jpreston

iTrader: (4)

Dunno if it's typical. Seems like a bigger loss than I've ever heard for manual vs automatic.

The car was WRL power-to-weight classed based on the reduced hp so it was about as fast as I expected. Definitely slower than other 2.5 swapped NCs I've driven though. No amount of fast shifting will make up for 25hp lol.

wombat57

got some pieces in from Domiworks. They are nicely machined and fit well. Ignore all the **** on my worktable. Unfortunately my brother's very fit wife died unexpectedly of Vfib ( I had never heard of it) last week so my project is on hold helping my brother get thru the ****. She was wonderful. Really a tragedy.

I'm still a bit on the fence, but am unconvinced about clutch wear fears as in my previous posts

adapter - needs a big starter cutout


. The parts shown are not really light - probably 15 lbs - so adding that to the TC means a ~ 50 lb flywheel. Yuck. Trans side of TC bell will be machined off as part of adapter as seen in some of the adapters done in the FB posts, and I'm going to machine the Domiworks pieces to remove weight too. Hoping to make more progress in about 10 days.

Slow_1.6

Hey OP,

What you are doing is exactly what I had planned for a while for my rods-only turbo VVT in a 95 NA chassis. I am running the Kraken full kit with a pulsar GTX2860r @ ~250whp. I will be following closely. Plese update us on any progress you are making as I am eager to see how it all works out.

wombat57

an update: after a bunch of head scratching and playing around with parts, I finally came to a setup I think will work. Unless I've missed something with a brainfart (not unusual) the assy will consist of:

domiworks engine to trans adapter plate
NB miata auto trans flex plate
6 puck sprung hub clutch disc for an LS V8. I actually cannot remember it may have been for a 5.0 Ford, but key point is sprung hub for V8/Turbo Miata torques, and o.d. a bit bigger than the i.d. of the lip on the flex plate - you can see in the pics below.
the two splined hubs cut out of the ZF8 TC.

The splined hubs have been shown in previous posts. I had a morning shower aha thinking about the Miata auto trans flex plate - unfortunately my aha came months after paying for the Domiworks adapters. His stuff looks really nice, but I think the total kit cost can be much lower if you are going without the torque converter.

The auto trans flex plates are cheap as dirt - $30 or so.
sprung hub 6 puck disc $79 delivered, so ~~ under $150 all delivered.

I drilled the rivet on the metallic pucks and they came right off, then chucked the disc in my itty bitty lathe, and created an sub micron tolerance o.d. grinder set up. Call me Mr. Jank.
Ground the od of the disc to 10.040", which fits right into the lip of the Miata flex plate.
I'll space the disc out from the flex plate face to the edge of the lip to clear the crank bolts underneath.
I'll have to match drill thru the disc face and flex plate and will probably tack weld nuts to the back face of the flex plate to receive bolts from the front of the clutch disc.
the disc hub will be welded up as an assembly with the two splined hubs. I need to cut a spacer approx 3" od by 2.5" id to get the proper space between the two splined hubs then that will all be welded together.

Assembly will be bolt flex plate to crank, disc/hub spline assembly to flex plate. This basic configuration has all been done by the guys named above in much the same way so credit to them. If you're willing to do a bit of work yourself and either have tools or buddies with tools this part can be done pretty cheaply.

I'm more convinced than ever that the clutch "issue" is a figment of keyboard warrior imaginations.



sub micron precision od grinder


V8 6 puck sprung hub w pucks removed, in NB flexplate


NB flexplate

wombat57

One of the other things I've learned is they apparently are output shaft speed limited in 7th and 8th gears - I think because the planetary set has to over speed by the underdrive ratio so it gets zinging up pretty good. Lawisme blew his ZF with a high speed 7th gear (and I'm talking hauling ***) K24 turbo NC pull. I think he was doing over 160mph. So a taller rear than the 4.3 will be rqd.

Food for thought.

Padlock

I am glad you posted this because I saw him post the same thing a few weeks ago. I was going to start asking a few people about top speeds they reach on local tracks to me with 400-500hp miatas to see if I'm setting myself up for the same failure as Lawisme. With 230hp, I'm reaching 135mph with 6spd/4.3 at Road America. Not sure how much more speed I am to expect when I have twice the power

Newaza

awesome work and engineering! Are you going to do a pilot of some sort to register the transmission input shaft into the back of the crankshaft?

wombat57

Re: top speed and output shaft rpm - I contacted lawisme directly and he said he’d run his WAY over the output speed ZF recommends many many times. He also sent me a link to a 3.3 Miata ring & pinion - which I didn’t even know existed. I thought the lowest was a 3.6. Another option is the Caddy/Camaro diff (?) being run - I think those can have a 3.27. And, I think 150


or so will be fast enough for me. I’m old and my bones are brittle. And my plums have shrunk.

re: piloting trans input shaft- the shaft is recessed about 2” past the face of the trans, and, the torque converter is just bolted to crankshaft with the nose of the shaft sealing in it. I’m aiming for about .002 TIR

Shown are the two Domiworks pieces that won’t be needed. Though the black piece is aluminum, with it, the steel ring gear and piece of the cut up TC I showed earlier we’re still not what I’d call a low inertia “flywheel.” The auto trans flex plate, sprung hub disc, and small dia hubs connecting to trans otoh should have significantly less inertia than a 949 twin disc. Total assy weight looking like about 7 lbs, with half of that under 3” od.
😳