Why not? A Miata subframe swap?

From doing some reading and looking seems like

1.the Miata front and rear subframes/suspensions are pretty much contained units. 

2. I read both front and rear attach to the body with 6 bolts?

3. Seems everyone loves of Miata handles, even if they don’t love the looks. 

So why don’t more people looking upgrade older cars, just swap the subframe from Miata, onto their body?

I’ve seen many partially stalled projects on forums of people thinking about doing this on old Datsun trucks, or 240z, and older British small cars. But no real finished builds. 

What gives? Why doesn’t this work. Seems like it would. 

The kind of pain with the Miata subframes is that they mount high up and inboard in the chassis, especially the front, because the upper arms attach to the frame and so the tub necessarily has to be narrow there.

I very briefly looked into Miatafying my RX-3.  When I realized that it would go easier if I also used the floorpan and firewall, I stopped looking into it.  Similar would be true for any other strut suspension car.

The rear subframe  has been used in some locosts.

I have given some though to this.

If you are talking of just using the front and rear suspension sub-frame assemblies, the rear is not hard to do. The front is a bit more complicated and of course both levels of difficulty will depend on what you start with and what level of fabrication you are comfortable with.

I had the rear subframe in place and looking good like you said six bolts and you are good to go. Then I went to the front and ran into a wall of reality that convinced me to abandon this path.

In front, I did go as far as abandoning the factory Miata K member and fabricating a steel structure that would locate the Miata suspension  to the P1800 front frame by just slipping over the frame rails.  Not a trivial bit of work. As you can see on the model the pivot points for the upper a-arm still require a clearance solution as they want to co-habit the same space as the frame rail. And you still need to locate the top of the spring.

Even at the rear, the subrame gets in the way of stuff like back seats, fuel tanks spare tire wells and exhaust. All solvable but it takes some thinking.

Pete

If compact well designed suspension swaps are whats needed I'd look at front suspensions from 4th or probably better 5th gen civics.

 The crossmember to mount the lower control arms also contain the steering rack,not good though if front engine rwd is the plan.

 Using just the arms and struts should be doable,I'm building an '82 civic hatch with a K20 in the back and will be using the crossmember and strut towers from a 5th gen grafted in front and rear.

There are successful Miata subframe swaps out there. I can think of an MGA, a Nash Metropolitan and a couple of Morris Minors off the top of my head. Then there are the Exocets and Catfishes.

On my MG, I decided it was just as easy and lighter to build control arm pickups instead of mounting the subframe. The Miata subframe design is great if you’re doing mass production or building for crash repair, but it doesn’t have any attributes that give better handling over a well-set-up front end with the same pickup points. 

This concept is fairly common with S13 and C4 Corvette subframes as well.

In reply to NOHOME :

So on the rear you had to cut the floor pan. To locate the sub frame top in where the back seats would be? Bc it mounts so high in the chassis? Also do you have the whole Miata suspension mounted up. Or still a work in progress?

In reply to Keith Tanner :

Keith do you have a build thread or anything where you show how you built those pickups? 

I saw a Mini a few years ago with Miata suspension grafted in... don't think he used the whole subframe because of the narrower track width.

Oh, it was also RWD, powered by a mid-mounted turbo Hyabusa engine...  

Somebeach said:

In reply to Keith Tanner :

Keith do you have a build thread or anything where you show how you built those pickups? 

 

Start reading around here: http://slowcarfast.com/MG/diary.php?start=84

You'll also find a build diary in this forum.

In reply to Somebeach :

Actually, the rear required very little cutting. Had I simply welded in some flat structure to mount the Miata subframe, it would have been easy to do. This is all the clearance that was required in the back seat area. ( Car is a Volvo P1800ES)

In the end, I took another direction with the project and abandoned grafting Miata suspension on to the Volvo. Sorta.

Pete

In reply to Somebeach :

Much too wide in the rear end to fit my Alfa Romeo spider 

In reply to Keith Tanner :

Thanks!

In reply to NOHOME :

That doesn’t look too bad.