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  1. #1
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    High/Low Gear Shifting sticks

    I just got the Summit I bought last week. (had to wait 'cause wanted Red.)

    I got it out to test and see if it all worked, I found it was stuck in low gear.
    At the time I only shifted while at a stand still.

    I turned it off, a few hours later at home, I check out the shift from the servo. The servo is shifting, the spring is putting tension on the shift shaft.
    I can manually move the shift shaft, and noticed that in both low and high gear, it sticks and stays in either one.

    So to clarify, it binds in low gear, and it also binds in high gear. The servo does move, and places tension on the spring. When I manually move it, it does go into high gear, and the same when I manually move to shift to low gear.

    After working it back and forth a few times, it still binds. Shifting while at slow speed still sticks.

    The spring appears to be to small ? or maybe something isn't smoothed out on one of the shafts? Reading the troubleshooting for similar problems, says to replace the gears that are stripped and and shift arm. Well its brand new, and no stripped gears. Got any tips, hints?

    There is lube on the shaft where it meets the tranny.

    Would it be specific to part 3985X, or the shift shaft 3989X? OR do I just need to rip into it and see whats binding?

    I see in the diagrams if 3969 was out of tolerance, it would keep 3985X from moving freely also.

  2. #2
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  3. #3
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    Found out it shifts from high to low, but stays in low

    I ran the summit outside.

    When fiddling with the gear shift manually. I noticed if it did not go all the way out, it would be easier to shift back to high (it would not feel stuck).
    I wonder if I can slip some washers on the inside of the shifter to space it out (so it won't slide to the stuck position), I'd have to check the gears to ensure they meshed properly. I'll check the diagrams, I don't recall seeing washers on it.

    Thanks for the link "highrisk" sorry to hear problems that are related (servo's tweaking out). Its the price paid for "made in Taiwan" to have inexpensive products.

    I have a feeling I'll be calling traxxas support tomorrow.

  4. #4
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    I have the same problem. No matter how I lubricate the shaft it still sticks in low gear until I manually pull it out.
    JRx2, Mini-Z, MRC, Summit, Slash, Revo VXL, etc.

  5. #5
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    Smile Fixed the Shift sticking problem

    Ok.

    The shift mechanism has wells that a small ball locks into. There is a spring that holds a ball against the shift lever. If that spring is to tight, the servo cannot shift the arm.
    You cannot see the spring, or the screw to adjust the tension without taking the transmission all the way out. And full disassembly of the transmission.
    Fortunately you do not need to disassemble the transmission.

    1. I had to unscrew and remove the motor, transmission, the bottom plate protecting the transmission drive shafts, and remove the transmission from the revo platform.

    2. Do not disassemble the transmission like I did (whoops).
    See the picture below, there is a small hole with a Hex accessible screw.
    insert your hex wrench and loosen that screw.



    3. My problem was that after just 1 turn, the screw was ready to fall out.
    so I took the spring all the way out, and compressed it slightly, maybe 1mm or less. Heated it with a torch so it took on its new shape. and re-inserted it. I used a magnet to ensure the spring did not let fly while hot and get into my eyes, sofa etc.



    4. After re-insertion of the spring, and placing the screw in. I had plenty of play to tighten it in.

    5. Tighten till its good and shifts like before, then gradually loosen 1/4 of a turn till it is smooth, but still has some resistance to shift.

    6. Use the servo shift spring to test out how stiff you have it, before fully re-assembling the summit.


    A. There is a solution
    B. There is about 1-2 hours of work involved to make the summit shift properly.
    C. Hope that no one else has to compress the spring, do so at your own risk/peril of your eyes, or someone elses.
    D. The solution worked for me, I can now smoothly shift between high and low.
    E. No parts to replace.
    F. Shifts properly into high or low, no problems
    G. All screws re-snugged, including the spring tension for the shift mechanism.

    I'm happy now.

  6. #6
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    Sounds like a good fix, nicely done!
    Won my first race in 1985...

  7. #7
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    I found this screw on my E-revo. It worked for me to. Nice discover Wthomps.
    Thank you.
    E-REVO:8 LEDs,2 speed,Novak HV 5.5,Road Rage tires

  8. #8
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    I'll bump this thread up.

