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  1. #1
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    Clicking noise with shimmed differentials

    So i contacted the person i bought my merv from and also looked at the listing and it appears that the diffs were shimmed, there was also a pack of shims in the box

    however the revo is making a clicking noise when i accelerate with the wheels on the ground

    from my research it seems the clicking is a result of the diffs, but with shimming it should not really happen

  2. #2
    RC Turnbuckle Jr. Petertje60's Avatar
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    Shimming is a way to decrease the risk of damaging your diff gears, but not a 100% solution that will prevent it.
    If you have clicking sounds during acceleration, in 90% of the cases that is the rear diff gear being damaged.
    Nobody is born with experience

  3. #3
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    Quote Originally Posted by Petertje60 View Post
    not a 100% solution that will prevent it.
    .
    This is VERY true. while a good idea I personaly think it is "parroted" into some save-all setup

    it's also possible you have a piece of gravel in the center driveshaft channel bouncing around -happens to me all the time
    There are lots of ways to do that. Most are wrong.

  4. #4
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    Does it have plastic bulks, plastic skid plate and plastic shock mount?

    The reason I ask is the stock bulk with nothing but plastic surrounding it is very flexible. When in your hand there is no resistance on the wheels so the diff isnt really torqued in the case. Put the kit on the ground and the wheels have to move the weight of the kit, the diff gets torqued causing the plastic to flex ever so slightly the mesh on the ring and pinion move apart and voila grinding sound.

    Shimming minimizes this, but even with shims the plastic will flex and the mesh will not be 100% consistent.

    Alloy bulks solves this but is not the only solution.

    An alloy skid plate and shock mount will do the job. The skid plate will hold the bottom of the bulk securely shut while the alloy shock mount (or you can use the alloy chassis brace from the Toyz to mount the shocks) this will secure the top half of the bulk COMBINED with a properly shimmed diff (Meaning BOTH sides get shimmed, not just the ring side) will give the longest life out of your diffs.

    An alloy bulk and properly shimmed diffs is the closest thing to a Bulletproof set up. While we are still using the same POS ring gear its not going to be truly Bulletproof.

    I will also mention that the alloy bulk shimmed up and or Alloy skid with alloy shock mount shimmed up will alloy bad ring gears to run fine, you would be surprised how long a chewed up ring gear will last if its shimmed up tight in an alloy bulk.

  5. #5
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    I agree about the aluminum skid plate. It's a cheaper, fix though maybe not as effective.
    Also the past six new bulkheads I attempted to shim took zero shims. Yours could have been the same which would explain the pack of shims in the box.

    However, shimming both sides of the carrier yields a gain of.... ZERO in terms of gear engagment. This is wrong.
    (unless your bulkhead has an outragous amount of slop in which case I would just throw it away.)
    Last edited by photon_trap; 05-07-2013 at 02:07 PM.
    There are lots of ways to do that. Most are wrong.

  6. #6
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    To elaborate a bit on what I mean, and why I believe its important to shim both sides, not just the ring gear side.. Theories are great in theory, but sometimes we learn more experimenting in practice

    Shimming both sides Why? Well it is simple really, the mesh can either get too tight, or too loose, Simple as that... Neither is good.

    Shimming ring side only, will only work to keep the mesh from getting too far apart, but does nothing to stop the mesh from getting too tight. Shimming both sides will keep the diffs nice, smooth and consistent, practically fixed in place, this is important because it give you a consistent practically fixed ring and pinion mesh.

    That little tight spot on a new ring (if you have done a few you know what Im talking about) well that was perfectly smooth for me on a fresh install.

    Originally Shimming only ring side, that tight spot was still there for me too, all was nice as it should be, I had 2 shims ring side & nothing on the other side (Alloy bulks ) it was as usual "smooth smooth tight spot, smooth smooth tight spot", etc (and the experience is shared by everybody I spoke with who has a MERV at the time, it is normal, and occurred on every bulk I put together, I build kits from the ground up, no RTR's) It bothered me though, everybody saying give her a few packs it will smooth out and at that time check if you need to add a shim... I didn't like this, but it was the general consensus...

