IRS/8.8 swap

[Shane361]

I'm starting to look at swapping my Mach1's rear end for my Cobra's rear end. Looking at dropping everything at once and rebolting it back up. One is a 5 speed and one a 6 speed but not sure how much impact if any that will have. I would assume the gears would have to be swapped out within the pumpkin though. Any insight would be great.-Shane

 

[0ne_sik_notch]

i put the irs in my fox coupe

 

[smashedheadcat]

You don't need to do any pumpkin stuff. The only parts you will need to buy is one u-joint for each car. The rotors/pads will stay with each car, the ABS will plug right in as well. I did the swap with a 97 cobra and with the exception of the pinion flanges (which is why you'll need a u-joint for each car), everything bolted right up. If you have any specific questions, please feel free to ask.

 

[Shane361]

You don't need to do any pumpkin stuff. The only parts you will need to buy is one u-joint for each car. The rotors/pads will stay with each car, the ABS will plug right in as well. I did the swap with a 97 cobra and with the exception of the pinion flanges (which is why you'll need a u-joint for each car), everything bolted right up. If you have any specific questions, please feel free to ask.

I am going 4.10s in both cars so figured I would do them both at the same time. But..might make that another day as to not where myself out or anyone that might be helping. Thanks for the input. Little more on replacing the U-joint would be nice, why replace it? -Shane

 

[yosemiddysam]

Shane it is a huge PITA to swap the gears in the IRS so I would swap them while you already have it out.

 

[Shane361]

Shane it is a huge PITA to swap the gears in the IRS so I would swap them while you already have it out.

Not good to hear...lol. Changing the Mach1 is more of a priority at the moment. Getting the 8.8 in the Cobra even more. It'll be after you get back..I'll wait just for you James...HA HA-Shane

 

[yosemiddysam]

From what I have heard you pretty much have to drop the IRS to swap gears. I have to drop mine anyways to change out the bushings.

 

[smashedheadcat]

I am going 4.10s in both cars so figured I would do them both at the same time. But..might make that another day as to not where myself out or anyone that might be helping. Thanks for the input. Little more on replacing the U-joint would be nice, why replace it? -Shane

Now, I don't have any mach 1 experience, but if the driveshaft is the same as a 97 then it uses 1330 size u-joint. The 03 cobra used a 1350 sized u-joint (little bigger). Anyway, the pinion flange on the 03 cobra driveshaft doesn't physically bolt up to the 97 cobra rear end and vise-versa. So the cheapest way to make this happen, is to keep the pinion flange (on the aft end of the driveshaft) with it's original car. So when I did this:

Each car kept it's driveshaft.
Switch rear ends.
Remove the pinion flange off of the aft end of the driveshaft and keep it with it's original rear end.

In my case, I ended up with a set of 1350 sized holes for a u-joint in the 03 cobra driveshaft, but 1330 sized holes on the 97 cobra pinion flange. Since the holes are different sizes, I could no longer use the stock u-joint. So I used a Precision 448 U-joint, one for each car. This is an easy swap and a pretty tough little u-joint. I haven't broke it yet, that's about all the R&D I can give you as far as the strength goes.

As for 4.10's in an 03 cobra, I had 4.30's in mine and kind of liked it. The only bitch I had was you'd be in 6th gear and the little shift arrow would show up. I killed it in the tune though. I was on the stock pulley at the time and thought it made for an excellent combination. With more power, I wouldn't go any more agressive than a 3.90. 4.10's minimum in the mach though.