Results 1 to 14 of 14
  1. #1
    RC Competitor
    Join Date
    Feb 2020
    Posts
    68

    Angry T-Maxx Stripping 4995 Tranny Gear?

    Hi,

    I recently installed the traxxas 5351x slipper conversion kit on my T-Maxx. I had some issues that got solved on my last thread (pin was slightly misaligned on slipper assembly.) When installing the kit, though, I found what looked like a gear tooth in the tranny. I didn't see any bad gears so I just left it for testing. When driving it around it had a random clicking which was really bad in reverse. I opened up the tranny to find the bearing of the metal gear at the back of the tranny had a destroyed seal and the 4995 gear was missing teeth. I thought this all happened because of the slipper being installed wrong. I had a spare gear as I had ordered it to replace the set screw which snapped on me a while ago so I replaced the gear. The messed up bearing spun smooth so I put the seal back on and relocated it to a different spot where it was facing into the housing. Put everything back together, fixed the pin on the slipper, and it ran great up until 2 days ago. I ran it for a while and on concrete the torque from a stop was amazing. In the grass though it wasn't doing well at all. Then I started to notice the clicking noise again. I thought it was the slipper binding but it was fine, and I suspected the differential but I couldn't really tell. Putting it into reverse had the same horrible noise. The sign that makes me pretty sure it's that same 4995 gear is that when I spin the spur counterclockwise it feels like it's binding and then spins for a bit and binds again. Haven't opened the tranny again (tired of opening it over and over lol). Any idea why it could be doing this?

    Other things to note:
    -I did jump it and didn't let off the accel in time close to before it started clicking, so could it be that my slipper is adjusted wrong?
    -Recently the truck hasn't been shifting. I've been trying to figure out what's been going on as I've never messed with the shift point.
    -When in the grass it seems like the rear wheels are getting more power as they seem to spin and also I can't steer well. It seems like the front wheels are just hovering above the grass.
    The whole reason I upgraded the slipper was because I was running it a month ago when I went into a bush and got stuck. Tried to reverse out and was still stuck. Suddenly it wouldn't move and I saw that the slipper was completely stripped. Could something else have broken that caused this?
    -I've tightened the brake disc a few times as it's wearing out, but every time I do it the brakes are almost gone again after a tank. Last time I did it, it seemed like the rolling resistance increased a ton but brakes didn't get better. By the end of the tank it was clicking horribly. Had almost no brakes and there was no resistance at all when rolling it. Keep in mind when on concrete and full throttle it takes off like never before despite the clicking.


    TLDR: 4995 gear in tranny is stripping. I got stuck in a bush and tried to reverse out, spur gear stripped. Upgraded to 5351x torque control slipper. Installed pin wrong and heard clicking sound when testing- worse in reverse gear. Fixed pin and also opened tranny, found destroyed bearing seal and stripped 4995. Replaced 4995 with spare and swapped bearing to different spot. New gear lasted a tank and I hear the same sound again. Main symptom- spur gear randomly binds when spinning counterclockwise.

    A bit frustrated as I've opened up the tranny 3 times lol. Any help is appreciated.

    Thanks,
    Len
    Last edited by len- tmaxx 2.5; 09-14-2020 at 03:34 PM.

  2. #2
    RC Racer
    Join Date
    Aug 2020
    Location
    Bay City, TX
    Posts
    123
    I’d open the transmission and replace the bad bearing. It may spin but a tiny bit of excess play could cause issues. Matter of fact, I’d replace all the bearings after the amount of stress it sounds like the tranny has gotten. Check all the gears. If that doesn’t fix it then it could be front diff, but I’m betting on transmission. Adjust your slipper while you have the tranny out of the truck. With the wrench inserted in the shaft try to turn the spur gear. It should take some force to make it slip. Leave it there and fine tune with small changes after you put it back together.

  3. #3
    RC Qualifier nebulous.cow's Avatar
    Join Date
    Feb 2012
    Location
    Seattle by summer, AZ by Winter
    Posts
    361
    +1 replace the bearings. Transmission bearings are really important, like redux said, they maintain a very specific tolerance between gears, and any play can cause the shafts to wobble in and out of the right axis, especially when switching from forward to reverse. A set of bearings for the entire trans is usually a small price to pay for some peace of mind, and usually nitro transmissions don't have much in the way of torque-induced damage, since it's not as powerful as electric.

