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  1. #1
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    Tuning questions

    Even though I've owned a t max for like 6 years now, I've never been able to get it doing wheelies. Ever.

    I know day to day you need to make adjustments becuase every day the air, moisture, etc are different.

    You've all seen my rig, and that I have a 3.3 engine, and that's -more- than ample enough to get constant wheelies.

    However, I've yet to be able to get them. I suppose I've always ran so rich that I've never gotten the real performance I could but I don't wanna run to lean, that is an engine killer.

    I've come to realize, when leaning out the HSN, if the exhaust is spitting drops of fuel, it's still really rich. I've leaned it out probably a 1/4th turn and seen a increase in performance. I need to go and buy more fuel as I am dry right now but still.

    How much leaner can I go with the HSN, and should I change the LSN too, to get those wheelies? I had a bad habit, when I first my my maxx of the front end meeting cars, and thus destorying the front end so I've been babying it. I am more confident in myself now that I am older and want to really tune this thing till it's nearly flipping when I go WOT.

    If you want pics of my current settings, please don't hesitate to ask. I've read my booklet that came with my maxx and even though it's for a 2.5, I still feel it has almost all the info I need.

  2. #2
    RC Turnbuckle Jr. Snook Man's Avatar
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    If you cannot pop a wheelie with a 2.5model 4910 with a 3.3 engine and stock gearing, you are simply not tuned well and/or your slipper clutch is too loose.
    With the short chassis and 3.3 and stock gearing you should easily be able to flip the rig backwards on its lid when you have a good tune. It actually is an anoyance when you get it tuned well
    Generally you lean the hsn until you no longer see an improvement in high speed performance. If the engine starts barking at you l(lean bog , starving for fuel) or engine temps climb too high, back off the hsn slightly until the bog or high temps return to normal.
    Once the hsn is set then you adjust the lsn (which controls the wheelie popping power) If the lsn is too rich you will not get the response from the engine needed to get the front wheels up. The pinch test for the lsn will get you close. After a high speed pass immediately bring the rig in and pinch the fuel line closed a few inches away from the carb, The engine should increase rpms and die around 3 seconds after you pinch the line closed. 5 seconds indicates the lsn is too rich – 2 seconds indicates it’s too lean.
    The 3 seconds is just a average number and everyone counts a little differently so it’s not exact but will get you close.
    Another tip would be to install friction pegs in all 12 holes of the spur gear instead of the stock 6 to help the slipper get more bite. The stock 2.5 slipper was designed for the smaller displacement engine and the 3.3 can overpower it easily if the adjustment is a little too loose.
    No slipper/tall gearing/power = broken parts.

  3. #3
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    I don't have the stock plastic spur, I have the upgraded all steel one.

    I suppose I just need to lean the HSN a little bit more, then play with the LSN.

    I might, when I buy some fuel, make a video for you guys and see what you guys thing I may need to do.

    Plus I like playing with my T maxx, what else is there.

  4. #4
    RC Turnbuckle Jr. Nitronaught's Avatar
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    Quote Originally Posted by fuzzum111 View Post
    I don't have the stock plastic spur, I have the upgraded all steel one.

    I suppose I just need to lean the HSN a little bit more, then play with the LSN.

    I might, when I buy some fuel, make a video for you guys and see what you guys thing I may need to do.

    Plus I like playing with my T maxx, what else is there.
    Humm,,, I'd say tune with the body one, never tune with more than 1/2 a tank of fuel, have tiny holes where your tuning driver can get to the LSN and HSN...

    Then,,, From where you are at, get it up to operating temps, tune the LSN using the pinch test, then tune the HSN.... Have your slipper not completely locked down, if you use the red pegs, use all 12 , not just the six...

    From there, maybe you shocks on the rear need to be stiffened up a little bit, if you RC is squatting it prevents the front wheels from coming o the ground (something us racers don't want,,,, can't contol a car with two wheel in t air compared to all 4's)....

    Spur gears, as in, Steel or Plastic, have nothing to o with wheelies... But a slipper being too lose would...

    No need for steel spurs,, Never used them and I know tons of BB Monster trucks using plastic spurs... Hope you have a hardened CB cause a regular one will get chewed up by a steel spur...


    IF you changed the spur, and the CB,,, did you change your gearing by any chance? What is your current gearing? NN
    Robin Williams
    He will be greatly missed...

  5. #5
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    IIRC my gearing is standard 72/20

    I am just using a normal 20t clutch bell from traxxas, I was told they don't make more resilient versions of them and just to be more gentle with the throttle to prevent it from getting shredded. I already had to replace it once, it did last a good long while.

    Here are some pics of my spur, carb and such. Tell me, do you think i need to loosen, or change the slipper? I didn't do the work on it myself, when I got the 3.3 and spur installed, took it to a hobby shop becuase we simply didn't have the means to do it ourselvs at the time. I am more willing to do the work myself now.



