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PostPosted: April 7, 2006, 1:07 am 
It seems that a Mazda Miata 1.8L engine, trans, rear end would be a simple
solution. Is there a problem with this ? Cost ? A weak component ?
Wrong size ?
The Ron Chapman kits used the Miata as a donor.
I am trying to decide between a Zetec or Miata donor. What is the difference between a Ford T5 trans from a V8 Mustang and the Miata 5 speed
transmission ?
Just getting started so many questions.
Thanks for any advice.


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PostPosted: April 7, 2006, 2:03 am 
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Joined: September 22, 2005, 10:29 am
Posts: 398
The Zeec may be easier to get normally aspirated power out of, but the Miata mill can put out insane power under boost. It's also rock reliable, and with it's other components you can go single donor.

I highly recommend you get this book:

http://www.amazon.com/gp/product/0760322872/104-9873964-6069537?v=glance&n=283155


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PostPosted: April 7, 2006, 9:57 am 
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Joined: August 15, 2005, 10:13 pm
Posts: 7048
Location: Charleston, WV
I am going to build mine "out of" a 1.6liter 1990 Miata. I should be able to get about everything I need from the one car. Not much power but it allows me to go extremely lightweight. I should be able to acheive some impressive performance numbers by virtue of the favorable power to weight ratio. If I ever get bored with it I can always boost it.


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PostPosted: April 7, 2006, 10:52 am 
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Joined: August 16, 2005, 10:29 am
Posts: 1070
Location: Alberta, Canada
The T5 is a rather tight fit in a book size frame ...


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PostPosted: April 7, 2006, 6:50 pm 
By "Ron Chapman", do you mean Ron Champion? Or are you referring to the Champion Motorcar Company products?

The biggest problem with using a Miata as a donor is that there's no good documentation of a rear suspension with the IRS. One solution is to simply modify your frame to bolt the entire rear subframe from the Miata in place. There's a build underway right now where that's being done and I think that's what Coveland does in their kits. The transmission is one of the best-shifting units in production but it won't hold up to a V8's torque.

It's probably the best single donor for a small Locost in the US unless you want to go hunting for vintage Toyotas.

I think you should get that book too, but I have an alterior motive :)
Keith


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 Post subject: Miata Donor Questions
PostPosted: April 8, 2006, 1:17 am 
Hi Keith:
Yes I meant Ron Champion's book. I just ordered your book.
In the meantime. How does the Miata engine compare in size and weight to a Ford Zetec 2.0L ?
Is the Miata 5sp smaller than the Tremac T5 ? Will the Zetec bolt up to
the Miata 5 sp trans.
Regarding the rear end. Is it possible to separate the differential from the
subframe and bolt it into my chassis ? It looked like they did it in the
Grassroots Motorsports CMC buildup.
What other options are available for IRS from USA cars ?
Sorry for all the questions.
I need to supply the specs on my donor parts soon for a kit builder in England.

Thanks for your help;
Roger


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PostPosted: April 8, 2006, 1:22 am 
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Joined: August 15, 2005, 10:13 pm
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Location: Charleston, WV
You are aware that Coveland in upstate NY makes a miata based seven kit for a very reasonable price. Why order from across the pond when you can buy right here in the good ol USofA. Below is a quote from the Coveland site.

Quote:
IRS (Miata)
Specifically designed for the Miata drivetrain , and will work with other IRS drivetrains with simple modifications. Designed to need No welding to mount a 1.6 or 1.8 litre Miata. This frame has been specifically dimensioned to properly fit the Miata engine and transmission. The rear differential mounts are located and a double plate used for strength. A plate has been added under the differential giving strength to the frame and the differential. Brackets are already welded to use stock Miata emergency brake, brake lines, and Miata steering column. Other parts used directly from the Miata include wiring harness, guages, Brake calipers, uprights, rack, exhaust header. Upper and lower front and rear wishbones included with the kit. $2,700


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PostPosted: April 8, 2006, 10:40 pm 
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Joined: August 16, 2005, 10:29 am
Posts: 1070
Location: Alberta, Canada
Keith - how tall is the Miata motor from bottom of sump to top of valve cover? Does it fit under a "standard" locost nosecone? Thanks!


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PostPosted: April 8, 2006, 11:41 pm 
Keith Tanner wrote:
The biggest problem with using a Miata as a donor is that there's no good documentation of a rear suspension with the IRS.


What sort of ducmentation are you looking for? A complete design?
Just curious. I have a pretty decent design (I think) that implements the Miata IRS geometry but it probably won't ever get off the drawing board.


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PostPosted: April 9, 2006, 12:18 am 
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Joined: August 15, 2005, 10:13 pm
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Location: Charleston, WV
If you are looking for an interested party look no further. I'm picking up my donor Miata next week. If you have a design you are willing to share please do so by all means. :P I would love to see what you have in mind.


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PostPosted: April 10, 2006, 4:35 pm 
I believe what Keith is referring to is mounting the IRS to the chassis. When Grassroots Motorsports magazine built a Champion kit the IRS sheared off the mounting ears on the IRS.


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PostPosted: April 11, 2006, 2:02 pm 
I'd definitely like to see a good IRS design.

GRM had the front mounting point of the differential fail. Not on the differential itself but on the frame. The side mounting ears were fine. CMC's thinking showed a complete lack of understanding of the forces involved and even in how differentials work.

This is a problem that faces the Miata-based builder whether they use the subframe or not, as the rear subframe does not supply the front mounting. I've solved the problem in my car by bolting the nose to a reinforced section of the transmission tunnel. Others have solved it by making a short version of the Power Plant Frame used by Mazda although this is redundant stiffening in my mind.

Height of engine appears to be bang on 24". I can't tell you if it fits under a standard nosecone because that will depend on a lot of factors. I can't compare it to a Zetec although I know Skip Cannon has put a Miata engine in his Caterham SV chassis easily and the transmission fit in the tunnel. Just.


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PostPosted: April 11, 2006, 4:43 pm 
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Joined: March 10, 2006, 12:48 am
Posts: 282
Location: CT
Anybody have a transmission handy? What's the length from the front of the transmission to the shifter? I'm hopefully going to the junkyard on Saturday, if so, I'll bring a tape measure and measure whatever I can. So far on the list is the Mazda 1.6 and 1.8 length and width, Miata tranny length, Ford 1.9 CVH height, Ford 1.9 SOHC height. Anybody need anything other measurements?


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PostPosted: April 11, 2006, 5:09 pm 
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Joined: August 17, 2005, 1:30 am
Posts: 2403
Location: So CALIFORNIA
Ford/Mazda Duratec 2.4 & standard transmission is you see one in the scrapper.

_________________
I'll keep an eye out for you!

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


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PostPosted: April 11, 2006, 5:26 pm 
Man, I had to walk all the way over to the other shop to check this one :) 32" from the front of the tranny to the centerline of the shifter.

For the engine width, where do you want that measured? Engines aren't boxes...


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