Unlimited Engineering, Inc
500 Dunwoody Drive
Simpsonville, SC 29681


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SKU: 13471

Catagory: Transmission Manufacturer: UE

Description: Super 6 Forward Only Conversion
Fits : Discontinued


Three years ago Unlimited Engineering pioneered the forward only conversions and brought you the 8mm & 10mm composite FOCs. They became world renowned for strength & performance. An unbeatable combination that no one could break.

Over the last three years we've steadily increased the amount of horsepower we can install in the Maxx, far beyond anyone's imagination 3 years ago. Along with this we've improved the strength of the driveline with stronger differentials and driveshafts to withstand this increase in horsepower. Then we've greatly improved the power delivery with much stronger clutches. And during all this time the UE FOC's took everything anyone could throw at them.

Along the way we designed the reversing transmission which is based on the 8mm FOC design. In final testing I found that it was failing when subjected to these high horsepower engines and drivetrains. This told me that even though I'd never personally destroyed a 10mm FOC I knew that we were close to it's threshold.

There were also some failures of the output shaft right where the hole is for the cross hole drive cups. We have the strongest possible steel for this application and this hole had to be there to maintain compatibility with the stock Traxxas driveshafts. Failure mode came about when a drive cup would loosen, shift backwards and apply all the load to the end of the shaft past the hole. Another factor which would break shafts was when a driveshaft got into a bind from an overlong driveshaft (improper design) or very flexy chassis. This would actually cause the shaft to be bent during it's rotation - so it's bent back & forth with every rotation.

In December of '02 I realized it was time to begin work on a new solution for the FOC market.

We know that aluminum to aluminum gears have many issues and didn't want to even begin to deal with these. There's no more room in the case to make a wider foc (like a 12mm...) This left the only viable option: steel. Steel gears are very expensive to produce and traditionally very heavy to boot.

The goal was a lightweight, affordable,  strong steel solution to the FOC need.

Enter the UE13471 Super6 FOC:

  • At a mere 58 grams it's ONLY 2 grams heavier than the UE 10mm FOC!
  • One piece shaft & gear construction for the ultimate in strength.
  • No cross hole in the output shaft (sorry plastic driveshaft owners, you can't use this kit)
  • Large diameter shafts give more rigidity eliminating shaft flexure, the leading cause of gear failure.
  • Optimized for the 7.5 differentials. We upped the gear ratio from the stock .93:1 to .86:1 to help compensate for the lower ratio of 7.5 differential gears which are the favorites of .21 runners everywhere.
  • Fits inside any transmission cases made to Traxxas standard - no modifications necessary.
  • Introductory price of $99.99

These gears begin life as a bar of steel over an inch and a quarter in diameter!

The kit is optimized for the high horsepower truck. It was designed with the 7.5 differential gears & 1/8th clutches in mind. It's light weight will keep the impact on acceleration to a minimum. High strength should take anything we can throw at it. Extremely high horsepower is no problem.

Final abuse testing of this was done with SuperMaxx One (my test mule who's been around since the beginning.) It's driveline configured as follows:

  • Heavily Ported RB Concepts S7 (a brutally fast, torquey motor)
  • 7.5 differentials
  • 4 shoe clutch
  • Strobe slipper (locked tight)
  • 17/51 gearing

When I took it out with the Super6 I dropped to a 17T bell since I've changed the ratio of the FOC a little. With the 10mm FOC it had an 18T bell. This gearing is idea for this motor. Tons of bottom end torque and enough top end speed to explode tires (we blew apart two different tires and have destroyed every other set I have from excessive speed.)

We now have the ability to gear higher once we find a tire that will withstand these forces, we can also drop all the way down to a 11T clutch bell for stump pulling grunt.

Super 6 Forward Only Conversion

What Is Removed.

This conversion is over ~100 grams lighter than the stock Traxxas setup!

Small Block users:

This is NOT the ideal kit for the small block runner. A lighter version with cross holes & the std ratio is in the works just for you. The reasons are the following

  • Though the Super6 is lightweight for a steel gear, the 8mm FOC is lighter. Also the polar moment of inertia is significantly lower on the 8mm FOC. This translates to better acceleration. Where the big engine trucks have the horsepower to overcome this and make it unnoticeable, the smaller engines might notice a difference.
  • No cross hole in the output shaft for compatibility with stock Traxxas driveshafts.
  • The Super6's gear ratio has been optimized for the 7.5 differentials.

Lubricants: Lubricant is not supplied and is needed for this kit. The best source we have found for this is your local autoparts store. Look for a tube of premium moly grease. This will cost $3-$5 and last a long time. There's a number of 'miracle lubes' on the market. We've tested several and found no difference - they don't appear to harm anything either. Use them if you choose.

Q: With the Forward Only Conversion do you retain the use of the two speed
A: Yes, the 2 speed is fully functional

Q: Other than the SuperMaxx Foreward Only Conversion, what other parts are needed to make up the tranny kit?
A: Taken from TRX's web site:
     4992 - Drive gear, two-speed (17/22-teeth), slipper shaft
     4984 - Spur gear, 43-T (1st speed)
     4985 - Spur gear assembly, 38-T (2nd speed)
     4986 - Gear hub assembly, 1st, one-way bearing, snap ring
     4987 - Rings, snap (14mm) (2)
     4889 - Ball bearing (1)(10x19x5mm)
     4988 - Drive hub assembly, clutch, 6x8.5x0.5mm teflon washer (1)
     4897 - Grub screws, 4mm (6) (threadlocked)
     4472 - Spur gear (72-tooth) (32-pitch)
     4685 - Friction pegs, slipper (12)
     4622 - Pressure rings, slipper (notched) (2)
     4625 - Pressure plate, slipper (2)
     1994 - Slipper tension spring, spur gear bushing & locknut
     4967 - Brake cam (blue), cam lever, 3mm grub screw
     4966 - Brake adapter, hex aluminum (blue)
     4964 - Brake disc
     4965 - Brake pads (2), brake piston, 3x15mm cap hex screws (2)
     4612 - 5x11x4 Bearings (6 Total - three sets of 2)

Q: I have a UE FOC now and would like to upgrade, is an upgrade path available?
A: Yes, the Unlimited Engineering Trade-Up Program (UETUP) applies

List Price: $79.99 Sale Price: $64
That's 19% off! YOU SAVED $15.99
Out Of Stock
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