    I just found the screw on my Summit and it fixed the shifting problem immediately. Thanks.
    Summit, CEN MG10-TR, Losi Micro-T

  9. #9
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    I need to give this a try...

    Is there a guide for removing the tranny? I'd like something a bit more than just the exploded views.
    JRx2, Mini-Z, MRC, Summit, Slash, Revo VXL, etc.

  10. #10
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    Quote Originally Posted by egnix
    I need to give this a try...

    Is there a guide for removing the tranny? I'd like something a bit more than just the exploded views.
    1. Remove the bottom skidplate (you don't have to, but it makes it SO much easier to put it back together) (you also need to remove the center screw on the front skidplate so you can slide the middle one out)

    2. Remove the drive shafts from the transmission

    3. Disconnect the shifting linkage from the micro servo

    4. Remove the four transmission screws

    5. Slide transmission out and adjust screw

    6. Put back together


    It took maybe 20 min tops.
    Summit, CEN MG10-TR, Losi Micro-T

  11. #11
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    Shift Spring

    Instead of heating the shift tension sping(which causes metal to become brittle or mis-shapen) try trimming or cutting spring. Should shift smoothly and retain ball in proper location with less spring tension. That little ball if let loose in the tranny will cause much havoc with your gears, or what will be left of them, which I have seen first hand in my buddy's Summit after heating and smashing the spring.

  12. #12
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    Quote Originally Posted by ieatfish
    I'll bump this thread up.

    I just found the screw on my Summit and it fixed the shifting problem immediately. Thanks.
    After burning through 5 transmission servos, I'm about at my wit's end. If there is any load on the drivetrain of my truck it's almost impossible to shift gears. As an example, if the truck rolls back slightly on a hill and takes the slack out of the drive train...it either won't shift or takes quite a bit of effort...and, if I fool around long enough trying to shift, sooner or later the servo toasts....

    I have a question for those of you who have worked with the spring and plunger. Take the slack out of your drive train by pushing the truck slightly forward or back until your wheels stop. With gentle pressure hold the truck in that position.... THEN try shifting your tranny by hand. Can still easily shift your tranny by hand? Right now I'm running with the tranny 'zip tied' in high gear....I don't want to try another servo unless I'm pretty certain there is a real fix for this problem....

  13. #13
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    You shouldn't be able to shift with pressure on the transmission. It will only shift when there is no pressure. If you shift and it won't engage all the way, roll the truck just a little and it should shift.
    Summit, CEN MG10-TR, Losi Micro-T

  14. #14
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    Quote Originally Posted by ieatfish
    You shouldn't be able to shift with pressure on the transmission. It will only shift when there is no pressure. If you shift and it won't engage all the way, roll the truck just a little and it should shift.
    All I know is that the shift linkage is easy to move back and forth by hand when the drive train is not loaded. However, I keep on burning up servos...I can't see any reason to trim that spring unless the detent was excessive....I've even put a Futaba 4PK in there so I can personally set endpoints....no help....Did trimming the spring make moving the linkage easier throughout its entire movement or just easier to pop free at the ends of its travel?

  15. #15
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    Looking through the posts, it sounds like people have both loosened and tightened this screw... How do you know which to do? How do you know what it is "tight/loose" enough?
    JRx2, Mini-Z, MRC, Summit, Slash, Revo VXL, etc.

  16. #16
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    Quote Originally Posted by egnix
    Looking through the posts, it sounds like people have both loosened and tightened this screw... How do you know which to do? How do you know what it is "tight/loose" enough?
    I loosened mine. You can tell a difference when you adjust it. I just pushed the pin in and out with my finger until I liked the resistance.
    Summit, CEN MG10-TR, Losi Micro-T

  17. #17
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    yes the spring thinggy for the high/low "SUCKS",there needs to be a more solid linkage system similar to the e-maxx,my maxx works flawless,i'm currently in the process of coming up with a solid linkage that goes directly from the servo to the shift arm,if i'm successful i will update with pics.
    Garybillyb

  18. #18
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    I think I found the prob..