    As for the brakes, check the temperature of them when they start working poorly. It took a lot of experimenting, but my Jato needed brake mods, and the first thing I noticed was that stock, the brakes got to like 350 degrees, no wonder they stopped working.

    Also, for reverse, make sure the servo moves all the way, and there is no binding, and make sure the truck runs normally in forward only before experimenting with reverse. I ended up removing reverse in my classic maxx, and it's been a dream ever since, but in my Revo I have left it, since it hasn't messed up yet. But I use reverse sparingly, and I always hold the brakes when I shift to reverse and back, just in case, and it's been great.

    Try to hold the rear wheels in your lap while trying to forcibly turn the front wheels, it'll help you see if there is stripped gears in the diffs or the center drive shafts.

    Good luck. Make sure you're not missing any parts, and make sure everything in put together right, greased if it needs, and don't overtighten the slipper. My classic maxx needed a steel spur to behave right, and ever since then it's been perfect.

    -Mike

  4. #4
    RC Racer
    Join Date
    Aug 2020
    Location
    Bay City, TX
    Posts
    123
    Forgot about the brakes. I like zero brake drag at neutral. My truck rolls freely. Some people set up a tiny bit at neutral. Whatever you do, be SURE that the brakes release completely before the clutch engages. If you don’t you can burn up the clutch and the brakes. Thinking that might be what’s happening with yours.

  5. #5
    RC Competitor
    Join Date
    Feb 2020
    Posts
    68
    So, I just took apart the truck... :facepalm: Was removing the set screw pins from the driveshafts and realized I swapped them by accident last time when fixing the slipper! Not sure why I even took off the front one. I thought it was easier to remove it but it just slides off the other half of the shaft. Anyway the set screw head on the front pushed itself downward into the driveshaft and the blue anodized piece that the brake stops was just spinning. No wonder I had no brakes lol. Anyway I've been having brake issues since before this so I'll make sure to check the temps. Also my brake disc is almost worn out. Are there any stronger Traxxas or aftermarket dics?

    Back to the main topic: Just opened up the tranny and found what I expected- 4995 gear is destroyed. This is the plastic gear at the back that meshes with the metal gear attached to the housing. Could this still be the bearings? I'm wondering if I could have possibly put the wrong gear on the wrong side of the shifting shaft (on the exploded view they say "shiny pawl" and "black ring")? Or could my slipper be too tight? I can spin it by hand if I really try but it hurts my hand (the instructions said tighten until you can barely spin it by hand). Other than that I just can't figure out what could have caused the issue.


    I think I'll go ahead and replace the bearings either way- on my previous thread about the issue with my spur gear someone mentioned that AVID bearings are good. On their website they have bearings that have the water seal on only 1 side or just normal metal bearings. Apparently this reduces friction. I was thinking of getting the half waterproof for the bearings that are exposed and metal for the ones that are fully inside the housing. They are all $1 but are there any disadvantages to these over the fully sealed ones?

    Thanks
    Last edited by len- tmaxx 2.5; 09-17-2020 at 05:36 PM.

  6. #6
    RC Qualifier nebulous.cow's Avatar
    Join Date
    Feb 2012
    Location
    Seattle by summer, AZ by Winter
    Posts
    361
    I would go fully sealed honestly. The friction is negligible, but more importantly, if (or when) another gear explodes inside the trans, bits of the gear (or just gear dust from long term use in the grease) can't get inside the bearings and damage them. In fact almost all the RC cars I've ever owned had rubber sealed bearings in the transmissions, no matter being electric or nitro. So I would go sealed all the way.

    On electric rc cars, I would say that it is entirely possible to strip out gears in the trans from the slipper being too tight. Electric motors have gobs of torque, and when you land a huge jump at full throttle, like many people accidentally do, it can certainly destroy the drivetrain in a number of ways. That said...

    Nitro isn't as powerful. Yes, of course, you can do the same thing and nuke a transmission, it is 100% possible and happens to people. But my point is that I've gotten away with a much tighter - or perhaps even cranked to the point where it never moves - slipper clutch setting on my nitros. I don't do huge jumps, and I drive pretty carefully, and enjoy the driving, so I am pretty easy on my cars.

    So unless you did a monster jump or messed up 8 landings in a row or something of that nature, no gears should strip out in the transmission, regardless of the slipper clutch setting. I haven't been inside my Maxxs transmission in years, but I would quadruple check where things are supposed to go. Maybe post a picture of the diagram and parts that are confusing you, and we could maybe help more! But yeah if the gears stripped and you were just driving around, then its more likely to be an assembly error of some kind.

