The Breakup (Miata build)

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drummingpariah
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Re: The Breakup (Miata build)

Post by drummingpariah »

I had a hard time accepting that a 'coupling nut' wasn't just a long nut, but couldn't find any evidence to the contrary until now. This weekend was pretty productive: Now that I have a membership at makeitlabs and I don't feel like I'm doing something wrong when I fire up a grinder, I've been encouraged to make stuff left and right. I just qualified on the TIG so I can use it whenever I want now (until this weekend, my welding experience was an hour of flux core welding and that was it), and have fallen in love with that thing. I'm not any good with it, but that really isn't the point.

While I'm waiting for the coupling nuts I ordered to come in (the same ebay seller I bought the coarse ones from was very helpful about pointing me in the right direction), I decided to work out a better mounting bracket. That quickly got out of hand (as it usually does).

The first version was an attempt to reproduce the commercial spec-miata versions of the mounting bracket. I have so many complaints about it, I'll leave it at that.
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I tried bending a basic turnbuckle mount together, but I didn't provide adequate clearance to fit the turnbuckle into it.
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I tried another, but it was too wide to fit the chassis:
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Because my measurements obviously weren't working out, I made a cardboard template:
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I eyeballed the bend, which was really challenging without a sheet metal brake.
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That looked plausible, so I tried another iteration bending some aluminum. It didn't like being bent.
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Although thinner or more pliable material may have worked fine, it was far too much work to make each iteration. I had to stop trying to bend metal on a bench vise, and decided to learn to use the TIG welder. It took a bit of practice, but I think my first tests came out reasonably well.
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A little while later, I had the lower (body-side) bracket finished.
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The upper (top-side) bracket wasn't quite as easy, so it took two iterations.
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This week, the new coupling nuts will show up and I'll be able to mock it all up. I may need to give the lower bracket a bit more offset to keep the mounts from trying to compress the top inward.
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Okemo is next weekend! I'll be in the Miata again, but at least this time I won't need to restrain my arms. Okemo looks much more straightforward to learn than Ascutney Long, and based upon the videos I've seen corner exits are generally visible from the apex, which is encouraging. The underpowered 1.6 Miata may be one of the worst suited for the hill, but I'll run it anyway and have a blast the whole way up.
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walterclark
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Re: The Breakup (Miata build)

Post by walterclark »

Grassroots at its finest! Just be sure you round the edges of everything so they cant act like knives. And if one of the brackets could come in contact with your helmet (such as along the top of the windshield), you put a bit of high density foam over it. A few places sell a specifically engineered foam pad for roll cage use - its got SFI 45.1 and/or FIA 8857-2001 Type A approvals - and we require it for use anywhere your helmet could contact a cage tube. As you move forward you will need it for a cage so buying a length to just use a couple inches now isnt a waste.

This is similar to what I am referring to:

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Not this, which is low density foam similar to water pipe insulation:

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Since its getting so close to Okemo, you may have trouble find a length in time. If so, odds are good someone at the hill will have a bit or length they can sell you. Don and I do not because that would appear to be a conflict of interest.
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drummingpariah
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Re: The Breakup (Miata build)

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As it stands, I'm leaving the top latches stock, which means molded covers and virtually no chance of interference. The 'top' and 'chassis' distinctions I'm making are both behind the seat, and I have as much of a chance of hitting my helmet against the fuel tank as I do of hitting those (the seat and belts would need to fail completely). I've been pretty careful to debur and keep SHARP edges off so I can handle them safely, but hasn't really considered the pointed-edge-in-an-impact. That's going to require some additional grinding, once I have a final design. I think I'm also going to overbuild it by adding some lateral gusset material into it so everything is tied together and won't flex.

Can't wait for Okemo, I suppose I should secure a campsite somewhere nearby. I haven't loved any of the options I've found thus far; I don't really want to have to drive to the hill and back every day.
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Re: The Breakup (Miata build)

Post by Chief Geek »

For lodging at Okemo, I just set up my tent in the parking lot. Beware of the street lights, they make the inside of a tent pretty bright. Last year I set up in the shadow of Sherman's bus.

If you're using your hammock, there are plenty of trees around the perimeter of the lot or maybe you can rent space on #25's new tire rack.

I bought the Rennenmetal hard top brackets, but I suspect the threaded studs will pull out of the fiberglass before the OEM latches break.
"Christina", New #13/#55x, '90 Miata: In progress
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drummingpariah
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Re: The Breakup (Miata build)

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Chief Geek wrote:For lodging at Okemo, I just set up my tent in the parking lot. Beware of the street lights, they make the inside of a tent pretty bright. Last year I set up in the shadow of Sherman's bus.

