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Old 04-23-2014, 03:06 AM   #1
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Default Custom 8.5" Clutch shenanigans

So for a while now I’ve heard about this local clutch god’s mom and pop shop… everyone swears by him and apparently he builds custom application clutches for high HP cars. I figured my Act full face was not going to cut it and I was going to need either a 4 or 6 puck for my build.
I decided to him a try, and as far as customer service and just being a cool dude I came out extremely happy.

Anyways, (cool story bro)

The dude really knows his ****. I was impressed, he really knew the Miata application, including the to various disk sizes (1.6 vrs 1.8) right off the top of his head. After a while of bullshiting and him talking way over my head about the technical aspect of various clutches and their applications.. He told me that a sprung 4 puck would be pretty dope. However, because of my sissy pants we compromised on a 6 puck sprung for better daily driving.
Also, he told me that he would use a 8.5 “smaller” disk for better rotational mass. He assured me that the smaller disk would not fault performance. I trust him.. however, I’m curious as to what others think?

Here’s some more information
PP: Act XT, which he tested at over 2200Lbs of force (resurfaced)
Fly: Act 1.8 Prolight (resurfaced)
Disk: Custom 6 sprung 6 puck. Because of the resurfacing on the PP and fly, the width of pads were compensated for no loss in force (Which I thought was pretty cool).

He said with this PP, it should have no problem with upwards of 325 lb-ft if not more..

note: ID of pad circle clear both disk edges. No hangover.



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Old 04-23-2014, 11:26 AM   #2
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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?
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Old 04-23-2014, 11:59 AM   #3
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Part number?

The clutch was custom built.

??? The slight diameter difference probably won't show much wight savings but I'm sure is better for performance . Its got to be better than nothing when your not sacrificing performance?

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Old 04-23-2014, 02:45 PM   #4
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Originally Posted by Failure View Post
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.


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Old 04-23-2014, 02:52 PM   #5
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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.
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Old 04-23-2014, 03:00 PM   #6
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Originally Posted by Failure View Post
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?

I like your user name.
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Old 04-23-2014, 03:19 PM   #7
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Old 04-23-2014, 03:40 PM   #8
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Oh, right, I forgot how a lightweight flywheel is worth 20 HP on the dyno. It's like 4 stickers or half a cold air intake.
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Old 04-23-2014, 03:42 PM   #9
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Oh, right, I forgot how a lightweight flywheel is worth 20 HP on the dyno. It's like 4 stickers or half a cold air intake.
Heh man this joke never gets old keep the good times rolling bro
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Old 04-23-2014, 03:45 PM   #10
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Oh, right, I forgot how a lightweight flywheel is worth 20 HP on the dyno. It's like 4 stickers or half a cold air intake.
Just because it doesn't add power doesn't mean it doesn't make you faster. Stop talking out your *** like an expert when you don't know basic ****.
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Old 04-23-2014, 03:48 PM   #11
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Oh, right, I forgot how a lightweight flywheel is worth 20 HP on the dyno. It's like 4 stickers or half a cold air intake.
Bro, do you even flywheel?
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Old 04-23-2014, 03:48 PM   #12
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Oh, right, I forgot how a lightweight flywheel is worth 20 HP on the dyno. It's like 4 stickers or half a cold air intake.
Dude! Put the shovel down and back away from the hole. The deeper you dig it, the farther the fall.

You obviously do not have the experience/knowledge to be commenting on such topics so it's better to just avoid it all together rather than look silly trying to defend an already inaccurate statement.

BTW - this is the nicest comment you will receive from this forum, so do yourself a favor and take my kind advice.
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Old 04-23-2014, 03:51 PM   #13
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Quote:
Originally Posted by Failure View Post
Oh, right, I forgot how a lightweight flywheel is worth 20 HP on the dyno. It's like 4 stickers or half a cold air intake.
Moment of inertia - Wikipedia, the free encyclopedia

Ignorance is OK as long as you work to get rid of it once you know it exists.
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Old 04-23-2014, 03:59 PM   #14
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Oh, right, I forgot how a lightweight flywheel is worth 20 HP on the dyno. It's like 4 stickers or half a cold air intake.
Annnnd you've gone full retard, even though you were warned about not going full retard.

Why do the noobs never learn?
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Old 04-23-2014, 04:14 PM   #15
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I see we ascribe to the "frees up power that would otherwise be sent to the wheels" school of thought here. Anyone care to attach a picture of a first gear dyno pull showing the half a horsepower it's supposed to free up?

Or is there something else that a lightweight flywheel is supposed to do? I can confirm that mine does indeed make rev matching much quicker, but my gutless 1.6 is still slower than ****. No magical 20 HP gain here.
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Old 04-23-2014, 04:15 PM   #16
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It was just linked to you.

Moment of inertia - Wikipedia, the free encyclopedia

Stop talking, start reading.
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Old 04-23-2014, 04:20 PM   #17
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Quote:
Originally Posted by Failure View Post
I see we ascribe to the "frees up power that would otherwise be sent to the wheels" school of thought here. Anyone care to attach a picture of a first gear dyno pull showing the half a horsepower it's supposed to free up?

Or is there something else that a lightweight flywheel is supposed to do? I can confirm that mine does indeed make rev matching much quicker, but my gutless 1.6 is still slower than ****. No magical 20 HP gain here.
You're probably one of those dweebs that thinks driveline loss should be a static HP number, too. You and Corky Bell would have that in common.
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Old 04-23-2014, 04:45 PM   #18
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I understand the concept of MOI. What I don't understand is exactly how much inertia you think it has when compared to the inertia of the entire car. Even with the gearing advantage of first, the inertia of the car is still an order of magnitude greater than that of the flywheel. In second and beyond, there is no significant difference at the wheels between a stock flywheel and a lightened one. Even in first a heavier flywheel is better for hard launches because it stores the same amount of energy at lower RPMs, giving you more time in first. So a light flywheel is better for soft launches and that's it. Whoop-dee-*******-doo.

Oh wait, then there's the reason you actually bought it: it rev matches faster and upsets the car less if you mess up. That's actually a pretty damn good reason to buy one.
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Old 04-23-2014, 05:18 PM   #19
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Holy **** youre dumb. I like how youre making assumptions about something that you do not understand.

Its not just the reduction of weight. Say you have a car with a 20lb flywheel and an identical car with a 10lb flywheel and a 10 lb weight sitting in the car. Both cars would have the exact same curb weight, the second car (with the light flywheel) would be measurably faster.
The car is faster because its not having to spin that added weight at 7000 rpm.

In Herb Adams book "Chassis Engineering" he says:
Quote:
Most car enthusiasts know that reducing weight will increase acceleration with the same horsepower. What is less well-known is that if the weight, and its distribution, of the driveline components are reduced, the improvement in acceleration can be much greater than that which would be realized for just reducing the car weight. The weight and its distribution of a driveline component about its center is called its rotating inertia.
He goes on to create an example in which a car minus 15 pounds off the driveline at crank speed (e.g. flywheel, crank, etc.) creates an improvement in acceleration equivalent to 32 horsepower.
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Old 04-23-2014, 05:21 PM   #20
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Originally Posted by Full_Tilt_Boogie View Post
He goes on to create an example in which a car minus 15 pounds off the driveline at crank speed (e.g. flywheel, crank, etc.) creates an improvement in acceleration equivalent to 32 horsepower.
That's almost 7 stickers worth.
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