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-   Suspension, Brakes, Drivetrain (https://www.miataturbo.net/suspension-brakes-drivetrain-49/)
-   -   Custom 8.5" Clutch shenanigans (https://www.miataturbo.net/suspension-brakes-drivetrain-49/custom-8-5-clutch-shenanigans-78654/)

Failure 04-23-2014 06:02 PM

Yes, but the difference made by the flywheel isn't chassis weight; it's drivetrain inertia. The flywheel is effectively a container that stores energy. Making it smaller means that you don't have to feed it as much energy as you accelerate, meaning more power reaches the wheels.

I think this is where our disagreement starts from: you guys seem to think that the loaded acceleration benefit of a light flywheel isn't measurable, but I know that it is, and I know how small that measurement actually is.

concealer404 04-23-2014 06:05 PM


Originally Posted by Failure (Post 1124460)
I'm not sure why people try to save mass on the clutch. I mean, even with the lightest flywheel and the heaviest clutch available for our car, the clutch still weighs about 1/3 as much as the flywheel. Stock it's less than 1/10.

Reducing flywheel weight is what gives you that quick revving in neutral. When you're in gear, there's no difference between a 7 lb flywheel and a 20 lb one. I guess a light clutch would make you rev faster when you're out of gear with the clutch engaged, so I suppose it would help if you double clutch your downshifts. Otherwise I see no benefit. No real disadvantages either, though.

Did you get a part number for the new clutch?


Originally Posted by Failure (Post 1124685)
Yes, but the difference made by the flywheel isn't chassis weight; it's drivetrain inertia. The flywheel is effectively a container that stores energy. Making it smaller means that you don't have to feed it as much energy as you accelerate, meaning more power reaches the wheels.

I think this is where our disagreement starts from: you guys seem to think that the loaded acceleration benefit of a light flywheel isn't measurable, but I know that it is, and I know how small that measurement actually is.


U SRS right now?


But yes, it certainly is measurable. I don't think you have any idea what the measurement is, though.

Full_Tilt_Boogie 04-23-2014 06:08 PM

Omg a DYNOJET is not REAL LIFE.
It shows a change in output from a change in flywheel mass because it is not a real dyno and the change is small because the drum is heavy as shit.
Inertia dyno's are a cheap substitution for a real load holding dyno, which would show no gains from a flywheel.

Leafy 04-23-2014 06:21 PM

Man I wish I wasnt so busy at work to miss this.

What you're missing is the fact that yes, the inertia of the car is a couple orders of magnitude larger than that of the flywheel, the speed at which the flywheel is rotating and the rate of acceleration of the flywheel are multiple orders of magnitude beyond what the car as a whole are attempting to do. Which is where the difference in the acceleration of the whole car comes from when reducing the rotational inertia of the car.

I want to know how much the OP paid for this custom clutch and flywheel setup and if it was even worth it. I hope it was under $600.

And some other things to clear up. The stock flywheel weighs ~20 pounds, the stock and most other pressure plates weigh ~9 pounds and the stock friction disk weighs about 3 pounds. So the weight of the clutch does matter and it makes up ~1/3 of the weight of the clutch and flywheel setup.

And did you know I can make a 10 hp swing on a stock miata engine on a dyno jet just by switching between BALLER 45 pound 18" wheels and silly 7 pound 13" wheels?

guttedmiata 04-23-2014 07:23 PM

Hey Failure, I'm sure it is you alone who are right and all the rest of us are wrong. But since you decided to ignore my earlier warning and now we have 3 pages of stupidity, let me throw this in the works. Ignore acceleration for a minute so you can stop talking about drivetrain losses and horsepower gains. a lighter flywheel will decelerate the car quicker as well, creating yet another performance advantage. But what do I know. What do we know. What do all of the car builders all over the world from history know. I guess nothing, so we should all put big lead flywheels in our rides since it makes almost no difference at all according to you.

leboeuf 04-23-2014 07:51 PM

In his defense, the title of the the thread does call shenanigans...
Shenanigans?!

blaen99 04-23-2014 08:34 PM


Joker 04-23-2014 11:13 PM


Originally Posted by Leafy (Post 1124693)
Man I wish I wasnt so busy at work to miss this.

What you're missing is the fact that yes, the inertia of the car is a couple orders of magnitude larger than that of the flywheel, the speed at which the flywheel is rotating and the rate of acceleration of the flywheel are multiple orders of magnitude beyond what the car as a whole are attempting to do. Which is where the difference in the acceleration of the whole car comes from when reducing the rotational inertia of the car.

I want to know how much the OP paid for this custom clutch and flywheel setup and if it was even worth it. I hope it was under $600.

And some other things to clear up. The stock flywheel weighs ~20 pounds, the stock and most other pressure plates weigh ~9 pounds and the stock friction disk weighs about 3 pounds. So the weight of the clutch does matter and it makes up ~1/3 of the weight of the clutch and flywheel setup.

