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Thread: Mini Diff Post

  1. #1
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    Mini Diff Post

    Here is a mini post on how to get more out of them. The first thing is you have to repack your bearings used in your diffs. It doesn't matter if they are Traxxas or not; if they aren't steel sided bearings (which are good, but difficult to repack), repack them. Most bearings are setup for racing and not for bashing in most environments.

    Looking at both sides of a new bearing, this is what a new bearing looks like. Notice hardly any grease. This is okay for racing, because racers change bearings after each racing day or before their next racing day. But, for us for us bashers, this bearing doesn't have enough grease.

    Side 1



    Side 2



    Here is a repacked bearing (this is what's needed for bashing)



    The next thing you want to do is either have SPLINE drive shafts or Traxxas CV drive shafts. If you use Traxxas CV's as I do (they have a big advantage over splines, but I'm not going to get into it now) you have to keep your drive cups from getting notched.



    Notching, of your drive shafts, keeps your diff's pinion gear from finding and keeping it neutral relationship with your diff's ring gear. What you want to do is un-notch you drive cups. Yes, a little slop is introduced, but now you have full advantage of drive cups over splines.



    The next thing you want to do is change your inner pinion bearing to a OilLite bronze bushing. You can either make one as I did here, or buy one from EBay. Also, you can change both diff pinion bearings or one as I have done here.



    Next, you want to shim any slop within the relationship of diff housing and its' internal components. Here is the diagram that we (us long time Emaxx owners) use. It's only a guide of where shims might be needed. There are many places to get these shims, bit I personally get my shims from Horizon Hobbies.



    Lastly what I do is, I reverse install my Traxxas CV drive shafts (placing the RED side to the transmission), and I put a 1.5mm shim (plus any above diagram shims if needed) between my drive cup and diff. This technique locks in my (pinion gear/ring gear) relationship no matter what my CV drive cup notching status is. Plus, it makes off season diff inspections easier and faster.





    You'll notice that the above picture also shows an aluminum case. I haven't used this diff yet, because I built it just before I figured out a way to make (now you can buy) OilLite bushings. Inside this diff is also a set of spirals, but again I haven't used it yet. The reason? Because, the OilLite bushings (along with the above) has worked so well I haven't had any premature diff failures.

    Anyway, you can use spend the money on aluminum diff cases and spirals if you want, but I wouldn't knowing what I know now. Why? Because, what I wrote here today does not make a bulletproof diff. It only makes a very much more reliable differential. If I do ever have a premature failure, I don't want to change maybe a 100-ish dollars worth of parts. I want to only have to change about 25 dollars in parts...nobody can guarantee bearings. If they think they can, then they're just kidding themselves.

    What I wrote here today...the whole purpose of this Mini Diff Post is to tell you all (I've gotten many PM requests) how to get though a RC season with your Emaxx diffs, and how to do it cost effectively.

    Still though, understand, that at the end of your RC season it will be necessary for you to break down each of your diffs, repack (or replace and repack) your diffs' bearings, and check the wear of your OilLite bushings. Like I said above, there is no such thing as a bulletproof diff.

    From there you can see how your diffs are holding up, and whether or not you can extend or shorten your inspection intervals. For me as an example, if I have a normal season with my Emaxx, I inspect my diffs every 9 months. A normal season for me is at least 8 hours of run time each week end form March though December.

    If any questions, (I know I didn't explain about a lot of why's, and how's) just let me know.
    Last edited by ReglarGuy; 03-03-2018 at 07:43 AM.
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  2. #2
    RC Turnbuckle Jr.
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    P.S. I forgot to say this, but all the above only applies to guys (like me) that use their Emaxx on dirt and mud. I can't even remotely say that the above will work for guys that play in water, on snow, or blacktop.
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  3. #3
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    Thank you Sir this is really going to help a lot, I was surprised how little grease was actually in brand new unused bearings. I can tell you from experience that with the amount of water we run in, these tips will improve our run time.
    If we out here didn't play in water (avg.12 ft a yr of rain) we would never get to run them it just takes a little more effort to maintain but it's not for everyone lol.

    Thanks ReglarGuy

  4. #4
    RC Turnbuckle Jr.
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    You are very welcome.

    If we out here didn't play in water (avg.12ft a yr of rain) we would never get to run them it just takes a little more effort to maintain but it's not for everyone (lol).
    Not a problem, but being that you do, you might have to go though your truck's diff's every 6months rather than every 9 months like I do. I'd run it (with my above suggestions) and see what time you get out of your diffs. Then go from there.

    This year I didn't have to break mine down, because I didn't get my normal run hours in this last season, and I know from experience with my truck that my diffs should still be good. That's what you need to do once you get your trucks diff's sorted out...get a feel of what you can, need and have to do to minimize your unscheduled breakdowns. Minimizing your unscheduled breakdowns is the name of the game with RC rigs.
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  5. #5
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    You are 100 % correct

    (Minimizing your unscheduled breakdowns is the name of the game with RC rigs.)