If you're using your hammock, there are plenty of trees around the perimeter of the lot or maybe you can rent space on #25's new tire rack.
Yeah, this time it'll just be me (no girlfriend on this trip) so my needs are considerably lowered.
Chief Geek wrote:I bought the Rennenmetal hard top brackets, but I suspect the threaded studs will pull out of the fiberglass before the OEM latches break.
That was my thinking as well. The concern is more cost and adjustment than ultimate strength. My turnbuckles showed up yesterday, so I can finally put it together and make a final iteration tonight (but I might work on another project that's been bugging me instead).
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Re: The Breakup (Miata build)

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I didn't want to deal with cooling issues again, so I had tossed an inexpensive ($130 shipped) aluminum radiator from cxracing in. I didn't expect it to put me in Street Prepared instead of Unprepared, but that was inevitable anyway.
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I'd like to add some nice solid mounts to the bottom of it, and an under-engine splash guard to protect the precious bits down there.

I'm still hunting my idle race issue, and replaced the IACV last night, removed the power steering, bypassed the intake charge coolant lines, and replaced a pile of vac lines in the hopes of identifying a vacuum leak that would cause a random race condition. I had no success even after all that work, and was left with a very interesting drive home with LOTS of brakes as the car tried to drive at 4k in whatever gear I happened to be in.

Because I'm in Street Prepared anyway, I decided to go with a better ECU, which should be here this weekend. I'll have to install a wideband prior to that, but that should be reasonably straightforward. More to come, I'm sure.
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Re: The Breakup (Miata build)

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Megasquirt PNP, an LC-1 wideband, and a pile of small improvements made it into the car for Burke I, and with Okemo II being my first non-rookie event I was hoping to do something kind of special to celebrate. My idle race condition still isn't completely gone, and I have given up on trying to identify where it's coming from. Instead, I ordered a second intake manifold and when it arrives it's going under the chop saw to make a flange for a new intake system. I don't know that I've ever heard of someone using ITB's to solve an idle issue, normally ITB's are what cause idle issues.
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This also gives me an accurate throttle position sensor, potential for two-stage injection (8 injectors), a safe place to mount my air temp sensor, and a FAR less restrictive airbox than the stock Miata components. I'm going to go out on a limb and assume that this means "non-stock induction" (just guessing as to its meaning). Even with that in consideration, I'm firmly planted in SP6. I just did some quick math, and it looks like I could turbo/intercool this, wear 15x9 wheels, and add decent anti-sway bars if I add a cage next season - but I'm not quite ready to commit to that when the Datsun is so close to done.

Realistically, I'm not going to have my backup intake manifold chopped, won't have these plumbed, won't have time to tune, and won't be able to shake these down in one week ... so maybe this will be an Ascutney II or Burke II addition. For now, I can certainly add some timing advance if I start running higher octane fuel than 87 (it's worked so far, but a little more low-end grunt would solve all of my issues with the car on Okemo).
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Re: The Breakup (Miata build)

Post by walterclark »

I take it the IAC valve is being driven full open at times when you expect it to return to idle? Has the Megasquirt Forum been no help? Can you post a link to your .msq and a log when it occurs? I had that happening to me early on in my tuning.
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Re: The Breakup (Miata build)

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walterclark wrote:I take it the IAC valve is being driven full open at times when you expect it to return to idle? Has the Megasquirt Forum been no help? Can you post a link to your .msq and a log when it occurs? I had that happening to me early on in my tuning.
I haven't queried the Megasquirt forum yet; This happened before and after installing Megasquirt, so I'm fairly confident that I can rule out the ECU. I would certainly agree with you, but I deleted both IAC valves (there are actually two on the 1.6 Miata). I'm sort of at a loss, and I'm clutching at straws by thinking that replacing the intake manifold will solve it - but that's really all that's left, at this point.

Do you use MegaTune or TunerStudio right now? I've been working in TunerStudio because it apparently has good Linux support, but haven't been blown away with it thus far.
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Re: The Breakup (Miata build)

Post by walterclark »

I use Tunerstudio for programming and MegaLogViewer for log analysis. I also use the Android app ShadowDash MS on my Samsung S4 connected to my MS3 via Bluetooth with a couple custom "dashboards" to show me a couple things while racing.

Odd that it existed with the stock ECU and can occur without any IAC. Something must be opening a spot for intake air, or your throttle body is sticking open (I had that happen to me with my current TB...the lube in the bearings was about 20 years old and when the TB got hot sometimes the throttle plate rod would stick). It doesnt take much opening of the TB to have this happen.
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