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  1. #1
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    Rpm A arms part number?

    Just bought a stampede vxl 4x4 and is being shipped. I've heard countless ppl talk about putting in rpm a arms at least on the front. I'd like to get some ordered so they show up along with the truck. Can anyone tell me specifically which ones to order?

    Also, which aluminum shock caps to order and where from? Thx everyone this forum is very helpful.

  2. #2
    RC Racer FMcamaroZ28's Avatar
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    RPM 80702 is the A-arms.

    Seriously though, wait until the stock arms break. I had mine a year before i needed the RPM ones.

    The shock caps are 3767A for blue or 3767X for red. Those would be worth doing quick.

    Don't forget the bearing adapter. 6893X. That is a first upgrade too.

    I buy a lot of my stuff from tower hobbies. If you sign up for their super saver club you can get really good coupons.

    Beyond those, wait till things break then replace.

  3. #3
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    Great thanks for the help. I'll hold off on the arms for now. What's this bearing adapter you are referring to? Haven't read about that upgrade...

  4. #4
    RC Racer FMcamaroZ28's Avatar
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    Where the spur gear/slipper clutch assembly meets the motor mount, there is a bearing and a bearing adapter. The adapter is a plastic out of the box, and is usually the first thing to go due to melting.

    https://traxxas.com/explodedviews/St...ssion-Assembly

    See this exploded view of the rear/trans of the truck. At the bottom of the page you see the spur gear and the adapter (part 6893) this is the piece that gets replaced with an aluminum one. Its much more durable.

  5. #5
    RC Racer FMcamaroZ28's Avatar
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    If you search the forum for 6893X you will see many threads describing this issue.

  6. #6
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    Excellent, added to the list!

  7. #7
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    I'm going to keep bugging you FMcamaro...

    I plan on using nimh batteries for some time but like everyone else, will switch to 2s lipo at some point. What is a good economical charger that you can recommend that will do both types of batteries? And, are any adaptors required to hook up to it? Sounds like spc is a good lipo to go with I'll probably go that route when the time comes.

    How long is a typical charging time, an hour?
    Last edited by JIM33; 07-13-2015 at 08:39 AM.

  8. #8
    RC Racer FMcamaroZ28's Avatar
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    Hey we all asked the same questions once.

    Chargers really depend on your budget. A good read over at URC.

    http://www.ultimaterc.com/forums/sho...d.php?t=115188

    You can get a basic DC charger for $30 like the Imax B6, but you will need a power supply to power it, so add another $15 - $30 or so.

    You can also go to the moon with a charger that can do 20/30 amps and multiple batteries and spend $500

    A good starter setup would be something in the middle ground. A decent brand such as this Hitec X1 will be an all in one unit from a reputable brand name, and will do both NIMH and Lipo. No external supply needed.

    http://www.amazon.com/HiTec-44165-Pl...s=lipo+charger

    You will need a simple traxxas plug for it to work with your Nimh. Traxxas part #TRA2933.

    when you get to lipo, you will need a balance board.

    I think the X1 linked above comes with one, but they look like this

    http://www.amazon.com/Hitec-RCD-Batt...+balance+board


    ALSO - read about lipo and lipo safety. Lipo's are safe if you treat them right.

    Another good read on URC
    http://www.ultimaterc.com/forums/sho...d.php?t=115264

    Be sure when you get to lipo you are very sure about what you are doing when charging/discharging or ask here.


    Edit: charge times will depend. Typically after a day of use i set all my batteries to storage voltage (3.8V a cell) since i do not know when i will use them next. A 1C (1 x capacity, so a 5000mah battery can be charged at 5A) charge rate will have the batteries charged in less than an hour.

    Read more into lipos and this will make more sense. Some batteries, such as the SPC ones can do 2C safely, cutting the charge time in half.
    Last edited by FMcamaroZ28; 07-13-2015 at 10:55 AM.

  9. #9
    RC Turnbuckle Jr. jvogel's Avatar
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    Quote Originally Posted by JIM33 View Post
    ...2s lipo at some point. What is a good economical charger...?
    Remember, you get what you pay for. Many like the Traxxas chargers. I've been using a Hyperion 720i for years and love it.

