Jeff20B

iTrader: (13)

Expected power is 300HP and 200ft/lbs from the new engine.

NA S5 manual trans in my '81 FB. 225mm is the size I'm going to use.

The current setup is a 215mm centerforce stage I or II pressure plate (got it used so not sure), effort feels very good. Holds the power of a 7" Camden on a 13B and a 3" exhaust so far. Probably 150 to 170HP. No real torque as of yet.

The disc is just a no name OEM, drives fine and holds the power fine.

The flywheel is one of those rare superlight steel 8 pound Greddy 215mm jobs. Zings well and doesn't feel too light with the added rotational mass of the supercharger.

In all a very nice driving clutch with enough grip capacity for my needs at the moment.

This is all changing...

Jeff20B

iTrader: (13)

The new engine will make around 200 ft/lbs of torque so I need to find a clutch that will handle this much but I don't want a puck.

I have several discs and pressure plates in 225mm and 215mm sitting here.

Pressure plates:

225mm Centerforce I or II
225mm RB street strip (Exedy)
225mm OEM Daikin

215mm Centerforce I or II pressure plate (currently in the '81 FB)
215mm RB street strip
215mm OEM Daikin (I won't even bother with this one, just listing it)


clutch discs:

ACT Performance SS 225mm part# 3000203 (see pic below)
Daikin OEM 225mm

Daikin OEM 215mm
no-name OEM 215mm (currently in the '81, love it!)


And now to the good stuff. This is a file photo of the ACT performance street disc I have.


When combined with ACT's HD pressure plate, they claim it will handle 268ft/lbs.


That's more than enough capacity. However I only have Racing Beat's Street Strip pressure plate (a recent one made by Exedy; Daikin's performance division, so you know it's well built), and Centerforce's 225mm pressure plate (also made by Daikin but has a softer spring diaphram). Lastly an OEM capacity Daikin pressure plate, which I believe has a softer diaphram spring than the CF.

I don't really want to go out and buy another pressure plate. Think one of these will hold the torque?

Jeff20B

iTrader: (13)

I tested the "new engine" a few years ago in a different car and it drove well enough (untuned) with no clutch slip. Very down on power but still probably made 130 to 150 HP. That setup consisted of an RB light steel flywheel, a 225mm Daikin OEM clutch disc and an OEM 225mm Daikin pressure plate. The driveability was excellent and never slipped, but I couldn't push it past about 5k because the exhaust was grossly undersized.

The goal in the '81 FB is a clutch that drives well but handles at least 200ft/lbs. I don't need the full 268 as advertized above by ACT. I'll trade less capacity for better driving characteristics. I've had enough of super heavy pressure plates and really light weight flywheels.

By the way, the ACT clutch disc pictured above is actually very heavy. It feels like it weighs a full pound more than my Daikin disc. I wonder what that will do for shifting speed/speed shifting? lol


I'm kinda thinking I could choose one of these combinations:

centerforce pressure plate and ACT disc for easier pedal effort and still lots of grip but like an on/off switch.

or

RB SS Exedy pressure plate and OEM Daikin disc for higher pedal effort but a much smoother engagement with still probably enough overhead capacity for 200ft/lbs... maybe.

Jeff20B

iTrader: (13)

I should also mention I've got a REPU that also needs a new clutch package. I already picked up a resurfaced 26 pound GSL-SE flywheel (should be just about perfect and match the rotating assembly). I've got my eye on the ACT disc because it is very heavy compared with other clutches, and has a high copper content for better heat control; probably a good idea for towing, eh? The only downside I see is its lack of marcels. The REPU already has a really short pedal travel. Combined with a (nearly) solid disc like the above, it will drive like an on/off switch. Others have said they can drive their REPUs with a puck disc, which they could after learning where the narrow friction point is. Hmm I drove my REPU with a solid disc (RB HD made by clutchnet) last year and didn't like it.

Jeff20B

iTrader: (13)

I'll be pulling the old 13B from the '81 very soon so here's what I'm thinking. With the engine suspended in the air from the engine crane, why not swap clutches and drop it back in temporarily to test various clutch packages?

eage8

iTrader: (9)

I have the ACT performance street disc on my turbo with the xtreme pressure plate and it deals with my 235 ft. lbs of torque easily. (with an ACT prolite flywheel)

the clutch pedal is a tad heavy though. I think the HD pressure plate and the performance disc will be perfect for your setup.

I used to have a centerforce pressure plate on some sort of disc (I'm assuming centerforce) and I blew through that pretty easily on the dyno, thankfully it was on one of my last runs.

Jeff20B

iTrader: (13)

Thank you for your feedback. I'd like to get started on the engine pull as early as tomorrow if the weather improves.

Jeff20B

iTrader: (13)

I only had enough time today to test one combination; the RB SS pressure plate and the ACT disc on the new aluminum flywheel. Not too hard on the left leg. I'm sure as it breaks in it will get heavier as the disc gets thinner, but over all I'm impressed. It's about a medium-high on the effort scale. Certainly driveable. If it only holds maybe a max of 200ft/lbs, I have a feeling my engine won't be making much more than that.

Jeff20B

iTrader: (13)

I take that back. It is too heavy for daily driving. Gonna swap to the centerforce pressure plate but leave the ACT disc in there.