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Actually the rear brakes will get more of a workout than you expect... because you will be going faster than you expect. I've never seen a slow rotary MX-5
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Jul 1, 2016 04:33
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th vwls hv scpd posted:I like this thread killjoy, I just don't have much to add because I don't have a clue about most of your stuff. Sorry no one told you to build a tube chassis car. That would be a neat thing to see over the internet. Well, there's another aspect to it too that weighed it towards "rotary Miata" - I'm kinda also planning in terms of "what can I still finish if I have kids". It's not like they're going to un-invent steel tubes or fiberglass so I can always go back later and make the tube car. Also, the STU Miata would be towards the pointy end of its run groups while the GT-3 car would be towards the slow end of its run groups... so why not go with something where I'll have more competitors on track at once, and not have to watch the mirrors constantly? CAT INTERCEPTOR posted:Actually the rear brakes will get more of a workout than you expect... because you will be going faster than you expect. I've never seen a slow rotary MX-5 Well, maybe? I'm cribbing brake guidelines from guys who are running turbos or V8 swaps, but I figure going from solid to vented rotors never hurt anyone. Ok, pictures!  Rear Afco Dynalite clones. Got them because Speeway Motorsports had a sale and I wanted to check out the quality. I think I like them a lot more than the Wilwoods. Will wait on the front calipers because *those* aren't on sale.  Opened up the Subaru transaxle that will be going into the WRX. For those of you keeping score, it's a TY754VBAAA, which means it's the V5/V6 STI box. Or another way, it's got closer ratios than the lovely USDM WRX ratios and a 4.44 final drive instead of the lovely 3.90 USDM WRX ratio. Why this instead of an STI 6-speed? This is my DD and I don't have very grandiose power goals, so saving a couple grand by not overbuying is nice to me. Still viscous center diff too and open front. Don't worry, that'll be fixed.  New hotness on left, old shittyness on right. Did not get the extension housing though, which turns out would be important. See how the old lovely viscous center diff on the right narrows down next to the bearing on "top"? Keep that in mind.  Extension housing. You can see the inwards extension on the casting with a barely visible scrape. Turns out they did change that between the Phase 1 and Phase 2 extension housings. Now, I could get all panicked about this and go searching for a Phase 1 extension housing because it doesn't fit... ...except wait, I have a milling machine. gently caress it, I'll *make* it fit.  While I'm opening everything else up anyway, Chinese Torsen style front diff rebuilt with better hardware and belleville washers. The quality seems "OK" on these once you get rid of the hardware and stuff - let's be honest, Quaife is probably made out of the same factory - and working for a company that makes engines in China, usually they don't gently caress steel up too much.
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Jul 1, 2016 14:13
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No pictures, but woooo, found a rust free shell for a couple hundred bucks. I mean, no interior or ... lots of things... and it's got front end damage, but I have a rustbucket donor car in my parent's field to supply that stuff. And starting with an empty shell gets over the urge to leave anything extra in out of laziness.
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Jul 13, 2016 00:58
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v4/5 STI five speed if I recall correctly has some fairly strong internals and it's only a few steps from being a RA box so..... yeah that's going to be nooooooo problem at all.
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Jul 17, 2016 09:03
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Yeah, everyone in the US pretty much just goes to the 6 speeds nowadays. But I have all of about a third of what that would cost into this box even with the trick diffs, which means more money for the race car. I'm not even sure what the timeline is on bothering to do a built engine on the WRX; I have a lot of the parts but have to machine the case for rear thrust and there's no real signs of the EJ205 wearing out yet. It really would be nice to have a real rear LSD too, but I figure I can come back to that one easily enough. Oh yeah, leaving in about an hour to pick up the Miata shell. I'm not excited about that whatsoever. 
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Jul 17, 2016 14:17
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  Why hello there. No rust! Also got a front bumper cover and dashboard plus an extra door. Does have front end damage, but it just so happens I have a parts car with rust but no front end damage. So, a bit of welding, followed by a lot of seam welding and caging, plus all the other stuff. Great thing about starting off this bare of a chassis is that there's no temptation to leave in extra crap, simply because it's already stripped out.
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Jul 18, 2016 15:18
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I love this thread and your madness.
