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12a w/ TII gearbox swap. Flywheel/clutch suggestions?

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Old Oct 21, 2020 | 10:46 AM
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12a w/ TII gearbox swap. Flywheel/clutch suggestions?

Hi all, wondering how I should determine which clutch and flywheel I’ll need /want. Car will be a street driver, and my motors still stock, for now.

I know I need the TII diameter flywheel (135mm?)
I know it needs to be a light weight flywheel, but not sure how light-weight. Most common for sale seems to be 13lbs- 9lbs. How do I pick? (Stock on 12a is 23lb?) (stock Weight on 87 TII Flywheel? Unsure.) I understand with a lighter flywheel, engine inertia goes (down?) letting it rev up (faster?)

I know I need a TII diameter clutch. Oem? Stage 1? Stage 2? They all seem the same to me, except A) price and B) the amount of pucks or friction pads differ.
I won’t be racing the car, just fun driving and cruising. How do I determine what clutch I want/need. Other than the price of course

Scatter-brains, I know, but these are the little questions that I can't find definite answers to... any guidance is greatly appreciated

Last edited by LEGALIZECHEY; Oct 21, 2020 at 11:08 AM.
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Old Oct 21, 2020 | 11:06 AM
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From: https://www2.mazda.com/en/100th/
how much power are you going to make? a stock T2 clutch can only hold about 250hp.

with a Turbo trans, you need the turbo flywheel and clutch. you also need the balance weight for the 12A you have. this means aftermarket.

if its just a street car you probably want something on the heavy side, its more like stock. an FD is 23lbs, S4 t2 is about 3,000lbs...

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Old Oct 21, 2020 | 02:34 PM
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Originally Posted by j9fd3s
how much power are you going to make? a stock T2 clutch can only hold about 250hp.

with a Turbo trans, you need the turbo flywheel and clutch. you also need the balance weight for the 12A you have. this means aftermarket.

if its just a street car you probably want something on the heavy side, its more like stock. an FD is 23lbs, S4 t2 is about 3,000lbs...
everything is stock right now. I plan on building a motor for it eventually, but will go for 200/250hp max.

If I understand right, the automatic 12a counterweight will work also?

And when shopping for clutch and flywheel, everything labeled for turbo is the correct diameter? Not sure how much bigger the turbo flywheel/clutch is than my FB flywheel/clutch?
Basically anything lighter than stock is considered lightweight??
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Old Oct 21, 2020 | 03:20 PM
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Yes, anything is a lightweight flywheel compared to 1987-88 FC TII since that stock flywheel is 28Lbs.

Aftermarket is available in ultra light (just starter ring gear support) for 4" diameter low inertia race clutches up to heavier aluminum units in the 11-13lb range which will be more in the 13-15Lb range with the necessary automatic counter- weight and then about 40Lbs once you bolt on the TII pressure plate and sprung full face disk.

So, any flywheel 11-15Lbs will basically drive the same- the pressure plate rating and clutch disk consteuction/material will have much more effect on driveability than 2-4Lbs flywheel mass.
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Old Oct 21, 2020 | 07:50 PM
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I think I'm cleared up. So I'll be running my automatic 12a counter weight, might go with the ACT street-lite flywheel (@11.5lbs) or the Comp Clutch ST flywheel (@13.2lbs). Still not sure how to choose a clutch, might just go with oem replacement? Anyone have suggestions or thoughts about clutches?

http://banzai-racing.com/store/86-91..._flywheel.html

http://banzai-racing.com/store/86-91..._flywheel.html

Last edited by LEGALIZECHEY; Oct 21, 2020 at 07:54 PM.
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Old Oct 21, 2020 | 11:50 PM
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For a street car you want a clutch with a sprung hub. As far as clutch/pressure plate brand, I prefer Center Force dual friction. They are smooth and have light pedal effort.
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Old Oct 22, 2020 | 10:06 AM
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Does anyone know the diameter of the TII flywheel? When browsing clutches and some flywheels I see, 225mm, 235mm, 240mm. Does the clutch diameter need to match the flywheel diameter?
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