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View Full Version : My solid axle swap


smashedheadcat
09-08-2005, 11:31 AM
Well, I finished up the swap. I took my built up axle from my 97 cobra and installed it under the 2003 cobra. I will be putting the IRS under the 97 next weekend. The only problem I ran into was the torque boxes for the upper control arms. Since they are not used with the IRS, they had never been "squeezed" together. So I thought that the upper control arms would not fit. I put them in there and there was a good 1/2 inch of slop side to side. Also, the bolts from the 97 (upper control arm mount) were not long enough due to the "unsqueezed" upper mount. I got help from Lou @ Laurel Mountain mustang and he told me that the control arms I had would work, I just needed a longer bolt to squeeze the mounts around the control arms. I had already lost a whole afternoon thinking I needed new control arms. The next day I got cracking again. I finished up everything except for the driveshaft. The pinion flange wouldn't bolt up to the rear end so I had to switch the u-joints to allow me to retain the '03 cobra driveshaft. I had to get a Precision 448 u-joint to make it work. After that, it was smooth sailing and I finished it up before dark on day 2. These 2 pics are from my stopping point on day 1. This is where I ran into the road block. It took about 3 1/2 hours to get to this point.

http://www.modularfords.com/forums/attachment.php?attachmentid=16590&stc=1&d=1125870242

http://www.modularfords.com/forums/attachment.php?attachmentid=16591&stc=1&d=1125870242

These pictures are from day 2 during the install. The only parts I need to buy was the Lakewood 50/50 drag shocks, the steeda drag springs and 2 precision 448 u-joints to swap the pinion flanges around on the driveshafts. I had a set of 1/4 inch wheel spacers I used on the rear. The rear end from the 97 cobra is 3/4 of an inch shorter on each side than the 99-up rears. So the wheels would sink in 3/4 of an inch on each side. i put the 1/4 spacers in back there to push the wheel out a little bit.

http://www.modularfords.com/forums/attachment.php?attachmentid=16617&stc=1&d=1125965136

http://www.modularfords.com/forums/attachment.php?attachmentid=16618&stc=1&d=1125965136

This is the finished product. The car sits a little lower in the back than it did before in the rear, but only by about a 1/4 to a 1/2 inch. It doesn't look like it in the pics, but after driving it a few miles, the springs settled and it squatted a down to it's lower ride height.

http://www.modularfords.com/forums/attachment.php?attachmentid=16638&stc=1&d=1126045947

http://www.modularfords.com/forums/attachment.php?attachmentid=16639&stc=1&d=1126045947

Overall impressions- Well, I saved about 125lbs (estimated) by doing the swap. The car feels very stable. Wheel hop is completely gone so that just makes it more fun to drive. The 4.30 gears are in it now and it really woke the car up. I'm gonna hit my local 1/8 mile track and see what she does. I did pick up a little bit of road noise with the swap, but that's because of the spherical bushings on the axle side and polyurethane on the torque box side with the control arms. I'll use my xcal2 programmer to recalibrate the speedometer before I head out tonight. Overall, the swap took about 6 hours of work. It took 2 days for me though because of confusion no the upper control arm mounts and also hunting down a couple of u-joints.

blk04cobra1
09-08-2005, 11:38 AM
very nice...thinking about doing the same...but I love my IRS...who knows, looks like it'll be a coin toss :thumbsup:

smashedheadcat
09-08-2005, 11:49 AM
I don't miss that IRS one bit. I hate that thing. I liked it on my old 99, but it wasn't powerful enough to break anything.

InfamousSVT
09-08-2005, 09:36 PM
Looks good Josh! :thumbsup:

<----- Solid axle equipped also :D

smashedheadcat
09-09-2005, 08:53 AM
Looks good Josh! :thumbsup:

<----- Solid axle equipped also :D

Thanks bro. I took it to the track last night and didn't get any faster. 8.18 @ 88mph was my best. I went 8.17 @ 86 with just an air filter and the stinger catback. :(

blk04cobra1
09-09-2005, 08:57 AM
maybe not faster, but im sure you worries about breaking something (in the rear end) were gone :D

smashedheadcat
09-10-2005, 12:13 AM
maybe not faster, but im sure you worries about breaking something (in the rear end) were gone :D

That's true. I was hoping for 7's at 90 or more. My 60ft times were in the low 1.9's which is not very impressive. I was running 35psi in the rear tires which is very high. I should have lowered it, but I didn't feel like stopping at a gas station on the way home and airing them back up. The car felt great though at the track though.