LocostUSA.com
http://www.locostusa.com/forums/

First gen Miata suspension measurements.
http://www.locostusa.com/forums/viewtopic.php?f=5&t=1409		 Page 1 of 2
Author:  chetcpo [ November 25, 2006, 7:39 pm ]
Post subject:  First gen Miata suspension measurements.
I'm starting on my suspension soon and as step 1 I measured the Miata stuff. The track width is said to be 56.5", but I think that is with factory negative offset wheels. I measured my rear track at 58" without the wheels on. (assuming zero offset)

There have been several requests for this information so here it is:
I can't guarantee perfect accuracy, the parts I measured came off a wrecked car but weren't noticably bent, other than the front subframe which has a slight twist to it.

Any other measurements you'd like, just ask.
Author:  chetcpo [ November 25, 2006, 9:06 pm ]
Post subject:  Miata spindle pics
These are in another thread, but I'll put them here as well.
Author:  whittlebeast [ November 26, 2006, 11:02 am ]
Post subject: 
So is the mission to:

Save all of the parts and determine where to mount the subframe.

Save the uprights and arms and give the NEW chassis pickup points.

Save the uprights and make new a-frames top and bottom (This is my option on my new car using Cobra uprights in the rear...I think)

or Other...

Below is similar to what I am doing. Several tubes have been removerd for clarity.

AW
Author:  chetcpo [ November 26, 2006, 4:36 pm ]
Post subject: 
whittlebeast wrote:
So is the mission to:

Save all of the parts and determine where to mount the subframe.

Save the uprights and arms and give the NEW chassis pickup points.

Save the uprights and make new a-frames top and bottom (This is my option on my new car using Cobra uprights in the rear...I think)

or Other...

Below is similar to what I am doing. Several tubes have been removerd for clarity.

AW


I think the mission as it pertains to me is to design a set of front and rear control arms that will work with my bookish chassis and the Miata spindles. Of the parts pictured above, the only ones I'm going to use are the spindles/uprights. The other pictures are for others who may be contemplating going a "different direction" and need the measurements.

I am currenly trying to establish ideal control arm lengths, angles, and pickup points to work with my the chassis as outlined in the pics below. I'm striving for a nice low roll center that won't move around too much.
Author:  toddwcarpenter [ December 16, 2006, 4:19 am ]
Post subject: 
The magic of linking.

http://forum.miata.net/vb/showthread.php?t=211921
Author:  RandyBMC [ May 1, 2008, 2:32 pm ]
Post subject: 
So how did this work out? 4.5" ride height is about what I'm looking for too. My tire diameter will be around 22.5" though. I am looking at a track of 57.5" - 58" (Miata) with the offset of wheels I'm looking at.

I cannot for the life of me get Wishbone to work, though I have been doing drawings on paper based on the Herb Adams book. I need to get a rear diff carrier and IRS design done as well as the a-arms and pick ups for the front and rear.

Thanks,
Randy
Author:  fritts [ January 3, 2010, 7:01 pm ]
Post subject:  Re: First gen Miata suspension measurements.
Has anyone confirmed these dimensions? Just doing a cad layout I don't believe they are correct. Especially when checking them against the 6.75" LCA and 22.8" wheel. Any idea of where the dimensions are off? If not can anyone tell me an approximate height for the LCA with a specific tire size? Trying to understand the angle of the lower arms at ride height to give me a better indication of where the dimensions are off.


Thanks
Author:  chetcpo [ January 3, 2010, 7:28 pm ]
Post subject:  Re: First gen Miata suspension measurements.
fritts wrote:
Has anyone confirmed these dimensions? Just doing a cad layout I don't believe they are correct. Especially when checking them against the 6.75" LCA and 22.8" wheel. Any idea of where the dimensions are off? If not can anyone tell me an approximate height for the LCA with a specific tire size? Trying to understand the angle of the lower arms at ride height to give me a better indication of where the dimensions are off.


Thanks

I posted these measurements but admittedly have no idea what you are talking about when you refer to LCA with a specific tire size. (what specific size?) Are you referring to the front or rear? What leads you to believe something about these measurements is wrong? I assume you mean the lower control arm's outboard (on the upright/spindle) pivot's height??? As stated on one of those old pics I was basing those measurements on a 20" tall racing slick. I have a set of uprights and tires here and I can give you measurements if you state specifically what you are looking for.
Author:  fritts [ January 3, 2010, 8:41 pm ]
Post subject:  Re: First gen Miata suspension measurements.
Sorry that came from this thread. I am mixing up about 6 different threads I've been reading at once.
http://forum.miata.net/vb/showthread.php?t=211921

If you have a tire diameter and ground plane to LCA inner joint that would be great. I'm seeing I lot of - camber (4 deg) in my model at the 6.75 LCA joing and a 22.8" tire at static.
Author:  chetcpo [ January 3, 2010, 9:00 pm ]
Post subject:  Re: First gen Miata suspension measurements.
fritts wrote:
Sorry that came from this thread. I am mixing up about 6 different threads I've been reading at once.
http://forum.miata.net/vb/showthread.php?t=211921

If you have a tire diameter and ground plane to LCA inner joint that would be great. I'm seeing I lot of - camber (4 deg) in my model at the 6.75 LCA joing and a 22.8" tire at static.


