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Banged out some new endplates to replaced the bent ones. Little more... "reasonable" in size, also powdercoated instead of painted, and a little thicker aluminum with larger wing attachment points as well. Should hold up better then the paper thin ones I had before that required supports to prevent inward flexing. To make up for the smaller endplate I upped the size of the function/form decal.
I made a trip up to the Dragon on Memorial day. Very spur of the moment, woke up at 3am the day of, couldn't go back to sleep, so said **** it and made the 3.5hr trek up.
Got some great runs on the Dragon itself early in the morning, absolutely dusted a well driven ND and Ducati that wanted to play, then hit some of the other roads in the area as the Harlies started to clog up the Dragon. Ran a few new(to me) roads recommended by some friends, and of course had to visit the Dragon Hillclimb location for some *ahem* "scouting" runs.
Car felt awesome, planted yet playful, as cliché as it sounds really felt more "at one" with it on the back roads then I have in awhile. Of course you know they say things are always the best right before they break, and this was the case here.
Last run of the day, flying down moonshiner, try to do a 3-4 shift and it just... doesn't engage 4th. Can't get it into any gate, managed force it into a gear, but as soon as I try to change it again, same thing, locked out. From the weird noises it was making I thought the well abused 5spd had finally let go at first.
Did some quick troubleshooting and determined pretty quickly that it was not "just a slave". All hydraulics looked perfectly functional and the gears, once engaged, worked fine, but there was an issue of some sort inside the bellhousing.
I limped it home with no clutch, rev matching through the gears and keeping the RPM's low as I could feel a definite... "wobble" at idle. The same route that took me 3.5hrs that morning took me upwards of 4.5 to get back, avoiding standstill traffic and major highways.
The day after I got around to pulling the engine out and seeing exactly what went wrong. My guess was the throw out bearing had exploded, or some sort of pressure plate failure, but I would have never guessed what I found when I split the trans off.
I think all I said when I saw that was just... "Oh...."
Or as a coworker more aptly put it, "yah turned that 4 puck into a 2.5 puck".
This is/was one of Supermiata's ceramic clutches, rated for 340tq, hard launches on sticky tires, ect, but apparently I managed to shear that arm with less than 200ft/lbs of tq and launches that were more spin then propulsion. Cool.
Contacted Supermiata and they had a new disk headed my way almost same day for no charge, just had to send them my broken disk. I opted to switch from the ceramic disk to the organic. The organic is still rated for waaay more tq then I'll make on a miata transmission, and the ceramic was awesome to drive on track, but miserable on the street. Gee, who woulda thunk that? As the organic is also a full face disk, hopefully I'll avoid any more broken arms like with that puck style.
After getting hung up in FedEx shipping hell for a few days, the replacement friction disk arrived today and I tossed it in, re-installed the engine, fired it up on jackstands to make sure everything worked and... the clutch doesn't disengage. Goddammit.
Checked over all the hydraulics again, swapped in my spare master just to be doubly sure, but nope, pressed all the way in clutch stays engaged. Even tried FM's method of clutch rod adjustment to no avail. Something's off here and I don't know what.
Yanked the engine AGAIN same night to see if I had done something dumb like installing the pressure plate backwards, but nope... everything *looked* fine.
The only thing that *might* look a little off to me is the plate fingers look like they are already near full travel even when static. Almost like the new plate is "fatter" and the fingers don't have enough room to disengage the pressure plate? The calipers are measuring the distance from the tips of the fingers to the friction disk hub... or I guess you could call this the "total remaining throw" left in the clutch when static. I can't find any good photos of my previous clutch installs to see if I'm imaging this or if there is a definite difference here.
I did some digging and 99% people that run this clutch setup have zero issues. I found ONE person that seemed to have the same issue from four years ago.
Obviously I'll shoot another email to Supermiata in the morning and see if they have run into this with Kswap hardware before, or have any other advice, but I'm kind of at a loss for even how to troubleshoot this without stacking spacers blindly under the pressure plate and hoping I get clutch travel back before I just get clutch slip.
Not super confidence inspiring given I have the same clutch on my Kswap, but hopefully its just a weird outlying issue that you got unlucky with.. so far so good on my 4 puck..
