Honda Grom Gearshift Linkage Mod / Height Adjustment
The stock Honda Grom gear shifter has a lot of free-play because it's linked using a cheap piece of metal. A popular mod on this bike is to replace the stock metal link with a pair of rod end joints (aka “rose joints”). As part of this process, you can also fine-tune the height of your shift pedal.
Here's how I completed this project using the following:
- 1 x 8mm male threaded rod end joint
- 1 x 8mm female threaded rod end joint
- Set of 8M x 22mm bolts with nuts
To begin, I pulled back the rubber boots behind the gearshift pedal and then removed the cotter pins that hold the stock linkage in place.
Next, I needed to cut off about 15mm of the male rod end so that when the joints are screwed together, they match the length of the stock linkage. Before cutting, I put a nut on the threads. Unscrewing this later will clean up any damage to the threads caused by cutting.
Returning to the bike, I needed to address the two 7mm holes the linkage attaches to in order to accommodate the 8mm sizing of the new linkage.
To do this, I removed the bolt that fastens the gearshift arm on to the gearshift spindle.
Before removing the arm, I marked it's current angle as a reference point when re-assembling.
Here you can see arm is splined which allows you to adjust the angle of the arm, and as a result of that, the angle of the gearshift pedal once it's connected.
With the gearshift arm detached, I widened the hole using a 5/16th bit on a drill press.
I didn't want to disassemble the pedal assembly, so I just drilled that hole out directly on the bike.
Next, I re-attached the arm and then bolted on the new linkage.
And finally, I put back the gearshift arm bolt.