LocostUSA.com

Im curious as to why more people dont use the IRS from a miata in the rear. The subframe would be extremely easy to adapt to a seven style chassis.

Now I do understand this means that a custom chassis is in order. At least the rear end. I am now at the parts aquiring phase of my build and need some yays/nays with this idea.

Price I found for complete miata rear suspension disk to disk is $225. There are three at the local wrecking yard right now!

Nissan 240sx drivetrain will be used because of the cheapness around here in so cal. (all the 240 guys go to sr20's)

Here is a pic for some views. From Kieth Tanners Site

My guess is that the parts are just way too heavy for the Locost chassis. It would work fairly well, but would be way overkill compared to what is actually needed back there. I agree it would be an easy way to do IRS for someone that isnt up to doing all the math, but I think it would probably put a lot more weight in the rear than is needed.

FWIW, I have a bunch of photos of my 240sx KA24de based build in The builders log section if you want to see how the engine fits in the 442 chassis.

I did a dumb live axle....beause of simplicity and I am not sure I need an IRS to pick up groceries, drive my daughter to school, and commute to work.

Shrugs I guess I could have bought a Kia with a warranty but not even close in the coolness factor.

_________________
I'll keep an eye out for you!

To err is human...
I am more human than most.

my reason is that $225 is $200 more than my entire donor.

Yup, cost is basically it, plus a live axle is just easier to build.

On the other hand you pretty much have to be an incredible driver to really notice the difference between a ***properly set up*** IRS and a live axle on a seven type of car. Also to get the IRS set up perfectly is a task in itself.

In my humble opinion a better way of using a miata rear suspension is to make a dedion rear end a fraction of the weight and the simplicity of a live axle.

well here is something that I didnt explain...

this car probably wont have the typical 140 hp... it will be turbo charged in a slightly wider chassis to accomodate all the hardware. I think the extra beefyness? in the rear might be adventageous. My desire for irs is strong. so is tried and true excellent geometry in the rear, as is easy replacement of parts and bushings down the road.. thanks for the responses, its helping me narrow down the choices! I think using these components and a dedion might be the way, ala cmc

Mark Rivera is doing exactly that (Miata rear subframe integrated into the chassis).

See his work at:
http://rivera.fotomojo.us/g/MX7?page=8

-Erik