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Jul 18, 2016 19:19
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I've done, am doing, and will be doing a lot of research... and have a general principle behind this build. "Unless something is absolutely perfect for my purposes or there's no reasonable alternative, make the car accept commodity race parts instead of special snowflake Miata parts". This may have consequences that make this build not look like most other builds I've seen online. Oh yeah, in the mean time, almost have the T4 NC MX-5 back and ready to rock. Need to weld up a flange to make the NC MX-5 Cup muffler fit the Racing Beat midpipe and, if it comes in time, fit the Tomei LSD. No more one tire fire! Also working on the CAD design of control arms since it'll be a while before I can spend any more big bucks.
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Jul 18, 2016 19:45
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Are you chopping off the front end of the donor and simply welding it onto the new shell at the factory seams? Does it then require reinforcement to make it a non-death-trap? I'm not educated at all as to how that works for unibody cars, and I... may... need to do something similar soon.
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Jul 18, 2016 21:07
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I'm... not completely sure! I haven't figured out how far back it's crooked and where a good place to start is. I half had the thought of drilling out spot welds and then stitch welding to replace them, but like I said, not sure if that would work right.
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Jul 18, 2016 21:59
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What am I doing today (when I should be working)? Why, I'm figuring out shock valving! See, there's this great suspension calculator spreadsheet that is the result of someone going to the trouble of doing maths for a lot of basic handling stuff. Fun thing is that fairly accurate data for Miata suspension geometry is available so I stuck that in to come across what is at least a first cut of spring rates and bar selection (ok, in truth, it''s pretty close to what 949 Racing recommends; go figure they recommend a pretty solid starting point) I've added a bunch of sections to it, including data reverse engineered from published graphs for a lot of Miata shocks. I have a lot of those that I've found. Some interesting trends emerge.  Here's a graph of ... well, okay, the axes are labelled. It's two commercially available dampers that I went and picked vaguely approximately correct clicker settings (nobody provides a full sweep for obvious reasons, so stuff's a little off from perfect) for my given spring rates. No, I won't tell you which ones but I will say that I came up with all of this stuff without any proprietary information or disassembling anything so it's not too hard to do the same. I'd actually be really impressed if someone figured out which is which here, though.  Part of the fun part with analysis like this is figuring out which aspects are intended and which are a consequence of compromises in valving or the need to fit in the rear shock of a Miata. Why don't I just buy something? A couple reasons. The cheapest off the shelf solutions that I'm confident are good enough to be a good starting point run about $400/corner. If I convert to something that takes 1/2" rod ends on both sides though (which I can do) there are so so many options that it boggles the mind, I can upgrade the internals, tailor them to suit, and so on. And the big thing is that I want to learn this stuff anyway. Let it never be said I'm lacking for ambition on this project...
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Jul 19, 2016 18:47
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Oh yeah, here, have another graph. That's from the old shock dyno before I did any smoothing or anything of the raw data. I think it was a Koni wet converted strut for the RX-7. Sucker worked with an electrically controlled proportional regulator driving a directional valve and then a pneumatic cylinder. So stroke the shock in and out at a given force and measure velocity. Had all of a hundred bucks into it and really wish I had video of it going as banging back and forth at full speed was pretty impressive. New version I'm doing will be using a pneumatic servovalve so I can try to duplicate the results of the classic crank style dynos, in addition to doing all sorts of other inputs instead of just a sine wave. One cool part is that you can separate hysteresis from valving stuff from that caused by gas force.
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Jul 20, 2016 15:21
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No pictures right now, but status report. Got the NA shell into the barn and started drilling spot welds. Plan is to follow the FSM guidelines for where to cut and weld to replace the bits that are damaged because... well, look, why not? And then add stitch welding. Last race for a while on the NC was yesterday, which went OK - ABS wasn't working and one of the tires got flatspotted. Oh well. New Tomei diff seems to be working well though. Fun thing though is we paddocked next to some old friends of ours who used to run an FB in SCCA E-Production at national championships levels of preparation, and are now building a Miata. "Oh yeah, we have a couple OS Giken diffs we picked up used, and could sell on the Prather coilover setup after we move up..."  What was cool too is he gave me some tips about interpreting some rules, including that probably I can get away with doing the new Spec Miata-style seat floor modification to drop the seat down under the clause of "safety reasons". Which is nice because I'm right on the edge of too big for the car. He also confirmed that it really does seem like a pretty affordable way to do things, but neither of us are sure that it'll be a "potential to win national championships" level of competitiveness. Which doesn't matter too much because neither am I.