First of, 10/10 for SuperMiata's tech support. Ed and I exchanged 20+ emails checking dimensions, specs, and other bits of the friction disk and flywheel. Everything checked out perfectly, meaning... we have no idea why it wasn't disengaging.
My gut feeling is there's something thicker about the friction disk thats pre-engaging the pressure plate.
So I said screw it and spaced the pressure plate out 1.6mm with some washers. This seemed to give the fingers proper spacing from the clutch disk(~16mm, as opposed to the 9mm I did have).
And this seems to have done the trick. Put everything back in, got proper disengagement on jackstands. Did a light launch on street tires and didn't get any slippage.
Holy hell the organic disk is 100x more streetable then the ceramic was. Almost feels like a stock clutch, not the super on/off get it perfect or look like an amature the ceramic disk was.
Will put some miles on it to give it a little break in before I flog it around Road Atlanta next weekend. Looks like its gonna be hoooooot(95+) so good test of the cooling system capacity.
Thanks for the kind words regarding the support, just really bizarre that you had to resort to spacing that pressure plate out. We move a *lot* of these and this is the first time I've dealt with this in the 3+ years I've been here.
I'm still digging in to see if I can figure out what's causing it. Replied to your last email. Still want to figure this out even though you've cleverly resolved the issue for now.
You making it out this weekend for the NASA event?
I really wanted to, and had it on my "events I wanna be at" list at the start of the year, but unfortunately not, due to several reasons. I'll be there the weekend after with Jzilla.
I will probably stop by the track on Saturday to say hi to a few friends and watch some of the SM/Thunder races though.
I have the SPM clutch, 4-puck sprung on the Kmiata. No issues to report. I know this is super helpful Looks like you got it all sorted out with Ed, nice.
The issue lies in the height of the pressure plate standoffs.
When I measured this the first time, I thought half a millimeter difference wasn't enough to be a problem, but I was wrong. Our lightweight flywheel and the OEM flywheel measure at 19.9-20.2mm tall standoffs. When you combine that with the .3mm thicker Organic friction disc, I believe that's why it wouldn't release. With OEM-geometry flywheels that thickness difference doesn't matter, but since your standoffs are more than half a millimeter shorter, it was enough to keep it from releasing. Perhaps adjusting your clutch pedal further might have allowed it to disengage, not sure.
So, at the end of the day, flywheel dimension issue.
Apparently the fact that your puck disc was only 7.7mm thick (roughly .5mm thinner than the organic disc) was enough to allow that one to work fine with your flywheel.
So as a follow up.... You probably want to space out the pressure plate because of the shorter standoffs, but 1.6mm is probably a bit too much. Definitely reducing the clamp load relative to what it should have. You probably want about half the spacer/washer thickness you have now. If it works, run it, but I expect you'll find slippage in the not too distant future. guess we'll find out.
That combination of clearances/coincidences is absolutely bizarre, especially with how many people run the Kpower flywheel/SM clutch disks without issues. I do have .8mm washers on hand, I grabbed both sizes then opted to installed the fatter ones to try and avoid a 3rd engine removal. So far I haven't had any issues(~30 mi on it or so). I don't have any plans to add power with a miata transmission still in the car, but judging from how the Kswap is going, this engine will probably be pulled inside 3-4 months for one reason or another, I'll just have to make a mental note to swap them at that point.
I do have a few buddies also putting SM disks into their Kswaps, I'll be sure to get to them to measure the standoffs and disk thickness before installation. Again, just... bizarre.
I really appreciate the support and persistence on this matter.
For sure. I don't like leaving stuff like this unresolved.
Tolerance stacks are a funny thing. Plenty to cover tolerance stacks within the OEM envelope but sometimes you combine too many and it doesn't work properly. Like you mentioned, lots of people running these clutches on KSwaps without issue so my best guess is that your flywheel is ever so slightly different.
Ah, a weekend at Road Atlanta. In addition to being my home track, it's also in my top five favorite tracks I've driven.
Plan for the weekend was just to shake the car down at a high speed track, do some aero/tire setup testing, and hangout with some buddies at a DE event. The weather was HOT all weekend, even first sessions out in the morning were mid 70's and highs were in the 90's, so not exactly ideal record breaking weather.
Thanks to an additional ~100whp of Kpower, morning of day two I shattered my old PB of 1:42, which was set in ideal November conditions on take off hooisers.