    And then common sense smacked me in the face I got the shims keeping the mesh from getting too loose, but nothing to keep it from getting too tight. IF the ability to move enough to get too loose is there then the same ability to get too tight is also there, it has nothing to do with a faulty bulk.. If it can shift one way enough to cause a problem whats to stop it shifting the same amount the other way?

    Soooooo I took out a shim from the ring side and put it on the other side (still at the time 2 shims total) right away it got about 60% better, smooth(er) brand new ring, I then tossed in a second shim on each side, so total of 4 shimms, and I don't know a smoooooother running set up. Now think about that for a second. I had a Tight spot with only 2 shims, But Smooooth rotation after adding 2 more shims on Allloy Bulks. Basically this tells me that while it MAY feel tight and nice in my hand, even still a little bit of play can still be there when the power system puts power through it, we are talking play in the diff that is not perceivable squeezing it and trying to move the diff in your hand.

    Pack 1 to about 25 or so (who's counting really) and it feels the same as day 1, not to mention she's done countless standing backflips and backflips off ramps. The front bulk (also alloy) has 3 shims, 2 ring side and 1 on the other, it will be different for each bulk more or less. With an alloy bulk getting it spot on the first time, you wont have to open them for anything to do with the ring or pinion...

    My Rally has plastic bulks with alloy rear skid and alloy shock towers front and rear. Not as many shims in her, 1 on each side front and rear. Its good, but not as good as my MERV with alloy bulks, the MERV is much much smoother, the plastic bulks really are garbage but do the job, and as it is I have no worries about messing up the ring, and no grinding noise ever, aside from the annoying tranny whine lol...

    Ohh, I will also add that I went through a handful of ring gears before this current set up, so I am very familiar with the grinding nasty sound clicking on accel, embarrassing, everybody just asks "whats wrong with it" or ""Its broken, are you going to buy a new one" lol starts off as just a little but OMG it gets loud and nasty lol
    Last edited by SiNFULREVO; 05-07-2013 at 05:49 PM.

  7. #7
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    Your observations seem to differ from mine and most people here's.
    And personally, I do not believe you are anywhere near correct. I can elaborate later as I have no time for these activities now.
    There are lots of ways to do that. Most are wrong.

  8. #8
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    Ill read over your elaboration when you post it, but I'm good, I know what Im doing (MERV is toy stuff compared to my Savage XL's, with 3 times the weight it has to be built much much much more tough, especially the way I like to Bash and crash) the perfect mesh on my diffs is all I need But please, feel free to elaborate lf you like wont change my mind, or anything really.
    Last edited by SiNFULREVO; 05-07-2013 at 08:44 PM.

  9. #9
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    Clicking noise with shimmed differentials

    Your bulks must have more play than usual. Not saying your method is incorrect but an equal amount of shims on each side doesn't move the diff towards or away from the pinion. I could understand an offset amount of shims if theres excessive play in the non-ring side. As far as the tight spot in the diff ring, I think it should be there on fresh diffs. Every mechanical thing I've built/rebuilt has called for a "break in" period where the parts wear to each other to create tight tolerances. As far as the diff shifting and getting tighter, I don't see that happening. All the forces applied to the driveline make the ring and pinion want to separate.

    What I'm seeing is that you've created more of a gap in the smooth areas in order to smooth out the single rough area.
    Last edited by TheMajekalBum; 05-07-2013 at 09:01 PM.
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  10. #10
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    Your confused, the count need not be equal never said it did, the amount that is required will be different from bulk to bulk.

