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Fritts,

The small amount of difference won't effect geometry enough to worry about... just don't weld yourself into a corner and have to breakout the hacksaw (though you can find many cases where builders have cut off something and redone it... not that big a deal).
.

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Since he didn't I'll say it for him, thanks SCD, and thanks Tony. I just remeasured the upper CA and it was more like 8 7/16. And this time around it looked like the upper upright pivot was set inboard closer to 1 3/8". Since we've verified the UCA and the subframe and upright, by process of elimination the lower control arm must be the incorrect measurement. I waded out back in the snow and measured it again and it looks like 15 1/4 to me, so I think that's our problem. Maybe someone can post here what length they determine it to be.

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He is a wise man who does not grieve for the things which he has not, but rejoices for those which he has.

Sorry if I came across as a jerk as I'm very appreciative of the information. Looking at it again with the new dimension it appears to be very close (0.2" off UCA). Looks like that should be close enough with adjustable rod ends.

Hi
Sorry to resurrect this thread but was interested as I am in the process of designing my front suspension.
I would agree with the measuremnts of eurokraft on the distances between the upper and lower as my measurements were 757mm for A and 660mm for B.
My measurements for the upright are a little different however and incase there are differences in the models mine are from a NA. I was very carefull in measuring them and made a disc in the lathe to bolt the hub to so that I had a nice flat surface to measure from. one of the problems is finding the centres of the ball joints so made pointers to bolt in the holes.
The following were the results. Top b/j 25mm from top face and 127.5mm (5-1/32")from face of hub. Bottom b/j 32mm from bottom face and 77.5mm (3-1/32") from face of hub. Tie rod end pivot point came out at 20mm from face of arm and 66mm (2-19/32") from face of hub. Measured as per chetcpo square from the hub face the top b/j is 123.5mm from the centre and the bottom b/j 85.5 (3-11/32"). Measured between centres 212mm top to bottom b/j. Steering arm was 121.5 from centre and 58deg from bottom b/j and axle centre. Axle centre is 8.5mm offset from centre line between top and bottom b/j's. Of course the top b/j will vary given your choise as it is not standard part.
Chetcpo's measurements included the brake rotor whereas mine don't. Hope these are of some help to someone.
Bruce

FWIW IIRC my measurements on the upper BJ were done from the center of the ES247R tie rod end I was using with my control arm and not the factory balljoint. That may account for some discrepancy there. As for the others, I'd trust your measurements. It sounds like you did a good job.

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He is a wise man who does not grieve for the things which he has not, but rejoices for those which he has.

Hi,
Forgot to add that my control arms were 350mm for the bottom and 250mm for the top.
chetcpo do you remember where the centre of the top b/j you used was in relation to the face of the upright eg. mine was 25mm and likewise was not factory, but from a Mazda van.
Bruce

Please note that I have edited the post with the measurements in it as I got one wrong. I have rechecked and are satisfied that they are very accurat now.

FWIW, using the tools I had on hand, the rear LCA looks to be about 390mm center-to-center, confirming Chet's previous 15.25" to 15.5" measurements.

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Steve

I'm wondering if Fritts ever completed the CAD modeling of Miata NA suspension geometry. I'm planning on doing the same in SolidWorks, and would rather not re-invent the wheel if I could get a copy of his CAD drawings.

you are running into the same thing I was when I did my 1st Miata based car .
because mazda with the Miata go it pretty dam good out of the box I did not want to change up there suspension geometry and lay out all that much .
what we did was 1st take the Miata subframes and set them up on the frame bench as they would be in the car and take our measurements and then put the info into the design program .
there are CO's that make Miata adjustable control arms that should give you more then enough adjustment in them to lower the chassis ride height and still have good usable suspension travel .
the control arms cost less then they would if you built them your self .

if you were changing the suspension geometry much more then the stock Miata's is I would pick a different chassis for your donor car say like the rx8 with a different track and base .

Can you post some more info/pictures from your frame book? I, like everybody else here, am trying to recreate the Miata geometry and would like measurements of the suspension pickups as well as the rack location.
Thanks,
Justin

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Sorry, Sold my shop 2 years ago, frame books included.
But I do have jigs that I made based on the Miata subframes, front and rear

http://s196.photobucket.com/user/eurokr ... rt=2&o=127

http://s196.photobucket.com/user/eurokr ... rt=2&o=128

this was made using the jigs.
cheers Tony

Where does one find a frame book? What is the name of this frame book so I can search for it?
Thanks

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you can find them on Ebay, here's a link


http://www.ebay.com/sch/i.html?_from=R4 ... s&_sacat=0

Most body shops with frame equipment should have them, but its mostly digital now,
if you now someone in a body shop they probably wouldn't mind printing you a copy off what you need.
Ps. if you buy from Ebay, make sure they have ther car you want, pages might be missing, etc etc
Pm on you way

cheers, Tony