The 2020 GT500 launch was the most anticipated we had seen in fifteen years of doing this. Ford promised 760 hp and delivered it. Then the cars landed in driveways and the only question left was what to do first.
For GT500 owners the answer has always been the same: a smaller supercharger pulley. GripTec started engineering one months before the cars shipped, and we got hold of some of the first pulleys plus their special installation tool. This is the install, documented at Palm Beach Dyno and RareFab, with Will from RareFab doing the work and Ken B. handling the calibration.
The Baseline Numbers
Lund Racing got one of the first cars and put it straight on the dyno. Bone stock, it made 691 rwhp and 581 rwtq, which backs up Ford's claim with under 11% loss from crank to wheels. That is a remarkably efficient drivetrain for a car this heavy.
Why This One Is Different
Every previous GT500 had a conventional supercharger snout with the pulley out front where you could reach it. The 2020 does not. It runs an inverted TVS, meaning the blower is upside down, and there is no traditional snout. The shaft is enclosed in a casing below the blower and the pulley sits behind the thermostat housing.
Getting to the Pulley
- Drain the coolant from the thermostat housing and lines. A small pump is enough.
- Remove the coolant reservoir and the intake.
- Remove the 3 bolts holding the thermostat housing together. Zip tie the passenger side line out of the way for easier access.
- Remove the housing and take the thermostat out. Worth a look while it is in your hand: the 2020 uses a new dual-hot-side thermostat design, which Ford says is for higher coolant flow and cooling capacity.
- With the housing out of the way you now have access to the pulley. The pulley and shaft assembly is held by 4 bolts. Remove them, then use a bit of force to pull the shaft assembly out of the blower housing. It comes out in one piece.
Swapping the Pulley
- Remove the retainer on the bottom of the shaft assembly.
- Seat the shaft into the special tool, which locks it so the pulley can come off.
- Remove the plastic cap cover from the stock pulley.
- Use the included socket to unscrew the stock pulley from the shaft.
- If your GripTec pulley is still attached to its hub, separate them now.
- Put red Loctite on the shaft threads and install the GripTec hub with a 22mm 12-point socket. Torque to 65 ft-lbs.
- Put a drop of blue Loctite on the 8 small titanium bolts and install the pulley ring onto the hub with a T30 Torx bit. Torque to 60 in-lbs.
| Fastener | Tool | Loctite | Torque |
|---|---|---|---|
| GripTec hub to shaft | 22mm 12-point | Red | 65 ft-lbs |
| Pulley ring bolts (8, titanium) | T30 Torx | Blue | 60 in-lbs |
While it is apart, take a second to look at the belt surface on the GripTec pulley. The micro-groove technology on it is the entire reason these exist, and it is easier to appreciate in your hand than in a photo. We go into what it does in our GripTec pulley write-up.
Reassembly & Sealant
This is the step people rush and should not.
- Remove all sealant remnants from the blower housing and the shaft.
- Apply fresh anaerobic sealant, also sold as anaerobic gasket maker, around the shaft.
- Insert the shaft and pulley assembly back into the blower and reattach with the 4 bolts.
- Install and wrap the serpentine belt. Size depends on your pulley, see below.
- Replace the thermostat and reattach the housing with the 3 OEM bolts.
- Reinstall the coolant reservoir and the intake, then refill and bleed the cooling system.
Belt Sizes
Your belt length changes with pulley diameter. Get this right before the car goes back together.
| Pulley | Belt length | Part number |
|---|---|---|
| 2.850" | 70.23" | K080702HD |
| 2.750" | 70.23" | K080702HD |
| 2.650" | 69.88" | K080700HD |
| 2.500" | 69.38" | K080694HD |
What You Need to Buy
Includes the required install tool
Correct Gates belt included
Start here if you have none of it
8 titanium ring bolts
If you already have the tool
Includes the matching socket
Skip it and you risk the shaft
Frequently Asked Questions
How much horsepower does a stock 2020 GT500 make at the wheels?
691 rwhp and 581 rwtq on Lund Racing's car, which works out to under 11% drivetrain loss against Ford's 760 hp crank rating.
Why is the 2020 GT500 pulley swap harder than earlier cars?
The 2020 uses an inverted TVS with no traditional snout. The shaft is enclosed below the blower and the pulley sits behind the thermostat housing, so coolant has to be drained and the housing removed to reach it.
Do I have to drain all the coolant?
No. You only need to drain the thermostat housing and lines, which a small pump handles. Draining the whole system means pulling the front bumper, which is unnecessary.
Do I need the special GripTec tool?
Yes. It locks the shaft so the pulley can be removed. Without it you risk damaging the shaft, which costs far more than the tool.
What are the torque specs for the GripTec pulley?
Hub to shaft: 65 ft-lbs with a 22mm 12-point socket and red Loctite. Pulley ring bolts: 60 in-lbs with a T30 Torx and blue Loctite. Note one is foot-pounds and the other is inch-pounds.
What belt do I need with a smaller pulley?
2.850" and 2.750" both use a 70.23" belt (K080702HD). 2.650" uses 69.88" (K080700HD). 2.500" uses 69.38" (K080694HD).
Do I need a tune with a pulley swap?
Yes. A smaller pulley raises boost, and boost without a matching calibration is how engines get damaged. Line up your tuner before the pulley goes on.
Why does the old sealant have to come off completely?
Leftover anaerobic sealer prevents an even seal when the shaft goes back in. An uneven seal allows misalignment, and misalignment damages the blower.
Keep Reading
The First Mod, Done Right
Pulley, hub, tool and the correct belt. Get the tune lined up before you start.