    Quote Originally Posted by JIM33 View Post
    How long is a typical charging time, an hour?
    For a typical 5000mAh LiPo pack charged at 1 amp that should be about right.
    Last edited by jvogel; 07-13-2015 at 11:30 AM. Reason: I'm the typographical error king.
    Obstacle Magnet

  10. #10
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    Wow great stuff here guys thx again! Don't go too far I'm sure I'll come up with some more junk to throw at ya.

  11. #11
    RC Turnbuckle Jr. jvogel's Avatar
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    FMcamaroZ28 gave fantastic advice. I wouldn't charge a LiPo pack that was rated for 2C charging at more than 1C regardless because it shortens the life of the pack.
    Obstacle Magnet

  12. #12
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    So I just read the lipo link. Did I understand it correctly in that you want a higher discharge rate, say a 40c or 50c? I know it'll depend on the motor and the amps it draws but to have a battery with too low a discharge rate is bad news right?

    I've been reading a lot on batteries and had no idea what "c", "C", "S" meant. Very good information. Didn't realize there was so much to pay attention to in the battery/charger department.

  13. #13
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    Quote Originally Posted by jvogel View Post
    FMcamaroZ28 gave fantastic advice. I wouldn't charge a LiPo pack that was rated for 2C charging at more than 1C regardless because it shortens the life of the pack.
    Kinda holds true for most battery aplications then?- slow and steady wins the race.
    Last edited by JIM33; 07-13-2015 at 12:11 PM.

  14. #14
    RC Racer FMcamaroZ28's Avatar
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    Yes, the higher the C rating of the pack, theoretically the better the pack.

    The problem is that there is no set standard on measuring the C rating of a Lipo, so the manufactures can pretty much put anything they want. You can have a 25C pack sometimes do better than a "50C" pack.

    C rating is the amp burst raing. A 50C will be 50 times the capacity. So a 5000mah 50C battery should theoretically be able to sustain a 250amp burst. Now I know the vxl-3s speed controller will be able to support a 320A burst according to traxxas, but you will very rarely see that, if ever.

    Just go with SPC/SMC and you will be fine. Pretty much all the batteries they have are of excellent quality.

    The S means series or cells. 2S - 2 cell, 3S - 3 cell. A lipo battery has a nominal voltage of 3.7V, so typically for the stampede you start with a 2S. It has a 7.4V nominal voltage. When its fully charged will be 8.4V. You do not want your lipo to ever ever go below 3.0V a cell (6.0V total), and when you switch to using lipo, be sure to set the speed controller to enable Low Voltage Control or LVC (check the manual, i think you turn on, then hold the button for 10 seconds till it makes a sound)

    When you get further into this you can start looking at a 3S and higher. But by then you will have replaced or upgraded lots of parts and will be a pro. Just keep reading.

    Now don't confuse C rating of the battery with the C of charge rate. I always charge at 1C. Some will say you don't want to charge too slow either, so 1C is right.

  15. #15
    RC Turnbuckle Jr. jvogel's Avatar
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    I agree with FMcamaroZ28. He knows his stuff.

    Discharge rating (usually a small “c”): This is how fast a battery can be discharged safely. A high powered motor can damage or even burn up (fire) a battery with too low of a discharge rate. But buying a battery with a really high discharge rate would be a huge waste of money if your motor can’t use it.

    Charge rating (capital “C”): This is how fast you can charge the battery. This number is often not listed because most people aren’t interested in quickly charging their batteries since this puts a strain on them and shortens their life significantly. Most charge LiPo packs at 1 amp/cell.

    That's all I could add to FMcamaroZ28's brilliant post.
    Obstacle Magnet

  16. #16
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    Very good information. I've learned a lot from you two today. It's looking like 50c is about what I should be looking for, for a lipo and my stock motor.

    Outta curiousity, what do you guys have? Stampede as well?

  17. #17
    RC Turnbuckle Jr. jvogel's Avatar
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    Traxxas trucks: 1. P2de, 2. P4de, 3. Rusty, 4. Sla2h, 5. Sl4sh (Rally), and 6. Summit.

    Yeah, I like...no...love Traxxas trucks!
    Obstacle Magnet

  18. #18
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    Holy moly!!! I spose each one is special in its own way. Did you start with a p2de then get a p4de?

  19. #19
    RC Turnbuckle Jr. jvogel's Avatar
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    Nope. The order was: Sla2h, P2de, Rusty, Summit, Sl4sh, P4de. Each truck has been heavily modified and not one is even close to similar to any other.
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  20. #20
    RC Racer FMcamaroZ28's Avatar
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    I was in the same spot as you may of last year. I now own 12 rc's.

