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  1. #1
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    Question Differential Oil, Shock Oil, and Shock Springs

    *** Longish post warning ***

    Differential Oil
    Yesterday after a short bash, I decided it was time to do maintenance on my X-Maxx 8S front and rear differentials. When I grabbed my truck today to get started, I noticed that the wheels were not very free moving. I took apart the rear diff and discovered that one of the bearings was locked up completely, and the other, while moveable, was sluggish. So I ordered an entire set of "Revolution" bearings from Avid RC. We'll see how those go once they get here.

    Then I removed the differential and opened it up. Yuck. It was a sticky, gunky mess. I guess I should have been maintaining this thing more often. So I completely disassembled it and cleaned all the component parts. I looked through the X-Maxx manual https://traxxas.com/sites/default/fi...-OM-EN-R00.pdf and found this on page 29:

    "Tuning the Sealed Gear Differentials
    The action of the front and rear gear differentials can be tuned for different driving conditions and performance requirements without major disassembly or removal of the suspension system. From the factory, the differentials are sealed to maintain consistent long-term performance. Changing the oil in the differential with either lower or higher viscosity oil will vary the performance characteristics of the differentials. Changing to higher viscosity oil in the differential will reduce the tendency for motor power to be transferred to the wheel with the least traction. You may notice this when making sharp turns on slick surfaces. The unloaded wheels on the inside of the turn have the least traction and tend to spin up to extremely high rpms. Higher viscosity (thicker) oil causes the differential to act like a limited-slip differential, distributing more equal power to the left and right wheels.

    X-Maxx will generally benefit from higher viscosity oil when climbing or racing on low traction surfaces. Note: Heavier oil will allow power to be transferred, even with one or more tires off the ground. This can make the vehicle more likely to overturn on high traction surfaces."

    Differential Oil Weight Questions
    1) What weight of Diff Oil do you use inside your front & rear differentials if you are mostly on dirt?
    2) Do you notice any real performance changes in the X-Maxx when changing the oil weight?
    3) With thicker (higher weight) oil, when the truck has a wheel off the ground, that wheel will tend to spin faster. With thinner (lower weight) oil, when a wheel is off the ground, it will spin slower. Do I understand this correctly? If so, what is the benefit of thicker weight oil when bashing?

    Shock Oil and Shock Springs
    I'm using Venom 10500mAh 3S batteries, which are huge, and pretty heavy. I have all four of the shock springs loaded about half-way down the threads. For the most part, I think it handles OK, but I always wonder about getting better
    handling when landing jumps as well as turning.

    Shock Oil and Shock Springs Questions
    1) Have you changed out your shock springs for firmer springs and/or shock oil for heavier oil? If so, did you notice a big difference?
    2) Does heavier oil/stiffer springs effect turning and jumping conversely? That is to say, if I improve one, will the other suffer?

    Thanks for any answers you can give me. I'm still pretty new to RC, and this stuff is a bit confusing at times.

  2. #2
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    I'm going to guess this is your first RC. These are all RC 101 questions, I suggest you watch some YouTube videos on shock and diff basics so you have a better understanding.

    I went up 20k from stock on the diffs. 50k front 80k rear, this makes for a little less diff action. I also went to progressive VG Racing springs which are stiffer and 50wt all around. IMO it handles better in all conditions.

  3. #3
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    Quote Originally Posted by rcdudeguy View Post
    I'm going to guess this is your first RC. These are all RC 101 questions, I suggest you watch some YouTube videos on shock and diff basics so you have a better understanding.

    I went up 20k from stock on the diffs. 50k front 80k rear, this makes for a little less diff action. I also went to progressive VG Racing springs which are stiffer and 50wt all around. IMO it handles better in all conditions.
    Thanks for the response. Yes, this is absolutely my first RC. I've been searching for answers on YouTube, but what I mostly find are videos on how to change diff oil or shock springs, with little to no information on effect the changes will have on the performance of the truck.

    So by going with heavier oil in the diffs and having less "diff action", what benefit does that serve you? Aren't you losing power to spinning wheels that aren't on the ground?

    And as for the shocks, I imagine that having stiffer shocks will benefit jumping/landing, but does that come at a detriment to cornering? Also, I should ask this in general as well as specifically to the X-Maxx. We recently picked up a Slash 4x4, and it's so much lighter, lower to the ground, and, well, an entirely different beast. I can see how we could run the Slash on a tight track, but I don't think we'll ever see the X-Maxx racing on a technical indoor track. With that in mind, do the potential gains in corner handling present themselves as real-world results?

