How to shim your Arrma diff

[performula]

This guy has some XO-1 diffs available:

Holy smokes!

 

[Janneck79]

Hi together, i am a little bit confused about shiming the planetary gears. Some of you use one additional shim only on one side. In my understanding, that will produce additional stress to the diff because of different gear mesh between the sun gear and the plantetary gears. Two of them are tighter then the others. I am worried to get problems if the diff is not build symetric.

 

[Mr.Duke]

Hi together, i am a little bit confused about shiming the planetary gears. Some of you use one additional shim only on one side. In my understanding, that will produce additional stress to the diff because of different gear mesh between the sun gear and the plantetary gears. Two of them are tighter then the others. I am worried to get problems if the diff is not build symetric.

The 2 shafts that hold the smaller satellite gears allow them to self center within the differential so adding an extra shim on one end doesn't apply uneven pressure on the larger sun gears

 

[RCROD]

Hi together, i am a little bit confused about shiming the planetary gears. Some of you use one additional shim only on one side. In my understanding, that will produce additional stress to the diff because of different gear mesh between the sun gear and the plantetary gears. Two of them are tighter then the others. I am worried to get problems if the diff is not build symetric.

Instead of adding another shim to one side, I found changing the stock .15mm shims to slightly thicker .2mm shims works best. I also think this is a better way to shim the diffs, as everything is perfectly centered and diffs end up with no play, yet still buttery smooth. After countless dry fits, I found this worked best.

 

[Janneck79]

The 2 shafts that hold the smaller satellite gears allow them to self center within the differential so adding an extra shim on one end doesn't apply uneven pressure on the larger sun gears

How should it help to self center. The pressure goes against the housing. And if there is on one side one more shim, the pressure is uneven and out of center. That can not be good.

 

[Mr.Duke]

How should it help to self center. The pressure goes against the housing. And if there is on one side one more shim, the pressure is uneven and out of center. That can not be good.

Thousands upon thousands of diffs have been shimmed this way; and it works.
Can you show one example of diff failure to validate your concerns?

 

[Notorious J]

How should it help to self center. The pressure goes against the housing. And if there is on one side one more shim, the pressure is uneven and out of center. That can not be good.

I understand your apprehension, but almost every thread I've read, and You Tube video I've watched, all say the same thing about shimming the difs. I purchased a V3 Outcast (Notorious) and a complete set of brand new differentials from Jennys Rc. After taking apart the 3 loose difs, cleaning them and reassembling using the @Thomas P video, you could feel how much smoother the setup was. It's a case of longevity for the internal gears, pinions and ring gears. After a few good runs, I will be taking out the units from the new truck, and rebuilding them in the same way, using different fluid weights. I'll have two complete set ups, ready to go, and easily interchangeable. I'll be changing to the Fast Eddy rubber sealed bearings at the same time.

 

[olds97_lss]

Thousands upon thousands of diffs have been shimmed this way; and it works.
Can you show one example of diff failure to validate your concerns?

While it may work ok, I see his point. The teeth of the sun gear are contacted at different points from the edge of the sun gear on opposing sides if the side/spider gears aren't shimmed the same. So the load placement on the sun gear would differ from center from one spider to the other. I've read many shim this way and it seems to work out ok. Seemed odd to me as well to have them shimmed different. In that case, I'd do like @RCROD mentioned and use thinner shims so I could shim all 4 spiders the same.

I was fortunate as mine didn't feel overly tight with the 6 mugen shims in the diffs (1 under each spider/satellite and 1 under each sun/planetary).

 

[Mr.Duke]

You're adding additional shims to close the tolerances between gears as they mate together within the design of the housing. It's a fixed space you're working within, All you're trying to achieving is to reduce the void that already exist between gear teeth by literally thousandths of an inch on opposing cone shaped gears that travel 360 degrees on a fixed axis (x3). Symmetry on such a minuscule scale is irrelevant from a mechanical standpoint as long as you don't close the tolerances on opposite sides beyond a certain point. That "certain point" can be felt by hand as severe notchiness, binding or complete lockup at some point in the 360 degree rotation.
Also....if the level of force needed to reach any degree of concern regarding uneven loading on internal components where reached by adding one additional shim per shaft, you wouldn't be able to assemble and turn the opposing shafts by hand without feeling that severe binding and notchiness IN ADDITION TO a noticeable wobble from one or both of the external drive cups.

