jawsgear (Member # 8080) on :
 
Weaker and not as strong as the soild axle. Seen tons of problems with the IRS differential. I would not recommend, its like taking a step backwards in my opinion. If you are looking for disc brakes then just do a disc brake conversion.
 
Posted by 93HYWAY (Member # 6617) on :
 
This is like my 2oth mustang & I like to try new things.. I already have all 03 cobra fronts brakes , But I've been running drum In the back..

I was basically just thinking it would be cool to have all the 03 suspension.. As far as power I'm running a charged 306, with all the extras..
It's fast but I'm going for more drivability..
 
Posted by MustangNate (Member # 4559) on :
 
Sorry to hi-jack, just curious if it's all IRS that is weak or just the 03/04 Cobra IRS? Corvette's don't seem to have a problem making a ton of power through an IRS.

I know that comparing a $50,000+ car with a $30,000 car, but still.
 
Posted by gtowned (Member # 8156) on :
 
if your not launching the shit out of the car all the time and your looking for driveability then this will be good for you.i would look elsewhere for swap info i think most of the posters here dont understand what your asking.all they here is should i do this swap? [patriot]
 
Posted by 707vibrantcobra93 (Member # 4702) on :
 
no usable input from me but +1 for trying something different, be sure to post pics of end results, and +1 for going agains the norm

[ August 18, 2008, 09:05 PM: Message edited by: 707vibrantcobra93 ]
 
Posted by phildog (Member # 1214) on :
 
To bolt an IRS assembly into a fox, you will need to acquire the two brackets that bolt onto the framerail where the quad shocks originally mounted. The bracket uses three bolts, one of which should line up, the other two will be drilled into the frame. I would suggest using a sleeve inside the framerail so that it does not crush when you tighten the bolts. The gas tank is also nice to have out because the fuel filter is really friendly with the back of the IRS cage, and you may want to move it, or at least change the fuel filter.

The frame brackets can be found in specialty wrecking yards, however, they are only about 50 bucks new from Ford.

You will also need the rear brake lines out of a late 90's GT, I used a set out of a '98, because the brake lines cannot run along the rearend housing to the brakes. They have to run along the tunnel and then split, following the floorpan, to the calipers.

You will also need the e-brake cables for an SVO or Saleen Mustang if you want the e brake to work.

Your stock driveshaft will work with either a '99 or '01 pinion flange, not the '03-'04 pinion flanges.

The stock or aftermarket exhaust for an IRS Cobra will work, however, it will need to get shortened where it hooks into the H-pipe and the hangers for the tips will need to be modified, as they are different, Fox to Cobra.

THis is a swap which has been done time and time again by many Mustang nuts the world over, and the mags and web pages are occasionally graced with a how-to article.

The 2001 Cobra IRS is the easiest to swap, as it already has the correct pinion flange, and it is 31 spline. With the right mods, the IRS will be a superior setup in many ways. However, it is more expensive to go the IRS route if you want all the goodies to make it work under serious power. Dollar per dollar, a live axle rear will be superior to an IRS because the parts are so plentiful for the live axles.


But let's not forget that a live axle with a panhard rod and a torque arm has now become bellybutton on all the really built street cars. The IRS will turn heads.

[ August 18, 2008, 10:20 PM: Message edited by: phildog ]
 
Posted by phildog (Member # 1214) on :
 
A couple years ago,I spent about a half hour on the phone with Gerald from the Mustang Shop in Texas, hashing out the IRS swap for my car. He has done two of these swaps and was more than helpful to me over the phone.


Contact themustangshop.net and ask for Gerald.
 
Posted by itznotahighway (Member # 7934) on :
 
gm irs>ford irs
 
Posted by 93HYWAY (Member # 6617) on :
 
Well I will def. let every1 know how it goes, just waiting for this weekend to get it started.
 
Posted by lambonotch (Member # 5758) on :
 
I wasnt bashing the idea, i just remember an article in 5.0 magazine that listed like 20 different reasons why it was a bad idea.
 
Posted by 92_chp (Member # 5574) on :
 
I think this would be a great idea. Found this at Corral.net. Don't let the hater stop you from doing something different. You should find everything needed for this project. Keep us posted. [Big Grin]

http://forums.corral.net/forums/showthread.php?t=1031857&highlight=irs+fox
 
Posted by 93HYWAY (Member # 6617) on :
 
Well My rearend came out of an 03 cobra, So just wondering what to do about the pinion flange.. I have a tremec tko, with aluminum driveshaft.. & my rear end came of complete, so do I still need the brackets or can I use the ones tht I removed from the cobra...
 
Posted by phildog (Member # 1214) on :
 
Use the brackets that came on your 03 setup. I got my '01 IRS without them, and that is why I had some research to do. The pinion flange can be changed by any rear end shop, or by you, but overtorquing the nut can throw off the setup of the gears, so as for me personally, I would leave that to a pro. The standard 8.8 flange will work on your 03 rear. Swap that on.
 




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