McLeod Racing RST HD Twin w/ Aluminum Flywheel - 11-17 Ford Mustang GT/Boss 302 5.0L - 164T

Own a 2011-2017 Mustang GT or a Boss 302 with the Coyote 5.0L and the factory six-speed? The McLeod 6335825MD bolts an RST HD twin disc and a billet aluminum flywheel to the 8-bolt crank, with discs cut 1 x 23 metric to match the stock MT82 input. It is aimed at the S197 and early S550 driver who has added a blower, turbos or a tune and now feels the clutch letting go on the top end, but still drives the car on the street.

What this twin disc does in a Coyote Mustang

A single-disc clutch can only clamp two friction faces. This kit stacks two discs with a floater between them, so the same pressure plate force works across four faces. That is how McLeod gets more holding power while keeping the pedal lighter than stock. The RST HD discs use organic lining on one face for smooth take-up and segmented ceramic on the other for grip once the clutch locks. McLeod rates the RST HD at up to 950 horsepower, above its street RST and below the RXT.

The aluminum flywheel cuts rotating weight, which lets the Coyote rev freely and drop rpm quickly between gears, a real help on track days and with heel-toe downshifts. Expect to feed in slightly more throttle leaving a stop than with the factory flywheel. The complete kit ships at about 36.9 lb, around 8 lb lighter than the steel-flywheel 6435825MD.

Symptoms that point to a clutch upgrade

• RPM rises without matching acceleration on a third or fourth gear pull after boost or a tune
• The factory clutch shudders on takeoff once it has been overheated at the strip
• Smell of burnt clutch after spirited driving or a heavy launch
• Engagement point climbing toward the top of pedal travel as the disc wears thin
• Hard or notchy shifts that improve when the clutch is pumped, a sign the clutch is not fully releasing

Not every hard shift on an MT82 is the clutch. Notchy third and fourth gear changes are a known complaint on this gearbox even with a healthy clutch, so read our MT82 problems and cost guide before replacing parts.

How to confirm the clutch is the problem

Run a top-gear roll-on from low rpm at full throttle. If engine speed outruns road speed, the clutch is slipping. Check the fluid level and bleed the concentric slave first, since a hydraulic fault can mimic a worn disc. The slipping diagnosis guide covers the full test, and the manual repair cost guide explains what the job costs at a shop.

Fitment

McLeod lists 6335825MD for the 2011-2017 Ford Mustang GT and Boss 302 with the 5.0L, 8-bolt crank, 164 tooth ring gear and a 1 x 23 metric spline. Ford fitted the MT82 to the 2011-up GT, and the Boss 302 was built for 2012 and 2013. If your car has been swapped to a gearbox with a 1-1/8 x 26 input, buy the 26 spline RST HD aluminum kit instead. For a heavier flywheel on a street and drag car, the steel flywheel RST HD 6435825MD fits the same cars. If anything about your drivetrain has been changed, send us year, VIN and transmission so we can confirm before it ships. More parts are in the hard parts section.

Install notes

• The 2011-2015 GT uses a concentric slave and release bearing. Replace it while the gearbox is out; we stock the Exedy BRG0186 slave and bearing for those years.
• Fit a new pilot bearing and use the flywheel bolts and dowels McLeod calls for.
• Slide each disc onto the MT82 input by hand to make sure it moves freely before assembly.
• Torque the pressure plate nuts across the pattern, first to 25 ft-lb and then to 35 ft-lb, without thread locker.
• Bleed the hydraulics with fresh DOT 3 or DOT 4 fluid and do a gentle break-in before hard launches.

Does this fit my 2011-2017 Mustang GT with the stock MT82?

Yes. The discs are splined 1 x 23 metric to match the factory MT82 input, and the flywheel fits the 8-bolt Coyote crank with a 164 tooth ring gear.

Does it fit the Boss 302?

Yes. McLeod lists the 2011-2017 GT and Boss 302 5.0L for this kit. The Boss 302 was produced for 2012 and 2013.

What is the difference between this and 6435825MD?

Only the flywheel. This kit uses billet aluminum for quicker revving and less weight; 6435825MD uses steel for more inertia at launch.

Should I replace the slave cylinder at the same time?

It is strongly recommended. The concentric slave lives inside the bellhousing, so replacing it now avoids pulling the gearbox again later.

What power level is it rated for?

McLeod rates the RST HD twin at up to 950 horsepower with a lighter-than-stock pedal feel.

What fluid does the clutch hydraulic system use?

Bleed it with fresh DOT 3 or DOT 4 brake fluid, matching the type already in the system, and never mix in mineral oil or transmission fluid.

• Transmission Slipping Diagnosis Guide
• Automatic vs Manual Transmission Repair Cost