    Traxxas ones are p4de, p2de, summit, slash 4x4.

    And honestly the one I always bring with me is the p4de. It just never quits. It was my first buy into this hobby.

  21. #21
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    Well it sounds like I made a good choice for my first rc. Tracking says it'll be here tomorrow. Then I gotta figure out how to explain it to my wife...

  22. #22
    RC Racer FMcamaroZ28's Avatar
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    Easiest way is to let her drive it and hope she wants one too!

    Good luck with it! let us know if you have any more questions!

  23. #23
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    Hmmm well that's worth a shot lol, but my traxxas is in my state. I'll have my hands on it tomorrow after work. Ant waaaait!!!! Won't be able to run it because I hear it takes 8 hours to charge a freakin battery with a car charger. What the heck r they thinking sending car chargers out with the trucks?!? I don't get it.

  24. #24
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    So when my truck is fully upgraded 1000's of dollars later and it goes 100mph and everything has been broken and fixed five times then what? Buy something else and do it all again?!?!

  25. #25
    RC Turnbuckle Jr. jvogel's Avatar
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    Well JIM33, all I can say is SPC LiPo batteries and Hyperion charger. About an hour to charge up a 5000mAh pack.

    I have somewhere around $500 into my P4de. This hobby is not for the faint of heart. It really is addicting and very expensive once the upgrade bug bites.
    Obstacle Magnet

  26. #26
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    Yes, I can see that. I need a charger asap. Thinking I might run down to the local hobby store and see what they have. They'll try and talk me into something I'm sure.

    But if I buy a $75 charger now that just means the nice charger I'll end up with will be $75 more. So if I've learned one thing in life with my many hobbies, it's get the good stuff the first time around.

    The trick is figuring out what the "good stuff" is.
    Last edited by JIM33; 07-14-2015 at 07:49 PM.

  27. #27
    RC Turnbuckle Jr. jvogel's Avatar
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    That's good reasoning and I try to follow that mindset as well. That's why I got the Hyperion 720i and LiPo packs from SMC and/or SPC.

    http://www.amain.com/rc-cars/hyperio...GZDBoCVSXw_wcB

    http://www.smc-racing.net/

    http://www.spcracingbatteries.com/
    Obstacle Magnet

  28. #28
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    I just checked out your links and noticed the spc hard pack is on sale. It's 5000mah at 40c. 40c is the discharge rate correct? And, is 40 high enough for my brushless p4de? 25 bucks a piece can't go wrong. If this will work I'll order up a couple. Thanks for the heads up jvogel

  29. #29
    RC Turnbuckle Jr. jvogel's Avatar
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    40c is the discharge rate and it is more than high enough for a stock Traxxas motor. Traxxas packs are 25c.
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  30. #30
    RC Racer FMcamaroZ28's Avatar
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    You'll start with the p4de. Then you will go check out some buggies. Then some 1/8th scale stuff. Then some rock crawlers. Then you'll see how awesome the summit is. Maybe some racing. THEN you'll go 1/5 scale.

    It happens to the best of us.

    The 40c SPC packs are great for the p4de, I have two myself, and 8 other SPC batteries. Highly recommended. For a charger, see what the LHS has available. Most carry ONYX stuff, which is OK. It will be pricey compared to what you can get online.

  31. #31
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    Well we will see about that FMcamaro. Hopefully that's very far down the line. 2 spc Batts on order. Should be ready to do some serious bashing by the weekend!

  32. #32
    RC Turnbuckle Jr. jvogel's Avatar
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    Quote Originally Posted by JIM33 View Post
    Well we will see about that FMcamaro.
    I'm betting FMcamaro is right on the mark!
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  33. #33
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    Well it's here! Box on the back deck when I got home from work. Ripped it open and got the battery charging stat! Got the battery to half charge and decided I couldn't wait any longer.

    All I have to say is wow. Thoroughly impressed and nothing has been done yet to upgrade it. It must do at least 30-35 out of the box. She rips.

    Only had about a 10 minute run but it was something. Can't wait to giver another go tonight. Only managed to flip the dang thing like 4 times

  34. #34
    RC Racer FMcamaroZ28's Avatar
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    You using lipo or nimh? Make sure you read the manual about LVC. Dont want to kill those shiny new lipos!