    I had planned on keeping logs and in the process of numbering my diff's just for personal reference to log hrs and conditions.
    Lucky I crashed last week and decided to check the diff's, front had inner bearing starting to come apart (good save) but the rear diff (stock plastic) had a split inner diff cup but everything was good internally.

    This should extend the complete tear down (every 3 months) to maybe twice a year.

    If Traxxas ever wants to send me any NEW machines for water testing I'm up for the challenge lol.

  6. #6
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    If Traxxas ever wants to send me any NEW machines for water testing I'm up for the challenge (lol).
    There you go. (lol)
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  7. #7
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    Diff's are done in one truck and decided while it was apart to change front bulkheads, I thought I might as well re-pack all my bearing so everything starts out fresh lol.

    Figure I might as well rebuild the second E maxx (tomorrow) and pack all those bearings and then do the stampede lol.

    Thanks again ReglarGuy for making life easier.

  8. #8
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    Thanks again ReglarGuy for making life easier.
    That's what RC friends are for, right.
    The ReglarGuy is kid tested and father approved.

  9. #9
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    The truck's bearings and diff's are done and I coated the tranny gears with the marine grease as well and now the tranny seems like it has a center diff, barely any front wheel lift and more traction lol.

    Repacking the bearings was an awesome idea because so many had next to none and with all the water running we do this is definitely going to save on parts wear and tear.

    Only 1/2 hr running to test but after the long list of everyone else's project's I'll start the other 2 trucks.

    Thanks again ReglarGuy keep the tips coming the more money I can save the closer we get to adding another RC lol.

  10. #10
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    Quote Originally Posted by Rain Dawg View Post
    Curious as to what aluminum diff housing in that pic on your thread and did you put an aluminum cup in also and if so what make thanks.
    The diff housing is from Integy ($20), and yes, I did put in an aluminum cup. It was from Hot Racing ($15). Both were good prices, so I figured I'd give them a try. I haven't used them ret though, because using those bushings instead of bearings (as I describe above) has really worked out well.



    Last edited by ReglarGuy; 03-07-2018 at 01:58 PM.
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  11. #11
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    Thank you thought it was Integy but wasn't sure.

    Prices here are insane the best I can come up with is (HR) 34 + shipping for the diff cup and (Integy) 43 + shipping for the housing.

    I just like the looks but the stock plastic are cheap and easy to come by and if I would have had more knowledge at the time and shut it down when I heard the clicking the inner bearing that had let go and destroyed the ring and pin the damage to the housing could have been avoided.

  12. #12
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    Squeezed in a solid jumping and bashing session after dinner tonight which totals 3 runs since the diff build and no issues (or fence posts) and could of had one more round of batteries but the little guy decided that the weather had dictated archery season so zinging arrows took priority lol.

  13. #13
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    I agree with you with regard to alloy cases. They look nice, but they're not needed. I just got a really good deal on them, so I bought them.

    As far as the other stuff you mention, I'm glad doing all that stuff worked out well for you with getting you better diff reliability, but I'm saying you don't have to go though all that. Nothing wrong if you do, but I'm into easy, simple, and things like cost effective.

    If you read the very beginning of my post, you will see what I did to get a year of trouble free bashing out of my diffs for a whole lot less money and time than what your way is. For me, that is the game of the game...easy, cheap, and reliable. Yes, there are those who call me crazy, call me a rebel for having that philosophy; but as a ReglarGuy I can't help myself.
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  14. #14
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    Technically out of the 4 diff's I've damaged everyone has been because of the inner bearing fail which led to the ball bearings going into the ring and pinion.
    I know that this bushing swap method will solve that problem (a larger bearing would be perfection) I 100% trust in ReglarGuy's opinion and R&D that him and his friends make this work.
    I joined these forums to solve my diff problems and was all in on the LST2 swap, more research and a simple fix puts more money in my pocket.

    Almost 2200 hit's on this thread in 7 days tells me a lot of bushing are being sold. I've posted before the only true bullet proof RC is the finger on the TX.
    I am literally trying to blow my diff's in the 3 runs I've had 100 ft wheelies tires ballooning finger mashed all the way back and my slipper torqued down double nutted, I want to see how this holds up for my self and the Truck is performing above my expectations so far.
    10 ft high impacts off jumps and nothing broken yet lol, after 10 battery sets I'll pull the diff's and check for wear on the bushing but I also think using marine grease instead of oil helps with proper shimming.