  6. #6
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    What Snook and Nitro said lol. Hows it shift? Can you here it run up and shift? Mine was shifting so quickly and early, it was like one long run up to 40mph. Robinson makes a hardened 22T CB fyi. But I suspect most of this is tuning. On you're setup, you have to use all 12 pegs, no way 6 can hold a 3.3. The pro I worked on awhile back had a 3.3, hard to keep it from wheelieing.

    Correction,
    Part # Description Price
    8119 T-Maxx 2.5 Hardened Steel Clutchbell 19T $10.95
    8120 T-Maxx 2.5 Hardened Steel Clutchbell 20T $10.95
    8121 T-Maxx 2.5 Hardened Steel Clutchbell 21T $10.95
    8123 T-Maxx 2.5 Hardened Steel Clutchbell 23T
    http://www.robinsonracing.com/catalog/tmaxx25.html

    This sounds like a hardened CB.
    http://www.ebay.com/itm/Traxxas-20-T...item2eb13c64f8

    Here's a 22 hardened.
    http://www.ebay.com/itm/Traxxas-20-T...item2eb13c64f8

    ETA, by the looks of the shiny metallic powder looking stuff, I would say you're already eating a CB. My son had a steel spur, his CB last ten minutes, ate the teeth right off.
    Last edited by Oldrcguy; 04-14-2013 at 05:39 PM.

  7. #7
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    It makes a very clear shift. I have to guide it into 2nd gear though, if I just go WOT it'll rev into 1st and just climb the RPM's without shifting. I have to go up to 2/3rds throttle, let it shift then pull harder once I hear it. It does shift, and does a clean shift so long as I don't let up or play with the throttle to much when it's about to shift.

    About these pegs... how do I know if I have any I don't know if I even have any pegs on hand. lol.



    This was the original 72T spur before the hobby shop replaced it. It has 5 of those little red pegs, correct?

    I was never given any pegs, or spares or the like and I sifted through all my bobbles and parts I have. I did not see any, so should I assume that all 12 are already on there?

    How much of a pain is it to get a spur off, or to check the pegs? Do I need to remove the engine too?
    Last edited by fuzzum111; 04-14-2013 at 05:45 PM.

  8. #8
    RC Turnbuckle Jr. Snook Man's Avatar
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    Quote Originally Posted by fuzzum111 View Post
    It makes a very clear shift. I have to guide it into 2nd gear though, if I just go WOT it'll rev into 1st and just climb the RPM's without shifting. I have to go up to 2/3rds throttle, let it shift then pull harder once I hear it. It does shift, and does a clean shift so long as I don't let up or play with the throttle to much when it's about to shift..
    Perfect example of the slipper sliping too much.

    You will need to remove the spur gear to look/see the friction pegs.
    No slipper/tall gearing/power = broken parts.

  9. #9
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    and is the spur a real pain to get off to be looked at? Should I just youtube a tmaxx video of how to remove and change the pegs?

  10. #10
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    The hardest part is getting it off. Then you push the pegs out with something, and very carefully push them into the empty holes of the gear you're using. When you pull the clutch apart, go ahead and dob a spot or two of glue on the shiny silver discs and glue them on the tapered covers. You'll see a tiny peg sticking up, and a notch in the shiny disc, line those up. It's a pain to have the shiny discs falling out of place as you reassemble it.

    Fill up all the holes you have pegs for.

  11. #11
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    How do I get it off

    Do I need to remove the fuel tank and engine? It appears I'd have to disassemble quite a bit more if I wanted to remove the tranny itself sadly I don't think I have any glue

  12. #12
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    Quote Originally Posted by fuzzum111 View Post
    How do I get it off

    Do I need to remove the fuel tank and engine? It appears I'd have to disassemble quite a bit more if I wanted to remove the tranny itself sadly I don't think I have any glue
    yes both come off. Before I started gluing mine on, I would stand the truck up as I reassembled it, to make sure everything stayed aligned.Tranny stays in.
    Last edited by Oldrcguy; 04-14-2013 at 06:11 PM.

  13. #13
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    Sadly, all was for naught, the guy that installed it was smart, all the peg holes are filled already, all I had to do was peak behind the cover once I got the screw and spring off, without any problems everything was realigned and put back on. So all 12 holes are filled. What do?

  14. #14
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    Tighten it up all the way and back off an 1/8th of a turn. Then tune it.

