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  1. #1
    RC poster
    Join Date
    Aug 2017
    Posts
    16

    Hot Racing Diff Mod

    I wanted to share my mod for the leaky Hot Racing sealed diff. I milled the o-ring bore area to a size of 7.95mm x 1.95mm deep. The corner radius of the new bore is .397mm(1/64"). I ordered X-ring o-rings from Mcmaster Carr the same size as the originals that come with the diff; 5 x 8 x 1.5. I thought the x-rings would help since they have more contact points to help seal. I milled it deep enough so a traxxas 5 x 8 x .5 teflon washer would fit between the o-ring and the output shaft. Now the o-ring can't be chewed on by the gear. My diff would also leak from the screw holes on the cap with the countersink's. I cut o-rings in half, this was tough, and installed each screw with half an o-ring. My diff has been rock solid since these this mod as far as leaking.

  2. #2
    RC Racer
    Join Date
    Jan 2018
    Location
    Australia
    Posts
    117
    Great mod! Ive had a bit of luck with semi sealed stock housings, using orings on outputs.
    I've found using the supplied HR shims between the outdrives really helps with sungear chatter.
    I even file shim if needed just enough to apply pressure on orings.

    Sent from my Nokia 6.1 using Tapatalk

  3. #3
    RC poster
    Join Date
    Aug 2017
    Posts
    16
    I also added a .5mm chamfer on one side of each planet gear. I install the planet gears so the chamfers are in the middle of the diff. I did this because I noticed the planet gears could rub the sun gear on the opposite side of it. I use green slime on all of the orings too.

  4. #4
    RC Qualifier Synnergy's Avatar
    Join Date
    Jun 2017
    Location
    Orygun
    Posts
    895
    Thanks for sharing the specs! What kind of tools did you use to do this?
    MTFBWY

  5. #5
    RC Champion RazorRC22's Avatar
    Join Date
    Sep 2015
    Posts
    2,169
    Nice work! Hot Racing should have done this from the factory, makes me think they really don't know how to engineer stuff.
    youtube.com/c/RazorRCvideos

  6. #6
    RC poster
    Join Date
    Aug 2017
    Posts
    16
    Quote Originally Posted by Synnergy View Post
    Thanks for sharing the specs! What kind of tools did you use to do this?
    I did the housing mod on a CNC mill. It could be done on a lathe though. I chamfered the planet gears on a lathe. I've pretty much reverse engineered the housing and will eventually get around to making a new one.

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