This was a really sloppy lap even by my standards. 10mph off in T1, some tire snatching in T5, and a shoddy exit out of T7 means there was way more time there. The follow up lap I didn't **** up T1(normal min speed was 94-95mph) and was 1.5 seconds up before having to throw on the anchors for a radical going 50mph in the esses.
A good tire(that lap was on 245 RC-1's with a lot of heat cycles) and better weather and I think a low 1:35 is well in the realm of possibility for this car.
Day 1 I had done some playing around with aero and found shedding the second element was worth about 3mph down the back straight into 10A, but lost me about 2mph though T1, and negligible everywhere else. I think with additional mechanical grip in the form of good tires a single element in the rear set to 1-2* AoA is the way to go.
Also think 225 Hoosier or 245 street tire is the correct choice for tire width. I'm still able to stay flat out from 1-3, 3-5, and 10-1 even on the narrower(245 street) tire, so I think that's the move for lower rolling resistance and whatever marginal gain that brings.
Passenger seat was busy all weekend handing out ridealongs. I think everyone that sat in it had a great time. A coworker's dad stopped by and took some shots while makeing sure I didn't kill his offspring with my rambunctious driving.
A weekend this hot takes its toll on equipment, and I had a slightly longer list of failures then normal.
Day 1 during the hottest part of the day my very old and very abused set of hoosiers delaminated exiting T7. Looks like a flat spot let go and the rest rapidly followed. No body damage, just happy it happened in the slowest corner, not T12/T1.
End of day 1 my shift **** snapped off. I've had a LOT of issues with it vibrating loose and sometimes falling off on me mid-session, so last time I had applied enough locktite to kill an elephant and that seemed to do the trick... until the entire threaded section ripped out. I crammed it full of JB weld and that more or less kept it together for the rest of the weekend. I think I'm just going to strip it, weld the **** solid to the shaft, and repowder coat it. Can't come loose if its one piece, right?
I had lots of extra vibrations I had put down to old/unbalanced tires, but when they persisted day 2 on a newer set of tires I checked everything over and found my drivers hub had a quarter inch of play in it. I had a spare hub, but had both left it at home, and hadn't bought the heavier tools I would have needed to swap it trackside, so I said **** it and ran it for the rest of day 2, just kinda kept an ear out for the noises to get any worse. It lasted fine, just sounded absolutely atrocious on the drive home. More on this later.
I think this might have been due to the dieing hub vibrating around, but my expensive PFC pads on the drivers front delaminated themselves from the backer. Felt the pedal get soft, just figured I had finally cooked the pads/fluid so did a nice slow cooldown lap and parked it. Only realized what had happened when I went to swap back to my street pads.
Since my car was done @rdb138 let me take out his LFX V6 car for the last session to gather feedback and data. Man, that car is so goddam fun. The LFX is just(to me) an absolute torque monster, but is 100% controllable. I was worried I would have to aggressively manage wheelspin trying to exit corners and keep the car straight, but it's scarily easy to just lean into it in any gear and the car goes. It's a completely different animal then a K24 car. The K24 begs to be beaten, rung out and screaming for every last RPM you will give it. The LFX is much more refined and almost elegant with its flat but powerful power delivery, tons of grunt in the entire powerband, any gear, any RPM, yes sir you would like more torque? At once sir, off we go.
His car boasts power steering, and it really hit me 2-3 laps in how freakishly easy and less stressful that makes everything. I finish a session in my car and my shoulders hurt, my hands scream, and it takes a few minutes to relax everything. Having power steering allowed me to just point the car where I wanted it to go, no fuss, no fighting massive tire loads. I think an electric power steering setup just bumped itself up to the top of my list when I get a chance. Talking to a few people that have DIY'ed theirs, it actually isn't that expensive, and with access to a welder its fairly straightforward to do.
One other thing I really found myself appreciating more after driving Rdb's car was aero. His car is 100% stock body and I felt the difference the most under braking. My car I can go deeeep into 10A and whoa up at the 200ft mark from 130mph to make the corner with room to spare. His was nowhere near that steady, I was hitting brakes around the 400ft mark from ~139mph and sometimes still struggling to keep it pointed forward and the round bits round. There were of course massive cornering differences but under brakes are where I noticed the(lack of) effect most.
