mk4 mustang cobra IRS

[adriancnh]

Hey guys, seems like all the old pages on this topic are broken links. Anywho I have a beautiful 2003 cobra terminator donor and will be ordering the mk4 roadster after I hear what the big news from sema is :) I have emailed FF but they simply said it won't work, but Sergio on this site says otherwise (can't see his links or website). If anyone has a working link to his write up or their own good step by step of what parts I need exactly that would be awesome. Mostly whether I need the IRS chassis or solid axle chassis.

Thanks

[michael everson]

I think they told you that because they no longer support that IRS system. They are building there kits utilizing the 2015 Mustang IRS parts.
Mike

[adriancnh]

I know, I'm trying to avoid the hassle of trying to sell the irs I have currently and paying for the 2015 parts. I know it is possible to do and I will make it work I would just like a heads up on what I will need. thanks

[michael everson]

me Its not really feasible without getting the IRS frame from FFR. Anything is possible with enough money
Mike

[Jacob McCrea]

Welcome to the forum. If your question is "can I marry the entire Terminator IRS system/assembly (meaning the subframe, differential, driveshafts, control arms, spindles, etc.) to the MK4 frame as a whole unit," Mike is correct. That would be in the same league as installing an Allison aircraft engine - physically possible but a mind-numbing amount of very challenging fabrication, and surely not worth the effort.

The only practical way to use your Terminator differential and a few other parts is to replicate, on your own, the old Thunderbird-style IRS frame. This is assuming that FFR will not install the old Thunderbird-style IRS frame as an option, which sounds like it is the case. The new system appears to be a step up from the old one in multiple respects, and I think you would be much better served by going with it, even if you have to sell your Terminator parts at a loss.

[adriancnh]

oh I see, so the frame sergio used is simply not made anymore. Only part I don't understand is the solid axle ffr chassis can use all of the solid axle parts from the mustang right? when my IRS bolts right in to the mustang chassis. Or are the stock mustang control arms not compatible on the FF chassis?

[Jacob McCrea]

Your first sentence is correct. I recall that bolting the entire Terminator IRS system into a Roadster chassis was discussed on this forum at some length a while ago. I think I contributed to that discussion. It was a while ago, but I recall that regardless of whether the FRONT sub-frame mounts bolted up to the Roadster chassis, the REAR sub-frame mounts would have to be fabricated/located essentially in the middle of where the Roadster gas tank is. Also, I dimly recall that a lot of the Roadster's chassis forward of the pumpkin would have to be cut away to clear the Terminator sub-frame. Hence my comparison to installing an aircraft engine. If you can find that discussion, that would be pretty instructive.

[adriancnh]

ok awesome. Ive been searching for quite a few days now but seems everything I find is a broken link or the discussion ends with no result haha. Sounds like i may have to just sell the terminator IRS and go with the 15+. I will phone factory five and ask for a tech who may be able to help me out.

Thanks guys

[adriancnh]

well, after talking to FF I'm just going to run the 2015 irs and sell mine. Thanks again for the help guys. I didnt realize the 15+ parts were so cheap and easy to find

[CraigS]

Glad you got the final word from FFR. There are two advantages of the 2015 IRS. 1-It is a much better design than the old style from a geometry point of view. 2-The parts themselves, especially the knuckle and bearings are a big improvement. They were designed as a performance suspension where the T-bird stuff was done mostly for a better ride in a plushmobile.