Has anyone done the IRS upgrade on the first gen suspensions?

The way it works in my head is:
I want 5 lug anyways...
IRS is better for autocross and mountain driving...

might as well buy an FC3S and just do a full suspension swap!

Not sure how hard it would be to make it actually work though.

Any thoughts?

 

Would it not be easier to just buy the FC and drive that? Im an fb owner also, they actually handle as good as or better than anything else on decent roads with a decent panhard setup and well sorted springs/shocks/bushes

 

not sure if mountains have decent roads though, famous places like Mulholland Drive I'm not sure if the stock suspension will handle it well.

I haven't really broke into my car yet to feel it's maximum handling capability though.

 

It's been done on here. I forget who it was that did it. It's a bitch. I'm with others not quite sure I'd go through the trouble.

 

Many years ago, before the internet, when I began autocrossing, an old guy gave me the best advice ever. "Learn to drive your car as well as it can be driven before you start throwing money at it."
He said that as he was pointing to the clique of younger (my age then) guys who were forever fiddling with their equipment yet rarely finished better than middling.

 

imo, the FC rear suspension isn't that good, so its not really worth the ENORMOUS amount of work it would take to put it in a 1st gen.

if you're going to have to fab the whole back half of the car you might as well do something better like the FD, or Rx8, or go custom

the rear of the 1st gen has a couple of quirks, but once you address them, it works really well

 

IRS isn't automatically better. It takes a very well designed IRS to be nearly as good as a half decent solid axle setup, and most IRSs are horribly designed.

Ford proved that a well built solid axle is superior in every way but interior room and techno-cachet. The new Mustang has an IRS mainly because they are trying to sell the car in Europe and people there care more about the spec than how it actually drives.

 

What he said.

If you search, there are a few threads on this that have beat the topic of IRS vs Live Axle to death.

 

this! the FC suspension is nice because it offers lots of luggage room and a flat floor, while not being as bad as a typical swing arm suspension

 

I like swingarm suspensions... on AWD cars where the quirks are all beneficial, since you need a bit of instability in the rear to help the front work better. Mainly toe-out under cornering loads, although the unloading under braking due to the torque couple is nice to aid turn-in. There's also some unloading under acceleration as well, which helps the front tires bite, reducing power-on understeer.

Note that Mazda spent a lot of effort seriously complicating the swingarm idea so that they could get toe-IN under side loads instead of toe-OUT, which is more stable for a rear drive chassis. And it works so well that there are plenty of kits available in the aftermarket to eliminate that feature. But they still squat hard under acceleration and have brake hop.

 

haha well said! but honestly it's part of repairing parts. My car isn't completely drivable yet, so instead of just replacing/repairing the current suspension, considering swapping into another is an option.

 

That's a great quote right there

I agree completely though, I'd either get an FC and rock that for the racing and mountain driving and keep the FB stock as it is and learn to deal with the solid rear axle. It's not half bad once you get used to it!

 

I love the live axle setup on the fb. I have driven both live axle and irs, and while irs CAN make for faster cornering times, the live axle is much more predictable and easier to control....and its easier to work on...

 

Boy are you asking for trouble. As stated a well set up solid axle works fine for most folks. If you have to do it, I'd say to use the FD set up as it is packaged better for getting it under the first gen and more effective geometry wise. I know Whizbang is currently working on doing the swap in his 79 rally car, he has a build thread here. Either way it's a whole lot of work to make it happen. It really depends on just how bonkers you want to go, and how long you're willing to let it sit in pieces I guess.