Results 1 to 12 of 12
  1. #1
    RC Racer
    Join Date
    Nov 2010
    Location
    kylertown,Pa
    Posts
    190

    Slipper options for 3908

    Are there any other slipper options for the 3908 brushless setup other than stock?
    T-Maxx 2.5
    E-Maxx Brushless

  2. #2
    RC Qualifier
    Join Date
    Apr 2010
    Posts
    489
    the one that Robinson Racing makes for the e-revo should work.

  3. #3
    RC Turnbuckle Jr. 87 GN's Avatar
    Join Date
    Mar 2010
    Location
    kansas
    Posts
    8,677
    I think I have read something about the pads are a little longer on the Slash?? Pep are using the pads for the slipper..
    How tight or loose is you slipper??
    Would you go flip my truck back over??

  4. #4
    RC Turnbuckle Jr. Snook Man's Avatar
    Join Date
    Jan 2008
    Location
    Sugar Hill Ga.
    Posts
    8,397
    I made a friction disk from T6 7075 aluminum that is holding up quite well to testing.
    As an option to the stock pads itís not that difficult to make if you have decent tools.



    No slipper/tall gearing/power = broken parts.

  5. #5
    RC Turnbuckle Jr.
    Join Date
    Jul 2010
    Location
    England
    Posts
    5,777
    Hot Racing p/n TRX15HS x2
    +

    Hot Racing p/n TRX15GP

    or

    Robinson Racing #7960 & 7965 will fit perfectly

    The link to an on-line retailer has been removed. Please review Rule 11 of the Traxxas On-Line Community Rules, which prohibits the posting of links to on-line retailers.
    Last edited by cooleocool; 09-15-2011 at 06:52 AM. Reason: Old post brought into compliance with Rule 11 after being linked to in recent thread.
    Keeping the Mods busy is my specialty...

  6. #6
    RC Turnbuckle Jr. Wildman4910's Avatar
    Join Date
    Jun 2009
    Location
    Cocoa Florida
    Posts
    4,908
    Long aluminum pads p/n TRX15HSL
    Short aluminum pads p/n TRX15HS

    Long & Short graphite slipper pads p/n TRX15GS

    Put any of the above with previously listed p/n TRX15GP

    If you have the tools and the know how Snooks pad looks like the ticket!

    The link to an on-line retailer has been removed. Please review Rule 11 of the Traxxas On-Line Community Rules, which prohibits the posting of links to on-line retailers.
    Last edited by cooleocool; 09-15-2011 at 06:54 AM. Reason: Old post brought into compliance with Rule 11 after being linked to in recent thread.
    Look out for the tree/crunch!

    LiPo? Naw NITRO!!

  7. #7
    RC Racer
    Join Date
    Jun 2011
    Location
    Northern Europe
    Posts
    205
    I'm thinking of getting either the Robinson Racing #7960 or #7965 for my E-Maxx running a 2150kv motor , 2 x 2s batteries and 2 x UE Spider 8 diffs. Also getting a Robinson pinion, but what number of teeth would you recommend?

  8. #8
    RC poster
    Join Date
    Nov 2011
    Posts
    4
    As large as you can get really- the 1/8 diffs introduce quite a bit of gear reduction so a larger pinion & smaller spur is preferable to maintain a decent wheel speed. Looking at your truck & set up as a whole, I would say 24/65 or 22/60 is fine for around 40mph top speed ( 3906 transmission in 2nd gear, roughly 6.3" tires? ).

    Have a play with this though- just enter the known numbers and adjust the pinion & spur to get the desired result:

    http://scriptasylum.com/rc_speed/top_speed.html

    Here is an example I worked out:

    Differential Ratio: 3.3076923076923075
    Transmission Ratio: 1.7222222222222223
    Other Ratio: 1
    Spur Tooth Count: 65
    Pinion Tooth Count: 24
    Total Voltage: 14.80
    Motor KV: 2150
    Tire Diameter (inches): 6.3
    Tire Ballooning (inches): 0
    Motor Current Draw: 0
    Motor Coil Resistance: 0
    Spur/Pinion Ratio: 2.71 : 1
    Total Ratio: 15.42824 : 1
    Tire Circumference (inches): 19.79 inches (502.72 mm)
    Rollout: 1.28:1
    Total Motor Speed: 31820 RPM
    Vehicle Speed: 38.66 mph (62.09 km/h)
    Effective KV Value: 2150
    KT constant: 0.63 oz-in/A
    Motor Torque: Amperage not specified...
    Final Torque: Amperage not specified...
    Final Power: Amperage not specified...
    If you have larger tires ( Moabs? ), then just enter a larger diameter for that number & keep the rest the same, then adjust the pinion and/or spur as needed.

  9. #9
    RC Racer
    Join Date
    Jun 2011
    Location
    Northern Europe
    Posts
    205
    Good stuff. Thanks.

    This is my custom truck:



    - UE 8 spider diffs (ratio: 3.31)
    - Traxxas brushless transmission (ratio: 1.83)
    - Pro-line MASHER 40 series tires (#1105) (diameter in inches: 6.6)
    - Leopard/Hopf 2150kv 4068 motor
    - 2 x 2s 45C LiPo's
    - Traxxas brushless 54T slipper unit

    I used the calculator and adjusted it to the following. Does that look about right?:

    Code:
    Differential Ratio: 3.3076923076923075
    Transmission Ratio: 1.8333333333333335
    Other Ratio: 1
    Spur Tooth Count: 54
    Pinion Tooth Count: 19
    Total Voltage: 14.80
    Motor KV: 2150
    Tire Diameter (inches): 6.6
    Tire Ballooning (inches): 0
    Motor Current Draw: 0
    Motor Coil Resistance: 0
    Spur/Pinion Ratio: 2.84 : 1
    Total Ratio: 17.23482 : 1
    Tire Circumference (inches): 20.73 inches (526.66 mm)
    Rollout: 1.20:1
    Total Motor Speed: 31820 RPM
    Vehicle Speed: 36.25 mph (58.23 km/h)
    Effective KV Value: 2150
    KT constant: 0.63 oz-in/A
    Now, you probably ask why I use a 54T spur gear, but that's how the truck was built by the original designer. It confuses me why he used a 54T instead of e.g. a 65T as is Traxxas' recommendation for the E-Maxx. Perhaps you can explain something to me - here are two different pinion/spur combinations:

    54/19 = 2.84 gear ratio
    65/23 = 2.82 gear ratio

    The gear ratio being identical what's the practical difference for the motor, transmission and/or driveshafts choosing one spur/pinion combo over the other?
    Last edited by cooleocool; 11-14-2011 at 06:09 PM. Reason: merge

  10. #10
    RC Champion
    Join Date
    Jun 2009
    Location
    W Monroe, Louisiana
    Posts
    2,001
    You wont notice a difference between the two gear combinations. There is no practical difference. Sometimes one may fit easier... Thats about the only benefit.

  11. #11
    RC Racer
    Join Date
    Jun 2011
    Location
    Northern Europe
    Posts
    205
    Thanks anr2442. Sorry for being such a newb.

    So, running 54/19 won't put heavier load on the motor compared to the 65/23? I can't get my head around this, for some reason...

  12. #12
    RC Champion
    Join Date
    Jun 2009
    Location
    W Monroe, Louisiana
    Posts
    2,001
    65/23 will barely have more speed and load. The lower you go, the more load, and more speed.

    54/19= 2.84
    65/23= 2.82

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •