How to shim your Arrma diff

RCROD said:

Yes, maybe that's what happened. Actually I used "only" 3 shims total internally for the diff (not including the 13x16 shims for the outdrives). I used "only" (2) 3.5x12x.2mm shims on the planetary gears (Arrma already has 4 planet gear shims in the diff) & I ended up using "only" (1) 5x18x.2mm shim on the satellite gears (just on the crown gear side). Not sure about earlier models, but on the V3 diffs, you definitely don't want to have to take the satellite gear off the diff cup end, especially if you don't have to. It is extremely tight to get off the outdrive. However, the good news is, I found the diff does not like a 5x18 shim behind the satellite gear on the diff cup end (too tight & notchy), so should not have to remove this to shim?

I would like to hear what other members have found when shimming the new V3 diffs.

What is everyone using for "GREASE" between the external diff gears (between the 43T Spiral Diff Crown Gear & 10T Main Input Gear?) I have lots of Mobil (automotive/industrial) high performance 100% synthetic grease. It is white color, but looks like it would be good to use for this purpose? What do you think?

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Hi I use FUCHS - TITAN Race CVJ Grease the grease itself is for Rally Applications, 1 of its main propertys is to relieve pressures between metal contact areas, I have used it a few times on my 1/5 losi in the F/R diffs and also all of the sealed CV's and Dog Bones. Its avail on ebay can be pricey for 500g but well worth it in the long run. Do a bit of research into it and see what you think, Hope this gives you something else to try

Megasty said:

The tolerance on these RTR diffs have gotten much better than the V2. For my V2s, I was all over the place with the amount of shims worked for what diffs. However, for my V3 Kraton, Talion, & Typhon I did nothing. The gears are way too tight to try to wedge any shims. As the gears wear in I'll revisit them to see if they need shimming. I have already opened them for their 3 month checkup & they need nothing. I have to open the Talion & Typhon next month for the 6 mo review.

As for the grease, any white lithium grease will do so the mobile will work great.

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Just to clarify, your v3 Typhon you still have not had to shim any of the diffs @Megasty My Typhon arrives tomorrow and ready to go through it before I take it out

bluedeval03 said:

Just to clarify, your v3 Typhon you still have not had to shim any of the diffs @Megasty My Typhon arrives tomorrow and ready to go through it before I take it out

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I've had it for nearly a year & the diffs are as tight as ever. I've also been really beating on it as of late & I still haven't broken anything on it. I recently found a bash spot that seemed a bit too dusty so I had to open the diffs up to make sure it kept the dust out. Both front & rear was looking on the brown side of red so maybe the very fine particles made it inside. There's no way to keep particles out of the diffs. But I've bashed at that spot for weeks now & the diffs still look perfect. So the particles probably isn't some kind of sand that can grind any type of metal gear to dust.

I have a month old V3 Kraton and I have not shimmed. So far so good. I have replacement diffs so if one goes bad I will rebuild and shims if necessary.

I busted the tips off a couple teeth in the front diff on my v2 outcast.


I have 2 shims on the ring gear side. I can't put anymore in, they won't fit as the case doesn't have the slop for it. I might try putting one behind the pinion when my new diff shows up. I'm only running 4S too. 100k/500k/100k oil. I used just the 6 mugen shims inside each diff and removed the arrma shims on the x-pins.

My first Arrma car is arriving this week: a Notorious. My previous RC experience is with a Traxxas Slash 4x4 and Traxxas Stampede 4x4, both of which are absurdly upgraded. In the Traxxas 1/10th cars the best solution for indestructible diffs is to use the diff that comes with the Traxxas XO-1. Its a direct fit and the upgrades include a "I-bar" that goes between the gears and two small metal brackets that go on the outside of the gears (which fit into the XO-1 diff housing), which are basically "shims". The only upgrade to further improve the XO-1 diff is a metal diff housing to reduce any flexing. I've never heard of anyone shimming the XO-1 differential. Below is a picture of a XO-1 diff (the pictures also shows the stock housing and the upgraded HR housing).



