Project GD Subaru STI, Checking out the Ultimate Streetable Clutch with XClutch.

Finally, the pressure plate is installed on top of it all.

The XClutch pressure plate has a clamping force of 3300 lbs which is 50% more than stock.  This is great for holding power.  The leverage ratio of the diaphragm spring has been changed so the pedal effort stays near OEM even with the greater clamping load.  Usually, this results in a long pedal and slower clutch action and shifting but with the thinner uncushioned discs, the clutch action remains fast.  The XClutch design is all starting to add up!

The pressure plate like the OEM part is a pull-type with an iron pressure ring. Pull-type pressure plates are more efficient than your typical push type as the clamping force doesn’t work to flex the pressure plate cover and reduce clamp load.  Typically a pull-type pressure plate has 10-15% more actual clamping force for a given rate of diaphragm spring. This is great because many STI twin disc clutches require you to convert to a push-type hydraulic system.

The pressure ring has drive straps to assure quieter operation and a positive release. A lot of twin disc clutches allow the pressure ring to float where it tends to be noisy.

This ring on the diaphragm spring is so the throwout bearing can pull on it instead of push.  Thanks to its efficient design, the XClutch has a torque capacity of 740 lb/ft up from the stock 350 lb/ft


  1. Does the clutch/flywheel assembly need to be specially balanced? The lugs and lightening holes don’t look at all symmetrical.

    Looks like a well designed and made part. I really like the CNC’d lugs.

  2. Some really clever solutions to make this clutch the best of many worlds. Love seeing all the detail you provided in the article to explain why decisions were made. Looking forward to hearing some driving impressions!

    And surprisingly, I could actually get the same setup for my Volvo if I need a clutch to handle some big power. Not many companies support such an oddball chassis, so that’s kind of exciting.

  3. I was debating on a clutch setup for my Spec-B and I know from experience that the Exidy multiplate is OBNOXIOUS (but works well) I’ve been looking at the X-clutch for some time but after reading this analysis I’ve made up my mind! Now if only you guys hadn’t taken what seems to be the only one left in the country!

      1. Finally got my clutch in, 5 months from date of purchase. What an amazing piece, can’t wait to get going on my project again!

  4. Would you consider the unsprung version of this clutch would be manageable for a daily driven car? Could you kindly explain what differences in driving experience would running an unsprung version yield?

  5. I am so glad to have found this website! I’ve ben following you, Mike, since Sport Compact Car and that Nissan Performance web magazine you wrote for way way back. This clutch will most likely go into my bugeye once I destroy my current clutch

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