    What charger did you end up with?

  35. #35
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    I have some spc lipos on the way. I just threw in my nimh batt. I ended up buying a Venom Pro3 charger from my LHS. There were some other more expensive chargers there but for the money this was the one to get. So he says anyway. Have u heard much about these chargers? I paid 80 bucks for it and I'm seeing that same price online so it looks as tho I didn't get ripped off or anything. We'll see I guess.

    Do you charge your Nimh batts at 1C? I'm reading online that slower than 1C is probably better???

  36. #36
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    Up to 7 amps so I will be able to charge any battery I ever own at 1C. It also can discharge which I'm learning is handy to have to get the battery down to storage levels. On board balancer yata yata yata.

    The reviews I'm reading on it seem fairly good. If something happens to my batteries more than likely it will be because I screwed something up not the charger.

  37. #37
    RC Racer FMcamaroZ28's Avatar
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    It's a good starter charger. 7A charge is nice.

    For NiMH they wont really come to their own till about 5 charges in. You want to charge them at .5C ideally, but 1C is ok if you are in a hurry.

    You don't want to charge them TOO slow, like .1C UNLESS you time the charge. Charging them at that slow of a rate will overcharge them, heating them up and quickly killing them. Heat is the enemy for the NiMH batteries. At the end of the charge cycle they should be slightly warm.


    Now, regarding storage voltage for LiPo - Keeping the Lipo at full storage voltage (8.4V) when not in use will slowly reduce its capacity and longevity. If you are going to be keeping the LiPo unused for more than 2-3 days, you should connect it to your charger and select the storage mode. This will bring the batteries down to ~3.8V a cell (~7.6 total) where they are happier and can be stored. At the end of the day your batteries will most likely be close to this level as it is.

    Your charger will do a 1A discharge max, so set it to that.

    For me, at the end of each time out, I set ALL my batteries to storage voltage, since I never know when the next time Ill want to run them again. Since they are essentially half full, it only takes 30-40 minutes for them to be charged before you go out.

  38. #38
    RC Turnbuckle Jr. spenniepoos's Avatar
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    Quote Originally Posted by FMcamaroZ28 View Post
    It's a good starter charger. 7A charge is nice.

    For NiMH they wont really come to their own till about 5 charges in. You want to charge them at .5C ideally, but 1C is ok if you are in a hurry.

    You don't want to charge them TOO slow, like .1C UNLESS you time the charge. Charging them at that slow of a rate will overcharge them, heating them up and quickly killing them. Heat is the enemy for the NiMH batteries. At the end of the charge cycle they should be slightly warm.


    Now, regarding storage voltage for LiPo - Keeping the Lipo at full storage voltage (8.4V) when not in use will slowly reduce its capacity and longevity. If you are going to be keeping the LiPo unused for more than 2-3 days, you should connect it to your charger and select the storage mode. This will bring the batteries down to ~3.8V a cell (~7.6 total) where they are happier and can be stored. At the end of the day your batteries will most likely be close to this level as it is.

    Your charger will do a 1A discharge max, so set it to that.

    For me, at the end of each time out, I set ALL my batteries to storage voltage, since I never know when the next time Ill want to run them again. Since they are essentially half full, it only takes 30-40 minutes for them to be charged before you go out.
    Yeah keeping your packs fully charged for more than a few days with shorten the life of the lipo and eventually damage them so store them at 3.7-3.8v per cell is what you want to do....peace
    Famous last words...watch this!!!!

  39. #39
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    Is it good practice to fully discharge NiMH before charging? I understand discharging a lipo is bad news but do these NiMH batts have a "memory"?

  40. #40
    RC Turnbuckle Jr. jvogel's Avatar
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    LiPo Battery Permanent Capacity Loss

    at 40% Charge
    00C (032F) 02% loss after 1 year
    25C (077F) 04% loss after 1 year
    40C (104F) 15% loss after 1 year
    60C (140F) 25% loss after 1 year

    at 100% Charge
    00C (032F) 06% loss after 1 year
    25C (077F) 20% loss after 1 year
    40C (104F) 35% loss after 1 year
    60C (140F) 40% loss after 3 months

    Source: BatteryUniversity.com

    I keep my LiPo packs at 100%, rotate them, and store them in the fridge. Also, I use them practically everyday. I have a LiPo pack that is still going strong after four years.
    Obstacle Magnet

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