 

[Dutch213]

I understand your apprehension, but almost every thread I've read, and You Tube video I've watched, all say the same thing about shimming the difs. I purchased a V3 Outcast (Notorious) and a complete set of brand new differentials from Jennys Rc. After taking apart the 3 loose difs, cleaning them and reassembling using the @Thomas P video, you could feel how much smoother the setup was. It's a case of longevity for the internal gears, pinions and ring gears. After a few good runs, I will be taking out the units from the new truck, and rebuilding them in the same way, using different fluid weights. I'll have two complete set ups, ready to go, and easily interchangeable. I'll be changing to the Fast Eddy rubber sealed bearings at the same time.

The @Thomas P video is the best one ive seen...I didnt even know it was his the first time i saw...he did a great job with that vid...

 

[Janneck79]

You're adding additional shims to close the tolerances between gears as they mate together within the design of the housing. It's a fixed space you're working within, All you're trying to achieving is to reduce the void that already exist between gear teeth by literally thousandths of an inch on opposing cone shaped gears that travel 360 degrees on a fixed axis (x3). Symmetry on such a minuscule scale is irrelevant from a mechanical standpoint as long as you don't close the tolerances on opposite sides beyond a certain point. That "certain point" can be felt by hand as severe notchiness, binding or complete lockup at some point in the 360 degree rotation.
Also....if the level of force needed to reach any degree of concern regarding uneven loading on internal components where reached by adding one additional shim per shaft, you wouldn't be able to assemble and turn the opposing shafts by hand without feeling that severe binding and notchiness IN ADDITION TO a noticeable wobble from one or both of the external drive cups.

If you shim one side more i do not think you will notice a wobble. Usually you are holding the diff housing in one hand and turning one outdrive. The planetary gears are fixed in the housing. So what would happen is that the outdrive would come out in a little bit of an angle to the housing. That angle would stay at the same spot. That only can happen if the tolerances between sun gear and outdrive are realy bad. The thing thst will happen most likly is a uneven wesr in the bushing of the housing because of the aditinal pressure to a fixed point in the bushing. But ok, it seems that it works and some of you beating the hell out off your diffs without breaking. Maybe i am a little bit to concerned in that point it only does not feel right to me.

 

[Lazy Bushman]

Guys can can you tell this nube in simple terms two things re shimming the diff’s in my new V3 Kraton?

1) Why would I want to?
2) what risk or problem am I fixing that I don’t know about?

Thx in advance

 

[olds97_lss]

Guys can can you tell this nube in simple terms two things re shimming the diff’s in my new V3 Kraton?

1) Why would I want to?
2) what risk or problem am I fixing that I don’t know about?

Thx in advance

Shimming removes excess gear lash from the internal gears and the ring/pinion as you can add shims for that as well. Also, if your diffs don't have shims under the larger sun/planetary gears, having shims there may help the o-ring sealing the diff last longer as the o-ring will be pushed against from a nice smooth shim vs the back of the gear itself. I can't remember 100% if my outcast had shims on the backs of the sun/planetary gears or not. I don't believe it did.

Removing the excess gear lash puts more of the teeth into each other which makes them less likely to break the tips of the teeth off on hard landings or hard acceleration that these trucks are capable of.

 

[Notorious J]

Shimming removes excess gear lash from the internal gears and the ring/pinion as you can add shims for that as well. Also, if your diffs don't have shims under the larger sun/planetary gears, having shims there may help the o-ring sealing the diff last longer as the o-ring will be pushed against from a nice smooth shim vs the back of the gear itself. I can't remember 100% if my outcast had shims on the backs of the sun/planetary gears or not. I don't believe it did.

Removing the excess gear lash puts more of the teeth into each other which makes them less likely to break the tips of the teeth off on hard landings or hard acceleration that these trucks are capable of.