    I took my trans apart today after reading this and many other post. I found rust inthe spring and on the ball that goes to the shift link detent. I have gotten to take pics yet and will try over the next few day, but the trans isn't waterproof. My hope is when I get the trans back together, that it will shift smooth. after all the water dries and wipe out the rust.

  19. #19
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    pics of the damage

    well can't find a spot to attach pics


    sorry

  20. #20
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    Working well

    I pits on the ball still gives it a slight hang, but it now shifts with the servo. Before I had to pull it out with a guitar string and a lot of force. Good luck to anyone else doing this.

  21. #21
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    r u supposed to be able to shift on the fly, or should you be at a stand still before shifting gears?









    www.sportstalk4us.blogspot.com

  22. #22
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    I asked support that same question as I was burning thru shifting servos. He told me that you could shift on the fly, but you had to let off on the throttle while doing so. Just like the e-maxx. Unfortunately it doesn't work anywhere near as well as the Maxx does.
    bash 'em, break 'em, fix 'em & do it again!!

  23. #23
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    Quote Originally Posted by dsuida
    I asked support that same question as I was burning thru shifting servos. He told me that you could shift on the fly, but you had to let off on the throttle while doing so. Just like the e-maxx. Unfortunately it doesn't work anywhere near as well as the Maxx does.
    After going through 5 shifting servos I finally got the shift system working reliably. I believe the fix is a combination of trimming the detent spring so that the ball hardly has any pressure on the shift rod and then careful tuning of the servo travel endpoints. The endpoints can only be tuned if you know where the pots are in the OEM transmitter. I think someone on this forum has pointed them out in another thread...Sorry, I don't know where that post is. Tune endpoints such that there is only a slight amount of pressure on the shift lever spring when the shift rod has locked into either position. I'm using my own 2.4ghz radio system so endpoint tuning was easy for me...Shift on the fly at your own risk...Best to slow down to less than a few mph at least...then let up on the throttle too...

  24. #24
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    Different approach to same issue

    Hi everyone! First post and hello to all. I just got my Summit 2 days ago . I checked this forum and thread as I also had shifting issues.

    Mine had binding (rubbing) between the shift servo rod ball end and the rear differential lock control rod. The shift servo rod ball end was also hitting the square block of a wire wrap near by its travel end point.

    I first carefully moved the ty-wrap rearward and repositioned it so the shift linkage ball end did not bind against it as it moved back. Then I took out some of the bend in the very long differential lock rod in the first joint past the ball end. That forced the differential lock rod toward the center against the plastic. Now it sits in the middle of the shift linkage without binding. I also lubed the shift shaft with some dielectric grease where it enters the grommet.

    This simple fix completely cured my shift problems. Here is a link to the picture of the new linkage alignment.

    http://rfixhandymanprojects.shutterfly.com/122

    I'm brand new to R/C cars and chose a Summit as my first because I own almost 2 acres of woods and rocks to play in.

  25. #25
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    Quote Originally Posted by Hughes500Bob
    Hi everyone! First post and hello to all. I just got my Summit 2 days ago . I checked this forum and thread as I also had shifting issues.

    Mine had binding (rubbing) between the shift servo rod ball end and the rear differential lock control rod. The shift servo rod ball end was also hitting the square block of a wire wrap near by its travel end point.

    I first carefully moved the ty-wrap rearward and repositioned it so the shift linkage ball end did not bind against it as it moved back. Then I took out some of the bend in the very long differential lock rod in the first joint past the ball end. That forced the differential lock rod toward the center against the plastic. Now it sits in the middle of the shift linkage without binding. I also lubed the shift shaft with some dielectric grease where it enters the grommet.

