Installing a Fully independent suspension in an 05 Mustang GT


I am thinking about correcting the only lamentable featue in my car and change the ox cart girder to a fully independent rear suspension kit. I have seen some kits on the web. What is your opinion? Is it worth it? Will it help bring this pony into the 21st century.


Any improvement to the stock, log wagon, ride would be welcome. It would also be an unnecessary expense on a car that you don’t intend to race. The “cool” factor would be pretty high and it would be a neat project. The question being, Is it worth it to you?


FWIW, Solid rear axles are better for some kinds of racing (e.g., drag).
PS Isn’t an IRS an option in newer Mustangs? Couldn’t you just buy a used '05 that came with an IRS from the factory?


What is lamentable about the present rear suspension in the 2005 Mustang? Independent suspension doesn’t always guarantee better handling. In the 1966 Mechanix Illustrated magazine, the late Tom McCahill re-tested the first car he tested and reported for Mechanix Illustrated–the 1946 Ford. This 1946 Ford had solid axles and a transverse leaf spring in both the front and the back. This was essentially a “horse and buggy” suspension. He compared the 1946 Ford with the 1966 Ford. He had a co-worker drive the 1966 around a test track while McCahill raced him with the 1946. The 1966 could run away from him in the straightaways, but McCahill could get him in the corners. The 1966 had independent suspension in the front, while he 1946 had solid axles on both ends. My point is that changing to independent suspension in the rear won’t necessarily improve the handling. There are other factors to consider as well. Since “old technology” has a way of coming back–witness the rear wheel drive cars from Chrysler–maybe your Mustang is leading the pack in the 21st century.

I should add that I have a real bias here–I really enjoyed driving my late Aunt’s 1940 Ford convertible back in the 1950’s. I have a real affection for the Fords built between 1939 and 1948.


Yes, It will be as you said a cool project and maybe next time I take my car to a track, I will not spin as easily. As far as the worth goes, that depends upon what I get out of it. The thing is I am in love with the body, the exhaust and the engine, but the suspension just frustrates me to no end.


I believe the new Mustang Cobras have fully independent rear suspensions. Just swap in the entire rear and and suspension, along with (probably) the rear subframe. Should be a fairly easy swap.

Of course, it’ll take a trunkfull of money. But you weren’t planning on this being cheap, were you?


True, I was not planning on this being cheap the kit is around 8 -9 k complete. I was kust wondering if this really works. You know if the frame is too soft, all your effort goes down the drain because it will still turn like a drunk hippo.
I was looking at the pictures of the next mustang concept, and sadly they have killed the looks on that one. Also they are still debating on weither to fit an IRS in it.
The 05 shape looks great, sounds great and if will handle decent then it will be my dream car. You can always up the HP at a later date with a super charger.


I recall someone doing exactly what you are planning - and surprisingly, the old Hotchiss rear axle set up was better - in the big scheme of things.

I just wish I could remember which magazine it was - SportsCar, I think.


That’s a ton of money for IRS and IMHO the benefit you gain nowhere near justifies the cost. IRS will help the ride quality a bit and aid in cornering a bit while road racing but I have to assume you’re not headed to Road Atlanta with the car.

My Lincoln Mark VIII has IRS and no doubt uses many of the same components as the Mustang. I think the IRS would be a cool, and very expensive, novelty at first and after 6 months the novelty will be worn off and you won’t even think about it.
I think your stock suspension can be upgraded to make a world of difference and for far less than 9 grand. Get a copy of Muscle Mustangs and Fast Fords and peruse that. There are countless suppliers ads in there, tech tips, etc.
(And whatever you do, always save the original parts; somone down the road may prefer total originality).


ok4450, You are always the voice of reason. I will investigate your suggested path. Thanks for the advice.


I just wished you owned my Lincoln and your Mustang was mine! I absolutely love the new generation of Mustangs and the only ones I like more than the GT are the Shelby and the Roush 427R.
We’ve got a guy here who bought one of the new Sheblys and he also owns a 1967 Shelby in the same color. How lucky can you get.


I don’t know if it can be done with the newer models. The older 99-04 Mustang Cobras had IRS, and the Cobra suspension could be fitted to the lesser models, although it wasn’t cheap. Even the tuner versions of the new model (FR500C, Roush Black Jack,etc.) retain the solid rear axle.


I just wished you owned my Lincoln and your Mustang was mine! I absolutely love the new generation of Mustangs and the only ones I like more than the GT are the Shelby and the Roush 427R.

The new Mustang is by far IMHO the best looking car produced in the past 20 years.