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Aug 22, 2016 16:05
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mekilljoydammit posted:No pictures right now, but status report. Got the NA shell into the barn and started drilling spot welds. Plan is to follow the FSM guidelines for where to cut and weld to replace the bits that are damaged because... well, look, why not? And then add stitch welding. Looking forward to seeing how this goes so I can be inspired to pursue it on my own car. Good luck!
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Aug 22, 2016 18:21
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 Progress! Got sawhorses made and the car up on them. Now I can actually get at all the spot welds. Next up is taking off the crunched passenger side structure.
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Sep 4, 2016 02:26
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No new pictures yet because pictures of drilled out spot welds are boring until I have something to show for it, but on a "continued accumulation of parts" topic, have a Miata 6-speed tailshaft housing dealie showing up Friday, and an RX-8 6-speed showing up Monday. By their powers combined, I should have a reasonably-close-ratio 6-speed that bolts to both a 13B and a Miata PPF! All of which means I just have to make mounts to bolt to the subframe; no goofy adapter plates or any such crap. ...well, and I have to put a front end on the car, so I can test fit it, but you know. May just do a quick test fit into the rustbucket parts donor before I cut it up, so I can get an idea what idiocy I've gotten myself into. Speaking of getting myself into idiocy, started delving into the Speeduino code. I basically want a 36-1 wheel that runs a box to do a real timing map with 4 smart coils, and lo and behold someone did most of the heavy lifting. "All" I have to do is make it do rotary split timing and the no-lift-shift poo poo I want to do. Well, and ideally migrate it to a Teensy or something and roll my own little board to cut down on the space it takes up. You know, easy. (cue 2 years from now when I get fed up and throw a distributor into the thing)
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Sep 15, 2016 21:47
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If you can find one.... Get the S2 Rx8 gearbox... Much stronger but the gear ratios are not as good. (It's a Getrag from memory...) Biggest issue on the S1 was breaking shift forks. S2 is going fine sofar  But I'm pulling 9k rpm gearchanges... Because 12a rules.
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Sep 16, 2016 07:59
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I thought the S2 RX-8 gearbox was a Mazda in-house design and the same as the NC MX-5? We're both talking about the toploading one, right? Either way, problem is it'll be harder to adapt into an NA MX-5, and the RX-8 box solution is kind of an interim until-I-can-afford-a-real-box thing anyway. Though I wonder if there's some other version of the Aisin box I can raid for better forks. I'm hoping to do better than 9k RPM - a builder over here for a circuit class with similar engine rules but with requirements to use the 6-port irons was making power into the 10s on an extend port (that's what you call "not yet a bridgeport but lots of metal removed" down there, right?) And I'm intending to use a mix of S5 or S6 turbo (whatever the flowbench says works better) and 12A irons plus some carby tricks not allowed in the other class... and I'm all-of-a-sudden thinking I should maybe stockpile a few extra RX-8 boxes.
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Sep 16, 2016 13:22
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mekilljoydammit posted:I thought the S2 RX-8 gearbox was a Mazda in-house design and the same as the NC MX-5? We're both talking about the toploading one, right? Either way, problem is it'll be harder to adapt into an NA MX-5, and the RX-8 box solution is kind of an interim until-I-can-afford-a-real-box thing anyway. Though I wonder if there's some other version of the Aisin box I can raid for better forks. S2 box was in-house design. I don't remember if they reused it for the NC (I wouldn't be surprised if they did). I don't remember the forks being an issue, I do remember that there is some stupid plastic "bushing" on the end of the shifter inside the box that likes to melt at road racing speeds, which locks you into the current gear.
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Sep 16, 2016 19:26
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I think the NC got it first, actually. S2 RX-8 starts in 09, right? The 06 MX-5 my dad and I built for SCCA T4 has one. There's actually an update for the plastic thingy, and an updated shift fork too. Apropos of nothing, what's up with the RADL thing? </newbie>
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Sep 16, 2016 23:38
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mekilljoydammit posted:I think the NC got it first, actually. S2 RX-8 starts in 09, right? The 06 MX-5 my dad and I built for SCCA T4 has one. There's actually an update for the plastic thingy, and an updated shift fork too. A mystery rotary lover likes to find rotary enthusists and gang tag them with Rotary Anti Defamation League.