    This simple fix completely cured my shift problems. Here is a link to the picture of the new linkage alignment.

    http://rfixhandymanprojects.shutterfly.com/122

    I'm brand new to R/C cars and chose a Summit as my first because I own almost 2 acres of woods and rocks to play in.
    Well, you obviously picked the right truck. It is a lot of fun and I hope you have some money saved up, the upgrade bug hits almost everyone.
    Summit, CEN MG10-TR, Losi Micro-T

  26. #26
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    Quote Originally Posted by ieatfish
    Well, you obviously picked the right truck. It is a lot of fun and I hope you have some money saved up, the upgrade bug hits almost everyone.
    Isn't that why the warranty is only 30 days .... So you have time to research all the upgrades you want to do!! My list is starting to take shape already. I'm selling off R/C airplane stuff to get money for car parts!! The wife can't fly .... but she sure has fun driving the Summit.

  27. #27
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    this set screw was the INSTANT fix for me..

    I had to do my son's tonight after a long time needing it!

    Put a new shift spring in and adjusted this screw... WOW..

    shifts instantly now and smoothly..

    dont tear down your trannys!!
    Three Summits

  28. #28
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    Quote Originally Posted by milkman
    Put a new shift spring in and adjusted this screw... WOW..
    Which spring are you referring to? The one that puts pressure on the ball in the tranny or the one on the servo linkage?
    JRx2, Mini-Z, MRC, Summit, Slash, Revo VXL, etc.

  29. #29
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    FYI... I just did this fix, and it works great. You just have to take the tranny off to get the set screw. My spring was fine, and didnt need heated up or anything like that. I believe that my set screw was too tight, causing the shaft to stick. I loosened it up, and now it shifts no problem!
    ERBE, E-Slayvo Pro, Ext Stampy, 2xMERV's.

  30. #30
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    My spring was bad.

    The spring on the outside connected to the servo horn. The little ball on the end of the spring that snaps into the arm connected to the servo horn..

    BROKE OFF.. I dont know why..
    Last edited by milkman; 12-22-2009 at 02:13 PM.
    Three Summits

  31. #31
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    Kind of just bumping this thread but could use some info. Reading through here I see most have similar issues. Mine worked flawless the past two days and today it hardly wanted to shift into low gear at all. Long story short after a few hours of working on it my servo finally died and doesn't do anything now. My question is, 1 has anyone made a custom linkage such as the one on the e-maxx 2speed that simply puts a spring on the servo and a off of that has just a "rod" straight to the shifter? Therefore nothing to interfere or cause binding? And also anyone changed the 2065 servos to another brand? What brand and any waterproof with metal gears? Thanks
    Slash VXL
    Summit VXL
    they have to share for now

  32. #32
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    pull the tranny and adjust that set screw if you have not done so already. Mine was fine for a while and once I pulled the tranny, it was too tight..

    If shifts without any effort now. Stock servo has been fine too now...since there is no stress on it anymore.
    Three Summits

  33. #33
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    I took tranny out and adjusted and all has been fine till today, started hanging up shifting and by this afternoon the servos out. 2nd time in a month and $34.00 each. anyone have a picture of correct angle of linkage and recommendation for servo problem. shifts fine by hand no load

  34. #34
    I also tried the ball, did not help.
    Put on the draft gear hard shaft. Then to him the native spring. Solve the problem completely. Everything works well. Sorry, that's not fair, for the works.
    You can see here:
    http://forum.modelka.com.ua/index.ph...dpost&p=110693

  35. #35
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    Quote Originally Posted by TraxxasMac
    I took tranny out and adjusted and all has been fine till today, started hanging up shifting and by this afternoon the servos out. 2nd time in a month and $34.00 each. anyone have a picture of correct angle of linkage and recommendation for servo problem. shifts fine by hand no load

    Check out this thread.
    JRx2, Mini-Z, MRC, Summit, Slash, Revo VXL, etc.

  36. #36
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    Quote Originally Posted by wthomps
    Ok.

    The shift mechanism has wells that a small ball locks into. There is a spring that holds a ball against the shift lever. If that spring is to tight, the servo cannot shift the arm.
    You cannot see the spring, or the screw to adjust the tension without taking the transmission all the way out. And full disassembly of the transmission.
    Fortunately you do not need to disassemble the transmission.

    1. I had to unscrew and remove the motor, transmission, the bottom plate protecting the transmission drive shafts, and remove the transmission from the revo platform.

