Network
Automatic transmissions are an invention of black magic to many of us, just a series of fluid passages and clutches. And at some point they all seem to give up the ghost. For Project Magneto, a combination of high mileage and boost did-in its 10R80. Unfortunately, there are but a small handful of reputable builders of the 10R80, one of which we were most familiar from the NMRA (RIP) – SunCoast Performance – from sponsoring the 8.60 class, which appropriately was inhabited by many of its customers.
With aspirations of running a second or so slower, we felt in good hands enlisting SunCoast for help on our 2018 Mustang GT’s 10R80. After pulling the stock trans after our first dyno test at Pro Dyno, SunCoast had the trans turned around in about a week with shipping time – pretty impressive! The damage was, thankfully, not too bad. We never had a catastrophic failure, but it did slip and flair up on the dyno. Testing has its benefits in catching this early.
SunCoast is one of the few transmission builders that can also tackle your tow rig as well as your racecar, having a large diesel division. That experience comes in handy with these modern 6-, 8-, and 10-speed transmissions that have been adopted in the gasoline world as well. The 10R80 uses three overdrive gears, with a wide split that limits RPM drop to 20 percent between gears. It’s ideal for peakier engines, but it’s not without its faults. From the factory, it is notoriously clunky and susceptible to failure with boost and track use. Though its overall design is beefy, there are weak points that SunCoast has – thankfully for us – figured out how to dial in. Follow along as Montana Cherry from SunCoast gives us the full breakdown of the build.
Clutch and Grab
The OEM clutch packs are typically one of the top offenders when it comes to power-holding capacity. When the transmission is slipping, this is most often the culprit.
"Starting at the front of the transmission, the first clutch pack is actually the 'B' clutch. It works along side the one-way clutch — aka Sprag — to hold our P1 sungear. The factory clutch has its hands full with this one as it is used for Reverse as well as first and second, depending on the command from TCM. This clutch will see heat on cars that frequent the drag strip or have owners that like running hard red-light to red-light. We are solely replacing the soft shifting, lackluster factory clutches in favor of the more aggressive GPZ material and perfecting the clutch clearance." says Suncoast.
“All clutches used are Raybestos GPZ material. They have a higher friction coefficient than the stock clutches. This provides us with a higher holding capacity right off the bat,” Suncoast explains. “Furthermore, we are strategically adding clutch plates to severe duty areas in the transmission. These areas are the ‘E’ and ‘F’ clutch. ‘E’ clutches are used for first, third, and fifth through ninth. ‘F’ clutches are used for reverse, fourth, and tenth. What separates the SunCoast kits and transmissions is how we achieve additional clutches without the use of thinner steels or friction clutch plates. SunCoast machines the associated drums and/or application plates while also modifying the oil circuit to keep the correct cooling oil flow to the clutch pack.”
“The next clutch pack is the largest diameter clutch in the unit, the ‘A’ clutch,” Suncoast explains” Its job is to hold the P1 planetary in R as well as first through sixth gears. With such a large diameter it is fairly stout and does not require additional frictions to hold power, even into 1,500-horsepower territory. We opt for GPZ in this location as well. Most cars don’t see wear on this clutch but we have noticed the guys who use the trans-brake function tend to put some heat in this clutch pack.”
"Following the 'A' clutch, the 'C' clutch is the next in line," explains SunCoast. "It is the first clutch housed in our CDF drum. The 'C' clutch is used in most of our lower gears, coming off for 6th and is right back on for 7th then used again for 9th and 10th. Using GPZ again, we are not having to increase clutch capacity until we are well into the four-digit power range. The extra line pressure produced with the pump and valve body play a role in helping the GPZ's achieve this." "Our 'D' clutch is the smallest diameter clutch in this unit and also resides in the 'Triple' drum. This clutch engages on our P3 planet and is once again used for reverse gear. It is also applied in 2nd-4th, 6th-8th and 10th. Factory count is 6 clutches, which can be increased to 7 depending on the power goal you are after." "The 'F' clutch completes our 'CDF' drum. Its job is to lock the reaction shell to the triple drum. Clutch application is once again reverse and in forward gears fourth through tenth. This was the first clutch we noticed showing wear when the 10R80 was in our R&D lab. To combat the issues we retain the factory thickness steels and GPZ clutches while adding 1 each additional to the stack up (from the OE four to five) using CNC'd parts made right here on property in the form of a clutch apply ring and pressure plate." "The 'E' clutch will be the last clutch pack we talk about. This clutch was the next failure point once 'F' was addressed. Being used in first, third, and fifth through ninth, you can see how active this clutch is. Engaging and disingaging very rapidly in the lower gears results in a tremendous amount of heat. We tackle this challenge with the addition of an extra clutch and steel while calling on the GPZ material once more for assistance."
Making Diddy Proud
Since an automatic transmission is like a large fluid pump with various passageways, keeping it more lubed up than a Diddy party is essential to proper operation. “We address the factory defects within the unit such as lack of lube pressure to the planetary systems,” explains SunCoast. “We also update vital components such as the CDF (aka ‘Triple’ drum) to the latest Ford design as well as the aluminum reaction shell (aka ‘trash can’) that is prone to having the clutch engaging splines worn out.”
“We are once again retaining factory thickness steels and clutches by modifying the drum itself to accept more,” says SunCoast.
The pump and valve body are the final two crucial upgrades to the 10R80. SunCoast starts with a new, VIN-specific OEM valve body and pump that is first vacuum-tested before going through a gamut of precise modifications. Without being too technical, here are the highlights:
- Main line pressure is increased to 360psi from 285psi
- Torque converter lock-up pressure is increased for higher holding capacity
- Increased lube circuit pressure
- LPC accumulator modified
- Thermo-bypass for full-time cooling
- Solenoid stabilization inserts
- Latch valve circuit addressed
- Maximum pump decrease oil volume addressed
The valve body and pump modifications result in quicker shift times, more clutch holding capacity (both static and dynamic), and improved clutch and gear-train wear – all without sacrificing drivability.
"We are mindful of the oiling needed to this clutch pack and modify our drum to increase oil flow where needed." This is the CDF (aka triple drum) with failed bushing. When this bushing moves it can restrict vital oil flow to clutches making them not apply and release properly. This is the updated Ford triple drum design that prevents the bushing sleeve from moving.
This is the aluminum reaction shell that has damaged splines from the “F” clutch beating it.
Final Touches to Magneto’s 10R80
SunCoast is no fly-by-night operation. Magneto’s 10R80 transmission was assembled in its 75,000 square-foot facility in Fort Walton Beach, FL, which even houses the raw materials so that its 45-plus employees can build nearly every part they need for their high-performance transmissions. After adding the last few pieces, SunCoast shipped the transmission back to Fort Mill, SC with everything we needed to get back on the track.
Sam provides the finishing touches to Project Magneto's transmission. Torque wrench in hand, she completes the assembly process after dropping in the enhanced valve body.