  15. #15
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    tuesday is the soonest I can get fuel I'll buy some and go from there

  16. #16
    RC Turnbuckle Jr. Snook Man's Avatar
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    All 12 being filled doesn’t mean the friction pegs are not worn out. With your description of not being able to apply full throttle or it will not shift unless you feather the throttle to ¾ that tells me the slipper is too loose and/or the pegs are worn. With a stock plastic spur when you have excessive slip the center of the spur heats up and melts the friction pegs and spur gear. With the steel spur you are running the center will not melt out of the spur but the friction pegs will wear extremely fast with excessive slip like having to apply only ¾ throttle for the shift.
    I would pick up some friction pegs while at the hobby shop to have on hand when you go get some fuel.
    You may also want to think about a new pipe. That black plastic thing they call a pipe on your rig is killing the engine performance. A nice DC resonator and a high flow air filter will wake up the engine and once you get the slipper sorted out you will be looking for a wheelie bar or wing to keep it from flipping on its lid.
    No slipper/tall gearing/power = broken parts.

  17. #17
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    This is a bit off topic but I noticed you're using the 2.5 exhaust pipe with your 3.3.
    You can get more punch out of your engine if you upgrade to a Resonator pipe
    and a 3.3 air filter (if you dont have one already).
    Bash, Crash, Upgrade, Repeat..

  18. #18
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    Good points Snook, didn't think about that steel gear.

  19. #19
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    Ok quick update. GOT FUEL DDD

    So did some high speed runs, tuned it up a bit, got it running progressively better. Has some struggles with engine flooding, and when I had put everything back togeather I had the blasted fuel line going to the exhaust instead of the carb, so it wasn't getting fuel.

    Once i got it running I STILL had the problem with the truck only wanting to turn one direction. Here is a video for ya.

    It will make sharp turns in one direction, but very wide turns in the other. I've tried fiddling with everything i can think of, and I just can't seem to get it right.

    http://youtu.be/hXeqfoDzq8c
    Last edited by fuzzum111; 04-16-2013 at 04:42 PM.

  20. #20
    RC Turnbuckle Jr. Wildman4910's Avatar
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    To really make the 3.3 come alive you really need the high flow filter & DC resonator pipe, the old button filter & plastick pipe just don't cut it with the 3.3.

    What are you using for the steering servo? Still the stock 2055?

    If so I think it's time for an upgrade to a high torque metal gear servo & a new servo saver.
    The old on the servo servo saver can & do wear out.

    Is this something that just started happening out of the blue, or did you do something to the servo/steering and then it started?
    Look out for the tree/crunch!

    LiPo? Naw NITRO!!

  21. #21
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    Please stop telling me to buy new parts, as it is fuel is a rarity I can barely afford to buy.

    I can get it doing wheelies and such without those parts, it will just take more and more turning day to day that's all.

    Anyways. At one point the axle on one side came off because a screw came loose. So I had to take the tire, and both the ball screw and the pillow screws out to access the axle and screw it back on, and slide it back into place. I probably didn't tighten enough, or over tightened, or something. I don't know what to adjust to fix it, it only started doing that once I fixed the axle. I recall it being the right side axle, and I have messed with both left and right side pillow screws to try and fix it.

    So I don't know if I can "reset" them and go from there.

    also, yes it is the 2055 servo. I cannot afford to buy a upgraded one

  22. #22
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    Pop the servo saver off the servo, gently turn the wheels from lock to lock. See if possibly a pillow bearing is binding. Turn on truck and remote and let the steering center, make sure steering trim on the remote is centered fist. Re install the servo and try it again. BUT I would say the servo is getting really weak. If I had a good one, I would just send it to you, but I replaced mine because it was cracked, tabs broke off and falling apart. Truck sounds good though, and that's a nice scooter buddy. Put a WTB on craigslist, someone might have a stock one for a cheap price.

  23. #23
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    alright, the servo saver is what exactly? The bottom white rounded part that attaches to the little screw arms? Then turn the wheels freely to feel if the pillow screws are preventing it from turning properly? As well try and zero out the servo and see if that's the problem?

  24. #24
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    Quote Originally Posted by fuzzum111 View Post
    alright, the servo saver is what exactly? The bottom white rounded part that attaches to the little screw arms? Then turn the wheels freely to feel if the pillow screws are preventing it from turning properly? As well try and zero out the servo and see if that's the problem?
    You got it. When you turn the truck on and the remote, with the trim knob centered as well, it will self center. I've yet to figure out how it knows what center is, but it does. Push the servo saver on and sit it down and see if it looks centered, sometimes takes a few tries.

  25. #25
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    Did some more test runs. Even with lots of fiddling, it's getting worse and testing the fixes you suggested.

    Is a symptom of a dieing servo, the wheels locking to one side? If so, yea as much as I hate to say it your prognosis is right and I need someone with a kind soul to donate me a new steering servo. I cannot afford one. upgraded or standard, I am prolly going to need one.

  26. #26
    RC Turnbuckle Jr. Wildman4910's Avatar
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    Centering the servo is as simple as pulling the servo saver off(the round white disc), setting the radio steering trim to "0" and then putting the saver back on.

    If it's already centered & the suspension is not binding then it sounds like the servo is going.