    2. Do not disassemble the transmission like I did (whoops).
    See the picture below, there is a small hole with a Hex accessible screw.
    insert your hex wrench and loosen that screw.



    3. My problem was that after just 1 turn, the screw was ready to fall out.
    so I took the spring all the way out, and compressed it slightly, maybe 1mm or less. Heated it with a torch so it took on its new shape. and re-inserted it. I used a magnet to ensure the spring did not let fly while hot and get into my eyes, sofa etc.



    4. After re-insertion of the spring, and placing the screw in. I had plenty of play to tighten it in.

    5. Tighten till its good and shifts like before, then gradually loosen 1/4 of a turn till it is smooth, but still has some resistance to shift.

    6. Use the servo shift spring to test out how stiff you have it, before fully re-assembling the summit.


    A. There is a solution
    B. There is about 1-2 hours of work involved to make the summit shift properly.
    C. Hope that no one else has to compress the spring, do so at your own risk/peril of your eyes, or someone elses.
    D. The solution worked for me, I can now smoothly shift between high and low.
    E. No parts to replace.
    F. Shifts properly into high or low, no problems
    G. All screws re-snugged, including the spring tension for the shift mechanism.

    I'm happy now.
    This post is one of the best FYI posts I've ever read. This is the kinda stuff that makes this board and it's members priceless.

  37. #37
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    Has anyone found adjusted this screw lately?

    I am having compound shifting issues with my week old Summit. The first is that my servo is having some sort of interference or something, traxxas sent me a new one, but I haven't replaced it yet.

    The second is the one discussed in this thread. When the servo is working, it still doesnt shift all the time, and it sticks when it does.

    I figure this screw thing is worth a shot, has it worked for anyone lately?

  38. #38
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    Transmission of the summit is very basic (and thus maintenance free / foolproof). The Summit has no clutch.
    Thus, when there is any kind of stress on the driveline, you won't be able to shift. Period. If you do, the servo will try to pull, but only bend the spring (servo saver) on the outside of the tranny.

    I am able to up-shift while driving by temporarily matching my throttle to the current speed of the truck (effectively almost eliminating the stress in the transmission/driveshaft). But this will give your tranny a "smack" everytime you shift this way (ever up-shifted in your manual tranny car without using the clutch?).

    Downshifting is dangerous at speed, because the summits tranny is not synchronized (and there is no clutch), and it will result in a bit of a "smack" into the low gears (try shifting down your stick shift car without a clutch!). Dont do this, only when you're at a stand still, or, if you are "good" with cars, ALMOST at a standstill (<1km/h, <1mph) because then the drivetrain will still be moving. If you are at a complete standstill, and the there is stress on the drivetrain (hill / inclination, or just the accidental position in which the truck stops), the summit will have a hard time switching gears.

    Just remember that the Summit has no clutch, so the motor is always in direct connection with the drive-shafts / wheels. If there is any kind of tension / stress in that line, it will be harder for the Summit to switch gears.

    -- About waterproof
    I ran my summit in water several times, and I can confirm the tranny is not 100% waterproof, but is very much water resistant. After 5 water runs (REAL water runs, aka UNDER water), and 4 months, I opened up my tranny for the first time, to find out it was in perfect condition, EXCEPT for the outer bearings.

    All the bearings that are on outgoing shafts (shafts that stick out of the tranny's housing), will rust, but effectively keep out water. I just had to replace all bearings on outgoing shafts, every internal gear was -fine-.

    All in all, I think Traxxas did a very good job keeping this tranny as simple (durable, maintenance free and foolproof) as possible, while still giving us the ability to switch gears remotely and have a dual purpose truck.

  39. #39
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    Most of that is true, but I dont think traxxas did a great job. All I have had since I got this truck is transmission problems. It may be simple, but it doesn't just work, and it's not maintenance free. I have never shifted under load, and it didn't work right out of the box. I'm glad yours works, but mine doesn't. People have had luck with this adjustment, and I'm hoping it will help me too.
    I gots trucks and no idea what I'm doing!

  40. #40
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    My shift linkage was binding on the wire tie wraps. Once I moved the tie wraps it was fine.
    I make tap adapters and power harnesses.

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