Still, the freakish powerband almost makes me wish I had gone LFX instead of K24... almost. I still love the revy nature of the Honda engine, and I know there is toooon more bolt on power potential in it down the line with ample aftermarket support. Off the shelf power adders for the LFX are basically non-existent for the miata chassis.
So that hub that starting getting noisy at the start of the weekend... yeah it was well cooked when I got it home and pulled it apart.
These are BMW hubs using the Brofab kit. These were cheap rockauto hubs/bearings, NOT his fancy extra robust(but expensive) german hubs.
Looks like the plastic bit separating the ***** and holding the inner races in snapped some teeth, which allowed the races to walk, which resulted in the noises I heard/felt.
I remember packing these very thickly with good grease, but there didn't seem to be much when I took this one apart. I think I bought/installed these with one of the 2020 stimmy checks, so they would have had at least 10 trackdays on them and a good chunk of street miles. The lack of grease inside the bearing, combined with grease flug into the brake duct/knuckle assembly makes me think grease had been leaking out of these for awhile, so that might have been a contributing factor. I think I'll put these on a yearly check/bearing re-grease schedule and see if that keeps them alive longer.
For reference these were "GMB" branded hub assemblies.
Not that these are expensive or hard to get, I had a spare hub at home ready to go. I realized trackside that even if I had the spare with me, I lacked the bigger tools needed to do a hotswap trackside, much less what I would have needed to extract the studs and re-install them. I really need a fully assembled/studded hub and spare nut on hand so I can just remove the rotor, buzz off nut, pull the old one off, install the new one and be good to go.
The final weak point of the weekend was cooling. While it handled *most* of the sessions just fine, during the hot part of both days coolant temps crept up over 220 and started triggering my safeties. A cooldown lap would bring temps to a reasonable 205ish range, but I feel like there's still an air bubble somewhere back there thats stubbornly stuck. I think I'm going to fab up a tractuff style rear water neck for the Z3 so I can properly bleed the system, and do it without the hassle of jacking the nose 20ft in the air.
Next event for me is the SCCA Dragon Hillclimb in Robbinsville, NC, July 30/31. Should be a good showing and some stiff competition. As of the time of writing this, there are EIGHTEEN entries for my class(Sport Unlimited), which is almost half the total entries(52, cap is 100). This year's goal is to both take the class win and reset the class record in the process, but the first part of that might prove to be... difficult if people show up ready to wheel right out of the gate, but I should have a trick or two at my disposal to help level the playing field.
220 @ 2300lbs + good aero on a Dec or March morning = 1:33s. Keeping in mind TT4 record is 1:32.9
I didn't know you had Brofab hubs. Do you think if you had the nicer BMW bearings they would have lasted? The hot-spare method you're wanting to do is the same thing I do with OEM hubs currently.
Also, on the coolant bleed don't forget to turn it off/on/off/on and squeeze the hoses too. That let me get my bubbles out.
Can you share a photo of your brake duct at the spindle? Trying to figure out "custom" duct work and work with the ABS sensor and maybe your design will spark an idea.
What kind of oil consumption are you seeing on track? 2012 K24Z3 with 97k on it will burn 1/2qt of Redline 10w40 in a track day. 140-150 miles. The Honda PCV valve is in place and I have a oil separator between it and the intake manifold. Separator is bone dry.
220 @ 2300lbs + good aero on a Dec or March morning = 1:33s. Keeping in mind TT4 record is 1:32.9
I didn't know you had Brofab hubs. Do you think if you had the nicer BMW bearings they would have lasted? The hot-spare method you're wanting to do is the same thing I do with OEM hubs currently.
Also, on the coolant bleed don't forget to turn it off/on/off/on and squeeze the hoses too. That let me get my bubbles out.
1:33? Sheesh, that's hauling. I'm 2265 with me+3gal of fuel and can crank out 230whp on E85.
I think broson says the fancy hubs are good for 100+ track hours or something crazy like that. Don't remember if that's on a high power/high aero car or spec Miataish levels. Really couldn't say as to the expensive ones suriving. These generic hubs are so cheap that even if I was timing them out after a year regardless of condition I wouldn't even bat an eye.
Yeah I've done the coolant dance. It's just annoying and finicky. The A2 guys with the tractuff neck don't even have to jack up the car, which would be a HUUUGE boon if I ever need to do an emergency trackside bleed.
