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PostPosted: January 5, 2021, 9:09 pm 
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Joined: January 5, 2010, 12:13 pm
Posts: 25
Location: Little Rock, AR
I believe this is my first post ever, or at the very least in a long long time. Some background: In 2015 I finished my first mid-engined car, which was a tribute car to the McLaren M8A / M8B. I learned a lot during that 6-year scratch-build project. It was the first time I went from a pile of square tubing and fiberglass mat/cloth, to a finished car. Today, my thoughts are another car made in similar fashion as a retirement project. I wanted it to be much lighter (hoping for 1200 lb or less), and if I was in a real pinch, could cannibalize the "McCopy" being the suspension and drivetrain could just about go from one car to the other with some minor changes.

So to get to the point, I've very much enjoyed the expertise on this site in what is a great source of information in taking donor parts, and making them work on scratch-builds. With my plans for a much smaller project, I am planning on applying much of the "Miata" knowledge I've gathered from this site thus far, and putting it to work on my next project (moving toward a Lotus 49 at this point). With that said, I've gathered a few parts to start with components, and my first piece to investigate for feasibility is the '90 (or so) Miata so front spindle assembly. It appears to be fairly small, and has a good donor market out there. The one point I'm not happy with is that the steering arm (or boss) is twisted in such a way that a pre-bent OEM-style tie rod end is required, assuming the lower control arms are horizontal at static ride height. I thought about adapting to that in various ways, but tonight, I've considered cutting off the arm (or just the boss), and either 1) reweld the tie-rod boss to a horizontal configuration, or 2) welding a plate that allows adjustment to steering rate.

I've searched, but not found any references to the weldability of these spindles, so tonight I decided to investigate that. Considering 1) sparks from grinding it look identical in color and character to a steel piece I also ground, and 2) filing the spindle resulted in clean filings that didn't exhibit carbon or graphite-looking staining on white paper as I rubbed the filings on it, I became more convinced this may be safely weldable. So I cleaned up the seemingly unnecessary boss of material that seems to serve no purpose on it, and went almost to the worst case scenario in testing the weldability. Without any preheating, but using a leftover "cast iron" rod (really just partial nickel rod content of undetermined amount), I welded a 1/4" by 1" piece of steel bar onto the spindle with a single uninterrupted pass on each side...period. I allowed it to cool in the open air, which was fairly quickly. Then I clamped the steel bar in a vice, within about a 1/4" from the weld, and then wailed on the spindle with a large hammer. Surviving that test, I then applied a large wrench to the caliper bosses and attempted to break the weld that way. My expectation was that the weld would fail not on the new material, but on the OEM existing material. But I was pleasantly surprised to see that the bar, clamped in the vise was what bent as I twisted the caliper. So unless someone here who has had a different experience chimes in, I have high confidence that a more carefully planned weld will no doubt, hold up well for what I want to do, which is straighten the steering arm boss so that I can use a spherical bearing in a traditional tie rod configuration, with the capability to ensure it rides in the same plane as the lower CA.

If anyone knows if the rear spindle/upright is made of the same material, please confirm that. It would be great to use them without resorting to fabricating my own uprights again. Looking to make the suspension using as many Miata pieces as is possible.

A couple of photos of the tribute car I built earlier, but it weighs about 2200 lbs, so looking for something to build that is smaller, easier to haul, and more fun to drive

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PostPosted: January 5, 2021, 10:14 pm 
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Joined: November 11, 2013, 4:47 am
Posts: 1617
Location: No. Nevada
Welcome to the mad-house!
Middy seems to be becoming more common.

My own future super-light middy is an old unfinished Tatum Formula Vee.
1.0 Suzuki three cylinder engine in place of the expensive and short lived 1200 type 1.
About 55 HP, just about what an FV makes, but with a significantly higher red-line.
Updating to ball-joint front and IRS rear for the win.
Should be about 900 Lb.
Proof Miata is NOT always the answer. :mrgreen:

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PostPosted: January 5, 2021, 11:47 pm 
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Joined: January 1, 2015, 1:55 pm
Posts: 327
I can't help you with your new build. I recently purchased a Manta Mirage "kit" that had never been built. Since then I've been online looking at pictures, videos, and builds of Mantas. I came across your car and I'm very impressed. You even put "my" number, 14, on it; :) I'm sure that your new build will be awesome.

If I recall correctly I saw a weight of 1430lbs for the Can Am car. The lightest V8 powered car that I built was 1650lbs.

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PostPosted: January 6, 2021, 12:13 pm 
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Joined: August 31, 2015, 2:24 pm
Posts: 260
Location: Delaware
Very nice project and good looking car! If you need another option: for my build I had a hot rod shop straighten out the miata spindles and reamed the top side to have top mounted outer tie rods.


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PostPosted: January 17, 2021, 1:14 am 
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Joined: July 29, 2006, 9:10 pm
Posts: 3160
Location: Oregon, usually
blueovalz wrote:
The one point I'm not happy with is that the steering arm (or boss) is twisted in such a way that a pre-bent OEM-style tie rod end is required, assuming the lower control arms are horizontal at static ride height.
I kinda like that feature of the Miata spindles, it makes it easy to set up for zero bump steer, but it does call for a non-traditional lower control arm shape.

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PostPosted: January 19, 2021, 11:46 am 
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Joined: January 5, 2010, 12:13 pm
Posts: 25
Location: Little Rock, AR
I went ahead and cut off the tie-rod end boss from the steering arm, and welded it back on with the bore axis vertical. What I really like about these spindles is that one can change camber settings without affecting the bump-steer.

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PostPosted: October 3, 2021, 11:32 pm 
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Joined: May 16, 2021, 10:42 pm
Posts: 15
Unsure on the metallurgy, but can't fault your process. Smith/weld on the side?

Only things I might suggest are hitting a scrapyard with the spindles. Most places that deal in volume will have a scanner on hand that will accurately identify a metal down to the alloy. (Xrf analyzer) Lowers the "skilled labor" requirement dramatically. That would leave me a lot more confident in welding a suspension component vs a well educated guess at the metal traits. (That said, I'm afraid of lawyers. Literally, apparently they gifted me PTSD. :lol: )

Might have to offer someone a six pack, but they could answer your question nearly instantly with two trigger pulls.

Separately, folks have made custom spindles with plate steel/aluminum, as well as cnc billet one offs.

Additionally - Sppedway has a ton of spindles.

https://www.speedwaymotors.com/shop/spi ... 5-600-7576

The Pinto II is a really well developed front end solution down to the nut and bolt, and readily available in tons of widths.

Hope something here helps. ^_^


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