Watterson02

I’m currently in the process of forging my motor. The blocks been at the machine shop for about a month, but haven’t heard any updates. Figured it wouldn’t hurt to go ahead and figure out what clutch I’d like to run. So here are my thoughts:

I’m currently running a 2560R and with my current build I’m hoping to see 280-300wtq. However I’d like the ability to step up to a larger turbo (maybe a 2871R) once I get bored and make around 400whp/380-350wtq. So for this reason I’d like it to be certified for ~350wtq or have examples of people putting down that power without them slipping. I’m also planning on reusing the stock flywheel (resurfaced of course), so there will be some inertia for pulling out from a stop. The car will be street driven, but not daily driven. Here in NE TN there are lots of hills, so pulling out from a stop can be a challenge at times. I don’t mind a challenge, but I don’t want a light switch for a clutch.

• The FM lvl 2 Clutch: $500 rated for 350tq @ the crank. Claims to be “Stronger than the transmission” (if true this is the clutch I want, can anyone verify?) with a “substantial” pedal effort. Also is organic, so overheating could be more of an issue. In the reviews one person claims to be running 320wtq and another claims 344wtq.
• The Supermiata Sport 6-puck 4 puck: $420, rated for 340tq @ the wheels. Claims to be “still daily drivable” with 35lbs pedal pressure. Ceramic so heat shouldn’t be an issue. I believe Andy Floyd is running the SM 4 puck at 370+ wtq without slipping, but I’ve read someone who had a previously used SM clutch which slipped around 340wtq. (I’ve read into the SM November sale, hopefully clutches will be on sale soon?)
• ACT ZM2-XTG6: $500, rated for 400tq @the crank. I’m expecting this to be the heaviest and most aggressive engagement by far, but should handle any abuse I can throw at it no problem. Not a huge fan of the high engagement point I’ve read about though. I’ve heard ACT underrates their tq capacity but not sure by how much. Should I consider the HD-6puck combo or the XT-organic disk instead?

So here’s where I’m at: 50/50 split between the FM and SM clutches, unless told otherwise. Only considering the ACT if one of those won’t be enough for 350-400wtq. Any thoughts or input from you all? Is the FM or SM clutch stronger? Should I just jump straight into the deep end with the XT 6 puck from ACT? I’d like an organic clutch but don’t want to worry about it slipping during hot launches with 200tw tires (drag strip and autocross).

I’d like feedback in the form of responses on here but if you don’t want to type out a reply here is a Straw poll to vote on which clutch I should pick. Any insight is greatly appreciated, and personal experience more so!

Z_WAAAAAZ

For what it's worth, I spoke to Ed at 949 Racing last week and he confirmed the SuperMiata sport puck clutch is rated for 340tq at the crank, not the wheels. It's also a 4-puck, not a 6, but the couple testimonials I've seen say it's not that hard to modulate.

See thread:
https://www.miataturbo.net/suspensio...onials-107487/

curly

iTrader: (25)

There's isn't a huge difference between 4 and 6 puck. They'll have the same drivability sacrifices, life, etc. A full face ceramic would just be undrivable, so they limit the contact patch.

For your torque goals, I would NEVER suggest an organic disk. In order for them to hold enough, the pressure plate has to be extremely heavy, and I'd rather modulate a sticky clutch with a light pedal, rather than a stock-like clutch with an extremely heavy pedal.

I've been very happy with the many FM2 and SM clutches I've driven, although I currently have the ACT light pressure plate and 6-puck disk. It's holding my 280ft/lbs amazingly. That's with 330hp, I'll eventually add E85 to shoot for 400, I expect it'll make around 350ft/lbs and not have any issue. I did have this same pressure plate with ACT's organic disk, and while it was easy to modulate, if you slipped it just a little too much in first, by the time you get to 4th or 5th, it would slip on boost.

sonofthehill

iTrader: (1)

I have been very happy with my FM level 2 pressure plate combined with the SM sport friction disc. I have it apart at the moment, after a year of launching at the drag strip, and the thing looks almost new. I think the FM level 2 and the 400 ft/lb ACT pressure plates are pretty similar. However, the SM friction disc is about a half inch bigger in diameter than the FM 2 disc was.