    The shims position the ring and pinion mesh. If you have 4 shims (to keep it simple) 2 on on each side, take one shim off the ring gear side and put it on the other side, you have move the ring gear away from the pinion, if you do the opposite. Starts with 4 again, 2 on each side, you now take one off the other side and put it on the ring gear side, you have now moved the diff closer to the pinion.... The shims are used to position the mesh perfectly preventing it from getting too tight or too loose, how many you need if any on each side will be different bulk to bulk, point is if your shimming don't ignore the other side, see if it too needs a shim or 2

    Equal amount not required and even as I said its different bulk to bulk some may not even need it, its wrong IMO to not address both sides when shimming, people seem to think you only toss shims on the ring gear side, thats not right if they completely ignore the other side simply assuming it doent need a shim when it very well may need one. From my experience adding one give better result then ignoring it, actually better then most as I have a smooth diff from pack 1 to current and its the same over 20 pack later consistent smooth performance

    Um alloy bulks may need a bunch more shims they are solid and the shims are used (as I said) to set the mesh, how many you need is not as relevant as you having all the shims you need. If its 2, 3, 4, or 5 even, it doesn't matter as long as your mesh is set correct.
    Last edited by SiNFULREVO; 05-07-2013 at 09:21 PM.

  11. #11
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    Clicking noise with shimmed differentials

    Read my post again please, I did mentioned that point.
    Dye-no-mite Pow-er Go Fast, Wirrrrr Screeeech BOOM

  12. #12
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    Quote Originally Posted by SiNFULREVO View Post
    feel free to elaborate lf you like wont change my mind, or anything really.
    I have no reason attempt to to do that so considering my elaboration would be largely noise on this forum I'll do everyone a favor and keep it short.

    My belief is that the plastic bulkhead is a POS and beyond shimming the ring side as usual, I don't think there is a whole lot more to be had as there is (in my experience) not any play left on the other side due to how the whole thing contorts when screwed together, and, again when attaching to the chassis and, again when attaching the skid plate.

    Aluminum bulkheads are another story but, due to their inherent (improved) rigidity and the lack of shims thinner than .005 (at leas as far as I am aware of) I am doubtful of this too unless there is so much slop that the pinion bottoms in the ring gear valley. I have never seen this.

    Again all my latest bulkheads (new ones) have required minimal shimming to achieve near zero measurable side play.
    There are lots of ways to do that. Most are wrong.

  13. #13
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    If they require 0 shimming they require 0 shimming, the point of shimming is not to forcefully add shims but to add them where they are needed regardless of what side its on tighten the bulk screw down and you will find your valley lol Or are you really saying you can torque the screw securing the bulk all the way down and have free rotation, THAT I find very hard to believe.......

    I also agree they need to be broken in, but mine is smooth from install to broken in, amd consistent the whole time, while yours has to smooth out... Perfect mesh from day one or work your mesh out over a number of packs rough at the start? hmmmm A lot of what your smoothing out is simply grinding off the very tip of the teeth in the tight section of the gear, once the tips are gone its smooth(er) not even close to how I got them (been there before lol) the shims and tightened bulk keep it from getting too loose so it works, but probably is still a bit noisy, noisier then what I got I'm certain. I also think it will last a good time like that too, but never get to the level of smooth performance than as if it was done right the from day 1...

    The plastic bulks are garbage, greatly because of how its held together and the stupid screw being able to tighten past the optimum position, your method basically allows for you to tighten down the screw holding the bulk together tighter then you should having that over torqued to keep the diff in place. Well many people have alloy Bulks so if giving advice on setting up the diffs that should be taken into consideration and your method of keeping your diff safe is irrelevant as you cannot over torque the diff screw to snug it in. Now we have to properly shim the diff to do it right.

    Its not even a question of opinion, that's whats funny about this. To say its impossible for a shim to be required on the other side is an assumption at best lol should learn not to make assumptions, leads to big mechanic bills, but hey, I would be out of business if people could all fix their own stuff lol and my biggest bills are most often handed over to somebody who tried to do something themselves because they got great advice online.....

    The margin of error on these alloy parts is beyond .005 It would be a serious accomplishment for them to achieve that level of precision, NOT happening, but would be nice if they could.
    Last edited by SiNFULREVO; 05-07-2013 at 09:58 PM.