Originally Posted by bimmerboy
Can you share a photo of your brake duct at the spindle? Trying to figure out "custom" duct work and work with the ABS sensor and maybe your design will spark an idea.
I trimmed my ABS tabs off which is why I can dump air so closely into the backside of the rotor. Could probably do the same design, just on the backside of the spindle to work around the ABS. Would just be some additional ducting length needed.
It's nothing fancy, just a tube with a little bracket welded to it. Bracket attaches to two of the dust shield holes, obviously I don't have dust shields.
Originally Posted by bimmerboy
What kind of oil consumption are you seeing on track? 2012 K24Z3 with 97k on it will burn 1/2qt of Redline 10w40 in a track day. 140-150 miles. The Honda PCV valve is in place and I have a oil separator between it and the intake manifold. Separator is bone dry.
I don't run any PCV. Just valve cover vent and block vent right into a can that then VTA's. My first motor always had a ton of liquid in the can, especially when there was E85 in the tank. Mostly water. This motor I get basically zero of anything in the can, just a light film of water/oil mix.
I think both track weekends I've added about a 1/4th quart to move it back to "just over full". I could easily go a full weekend without adding any oil if I felt like it. Running Valvoline 5w-40 with a single quart of VR-1(40w-50 high zinc) added at each oil change. 2010 motor with 130k I think?
Since my car was done @rdb138 let me take out his LFX V6 car for the last session to gather feedback and data. Man, that car is so goddam fun. The LFX is just(to me) an absolute torque monster, but is 100% controllable. I was worried I would have to aggressively manage wheelspin trying to exit corners and keep the car straight, but it's scarily easy to just lean into it in any gear and the car goes. It's a completely different animal then a K24 car. The K24 begs to be beaten, rung out and screaming for every last RPM you will give it. The LFX is much more refined and almost elegant with its flat but powerful power delivery, tons of grunt in the entire powerband, any gear, any RPM, yes sir you would like more torque? At once sir, off we go.
His car boasts power steering, and it really hit me 2-3 laps in how freakishly easy and less stressful that makes everything. I finish a session in my car and my shoulders hurt, my hands scream, and it takes a few minutes to relax everything. Having power steering allowed me to just point the car where I wanted it to go, no fuss, no fighting massive tire loads. I think an electric power steering setup just bumped itself up to the top of my list when I get a chance. Talking to a few people that have DIY'ed theirs, it actually isn't that expensive, and with access to a welder its fairly straightforward to do.
One other thing I really found myself appreciating more after driving Rdb's car was aero. His car is 100% stock body and I felt the difference the most under braking. My car I can go deeeep into 10A and whoa up at the 200ft mark from 130mph to make the corner with room to spare. His was nowhere near that steady, I was hitting brakes around the 400ft mark from ~139mph and sometimes still struggling to keep it pointed forward and the round bits round. There were of course massive cornering differences but under brakes are where I noticed the(lack of) effect most.
Still, the freakish powerband almost makes me wish I had gone LFX instead of K24... almost. I still love the revy nature of the Honda engine, and I know there is toooon more bolt on power potential in it down the line with ample aftermarket support. Off the shelf power adders for the LFX are basically non-existent for the miata chassis.
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The LFX is much more refined and almost elegant with its flat but powerful power delivery, tons of grunt in the entire powerband, any gear, any RPM, yes sir you would like more torque? At once sir, off we go.
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i agree completely.
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The LFX is much more refined and almost elegant with its flat but powerful power delivery, tons of grunt in the entire powerband, any gear, any RPM, yes sir you would like more torque? At once sir, off we go.
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i agree completely.
It might be considered a conflict of interest if I agree too?!?! I love the review, I think you captured the car perfectly in your description. I must admit, I wasn't expecting all the torque when I built her, but I'm an addict. An addict with a **** eating grin on my face every time I push down on the throttle.
BTW...Thanks?!?! for showing me just how much of a turtle I am. You take the car out on the hottest part of the day for 6 laps with a heavy passenger weight penalty and still had 5 seconds on the best I could manage all weekend. In all seriousness, I definitely found ways I can improve. THANK YOU!
Had a lot of fun over the weekend. Looking forward to the next time!
04-27-2022, 12:14 PM
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Looks like you got it all sorted out with Ed, nice.