    Again, I know that this is RC 101 stuff, and if you would rather point me in another direction, I'd be happy to do my research and ask these questions elsewhere.

  4. #4
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    Less diff action means it will spin less, you have it backwards. Stiffer can be better for both jumping and on road conditions. Less body roll on road and less likely to bottom on jumps. It may suffer on bumpy off road conditions, but not if the truck is heavier. Not enough diff action can cause poor cornering.

    With shocks you need to balance dampening and rebound. If you just put heavier oil and the spring is to light you won't get quick enough rebound.

    Heavier diff oil=Less diff action=closer to locked. Locked =exact same power or spin to both wheels.

    Lighter oil=more diff action=closer to open.
    Open=more power to wheel without traction

    Jang has a great 101 series on YouTube.

    https://youtu.be/aQykao20ifw

    IMO yes a truck that is setup well for the track is also good in the real world, others might disagree. This doesn't really apply to the x maxx.
    Last edited by Double G; 05-18-2017 at 07:31 AM. Reason: merge, use the edit button to add more

  5. #5
    Marshal Double G's Avatar
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    Quote Originally Posted by VistaKing View Post

    Differential Oil Weight Questions
    1) What weight of Diff Oil do you use inside your front & rear differentials if you are mostly on dirt?
    2) Do you notice any real performance changes in the X-Maxx when changing the oil weight?
    3) With thicker (higher weight) oil, when the truck has a wheel off the ground, that wheel will tend to spin faster. With thinner (lower weight) oil, when a wheel is off the ground, it will spin slower. Do I understand this correctly? If so, what is the benefit of thicker weight oil when bashing?

    Shock Oil and Shock Springs
    I'm using Venom 10500mAh 3S batteries, which are huge, and pretty heavy. I have all four of the shock springs loaded about half-way down the threads. For the most part, I think it handles OK, but I always wonder about getting better
    handling when landing jumps as well as turning.

    Shock Oil and Shock Springs Questions
    1) Have you changed out your shock springs for firmer springs and/or shock oil for heavier oil? If so, did you notice a big difference?
    2) Does heavier oil/stiffer springs effect turning and jumping conversely? That is to say, if I improve one, will the other suffer?

    Thanks for any answers you can give me. I'm still pretty new to RC, and this stuff is a bit confusing at times.
    RC and automobiles have similarities. Power to the wheels will take the path of least resistance so if you have thin diff oil and one tire is off the ground and the other has traction, the one off the ground has little resistance holding it back so the power will unload to that one. The thicker the oil, the less likely it will do this and if the oil is thick enough (or the diff is locked) the power will be more evenly distributed between the tires. If the diff is locked that means the tires cannot spin independently of each other so when you go around a turn (where one tire needs to spin faster than the other) you will strain the drive train.

    Tuning the diff does not stop at just one. You need to do both so that they make the truck perform the way you want to. I don't have an X-Maxx so I don't know what others run, however, in my nitro Revo I run 50k in the front and 30k in the rear and it performs to my liking.

    Tuning the shocks is another balance between springs and oil. Springs hold the weight of the truck, the shocks absorb the differences in terrain. Thicker oil needs stronger springs otherwise the shocks will not fully decompress. On the flip side strong springs and thin oil will cause the truck to bounce (ever see a car tire bouncing rapidly as the vehicle moves down the highway? The shock is toast and cannot stop the motion of the spring.) and this is horrible for traction.

    As noted, review the linked video as it is very good information. Nothing wrong with asking what people installed here and over time you'll get see what others generally run with. Experiment a little and see how the truck performs with different combos and leave what you like.
    The Super Derecho

  6. #6
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    My Xmaxx's Run;
    V1 Xmaxx has stock blue V2 shocks- 500,000 diff fluid Front an Rear , vxl8s esc 1600kv motor
    V2 Xmaxx has red V1 shocks,50k shock fluid- 1.53 spring rate , 500,000 diff fluid - vxl8s esc 1600kv
    Get out there an Play
    fabricator

  7. #7
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    Quote Originally Posted by CrazyXMAXX View Post
    My Xmaxx's Run;
    V1 Xmaxx has stock blue V2 shocks- 500,000 diff fluid Front an Rear , vxl8s esc 1600kv motor
    V2 Xmaxx has red V1 shocks,50k shock fluid- 1.53 spring rate , 500,000 diff fluid - vxl8s esc 1600kv
    Get out there an Play
    Your V2 has a 1600kv motor? Did you swap out the 1275kv?
    V1 6s w/8s conversion
    Max5 Leopard 1090kv

  8. #8
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    Oh yeah
    More rpms
    Go until it blows
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  9. #9
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    Quote Originally Posted by rcdudeguy View Post
    ...I also went to progressive VG Racing springs which are stiffer and 50wt all around. IMO it handles better in all conditions.
    Where are you setting your shock spring collars?

