68RFE Frequently Asked Questions

1) Why do 68RFE transmissions have such a high failure rate?

Tuning, overpowering, and overloading! As we all know these days the Cummins motors can make huge torque #’s and as we all like to do, we pull heavy. The 68RFE is a double overdriven transmission, once we start putting oversized tires on the truck, pulling 15,000 + lb. loads behind it, or turn up the power, you are guaranteed to have a failure at some point. This transmission was designed perfectly to pull a 10,000-12,000lb load for 150,000 miles at stock power. When you do what we all do with the truck therefore you need the added clutch material, added line pressure, as well as billet parts to hold the power and pull loads like we want to use our trucks for.

2) Can you go over the differences in your (2) 68RFE valve bodies and do they come with new electronics?

Yes! We have a standard version that utilizes factory castings, and we have our billet version that utilizes our billet channel plate. We always push our billet version because we know there is less flex as well as less pressure loss with our ridged billet channel plate and our bonded separator plate. The billet version is what goes into all our Signature Series Transmissions here at RevMax. When purchasing one of our valve bodies they do not come with electronics. In some cases, you do not need to replace your electronics. We recommend replacing your electronics if your truck had a massive failure where excessive material was pumped throughout the transmission or if you have over 80K miles. The factory solenoid packs are known to fail around 80K – 100K miles. For the 2007.5 – 2018 68RFE transmissions we send out an OEM white solenoid pack, these pack will fit all years from 2007.5 – 2018. The 2019+ trucks have a blue solenoid pack and are much different than the early style packs.

3) What are the major upgrades to your 68RFE transmissions, compared to the stock unit?

Depending on what series of transmission you go with here is a list of most of our upgrades.

• RevMax Patented Direct Oiling Billet Input Shaft
• Billet Stage 5 Triple Disc Torque Converter w\ Custom stator assembly
• RevMax Proprietary 550, 700 or 850 High-Capacity Input Clutch Housing
• Billet OD Pressure Plate
• Billet UD Pressure Plate
• 2x Thick Accumulator Plate with Reinforced and Added Threads, Hardware
• Billet 3/2 Triple Double Seal Accumulator Pistons
• Transgo Steel SSV Valve and End Plug
• Upgraded Smooth-Lock TCC Switch Valve
• Billet ZeroFlex 6061 Billet Valve Body Channel Plate
• RevMax leak free bonded separator plate that is 2.5x thicker than OEM.
• RevMax billet steel center support with 4th clutch 2nd clutch with GPZ clutches
• Billet 2nd clutch piston assembly
• Custom 4th clutch pressure plate
• Red Eagle High Performance Low /Reverse Clutches
• High Energy Reverse Clutches
• RevMax High Pressure Pump
• RevMax Billet Towing HD Valve Body
• RevMax Billet valve body accumulators with a triple seal set up
• Brand New Internal Solenoid Pack
• Custom calibrated RevMax performance valve body, fully tested on our computerized valve body dyno
• Extra deep 4.5-quart additional cast aluminum pan with drain plug
• Billet Filter Screw

4) Please go over Torque converter stall speeds and what stall you recommend to customers.

Stall speed in a converter is where the converter achieves its maximum efficiency in the unlocked state at what engine RPM. For example, if you have a 2,000 RPM stall converter this would mean that the converter would not get any more efficient @ or above 2,000 RPM in the unlocked state. Once the converter does lock up then it is one to one and at that point there is NO slip and is 100% efficient. Stall will also change with power, weight, gear ratio, tire size even the length of the drive shaft can change the stall of a converter. The most popular stall converter we sell is a “LOW STALL”. This “LOW STALL” seeps to be best for most applications because it will put more power to the ground and not lag the turbo unless you are running an extremely large single turbo. The lower the stall the more efficient a converter is. The only downside of too low of a stall on a turbo diesel application is it can increase the turbo lag due to the converter not allowing the motor to rev up as high and letting the turbo spool as quickly as possible. With all these variables therefore, we never build a specific stall converter. All our converters are + or – “X” stall from OE Stock. Below is a list of our 3 most popular stall speeds and an explanation to them.

• STOCK STALL = This is what a stock converter would stall at in your application taking into consideration all your modifications. The more power you have the higher the stall will be in your application. We recommend “STOCK STALL” converters to a few different types of applications.
  #1. Trucks that have a very large turbo which would take forever to spool with a “LOW” or “ULTRA LOW” stall converter. If the turbo is EXTREMLY LARGE then we do have “HIGH STALL” applications, but these are built to order and are not used in towing applications, we would need vehicle specs to build.
  #2. Is a customer that is NOT modified and is just looking for a stock replacement and does not tow that much.
• LOW STALL = This will be between 250-300 RPM LESS than “Stock Stall” For example if a stock converter stalls in your truck a 2000 RPM, this converter would stall around 1750 -1700 RPM. This is our most popular stall for our converters. It is low enough to make the converter more efficient as well as let stock turbos or even slightly larger turbos spool in a normal fashion. Since the converter is more efficient this will put more power to the ground that a stock stall converter in the unlocked state. We typically use this stall in trucks with turbo upgrades no bigger than 67mm, once we get to around a 67.5mm turbo we can start to see a little bit of turbo lag. This would be fine for your daily drivers and towers as it’s still very efficient but not for your guys that want to have that quick truck off the line when it’s play time.
• ULTRA LOW STALL = This will be between 400-500 RPM LESS than “Stock Stall” For example if a stock converter stalls in your truck a 2000 RPM, this converter would stall around 1500 -1600 RPM. We recommend this converter for heavy haulers and high HP trucks with a compound turbo set up that spool very quickly. We would NOT recommend this for trucks with a larger single turbo above 65.5mm because it will increase turbo spool time and create a lot of turbo lag. If you are running close to a stock size performance turbo and you haul a lot, then this is the converter for you. It is the most efficient and puts the most power to the ground.

5) Do your 68RFE’s require tuning?

ALL tuned trucks or modified truck MUST have tuning. Tuning is required in these applications because we need the line pressure raised to provide more holding power in all clutch packs to keep from damaging them under extreme loads or power levels. We do not recommend any specific tuners or tuning platforms as we have no control of what the tuners send out in their files. We tell customers that it is their responsibility to make sure that the tuning parameters for this transmission are followed by their tuners. If damage occurs due to improper tuning the warranty would not cover the repairs. Below will be a pasted copy of the email we send out for all our 68RFE transmission builds.

Anytime you oversize the tires on a truck you are essentially changing the gear ratio and increasing the load on the transmission’s clutches. With this increased load, + added power, + pulling heavy it can increase the load exponentially and cause accelerated clutch wear. Any time you increase your gear ratio (going from a 3.55 to a 4.10 gear ratio) it will decrease the load on the holding clutches and intern increase the longevity and performance of the transmission. Below is a recommendation chart.

• 35” tires = 3.73 to 4.10 gears
• 36” tires = 4.10 to 4.30 gears
• 37” tires = 4.30 to 4.56 gears
• 38” tires = 4.56 to 4.88 gears
• 39” + tires = 4.88 + gears

7) What transmission fluid do you require for your transmissions?

We recommend the cheapest ATF+4 you can get your hands on. Even a Wal-Mart brand fluid will work great if its ATF+4. The reason we do not recommend expensive fluids is because some of these fluids have modifiers or metal penetrating compounds that lessen the holding power of the clutches.

8) Do you require a certified shop to install your products?