    I'm using a PowerHD servo for steering, $23 shipped.
    http://www.troybuiltmodels.com/items/HD-1501MG.html

    Flip the truck over & look at the servo saver & turn the wheels back & forth by hand, is there a lot of slop to the one side?
    Look out for the tree/crunch!

    LiPo? Naw NITRO!!

  27. #27
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    I don't understand by what you mean slop to one side?

    It will turn by hand both directions easily, I even made sure it did so with and without the servo connected to it.


    Once I got it running, and took it outside I nearly crashed 2 or 3 times becuase it would jarringly turn to one direction and when I lifted it up it would be turned ALL the way to one side, and I'd have to correct it by hand. I think the servo is dieing or something. It has fresh batteries and such.

    Sadly as nice as that $23 shipped servo may be, I simply don't have that money ;.; Fuel was a expense I only incured becuase $12/qt is not bad.
    Last edited by fuzzum111; 04-16-2013 at 08:08 PM.

  28. #28
    RC Turnbuckle Jr. Wildman4910's Avatar
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    I know where your coming from.

    Sounds like the gear train in your servo is stripped, you can verify this by pulling the top case off & looking at the gears.

    What I meant was to verify the servo saver was still working, if the servo saver was bad it would just flop back & forth.

    If you pull the top plate & the gears are bad/chewed up, they are not very expensive ($4)& easy to replace.
    http://www3.towerhobbies.com/cgi-bin...?&I=LXDUY7&P=7

    Gears should look like this.


    Last edited by Wildman4910; 04-16-2013 at 08:41 PM.
    Look out for the tree/crunch!

    LiPo? Naw NITRO!!

  29. #29
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    This just got more bizarre. The servo gears look brand new. Like, not chewed up or even damaged at all. So it's not the gears.

    The only thing I can think of is it's not zeroed out, OR the computer component got fried somehow. (We all go through mud, or little puddles now and again) I have not gone through any deep water or anything even close to that.

    Here are pics of the servo gears.

    What are you suggestions at this point, this is so weird. It was turned REALLY hard to one side and wouldn't unstick so I can't fathom why it's doing that. I don't see any cracks or breaks or anything.




  30. #30
    RC Turnbuckle Jr. Wildman4910's Avatar
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    Wow, that is strange.

    Swap the throttle servo plug & put it into the steering servo port on the RX & see if the throttle servo behaves the same way as the steering servo does.

    If the throttle servo works like it should, plug the steering servo into the throttle servo port & see if it still acts up.

    This will help narrow down the problem, if the throttle servo plugged in the steering port acts the same way as the steering servo does then the issue is in the RX or TX, if the throttle servo turns like it should & the steering servo still acts up in the throttle servos port then it's narrowed down to something in the steering servo.
    Look out for the tree/crunch!

    LiPo? Naw NITRO!!

  31. #31
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    Well here is another bite of information. I was missing a screw! this is the 2nd time I've had to replace this little bugger. It's the screw that goes in on the skid plate that screws into the post, that part of the steering assembly is based on. I had to re align it, and put a new screw in.

    After 2 or 3 attempts to zero it, I still have a similar issue with it turning all the way 1 direction and about half as much the other direction. I cannot figure out why. Maybe the servo really isn't powerful enough? Or... I don't know.

  32. #32
    RC Turnbuckle Jr. Wildman4910's Avatar
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    With the front end off the ground is should turn the wheels all the way side to side without a problem, it will not do so on the ground when not moving with a 2055 servo but in the air it should.

    Screws that go into aluminum need to be loctited with the Blue loctite.
    Look out for the tree/crunch!

    LiPo? Naw NITRO!!

  33. #33
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    Well even in the air, with the screws locked back in. It still won't go -all- the way to one direction. The left side it will, but the right it won't. No amount of trim fixes it and in some ways can make it even worse. It's like the servo can't or won't push it all the way one direction is is strange x.x

    I did the switching ports thing too and it still did the same thing, but the throttle remained normal, so it's not the RX or TX as you said in your above post.

  34. #34
    RC Turnbuckle Jr. Wildman4910's Avatar
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    Sound like something internal in the servo's circuit is has goofed up.

    That was why I said to swap the servos plugs, now you know the problem is isolated to the steering servo itself, granted it doesn't help get you running till you get another servo but atleast you know what/where the problem is without blindly replacing parts.
    Look out for the tree/crunch!

    LiPo? Naw NITRO!!

  35. #35
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    get a new upgraded servo for anyoness sanity. Second if u have the new 2.4GHZ transmitter receiver system reset it to defaults to rule out some setting making the servo stop on a steering max to one side and partially to the other side.

  36. #36
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    Yea, well if anyone here wants to be extremely kind I'd love it if someone could donate a steering servo to me :3 Preferably a little bit better than the standard issue one but hey. I can dream lol.

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