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Sep 16, 2016 23:43
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Progress some more. So Friday, an NB 6-speed tailshaft housing showed up - thanks to a kind member of the Miataturbo forum who has gone through a few 6-speeds. And then today my RX-8 6-speed showed up. 61k miles on it, paid all of $170. Thanks car-part.com! So a half hour ago I went outside to take pictures to prove that stuff is happening. Like so. But then... I had to know. I had to. It should work, oh god it should, but I had to try it. A few bolts here and there and the RX-8 tailshaft housing was off.  And then... ... then...  MOTHER loving YES! It fits and shifts! Cheap 6-speed that bolts to a rotary *and* a Miata PPF! I KNEW IT! So yeah, that was my day. Now I just have to cut more spot welds. Still. Well, and then strip the parts shell, cut the replacement sheetmetal off of it, put the seat lowering pan and trans tunnel notch panel in, design, bend and weld a cage, modify the unibody if necessary to make the exhaust and stuff fit, fab or buy control arms... and you know, stuff like that. .. oh, and also, thank you whoever tagged me.
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Sep 20, 2016 02:56
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I would like to know where this plastic bush is on the s2 box!
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Sep 20, 2016 03:21
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Kaptainballistik posted:I would like to know where this plastic bush is on the s2 box! http://www.miata.net/garage/Mazda%20P66M%20Transmission%203-4%20ADJUSTMENT%20MANUAL.pdf Page 11 or so and then on. They mention that S2 RX-8 should have the stuff corrected already, though.
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Sep 20, 2016 03:32
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mekilljoydammit posted:MOTHER loving YES! It fits and shifts! Cheap 6-speed that bolts to a rotary *and* a Miata PPF! I KNEW IT!
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Sep 20, 2016 04:04
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Wait a minute. Aisin built all or some of the boxes we are talking about? Can you get me a decent quality pic looking into the bellhousing? Curious about something.
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Sep 20, 2016 04:39
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kastein posted:Wait a minute. Aisin built all or some of the boxes we are talking about? Can you get me a decent quality pic looking into the bellhousing? Curious about something. If it's the same as the Toyota Is200 box or the s15 box? Very likely! There is 2 variants, the Type used on the MX5/rx8 and the Larger unit used in things like Commodores. The S2 RX8 IS NOT an Assian gearbox Correct me if I'm wrong here... (I'm the only person actually using a second generation RX8 box in an RX2... It's a much tighter fit.., and apparently the first Non RX 7 to do it anywhere with the S1 box.) The S1 box is now a pile of really worn parts ! Kaptainballistik fucked around with this message at 08:53 on Sep 20, 2016 |
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Sep 20, 2016 08:44
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kastein posted:Wait a minute. Aisin built all or some of the boxes we are talking about? Can you get me a decent quality pic looking into the bellhousing? Curious about something. Into the bellhousing from the engine side? Sure. Any particular thing to try to capture?
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Sep 20, 2016 11:31
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mekilljoydammit posted:Into the bellhousing from the engine side? Sure. Any particular thing to try to capture? the bolt and locating peg pattern where the BH bolts to the trans, mostly. And the input bearing retainer / TOB quill bolt pattern. Curious if it is shared with some other units I am familiar with.
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Sep 20, 2016 13:43
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kastein posted:the bolt and locating peg pattern where the BH bolts to the trans, mostly. And the input bearing retainer / TOB quill bolt pattern. Curious if it is shared with some other units I am familiar with. Bellhousing on these looks to be part of the casing - or at any rate, is bolted to the next section of the casing with bolts on the exterior. One of the ones where if you pull off the bellhousing, fluid comes out, if you get what I'm saying. I'll get pics of it when I get home tonight. Known other applications of it are S15 (the one we never got here), IS200/Altezza (which we never got), NB Miata 6-speed, 04-08 RX-8, and the FR-S/BRZ. Honda S2000 is rumored to be a heavily modified version of the same guts, but I'm skeptical. ... oh, and I know it may be marginal for what I'm doing, especially with intent to mess with spark cut based no-lift-shift and stuff like that to minimize shift time, but the price and fitment is right. Really would like one of about 4 sequential boxes, but 6500-8000 is a lot to swallow for a gearbox when $270 in it (so far) is enough to get on track and I have a lot of other stuff to spend money on.
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Sep 20, 2016 14:21
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Huh. For some reason I thought I saw a bolted joint there, now I'm not sure. You can replace a $270 transmission a lot of times before you have spent $6500... 24 times in fact. Hell, if you buy parts boxes and pillage them to fix yours every time you blow it up you could spend a lot less, unless you keep blowing out the same parts every time.