I'm confused about why Arrma diffs need to be shimmed? I've also read the official instructions for a Tekno MT410 (which supposedly has build quality that is as good as it gets) and they state that you likely need to shim the diffs. (and shims are included). Tekno MT410 instructions:




Questions:

1. Has Traxxas figured out how to make a diff that doesn't need to be shimmed but Arrma and Tekno have not figured out the same thing?
2. Why don't Arrma and Tekno manufacture the diff in a way that does not need shimming?
3. Why doesn't Arrma include shims if the diffs commonly need to be shimmed? Tekno includes diff shims with its cars and instructions for shimming is in the manual; Arrma's manual doesn't say anything about shimming the diffs (not that I can find).

UPDATE: I checked the Notorious parts explosion and then looked up the parts. AR310436 (diff rebuild) includes 4x shims. Now I'm more confused than ever about why I would need to shim the diff on a new Arrma. Does it not come pre-installed with the proper shims?




Site note: I'm very pleased that this forum lets me directly upload images. The official Traxxas forums are still using the same functionality that forums had ~15 years ago... which seems to be a common theme with a lot of Traxxas products.

IMHO, As a company, saying your diffs never need shims is to either be (1) willfully ignorant of manufacturing tolerance issues, or (2) deliberately ignoring issues you know you have.

And considering pretty much every Traxxas car has a full catalog of possible upgrades, vs Tekno's "best in the business" does not need upgrade status, I suspect #2 for Traxxas.

This guy has some XO-1 diffs available:

I am a recently converted Traxxas fan myself, and I have shimmed every one of my Traxxas diffs. Original TMaxx, Summit, Rustler
As for why manufacturers don’t do it is because of cost. Do you want to pay for the extra man hours for them to get your machine right, when most of us blow them apart to double check their work anyways?

bicketybam said:

This guy has some XO-1 diffs available:

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Ohhhh ouch. I cringed the first time I saw that video.

Full size truck diffs. all use shims to get the correct gear pattern and backlash. To compare a Traxxas diff. to an Arrma or tekno diff. is like apples and oranges.Try running that Revo diff. that has only 2 spider gears on 6s, it will explode in seconds. I still own a Revo converted to electric and we run it easy on 4s to keep driveline damage to a minimum.

So are the Arrma Notorious diffs not shimmed out the box? The Arrma diff rebuild kit includes shims, so it seems like they would install the shims when you buy a new one?

sevin7 said:

So are the Arrma Notorious diffs not shimmed out the box? The Arrma diff rebuild kit includes shims, so it seems like they would install the shims when you buy a new one?

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Shimming the diffs means adding additional shims to the 4 that are already in there.

sevin7 said:

So are the Arrma Notorious diffs not shimmed out the box? The Arrma diff rebuild kit includes shims, so it seems like they would install the shims when you buy a new one?

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Stock, yes, there are the 4 small shims. The V3 diffs are tighter than the V1 or V2 diffs - sometimes those 4 shims are enough. It is still a good idea to check, though. Sometimes one more large shim under the sun gear is needed, sometimes not. With the V1 diffs, one sun gear shim was always needed, sometimes 2 (one both sides).

Also, for the outside of the diff, sometimes a shim is needed at the gear side outdrive bearing. For the V1, sometimes 2 or 3 were needed.


The Arrma cars are getting better, but with molded plastic and sintered gears, shimming is something that we always need to check, on every rebuild.

The precision on the new parts are real good. Its a trur pain to get the sungear off the outdrive..i put ma diff on a stand, so the outdrive are fre under, and uskng a small hexdriver placed on the outdrive INSIDE the diff cup, and hit it with a small hammer, it loosen the sungear, and then using a plier, and lot of force..

I pulled the front and rear diffs. They seem(?) to be okay, the outdrive bearings were also shimmed - which I was surprised.

My question is, the diffs were smooth, I spun the outdrives back and forth. They were tight enough that I could feel the gearing clicks, but not enough to wear there was binding. This is correct?

I also left the stock diff oil in them because leaking diffs are a peeve of mine and I am terrible at it. In the manual the Kraton CST weight is rated for 10k front and rear. I was going to put 1mil in the center as I will check that diff next. Will this prevent the front tires from ballooning as well?

1 mil will orevent, it should be smooth BUT, feel the teeth so to speak..not bind with a hard ckilck cklick

Thomas P said:

1 mil will orevent, it should be smooth BUT, feel the teeth so to speak..not bind with a hard ckilck cklick

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Yes, exactly how it felt. I can feel the clicks in the teeth, but there is no binding.

Then i would test

Thomas P said:

Then i would test

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Test how? I’m guessing run a few packs and check them again.