I dunno, I can tell you that I measured at zero camber and a 22 7/8" tall tire (205/55/14) the rear upright's lower pivot was 7.5" above the ground. The upright's upper control arm attachment point was 16 3/16" above the ground and sits about 1.25" inboard of the lower.
Author:  fritts [ January 3, 2010, 10:34 pm ]
Post subject:  Re: First gen Miata suspension measurements.
Those dimensions at 0 camber don't line up with the dimensions above. Which ones would you expect to be more correct?

Hopefully this isn't coming across badly as I'm just trying to understand a few things I'm seeing in CAD. I very much appreciate the information given.

Thanks
Author:  chetcpo [ January 3, 2010, 11:17 pm ]
Post subject:  Re: First gen Miata suspension measurements.
fritts wrote:
Those dimensions at 0 camber don't line up with the dimensions above. Which ones would you expect to be more correct?

Hopefully this isn't coming across badly as I'm just trying to understand a few things I'm seeing in CAD. I very much appreciate the information given.

Thanks

I'm not sure which "other" dimensions you are referencing??? This is an old post and it doesn't appear to me that I gave any dimensions for the locations of the upright pivots until just now on my last post so I'm not sure what the conflict you're seeing is all about.

It might help for me to know exactly what you are trying to accomplish. Are you attempting to duplicate stock geometry or something else?
Author:  SportsCarDesigner [ January 4, 2010, 4:48 pm ]
Post subject:  Re: First gen Miata suspension measurements.
First let me say that it is difficult to measure parts, in the shop, with great accuracy when the features are offset to different planes, as most of the Miata rear suspension parts are. Nobody should expect perfection from those who went to the trouble of attempting it, and providing this valuable STARTING POINT information. There are bound to be some errors, and you should allow yourself some correction method or adjustment point when constructing. Know that if you finish weld your entire frame and all the suspension brackets before you have donor parts of your own to mock up... you may have a problem. The exception is if you duplicate someone else's design exactly, and they assure you it was within adjustment range to get the camber/caster/toe right.

I laid out Chet's subframe, LCA, and upright dimensions at zero camber as shown below, and ended up needing an UCA of 8.875" length rather than the 8.375" he measured. That's not to say his UCA dimension is wrong; it could be the 5.875" or 4.5" on the upright, or the camber adjustment may have been set to one extreme, or a combination of a few small errors that combine to make up the mystery half inch. If I had to build a frame just on the available info here on this post, I'd probably leave off the UCA mounts, and allow enough space to move them inboard/outboard a bit. UCA brackets are lightly loaded, so don't have to be right at a tube/tube junction.
Attachment:
miata_rear_geometry.jpg
Author:  eurokraft [ January 4, 2010, 6:21 pm ]
Post subject:  Re: First gen Miata suspension measurements.
chetcpo
according to my frame book your measurements off the back subframe are right on the nose, the front I find a diference, I also measured a subframe from a 94 that I have here and it is the same as my frame book, a bit diferent than yours.
Ill post some pics,
Is there a diference on the subframes from 90 to 94? this measurements sheet is what we use at the shop and acording to them the subframes are the same .
Acording to these the measurements are;
Front lower(A)=25"7/8 or 658mm
FrontUpper(B)=29"3/4 or 754mm
I circled the numbers on that sheet, dont know if its very visible.
Hope this helps

Image
Image
Image
:cheers: Tony
Author:  fritts [ January 4, 2010, 6:51 pm ]
Post subject:  Re: First gen Miata suspension measurements.
I'm trying to model the miata in Cad so that I can duplicate it on my vehicle. I was interested in the results that were showing different camber values than yours as well and trying to figure out where the differences are. Sports car designer illustrated the problem well with his diagram.

I was wanting to just thoroughly understand the suspension geometry a little better before I start the design of my chassis. I do plan on using the miata running gear with my own control arms. The Miata being a great handling car was basically a good start I felt on the design of the suspension. I'm currently looking for a donor miata so I have no parts to start measuring with.
Page 1 of 2 All times are UTC - 5 hours [ DST ]
Powered by phpBB® Forum Software © phpBB Group
https://www.phpbb.com/