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Sep 20, 2016 19:33
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kastein posted:Huh. For some reason I thought I saw a bolted joint there, now I'm not sure. I'll take some detail shots. What the hell, electrons are free. The problem with just replacing the RX-8 transmissions whenever I break them is two-fold. One is the question on what breaking them costs me in addition - best case, I lose a practice or qualifying session or something and a bunch of frustration of swapping the trans in the paddock, middle-bad I lose an entry fee and cost to trailer and everything because I can't finish the race, worst something bad locks up and leads to a collision. All of those are also demoralizing - my dad and I ended up backing off from the EProd 1st gen because we spent more time at the track fixing poo poo than racing. The second one is that the purpose built race transmissions are faster too and not just more reliable. RX-8 box, shifted at a 9k RPM (arbitrary but whatever) ends up at an average of 2k RPM rev drop per shift on the track gears (ignoring 1st) - the gearboxes I'm looking at are sequential dogboxes that can be shifted faster, and get the average RPM drop to around 1300 RPM by using all 6 gears. I mean, I still can't afford it to start with, but drat.
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Sep 20, 2016 20:56
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Yep, bellhousing is integral to the case. That threw me the first time I tried to disassemble it. There is 2 side bolts (one's the reverse gear shaft mount) you need to remove as well. Yes... Reverse is in the middle of the gearbox!
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Sep 20, 2016 23:10
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mekilljoydammit posted:I'll take some detail shots. What the hell, electrons are free. quote:drat.
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Sep 20, 2016 23:30
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All right, rl been intruding and all but been doing research. Long story short, looks like about the only reasonable dogboxes are the 4 speed ones. This isn't actually as bad as it sounds - most 5 or 6 speeds you end up with 1 pit gear and 4-5 track gears, so instead you just get a winch on your trailer. A 1.7:1 first gear won't be great for standing starts, but who cares? Rpm drops on upshifts between 1800 to 1300 and given the limited carb size, the powerband shouldn't be that narrow.
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Oct 30, 2016 18:25
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Working on the WRX this week - took a couple days off from work, so between that and turkeyday break, doing rust repair. Nothing all that bad, except for the classic "the loving plastic clips broke" poo poo. And PO fuckery. Gee, when the bumper cover is pop riveted to the holder bits and the sheetmetal under one of the taillights is shows signs of being de-crunched, I'm wagering there's an unreported accident. Oh well. Pictures whenever I figure out how to get stuff off my phone.
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Nov 22, 2016 00:12
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I was going to post updates on the WRX as I go, but after a few days of screwing around with the clutch, I feel more like I won't want to remember this. Got everything back together Friday, but lo and behold the drat clutch won't release. Bled the poo poo out of the system, replaced the slave cylinder, no dice. Last night I just said to gently caress with it and pulled the transmission completely out to see what's going on. Low of 0F tonight. This will be fun. I am getting a lot of use out of my new Wera Zyklop ratchet though - in addition to all the obvious nice things with the swivel head and smooth fine tooth action, the unobvious beautiful thing is that because of the plastic/rubber grip you don't freeze to it like you do metal ones.
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Dec 13, 2016 13:34
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Subaru clutch cylinders piss me the gently caress off. Try removing it from the bellhousing, cracking the bleeder, holding it so the bleeder screw actually goes into the highest point in the loving cylinder (it doesn't when it's installed on the car, thanks Subaru!) and then gravity bleed it by holding it down behind the bellhousing on the passenger side while keeping it at that angle. Not that it's helped much, my clutch is STILL being fucky, but it's less fucky than it was and I'm starting to think the fuckyness is that it's a garbage MC not that I didn't fully bleed it. I might be unreasonably angry about this, PROBABLY BECAUSE I'VE GONE THROUGH IT WAY TOO MANY GOD drat TIMES. gently caress YOU SUBARU. This is like a 15 minute task on a jeep and it bleeds right the first drat time, what is so hard?
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Dec 13, 2016 18:50
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kastein posted:Subaru clutch cylinders piss me the gently caress off. Try removing it from the bellhousing, cracking the bleeder, holding it so the bleeder screw actually goes into the highest point in the loving cylinder (it doesn't when it's installed on the car, thanks Subaru!) and then gravity bleed it by holding it down behind the bellhousing on the passenger side while keeping it at that angle. Never do a Miata slave cylinder because the ensuing meltdown will make Three Mile Island look like a sunday drive.
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Dec 13, 2016 18:54
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I never knew I was so glad I didn't buy a Miata in 2014.
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Dec 13, 2016 18:55
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