Well said. Notorious/Outcast V3 include one shim behind each of the satellites, none under the planetary/sun gear and they do include one on the outside of the bearing in the bulk head. I believe the last one is something new, as the Thomas P video shows him adding it where there was none in previous versions. I used the Mugen E0206 kit to add one shim per satellite shaft (each shaft has three now) and one shim under each of the planetary/sun gears

 

[olds97_lss]

Well said. Notorious/Outcast V3 include one shim behind each of the satellites, none under the planetary/sun gear and they do include one on the outside of the bearing in the bulk head. I believe the last one is something new, as the Thomas P video shows him adding it where there was none in previous versions. I used the Mugen E0206 kit to add one shim per satellite shaft (each shaft has three now) and one shim under each of the planetary/sun gears

On the ones in my outcast, I used the same shim kit as you, but I removed the stock shims wherever they were and used all the E0206 shims instead. I ran mine a bit in stock form, probably 3-4 packs before the diff oils and shims I ordered showed up. After cleaning out the old oil and putting the E0206 shims in, it didn't feel "notchy", but also didn't feel much slop when dry. I also have I think 3 shims on the outside of both ring gear bearings.

So, I have a single E0206 shim behind each satelite (spider) gear and behind each sun (planetary) gear for all 3 diffs as well as 3 shims on the outside of each ring gear bearing on the front/rear diffs.

 

[Notorious J]

On the ones in my outcast, I used the same shim kit as you, but I removed the stock shims wherever they were and used all the E0206 shims instead. I ran mine a bit in stock form, probably 3-4 packs before the diff oils and shims I ordered showed up. After cleaning out the old oil and putting the E0206 shims in, it didn't feel "notchy", but also didn't feel much slop when dry. I also have I think 3 shims on the outside of both ring gear bearings.

So, I have a single E0206 shim behind each satelite (spider) gear and behind each sun (planetary) gear for all 3 diffs as well as 3 shims on the outside of each ring gear bearing on the front/rear diffs.

Can you tell me, based on this pic, where you put the 3 shims on the outside? What size and thickness if you have the info. thanks

 

[olds97_lss]

Can you tell me, based on this pic, where you put the 3 shims on the outside? What size and thickness if you have the info. thanks

I put them in spot 2 between the outer race of the bearing and the diff case. Was a bit of a pain getting them in there. Was easiest to have the truck propped up at an angle then tilted the diff a little to the shim side so the shims/bearing would start in the boss of the case, then I dropped the other side down and gently dropped the diff in. There was virtually no side to side movement with 3 of those shims in there, but there was a hair tick of play between the pinion/ring gear. I did the same on the front and rear diffs.

I used these: SWX-101018 SWorkz 13x16x0.2mm

On the inside, I used all of these: MUGE0206 Mugen Seiki Differential Washer Set
One big one under each sun/planetary gear and a small one behind each spider/satellite gear. I did a completely dry fit of this before putting in 100K to make sure it didn't bind or sound weird when spinning the output shafts in opposite directions. Same on the center diff, but 500K there.

 

[Notorious J]

I put them in spot 2 between the outer race of the bearing and the diff case. Was a bit of a pain getting them in there. Was easiest to have the truck propped up at an angle then tilted the diff a little to the shim side so the shims/bearing would start in the boss of the case, then I dropped the other side down and gently dropped the diff in. There was virtually no side to side movement with 3 of those shims in there, but there was a hair tick of play between the pinion/ring gear. I did the same on the front and rear diffs.

I used these: SWX-101018 SWorkz 13x16x0.2mm

On the inside, I used all of these: MUGE0206 Mugen Seiki Differential Washer Set
One big one under each sun/planetary gear and a small one behind each spider/satellite gear. I did a completely dry fit of this before putting in 100K to make sure it didn't bind or sound weird when spinning the output shafts in opposite directions. Same on the center diff, but 500K there.

Wow, I can't believe you got two in there. The loose difs/bulkheads I bought from Jennys rc already had one each. After I finished shimming the internals, one did was too tight in the bulk head and caused the pinion and ring gear to bind. Took it out and felt perfect. Guess you never know with metal on plastic

 

[olds97_lss]

Wow, I can't believe you got two in there. The loose difs/bulkheads I bought from Jennys rc already had one each. After I finished shimming the internals, one did was too tight in the bulk head and caused the pinion and ring gear to bind. Took it out and felt perfect. Guess you never know with metal on plastic

I got 3 in both diffs and they don't bind.

 

[cootertwo]

Just did 2 center diffs, and wanted to add, naphtha cuts the silicone pretty well. Can be bought from Home Depot, or hardware store.