This Heavyweight version of our FI spool helps you add weight down low for a better overall COG.
The weight is so close to the center of rotation there is MUCH less drag on your drive train compared to wheel weights.
As an added bonus, there is less machining for us so they are less expensive for you!
When designing a full traction/diff replacement we wanted to make something indestructible, simple, cost effective, with a reasonable weight that allows you to attach your ring gear securely with or without gear nubs and of course offering a very, VERY tight fit to your axle shafts to eliminate slop.
Keeping in mind all of those things we have come up with our latest creation ... the "FI Spool".
This hardened steel axle spool is great for your Axial and Wheely King based vehicles that need 100% traction, 100% of the time. These 1.75 oz spools are sure to get you through the toughest trails and have stood up to our worst abuse. They are "F*****g Indestructible ... hence "FI".
Replace your wimpy stock "lockers" and plastic differential assembly with our one piece "FI Spool" and prepare to conquer all!
These spools are designed to offer THE tightest fit possible with stock and aftermarket axle shafts. Our tests have shown that some shafts will require a hair of "love" for a perfect fit ... usually just a matter of forcing them in and out a few times. Other shafts may require a bit of force to get the tang to comply (a light press fit or light polishing is not uncommon).
This "fitting" process is due to the variances among manufacturer measurements, tolerances, etc. This is the only way we are able to make these spools work with no slop for all the various shafts out there. Because of this, we suggest you test fit your axle shafts outside of the axle prior to final assembly.
Spools are sold individually and include M2 hardware.
If you are looking for a great set of shafts to go with your FI spool, we now offer our OT Shafts for Axial SCX10/AX10 rear axles.
Tested to fit:
HPI Wheely King
Axial SCX10
Axial Wraith
Axial AX10
Axial Yeti
Note: Stock gears will nee the 2 nubs removed ... but why run stock gears when you can get Heavy Duty bevel gears?
The center slot is created in a single machining operation to ensure "In Phase" outputs which can help to minimize drivetrain harmonics.
Good spool 
