RaceTwin clutch for K swap to Mazda trans
 

A little side project for Vegas, K24 endurance build that will run the Quaife sequential. We're building a custom flywheel for our existing RaceTwin clutch for the BP engine. We modeled our current 5.5 lb 4340 billet flywheel for the BP to set strength targets. Our design for 6061 T-6 K24 at 7.5 lbs matches the stiffness of the 4340 flywheel in the center where torque is transferred, a bit less outside of that in the less critical ring gear support area. The extra spacing dictated by the trans adapter adds mass to the flywheel. The image with green center is an FEA simulated 300 lbs ft. MOI of the 7.5 lb K42/BP Racetwin flywheel is 52% higher than the 5.5 lb 4340 flywheel. The standard 14.2 lb KMiata flywheel is 310% higher MOI than the steel 5.5 lb Twin disc flywheel. Add to that the MOI gains from the smaller 7.25" aluminum clutch vs the 8.9" OEM style steel clutch. Total K24/Mazda Racetwin weight should be around 16.7 lbs with flywheel.

We only needed one and a spare for our car but we suspect a few KMiata owners might also want to use our Racetwin clutch so we'll make a small run, perhaps 10. Once those are gone, we probably won't make more. Email us info@949racing.com if you want to be notified when pre ordering opens up for the complete K24 Racetwin and flywheel kit. We have no plans to offer anything for the BMW trans.

https://cimg0.ibsrv.net/gimg/www.mia...6a1d2772d8.jpg
https://cimg8.ibsrv.net/gimg/www.mia...cc0b3aadd0.jpg

Going into production now. We'll only do this one production run. Each kit mated to an order, no extras. If you want one, order it now. Production slot about 3 weeks from today so they'll ship around the end of September.
https://supermiata.com/racetwin-k24.aspx

Final K24 flywheel weighs around 8 lbs compared to 5.5 for the regular BP version. So still stupid light and quick revving. Gonna be fun behind the Quaife sequential in Vegas :)

Order placed. I guess I am officially doing a K24 swap over the winter.

Can we expect to see more K24 goodies coming out of Vegas' development and flogging?

Thanks for the order.

Probably no more development pieces, nothing planned anyway. That's Kmiatas playground and its a teeny market segment.
I'll start a new build thread for the swap and share anything useful we stumble across. Our primary market is BP Miatas so that's where our focus is. For every one K24 Miata customer, there are probably 1000 BP Miata customers.
We developed this flywheel because we needed one. Would have been a waste of good R&D to just make one though :)

Only a few orders so far so it looks like we'll be making about 6 of these. If you are hoping there will be some available later on, don't. We'll hit the go button on production Monday 31st.

Placed my order a couple hours ago. Hopefully it's not too late.

I honestly don’t understand why this isn’t more popular. The KMiata flywheel is $750 and then you need to add a Miata clutch and pressure plate. That’ll take you to over a grand, easy, especially if you go for something that’ll hold more torque. It doesn’t seem so crazy to spend a bit more to lose a few pounds and gain a better MOI....

It's because everyone typically already has the flywheel that came in their kit, and if you're just using a 6 speed Miata trans then there are normal Miata clutches that are capable of holding power up until the point that you'll grenade 4th gear anyways.

I think a lot of K swap customers still daily/street drive their cars, which this would make very difficult. Sick piece though, love seeing the FEA

For those here skeptical of the torque capacity of AZ6 or just how big a difference in MOI "rotational inertia", some additional information:


Walter Motorsports builds blueprinted AZ6s that will live well past 300whp.

The standard KMiata flywheel weighs more than twice what our racetwin flywheel weighs. Bolted to the K Miata flywheel is 225 mm steel pressure plate and sprung hu disc. The racetwin is a 184mm billet aluminum pressure plate cover and rigid hub disc. The difference in MOI is vast.

This kit is not for everyone. But for some people it's exactly the right part.

I am curious, what is the crank bolt pattern on the K24?

I'm doing a J35a4 swap and the J series has the same bolt pattern as a 2000 civic SI B series, an 8 bolt too (I don't have the specs)

It would be really cool if there was an up grade path for very torquey V6.

Thanks,
Cc454

Look at Honda part number 90429-PC6-900
https://www.hondapartsnow.com/genuin...9-pc6-900.html

Any update on the eta for these shipping out?

I too would like to know, but am not so inquisitive as to actually send an email.

Looks like if you purchased one, a progress update email was sent out. Looking forward to mine as well.

Yup, I emailed too and got a reply that said eta for shipping them out is late this month or early November.

It's almost time for my monthly email asking for a status update.

We've gone from "Going into production now. ... Production slot about 3 weeks from today so they'll ship around the end of September." to

"...we are experiencing a delay in manufacturing our K24 flywheel. Our supplier has run into covid-related delays and we are now expecting these to arrive end of October, possibly into November." (emailed update 10/10) to

"No update at this moment. Our supplier is behind schedule so we'll let you know when we get any new info from them. They are dragging their feet so we're reaching out to a second supplier as a back up." (emailed update 11/11)

This order made sense to me when there was a production slot and everything seemed ready to go. I've thought and rethought this next line a bunch given my respect for 949/SuperMiata/Emillio/Ed/et-al, but here goes.

I was hoping this would go better.

LOL please refer to the tecna coilovers 949 is working on

Drama from, as best I can tell, 2014? Please. Feel free to necro old shit just to get your rocks off, but please don't feel the need to share that with everyone you meet.

Considering most recently their claim was it would be available by summer 2020 it isn't that much of a Necro.