Dr.Sep

I run the ACT HD 6 puck and it really is not hard to modulate, clutch pedal is reasonable and it holds without issue with my 6758 and around 325whp

sixshooter

iTrader: (12)

My vote is for the stock clutch and pressure plate from a BMW 530i. And the 6speed ZF transmission that comes with it.

Z_WAAAAAZ

Watterson02

I've read through that, and its good info. I'm pretty sure that's where I got my 340wtq on a used clutch number.
I emailed SM to ask about their clutch and they told me the same about it being rated at the crank, but I thought I read Emilio on here say that it is at the wheels. Maybe they make the website say crank for the extra margin of error, but Emilio tells the actual capacity at the wheels on here? If only I knew what thread I thought I read that in. I think it was the announcement thread... idk.

One correction just to minimize misinformation, but friction is independent of surface area. The only factors involved are pressure and friction coefficient for static surfaces. A larger surface area would help with heat though. Tires are not static, so they're a different story.

Personally, I don't think I'd mind a heavier pressure plate too much, but I'll take your advice.

I was considering mixing pressure plates and clutches but was worried about clutch thickness varying. I'm considering that combo you're describing now. I wonder which pressure plate has higher clamping forces...

I'll be looking into transmission swaps after the 6 speed ***** the bed. Hoping it makes it through my last year or so of college

Watterson02

Oh also Andy replied to my DM:

So now I'm thinking I should go with either the SuperMiata clutch, the SM/FM combo, or still the ACT XT-6P clutch.
- SM: should be good enough. I don't think I'd want to be having transmission problems as frequently as Andy so I don't think I'd need more.
- SM/FM combo: maybe the heavy pressure plate from FM has higher clamp loads without being as much as the ACT one?
- ACT: Strongest, more than I'd need. Also, 6-puck clutch would give more surface area for heat dissipation over the SM 4-puck disk.

Does anyone want to talk me out of the ACT XT 6 puck? why shouldn't I just go for 'allofit' with the clutch too? Any experience with this specific clutch/pressure plate combo? Is the consensus that with ACT clutches that the engagement point will be at the bottom and cant be moved up much? I really would like my clutch to engage at the normal middle point. :/

Edit: reading back over this I think I almost answered it with "I don't think I'd want to be having transmission problems as frequently as Andy so I don't think I'd need more."
Do you think this is the right choice or go allofit with ACT? THE INDECISION IS KILLING ME. I just need to pull the trigger haha

Edit edit: Oh also here is my email from SM, hopefully, they don't mind me sharing it. Note how they say their clutches will be on sale in November. That pretty much seals the deal for me.

der_vierte

Just wait for the sale, everything in one package.
340wtq is a hell of a lot, I turned it down to ~300wtq and enjoy it just as much

turbofan

iTrader: (1)

I'd like to restate my first paragraph for clarity (i'm the one that wrote the response from Supermiata). I think I was perhaps not fully present when I wrote that haha

"The FM clutch friction material can make for a more progressive engagement, but theirs has MUCH heavier pedal pressure with a weird tipover point, so both clutches have drawbacks and perks for maintaining easy drivability but for different reasons"

Orange November sale link just because if I'm gonna post here I might as well post here: https://949racing.com/orange-november-sale/

208fabrication

I recently bought and installed the ACT 6 puck behind my 1.6 and FM flywheel that is running 30 psi from a 3071. I have no idea how much power it is making but the clutch is handling it well. The pedal effort is definitely higher than a FM clutch but is a non issue on the street. After a few miles I don't even notice it.

Neilv

iTrader: (1)

Following this and I'm actually interested in the same decision.

I've got a MSM engine w/ BNR 18g, 6spd trans (3.3 rear gear) and not surprisingly the MSM clutch (w/ kevlar disk) gave it up over 10+psi. the 18g is rated to max out at 360whp; the car is tracked as well as street driven, but I will be keeping the mazda 6spd(no getrag for me)

der_vierte

You'll want the puck style clutch