  14. #14
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    What brand alum bulks you got? My HRs didn't require any on the non-ring side, yes I did check when I did them(I understand drivelines, I work on 1:1) . Also another area you can shim that will help is the pinion, it has fore an aft play(atleast mine did), you'd want to shim it in towards the diff.
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  15. #15
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    Hot Racing front and rear, HR Pretty much everything, but the odd thing here and there lol TRX CVD not HR though





    Right on shimming the pinion, I believe some new models even come from factory with the pinion shimmed, I could be wrong though

    Quote Originally Posted by TheMajekalBum View Post
    What I'm seeing is that you've created more of a gap in the smooth areas in order to smooth out the single rough area.
    I was worried about this, so I opened her up after the usual 5 to 10 packs to see if I would need another shim at that point but it didn't it was the same, no shims added, just consistent. I had also noticed (when I was shimming only one side, ignoring the possibility of needing a shim on the other side.) that when it was broken in, not all the teeth were equally pointy, a small section was ever so slightly not as pointy as the rest. I was using plastic bulks on my merv at the time. Ive had the HR bulks shimmed on both sides since day one.
    Last edited by SiNFULREVO; 05-07-2013 at 10:24 PM.

  16. #16
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    Thanks for the posting, it will help and i will look into those tips

    Quote Originally Posted by SiNFULREVO View Post
    Does it have plastic bulks, plastic skid plate and plastic shock mount?

    The reason I ask is the stock bulk with nothing but plastic surrounding it is very flexible. When in your hand there is no resistance on the wheels so the diff isnt really torqued in the case. Put the kit on the ground and the wheels have to move the weight of the kit, the diff gets torqued causing the plastic to flex ever so slightly the mesh on the ring and pinion move apart and voila grinding sound.

    Shimming minimizes this, but even with shims the plastic will flex and the mesh will not be 100% consistent.

    Alloy bulks solves this but is not the only solution.

    An alloy skid plate and shock mount will do the job. The skid plate will hold the bottom of the bulk securely shut while the alloy shock mount (or you can use the alloy chassis brace from the Toyz to mount the shocks) this will secure the top half of the bulk COMBINED with a properly shimmed diff (Meaning BOTH sides get shimmed, not just the ring side) will give the longest life out of your diffs.

    An alloy bulk and properly shimmed diffs is the closest thing to a Bulletproof set up. While we are still using the same POS ring gear its not going to be truly Bulletproof.

    I will also mention that the alloy bulk shimmed up and or Alloy skid with alloy shock mount shimmed up will alloy bad ring gears to run fine, you would be surprised how long a chewed up ring gear will last if its shimmed up tight in an alloy bulk.
    however i am afraid of having too much metal and not enough plastic to absorb any damage, with all that metal the damage will transfer and possibly damage something more vital and expensive
    Last edited by cooleocool; 05-11-2013 at 04:30 PM. Reason: merge

  17. #17
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    Is the spur gear stripped?

  18. #18
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    just shimmed my rear diff today since was clicking and 1/5th of the teeth were getting short but shim still worked for now, but yeah the plastic bulkhead is no good, need 1 or 2 more screws somewhere on it to hold the thing together before even screwing it back onto the chassis/skidplate lol, all thats holding it together is the one screw they added and when it gets screwed into the chassis and skidplate, ideally the bulkhead should be nice and tight before its even put onto the chassis but its not designed like that heh, not sure how the metal bulkheads are put together but if its just one screw holding htem together even thats still flawed, and the shims on the ring side only make sense to me as the whole point is to keep the ring against the pinion as the pinion is in a fixed location(since the screw holding the bulkheads together is right at the pinion so its the diff thats probably gonna move not the pinion) even the manufacture process of all the parts arent accurate enough for everything to mesh and wear out perfect, it is just a toy, plastic would be fine if they designed it someway to keep the bulkhead together, be it add another screw on other side of it or whatever, and thats my rant lol


    Edited for language abuse. If you you see a starred out word in your post, you must edit it out to avoid earning warning points.
    Last edited by cooleocool; 05-27-2013 at 12:43 PM.

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