  15. #15
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    Totaling 7 runs and no diff problems, I managed 3 back to back runs after dinner with no down time except to change packs with no issues. These diff's so far have been torture tested and I'm loving how well they've held up to previous diff's.
    Changing the body pins out to double sided rubber grommets has been a blessing the body stays on no problem and with a couple of 20 ft cartwheels the body has come off with no breakage.
    Losing a shell every 3 to 4 runs was becoming a pain and now it looks like I might have solved that problem.

  16. #16
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    Quote Originally Posted by Rain Dawg View Post
    Changing the body pins out to double sided rubber grommets has been a blessing the body stays on no problem and with a couple of 20 ft cartwheels the body has come off with no breakage.
    Losing a shell every 3 to 4 runs was becoming a pain and now it looks like I might have solved that problem.
    Could you share some photos of this solution? It's always good to improve things with almost no cost..

  17. #17
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    I have this "Reglar" diff mod done on mine. It works perfect! I was amazed at how well it really is. I am running stock plastic cases with the inner oillite and shims where needed. I am a little confused as to why swap the driveshafts around. I have mine on normal way and I do have shims between the yoke and shaft pin. No wobble anywhere. Smooth as butter. I have only run 6s in it and mostly full throttle grunt all the time. My truck is pretty heavy from all the flm parts on it, so I don't do huge jumps. Lots of blacktop running so it sees lots of wheelies. I really have zero complaints. For maintenance, I do not plan on tearing down until it breaks. Only because I want to see how long it goes. Thanks for the R&D Reglar!

  18. #18
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    Same here everything stock but the bushing mod and my reasoning for torture testing my diff's in the 11 full pack runs I've had up to last night is not to disrespect ReglarGuy for all he's done, but to see for myself what kind of abuse these diff's can withstand through the mud and water I run in.

    I can honestly say no previous diff lasted 1/3 the abuse before letting go in one way or another. I broke my first part last night on the last jump which was the slowest and nothing over 2 ft (packs were running down) and it was p/n 4945 the tie bar between the servos.

    So thank you ReglarGuy for all the help and the cheapest and easiest fix an rc guy could ask for, it might not be bullet proof but even Kevlar has it's down falls lol.

  19. #19
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    Thanks for the R&D Reglar!
    You're very welcome.

    I am a little confused as to why swap the drive shafts around.
    Easier to maintain, remove and replace, and to shim the pinion gear for if/when the drive cups get notch-ey keeping them from tearing up the spur gear.

    It might not be bullet proof but even Kevlar has it's down falls, lol.
    I'm glad it's working out for you guys. I took the tip from the British guy in our other post, and ordered the Tamia truck bushings (which are the same size as the ones I was making). I changed mine over to the Tamiya bushings the other day, and I too have been running trouble free (diff wise). The Tamia bushings are a good alternative to making them.
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  20. #20
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    I don't think I've ever heard of someone breaking TRA 4945. If you mean 2537 coming out of 5349, then there's a fix for that.
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    It's the cross bar that hooks to the 2 post on the bell crank I'll try a pic but that's like winning the lottery with me.


    3 on my brushless and 2 on my stock
    Last edited by Rain Dawg; 03-30-2018 at 02:27 AM.

  22. #22
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    I think you're the first person ever in the history of Traxxas-ism to ever break one of those.
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  23. #23
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    Well I can't explain it (my driving) that's 2 in the 13 run's since doing the diff mods. I took the one out of my stock to continue running until my HR aluminum shows up. Chalk all 5 up to driving habits but considering the abuse this rig has been through I consider it a hiccup.

    At least the body clip mod has worked out the last 30 ft cartwheel was a doozy lol.

  24. #24
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    Well after 22 packs no broken parts minus the 2 pictured above. I pulled and stripped the diff's and they were both pristine with no slop or wearing.
    I am totally amazed at how something so simple (bushing mod) could make life so much easier and have so much more bashing and running time with a lot less worries.

    Thanks again ReglarGuy

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    Does anyone know the part number for the oilite bushings?

  26. #26
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    Quote Originally Posted by Nitrousman90 View Post
    Does anyone know the part number for the oilite bushings?
    You have to go to EBay and put this in:

    Tamiya 1/14 Semi Truck Trailer 1260 Type Metal Bearing 9415549

    and, they ship from England.
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    I purchased the bushings directly from Tamiya USA which ships domestically. Here's to hoping for a lot less troubles from my diffs!

  28. #28
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    Quote Originally Posted by Honaker91 View Post
    I purchased the bushings directly from Tamiya USA which ships domestically. Here's to hoping for a lot less troubles from my diffs!
    What part number and website did you use? I didn't have any luck when I tried finding them on Tamiya USA. I'd rather get them here then from overseas.
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    Last edited by Honaker91; 05-26-2018 at 07:54 PM.

  30. #30
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    I thank you and my Emaxx thanks you.
    The ReglarGuy is kid tested and father approved.

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