AS an FC guy, I would say it's not really worth it. For the time and effort to cut fab and weld, I would look into an 8.8 IRS install.

Back when I had my 82 rx-7 and my 97 t-bird I did a bit of measuring. I think the IRS out of the V8 powered t-bird or cougar would fit under an FB just as well as an FC unit. The width of the rear end is about the same as a solid axle mustang, meaning you can probably fit it with FWD offset wheels under the stock fenders. The V8 powered t-bird and cougar also came with an LSD equiped 8.8 diff, so your set there. More or less the same setup that came under the SVT cobra in the early 2000's but can be had from just about any junkyard. Be careful though, the v6 powered cars came with the 7.5 diff, much weaker but would probably still withstand a stock TII engine, though no LSD.

when the stock live axle can be made to pull ~1.2G in the skidpad, yeah it's a questionable gain.

Sounds like I need to do My homework!

Sounds like I need to do my homework too. I was struggling with this same issue. I have been considering the same situation and trying to decide if its worth the work. However, if the stock unit can be modded to that kind of results that seems like the way to go...

For those who didn't see his thread, he actually did go through with this swap here:

https://www.rx7club.com/build-thread...end-fb-998272/

He hasn't been on in months though so i'm not sure how it actually worked out when/if he got the car back on the road and running. Encouraging to know that it can actually be made to fit though..

you need to swap the entire sub frame as far as ive heard but its very plausible. you can also swap the entire front subframe as well. from what ive been told. but i could be wrong.

lets see bigger bolt pattern , brakes, suspension options, LSD all in one swoop.... somehow not worth it? :scratch:


ive gotten rollers before for free with turbo drivetrains in them. swap over call it a day. :icon_tup:

I have the FC front end, it's kind of a upgrade and a downgrade. You get more suspension options but you get worse suspension geometry unless you do some serious surgery to the body channel. Call it a wash.

Trailing arm suspension, however, is an answer to a question that shouldn't have been asked, namely "How can we make an IRS that sucks in every way possible?" Mazda did all of the funky links and squishy bushings in an attempt to alleviate some of a trailing arm suspension's more interesting handling quirks, but in the end you still end up with a suspension that you can't really put power down with.

Here's me carrying a front tire at a corner exit. A 3-link works, on any kind of surface. L/R is near full compression, R/R is drooping and still able to grip.

http://mtbshred.com/copper/albums/ft...l_IMGP8724.JPG

PS - Note the fender gap at the top of the door vs. the bottom - my car's getting a bit banana shaped :) Time for another one probably.

there was a guy on here that did and show lots of pic of what he did

Yeah I posted the link above ^^

Too bad he hasn't been back on to comment on how it's working out...

Am just in the process of doing this swap myself can you elaborate on the downsides of worse geometry? Looked like you pick up a bit of castor to me which can't be a bad thing and widen the front track. Would be interested to know the downsides so I can try to engineer them out a bit.

The front track doesn't get widened. You still end up with positive camber just like an FB, too.

There's little you can do about the worse geometry. I've seen people notch the body rail a few cm to get the subframe higher up in the body, but you're still stuck with control arms that are a lot shorter so rollcenter moves around a lot more.