    Hope this helps.

    -Mike

  7. #7
    RC Competitor
    Join Date
    Feb 2020
    Posts
    68
    Wow didn't realize how long it has been since I had this issue! Truck has been sitting in pieces as I was busy. Just found some time to work on it but got excited and ended up installing some 3D printed headlights on the truck. Looks great but the housing is too small so I will reprint soon. Anyway probably need to focus on actually getting the truck running again lol. So the same gear has stripped 2 times in a row- different issues both times. First it was the pin in the slipper and this time it was the axle set screws. I'm trying to figure out if both those assembly errors caused the issue or whether something else has gone wrong that I can't find. The original problem started when I got stuck in a bush and tried to reverse out- somehow destroyed the spur gear. I think the issue had already started at that point as I found 1 tooth of the gear in the tranny. Then after installing the upgrade kit (the pin was installed wrong) the gear fully stripped. Then I removed tranny to fix the pin and put in a new gear but installed the axle set screws wrong (this is why the brake wasn't working). Here's where I'm confused. I get the feeling something broke beforehand that has nothing to do with my assembly errors. When I first opened it after the spur gear got completely stripped I saw the 1 tooth sitting there but couldn't tell where it was from. I thought- well only one way to find out- and put it back together. Any idea how this gear (inside tranny) stripping could correlate to when I got the truck stuck in the bush? I am going to order new bearings (will get fully sealed- thanks for the info nebulous.cow) and a new 4995 gear but don't want to go through another gear stripping if possible. I had a spare the first time but now it's another $12 each time- hoping to save that for upgrades lol.


    Thanks!
    Last edited by len- tmaxx 2.5; 10-12-2020 at 08:37 PM.

  8. #8
    RC Competitor
    Join Date
    Feb 2020
    Posts
    68
    So... can't remember but I either forgot to Google before posting or didn't use the right search terms. I found this thread:
    https://forums.traxxas.com/showthrea...-striped-gears
    Based on this it seems like I just have my slipper too tight? I have it set so it takes a ton of force to turn it but if I really really try I can turn it with my hand. Also something to keep in mind- I have the torque control slipper now so it adjusts different from the stock version.

  9. #9
    RC Champion grizzly03's Avatar
    Join Date
    Dec 2014
    Location
    Adirondacks
    Posts
    2,271
    The torque control slipper is just the revo spec slipper. It has three pads instead of the friction pegs. In my experience you could run a very tight peg style slipper and it still slipped more than the new three pad style (revo spec) slipper assembly with a looser setting.

    I set mine so on a very hard take off it just barely slips for a moment. No need to tighten it down more.

  10. #10
    RC Racer
    Join Date
    Aug 2020
    Location
    Bay City, TX
    Posts
    123
    Given a choice between erring on slipper being too lose or too tight, I’d choose too loose. Easy enough to tighten on the truck if it is.

  11. #11
    RC Competitor
    Join Date
    Feb 2020
    Posts
    68
    Thanks- will definitely keep it loose for testing when I get it back up and running. Do you think the slipper is the cause of the stripped 4995 gear though?

  12. #12
    RC Racer
    Join Date
    Aug 2020
    Location
    Bay City, TX
    Posts
    123
    My best guess from what you described is the original stripped gear problem came from a bad bearing. Did you ever replace those?

  13. #13
    RC Competitor
    Join Date
    Feb 2020
    Posts
    68
    Ok, thanks. Will order them today. The truck has still been sitting as I haven't ordered anything yet. Just trying to find any other causes of the issue before putting everything together- don't want to take apart the tranny for the 5th time lol

  14. #14
    RC Turnbuckle Jr. Nitronaught's Avatar
    Join Date
    Oct 2005
    Location
    South Florida
    Posts
    19,522
    If a bearing seal popped off then usually that means the tolerances of that bearing are out of spec, they can spin freely when not under load but under load be binding. Tranny's are a pain!!!!!!! So do it right the first time, double check everything especially the bearing seats in the tranny case as well. Before closing it up everything should turn as smooth as silk. No notchy feelings if there are there is something wrong. I like Avid Revolutions Ceramics for the tranny. Rubber seal facing towards the dirty part the metal seal facing towards the clean parts.
    All Lives Matter
    United We Stand, Divided We Fall

Tags for this Thread

Posting Permissions

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