Grin Technologies GMAC User manual

GMAC Installation Guide
Rev 1.0
Thanks for your purchase of a GMAC motor kit! This motor has a number of
unique features that set it aside from other direct drive and eared motor kits
available on the market.
•Locked Clutch: Allows for effective and efficient re enerative brakin
down to very low wheel RPMs. When used with a Phaserunner
controller for virtual freewheelin , the dra torque present when pedalin
without assist can also be eliminated as well.
•Round 10mm Axle: By usin a round 10mm axle, the hub fits properly
inside the bicycle dropout slot and the disk rotor ali ns properly with
industry standard
•Integrated Torque Arm: An inte rated torque arm on the splined portion
of the motor axle allows for zero play installations to handle forwards
and re en torques without any slop. It also eliminates torque
transmission and spreadin forces on the dropout slot and transfers this
force to a securely to the chainstays with a pair of hose clamps.
•Side Cable xit: Better protects electrical wire from dama e and
provides flexibility for axle hardware chan es.

GMAC Installation Guide
Rev 1.0
Tools needed:
Adjustable Wrench (10mm-17mm) - T20 torx screwdriver - M4 Allen Key
Machined Torque Arm Components:
Torque Plate Installation:
•If the motor requires a disk rotor, remove the installed torque plate to
access disk rotor bolts. This may require pryin with a screwdriver.
•Remove the disk spacer rin and replace it with the disk rotor.
•Reposition the torque plate over the axle splines, ali nin the slot with
the wire exit.
•Ali n the splines of the axle into the torque plate and press or tap the
plate down until the splines protrude past the plate.

GMAC Installation Guide
Rev 1.0
Torque Arm Installation:
Once the torque plate is installed, the torque arm should be installed into the
neutral position as shown in the photo below. The system is meant to be installed
such that the wire exit passes throu h the dropout slot on the bicycle frame,
followin the arrow in the dia ram below.
If your frame has either a different an le on the dropouts, for example a horizontal
dropout, you would need to remove the torque arm from the torque plate and
rotate it such that the wire exit matches the an le of the dropout when the torque
arm is rotated to meet the frame’s chain stay. The splined interface allows for
rotation between the torque arm and torque plate in 30 de ree steps.
Once the arm orientation is set to then it can be screwed ti htly in place with
either 5 or 6 of the countersunk M4 Fasteners usin a T20 Torx Driver.

GMAC Installation Guide
Rev 1.0
The final sta e is to ali n the Frame Holder for the best fit to the torque arm. The
holder is made deliberately asymmetric so that it can be flipped 180 de rees in
order to accommodate a wide ran e of frame eometries with 4 different
ali nment planes. Select the one that fits most closely with the plane of the
torque arm, and then secure them to ether with the M5 bolt and flan ed nyloc
nut.
Finally, secure the Frame Holder to the chainstay usin the two hose-clamps. The
black shrink tubin can be installed over each band in order protect the paint
finish and have a more discrete look.
The M10 washers and axle nuts must also be installed and thorou hly ti htened
on the GMAC motor axle. We recommend ti htenin to at least 40 Nm (30 ft-lb).