Bpohlman13 Posted November 22, 2012 Share Posted November 22, 2012 I actually have a mustang I did the IRS swap on. Its not the halfshafts that make the rear end not able to handle power. It is actually the bushings in the rear that make the halfshafts break. What happens is that the stick rubber mounts allow alot of movement of the diff. This causes the axle joint angle to severely increase causing alot of strain on the joints during hard launches. The actual axles can handle alot of power. Ive seen people put 1000hp onto those stock axles after replacing the bushings without an issue. However, I have seen people put in those "1000 HP" halfshafts and break them with 500hp. The full tilt boogie kit is your best bet. the mms setup comes with alot of urethane bushings which wear out easily under large stresses. Also, it may seem hard to grasp, but the hard delrin bushings in the ftbr kit actually give a better ride the the softer rubber bushings that come stock in the cobra IRS. It is because it eliminates binding which eliminates the rebound the rubber bushings produce. Also, this will increase handling tremendously as it will remove all the play in the setup. I also just bought an S30. I am converting it to a double wishbone setup aswell, but it is completely custom. I am using z32 components and making a cradle to hold the diff and lower control arms. I am then mounting the upper control arms to the frame rails that are already there. Ill make a thread later on this week when I hope to finish up alot of the fabrication. Quote Link to comment Share on other sites More sharing options...
peej410 Posted November 29, 2012 Share Posted November 29, 2012 The ford IRS with its limitations is a designed solution. After months of thinking and planning I put 97 M3 suspension into my Z. It took a lot of hours to figure plan design and get everything together. There Is a lot to be gained. I didn't have the funds to make the Z rear end bullet proof. Do it, have fun, and learn along the way. One big note. Spend an exhaustive amount of time setting up your ride height and the subframes location in the car. I have my car running and over the winter am tearing it back apart to try to raise the subframe in the body more. Worst case scenario you have a modern adjustable suspension you can get real dampers and current aftermarket parts for. Quote Link to comment Share on other sites More sharing options...
rsicard Posted November 30, 2012 Share Posted November 30, 2012 I actually have a mustang I did the IRS swap on. Its not the halfshafts that make the rear end not able to handle power. It is actually the bushings in the rear that make the halfshafts break. What happens is that the stick rubber mounts allow alot of movement of the diff. This causes the axle joint angle to severely increase causing alot of strain on the joints during hard launches. The actual axles can handle alot of power. Ive seen people put 1000hp onto those stock axles after replacing the bushings without an issue. However, I have seen people put in those "1000 HP" halfshafts and break them with 500hp. The full tilt boogie kit is your best bet. the mms setup comes with alot of urethane bushings which wear out easily under large stresses. Also, it may seem hard to grasp, but the hard delrin bushings in the ftbr kit actually give a better ride the the softer rubber bushings that come stock in the cobra IRS. It is because it eliminates binding which eliminates the rebound the rubber bushings produce. Also, this will increase handling tremendously as it will remove all the play in the setup. I also just bought an S30. I am converting it to a double wishbone setup aswell, but it is completely custom. I am using z32 components and making a cradle to hold the diff and lower control arms. I am then mounting the upper control arms to the frame rails that are already there. Ill make a thread later on this week when I hope to finish up alot of the fabrication. Sure would be nice if there was a lot more detail in your post. Where are these bushings located that we talked about? There looks to be some spelling mistakes that make the post somewhat confusing. What is a full-tilt boogie kit and what EXACTLY does it do? Care to clean up the confusion? Quote Link to comment Share on other sites More sharing options...
Bpohlman13 Posted December 3, 2012 Share Posted December 3, 2012 It replaces all of the bushings in the rearend. The full tilt boogie racing bushing kit includes all of the bushings for the rear end. These bushings are made out of delrin. Which is a hard material that somewhat resembles plastic but can taking much more of a beating and doesnt allow much play. I personally dont think this setup in our s30's would work very well, but I was simply giving the OP other options. Which is why I am going with a full custom setup rather then trying to adapt and entire rear clip. I am simply just using the differential and knuckles from the 300zx and fabricating the rest myself. Quote Link to comment Share on other sites More sharing options...
Hypertek Posted December 6, 2012 Share Posted December 6, 2012 No one wants to do 240sx/300zx IRS huh? I think it would be a more suitable swap instead of the ford unit, save that for a vintage mustang =) Quote Link to comment Share on other sites More sharing options...
FLC Posted December 12, 2012 Share Posted December 12, 2012 more fabrication less talking i want results lol Quote Link to comment Share on other sites More sharing options...
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