And did you know I can make a 10 hp swing on a stock miata engine on a dyno jet just by switching between BALLER 45 pound 18" wheels and silly 7 pound 13" wheels?


Paid 120 for the clutch, 90 for the resurfacing. PP and fly came with the motor I bought so I don't have a price for those. Thanks for your input, I was hoping someone would touch on this..


Originally Posted by blaen99 (Post 1124743)
Shenanigans super troopers- 720p! - YouTube[/url]

Pretty funny because that exaclty what i was thinking when titling it. I almost went with "evil shenanigans" :rofl:

miata2fast 04-24-2014 12:07 AM

And to think that all the other lightweight rotating parts I slaved over all these years were such a waste of time and money. What a pity.

A+ thread.

sixshooter 04-24-2014 08:57 PM

Did you get it from Tampa Clutch over on 40th Street? He knows race Miatas.

Joker 04-25-2014 11:26 AM


Originally Posted by sixshooter (Post 1125126)
Did you get it from Tampa Clutch over on 40th Street? He knows race Miatas.


Yes, Jim over at Tampa clutch.

miata2fast 04-25-2014 11:37 AM

I didn't realize they were still in business. They were always good to us over the years.

Have you been driving with this clutch yet? Interested in hearing about the results.

Joker 04-25-2014 11:45 AM


Originally Posted by miata2fast (Post 1125312)
I didn't realize they were still in business. They were always good to us over the years.

Have you been driving with this clutch yet? Interested in hearing about the results.

They are still around, actually they seem to be doing very well since literally every transmission and clutch place I called in the area referred them.

Motor is going in on the 14th of May. After break in, I'll post my findings :cool:

bbundy 04-25-2014 05:41 PM

I just don’t get why anyone would stick with the 1.8l size clutch and flywheel if they are worried about rotational inertia. A stock size 1.6l clutch disk is only 200mm ~7.9” diameter. And weighs about a 1 lb less than a 1.8l. The pressure plate in an ACT clutch is about 1.5 lbs lighter for the 1.6l version and a Fadanza 1.6l flywheel is just over 7 lbs instead of something like 9 or 10 for many of the light weight 1.8L flywheels.

The 1.6l ACT MZ1-XTR4 on a Fidanza flywheel comes out something like 18 lbs for total rotating assembly. It is rated to hold 350 ft-lbs. I’ve broken 3 six speed transmissions with too much torque and haven’t changed the clutch or flywheel so I can vouch for its torque capacity. The car is plenty drivable on the street once you get use to it as well.

concealer404 04-25-2014 05:46 PM


Originally Posted by bbundy (Post 1125547)
I just don’t get why anyone would stick with the 1.8l size clutch and flywheel if they are worried about rotational inertia. A stock size 1.6l clutch disk is only 200mm ~7.9” diameter. And weighs about a 1 lb less than a 1.8l. The pressure plate in an ACT clutch is about 1.5 lbs lighter for the 1.6l version and a Fadanza 1.6l flywheel is just over 7 lbs instead of something like 9 or 10 for many of the light weight 1.8L flywheels.

The 1.6l ACT MZ1-XTR4 on a Fidanza flywheel comes out something like 18 lbs for total rotating assembly. It is rated to hold 350 ft-lbs. I’ve broken 3 six speed transmissions with too much torque and haven’t changed the clutch or flywheel. The car is plenty drivable on the street once you get use to it as well.


LA LA LA LA LAAAAAAAAAAAAAAAAAAAA I CAN'T HEAR YOU

bbundy 04-25-2014 07:16 PM


Originally Posted by concealer404 (Post 1125549)
LA LA LA LA LAAAAAAAAAAAAAAAAAAAA I CAN'T HEAR YOU

Oh its because the mass taken off the flywheel and cliutch is only about 4 times as effective at improving acceleration as if you took it off the weight of one of your wheels. assuming you are in a 1:1 gear and even more in lower gears.

Another little secret. Taking the rotating weight off at your alternator is about 8 times as effective it's got to spin up at ~2.5X engine RPM.

The rate at which things have to spin at has a big effect on the impact of their rotationl intertia.

bbundy 04-25-2014 08:08 PM

Fairly educational with math and science and physics and stuff. note in second gear flywheel/clutch weight has a huge effect on acceleration.

The Effects of Rotational Inertia on Automotive Acceleration

18psi 04-25-2014 08:22 PM

I think Failure finally "got it".

Joker 04-26-2014 11:19 AM

Yep, if I were to choose, I would go with the 1.6 Fadanza flywheel. However, (other than the clutch) this package came with the motor , so I'm going to stick with it.

TheScaryOne 04-26-2014 06:36 PM


Originally Posted by thenuge26 (Post 1124642)
Dude have you ever played Gran Turismo 3? The first mods you always do to a car are LWFW, stage 3 clutch, and carbon driveshaft. They are the cheapest and drop your lap time significantly.

Dude, what about L3 Weight Reduction and Chassis Stiffening?!!!1111


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