McLeod RXT 1200 Twin Disc Clutch Kit w/ 8 Bolt Flywheel 164T - 1-1/8in x 26 Spline Input Trans

If your 4.6L or 5.0L Ford V8 now makes far more power than any single-disc clutch can hold, and you are seeing slip at full boost, a smoking clutch after a few passes, or you are bolting a heavier-duty gearbox behind the engine, the McLeod 6435807HD is the clutch package to look at. It is the RXT 1200 (also sold as the RXT HD) twin disc on a dedicated billet steel flywheel for Ford modular engines with the 8-bolt crank, a 164 tooth ring gear, zero balance, and discs splined 1-1/8 inch x 26 for the input shaft.

What the RXT 1200 twin does on a modular Ford

Two ceramic-lined discs sit on either side of a floater plate, so the clamp load is spread over four friction faces instead of two. That is how a twin disc holds big power with a pedal a street car can live with. The RXT 1200 adds a higher clamp load pressure plate over the standard RXT, with strap drive between the plates. McLeod's older catalog copy rates the RXT 1200 at 1,200 horsepower; the current RXT HD copy rates the same line at up to 1,300 horsepower, and describes a moderate pedal effort.

The flywheel in this kit is McLeod's steel unit made for its RST, RXT and RXT 1200 twins: A36 steel with a heat-treated ring gear. Steel carries more inertia than aluminum, which helps a heavy car pull away from a light and keeps a ceramic clutch from being slipped in traffic. The kit ships at roughly 46 lb.

Symptoms that point to a clutch upgrade

• RPM flare with no gain in speed during a wide-open shift
• Slip in the top two gears when you roll into boost or nitrous from low rpm
• Clutch holds cold but gives up once it is heat soaked after a few runs
• Burnt odor, glazed disc or blue spots on the old flywheel
• Chatter on take-off, often from an oil-contaminated disc

How to confirm the clutch is the problem

Do a high-gear, low-rpm pull and watch the tach: if engine speed climbs ahead of road speed, the clutch is slipping. Before you buy, rule out the hydraulics. A tired master, a leaking slave or air in the line can keep the clutch from fully clamping or releasing and feel exactly like a worn disc. If the old disc is wet, find the rear main or input seal leak first. Our slipping diagnosis guide lays out the checks in order, and the manual vs automatic repair cost guide covers what clutch labor runs.

Fitment

McLeod's application line for this part reads 1996-2017 Ford 4.6L and 5.0L with the 8-bolt crank, 164 tooth ring gear, 0 balance and a 1-1/8 x 26 input; a second catalog line lists it for 2005-2017 Mustang 4.6L/5.0L. The spline is what matters most. Factory Mustang gearboxes in that span are not all 1-1/8 x 26: the 2005-2010 GT used the Tremec TR-3650 five-speed and 2011 and later V8 cars used the MT82 six-speed. McLeod sells the same clutch with other splines, such as the RXT 1200 for the 1 x 23 metric MT82 input and the RXT power pack with a 1-1/16 x 10 spline. Order this one when your transmission has a 1-1/8 inch, 26 spline input shaft. Count the crank flange bolts too, since some modular engines use a 6-bolt crank. If you are unsure, send us the year, VIN and transmission model and we will check it.

Not chasing 1,200 horsepower? The standard RXT on the same steel flywheel has a lighter pedal and is rated around 1,000 to 1,100 horsepower.

Install notes

• Inspect the pilot bearing and replace it if it is worn or nicked; a pilot bushing remover makes that easy with the engine in the car.
• The disc marked bottom goes on first, flywheel side forward, centered with the alignment tool.
• Line up the drive straps on the floater and pressure plate and the alignment marks on the ring and cover. Do not offset them.
• No thread locker on the studs or nuts. Torque the pressure plate nuts to 25 ft-lb, then 35 ft-lb, in a star pattern, and check that the diaphragm fingers sit at or below the cover surface.
• Balance weight comes off or goes on the flywheel only, never the adapter ring.
• Break it in with about 1,200 normal shifts on the street, traction control off, and never on a chassis dyno. Replace a worn throwout bearing and bleed the hydraulics with fresh fluid.

Will this fit my stock 2011-2017 Mustang GT six-speed?

Not as-is. The factory MT82 in those cars uses a 1 x 23 metric input, and this kit is splined 1-1/8 x 26. It is meant for a car running a gearbox with a 1-1/8 inch, 26 spline input. McLeod makes the RXT 1200 in a 1 x 23 version for the MT82.

What is the difference between the RXT 1200 and the standard RXT?

The RXT 1200 uses a higher clamp load pressure plate. McLeod rates it at 1,200 horsepower in older copy and up to 1,300 in current RXT HD copy, versus about 1,000 to 1,100 for the standard RXT. The trade-off is a moderate pedal instead of a light one.

Is the flywheel included?

Yes. This part number includes McLeod's billet steel flywheel for the 8-bolt modular crank with a 164 tooth ring gear and zero balance.

Can I break the clutch in on a dyno?

No. McLeod says to break it in with normal street driving for about 1,200 clutch cycles with traction control turned off, then drive it hard.

What else should I replace while the transmission is out?

The pilot bearing, a worn throwout bearing, any leaking rear main or input seal, and the clutch fluid. Inspect the input shaft splines; the new discs should slide on freely by hand.

• Transmission Slipping Diagnosis Guide
• Automatic vs Manual Transmission Repair Cost
• Shift Flare vs Slip: How to Tell the Difference