With the older Hydra Drive spur gears getting harder to find, converting to a more modern dual disk slipper makes a lot of sense.

If you already have a slipper equipped transmission it doesn’t require too many parts or a lot of money to go from the single disk to dual disk.

If your transmission setup looks similar to the ones in Images 1 and 2, you are not able to convert and need part a3120. If your transmission looks like those pictured in Images 3 and 4 then you can make the conversion.

You will need to purchase or find the following parts to add:

a3132 Slipper Backing Plate

a3123  Slipper Pad

Dual Disk slipper Spur Gear (see end for various options)

Start by removing the old spur gear and Hydra Drive if yours has one equipped.

If you only have the shorter silver spring used with the Hydra Drive, you need to locate the longer gold spring. Comes with a3124.

You won’t need any of the parts shown in Image 5.

At this time you may want to replace the old A3123 Slipper Pad.

Parts that you should have already and need are in Image 6. If you don’t have all these parts, see the end of these instructions for complete parts list.

Put the new spur on top of the inner Slipper Pad, then add the new Slipper Pad and the new Slipper Backing Plate.

Add the spacers and spring back on. Tighten the nut on to the shaft and you are done. (Image 7 and 8)

If you end up taking whole transmission apart and you are installing on the old LRM transmission or XX Retrofit transmission (Image 7) make sure you use the correct back plate on the inside of the slipper. They are different, the original one is longer. (see Image 9)

Image 9 also shows the different spring lengths.  Ideally you should be using the longer gold spring.  You might be able to use the shorter spring, but it is not recommended.

Complete required parts list by transmission type.

LRM Transmission or XX Retrofit

*1 x a3120 Slipper input shaft (only needed if transmission looks like Image 1 or 2)

1 x a3121 Slipper Backing Plate

2 x a3123 Slipper Pad

1 x a3124 Spring, Cup, Spacers

1 x a3132 Slipper Backing Plate

1 x a6305 4-40 Aluminum Lock Nut

a dual disk spur gear (see examples below)

XX Transmission

2 x a3123 Slipper Pad

1 x a3124 Spring, Cup, Spacers

2 x a3132 Slipper Backing Plate

1 x a6305 4-40 Aluminum Lock Nut

a dual disk spur gear (see examples below)

Examples of spur gears that will work

Older Losi parts a3928, a3929, a3930, a3931, a3932, a3933, a3980, a3981, a3983, a3985, a3987

Any of the newer TLR 22 Spurs