  10. #10
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    Quote Originally Posted by DirtDiver View Post
    Where are you setting your shock spring collars?
    All the way to the top on the front, and about 1/2 inch down from the cap on the rear.

  11. #11
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    Quote Originally Posted by CrazyXMAXX View Post
    My Xmaxx's Run;
    V1 Xmaxx has stock blue V2 shocks- 500,000 diff fluid Front an Rear , vxl8s esc 1600kv motor
    V2 Xmaxx has red V1 shocks,50k shock fluid- 1.53 spring rate , 500,000 diff fluid - vxl8s esc 1600kv
    Get out there an Play
    How you liking the 500,000 diff fluid? Trying to decide what diff fluid to use with the castle 2028 800kv

  12. #12
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    I will not change back to a Lower Diff Fluid
    I would Try even Higher Weight If I Find any
    fabricator

  13. #13
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    Quote Originally Posted by CrazyXMAXX View Post
    I will not change back to a Lower Diff Fluid
    I would Try even Higher Weight If I Find any
    Thank you CrazyXmaxx Ok I'm going to try the 500,000 front and rear

  14. #14
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    It's all good
    So 4dub has this challenge to ,while doing a back flip,
    He wants to pop a Balloon that is on his head (wearing a helmet) with the Xmaxx
    >not my challenge<
    fabricator

  15. #15
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    Haha....I hope there is a blooper real!

  16. #16
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    Hi im new to this. Is Shock oil Different than differential Oil?? The ones i have are team associated 45 and 30 but it says its silicone. Is it the same thing?? Thanks

  17. #17
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    Quote Originally Posted by Trx4x4 View Post
    Hi im new to this. Is Shock oil Different than differential Oil?? The ones i have are team associated 45 and 30 but it says its silicone. Is it the same thing?? Thanks
    They are both a silicone fluid, but they are different.

    You use silicone shock fluid in the shocks 35wt, 40wt,45wt, ect.
    https://www.amainhobbies.com/team-lo...r74020/p252365

    And silicone diff fluid in the diffs, 10,000wt, 30,000wt, 40,000wt.
    https://traxxas.com/products/parts/5136X

    Diff fluid is significantly thicker then the shock fluid.
    Look out for the tree/crunch!

    LiPo? Naw NITRO!!

  18. #18
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    Quote Originally Posted by rizz0d View Post
    au contraire mon frere...lol


    Mine on an 1/8th scale track.

    https://m.facebook.com/story.php?sto...d=279722488795
    Bash it,Break it,Fix it,Rinse And Repeat

  19. #19
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    No see +2
    Set up?
    what diff fluid , and shock fluid/spring are you running?
    fabricator

  20. #20
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    All stock.
    Bash it,Break it,Fix it,Rinse And Repeat

  21. #21
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    I'm doing a full tear down and rebuild of my 6 month old xmaxx i think I have around 250hrs of run time maybe closer to 300 maybe more and I can't keep spur gears in it anymore. So I called traxxas and asked what they use in diffs and shocks because personally I love the way the truck handles stock very little roll over even on the street, They told me to use an automotive grease in the diffs and 30k in the shocks, 30k seems really really light to me for a truck this size has anyone called and been told different?
    Bash it,Break it,Fix it,Rinse And Repeat

  22. #22
    RC Racer Magnus001's Avatar
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    30k shock oil is what it comes with out of the box.
    V1 6s w/8s conversion
    Max5 Leopard 1090kv

  23. #23
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    30 wt or 30,000 wt (30k)?
    The Super Derecho

  24. #24
    RC Racer Magnus001's Avatar
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    Quote Originally Posted by Double G View Post
    30 wt or 30,000 wt (30k)?
    30 wt, not 30,000, sorry for the confusion.
    V1 6s w/8s conversion
    Max5 Leopard 1090kv

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