Another Diff Post: Shims and Oil

[tektrixter]

There is a lot of info regarding what shims and what weights diff oil to use. I'm hoping some one you can consolidate it into a few options. If I get enough input I'll make a table for reference. Please make sure you include why/what conditions your recommendation is valid for.

First question, does the Outcast v3 need diff shims? If so which ones (to make a complete set)? I've seen the "bulletproof your diffs" video and several more, but I'm confused on exactly which parts/shims are needed to make a singe completed diff. Often it seems that people are using shims from multiple kits. Please let me know what shims kits (by part number) are needed and what ones are replacements/options for which other ones.

I've also seen many options/opinions for what weight diff fluid to use. I understand that higher weight limits the function of the diff, resulting in more even power going to each output at the expense of limiting the difference in output speeds (more even power = less ability to turn). To keep down the "pancaking" of the front tires a heavier oil is used in the center, but I'm not sure how that effects turn radius.

I've seen people recommend weights around 50k/100k/20k (front/center/back) and some recommending 500k or 1M in the center. What types of driving uses heavy vs lighter oils? For example, big air jumps vs small jumps vs stunts in small areas vs speed runs? How does changing one effect the others (ie, always keep rear thicker that front)?

Again, I'm planing on putting all of this into a table/article to help out new people, so try to give examples of why to use one option instead of another.

 

[olds97_lss]

I don't know if the shims were "necessary" on the v3 outcast, but I did put more in it than what it came with. I got my outcast new at the store a couple weeks ago.

I thought there were only 2 versions of the outcast though. I have AR106033. Is that v2 or v3?

Short version of what I have:
I run 4S currently
15/50 pinion/spur
100k/500k/100k associated diff oil
MUGE0206 shims inside the diffs
Fast Eddy 8x16x5mm rubber shielded bearings
SWX-101018 SWorkz 13x16x0.2mm - qty 2 on both front/rear diffs on the ring gear side
Proline Trencher 3.8 tires

I removed all arrma shims. The shims inside the diffs on the X shafts were pretty marred up after only a run or two as I didn't crack open the diffs until the other shims showed up. I didn't know the thickness of the shims outside the diffs, so figured I'd go with replacing the one shim with shims I did know the thickness of for reference.

I used the Mugen MUGE0206 shims for inside the diff on the X shafts and under the sun gears. To be honest, I didn't dry fit them to see if they were overly necessary first. I just didn't like the idea of the output o-rings being rubbed on by the pin and back of the sun gear directly. The material of the shims seemed to be much harder than what was in there which is why I replaced the arrma shims on the x-shafts. Figured the Mugen ones would wear better.

I used 2 or 3 of the SWX-101018 SWorkz 13x16x0.2mm shims on the ring gear side of the diff externally. I started with none to check gear lash and I think I did end up with 2 on both front/rear diffs as that's what would fit. There was very little gear lash remaining and no side to side slop at all. I also used Fast Eddy 8x16x5mm rubber shielded bearings on all 3 diffs vs the stock metal shielded ones.

I'm running associated oil in my diffs. 100k/500k/100k. I went with this due to having other MT's (Savage X, Savage Flux) that have 50k in the front rear diffs and I wish I had thicker oil when I worked on them as 50k isn't enough for a basher like me.

With stock oil in the diffs, I was getting a lot of diff unloading of the center diff to the front and when cornering hard it would unload on the inside tires pretty bad. Now it unloads far less for both, but still allows enough give to not shock the drive line too bad on off kilter landings.

 

[smkd13]

Good I for. I just got a notorious and was wondering about this. Will look into this

 

[Robm422]

I'm a noobie too, and in the middle of tearing apart my notorious for the first time. thanks for the info.

 

[JvG]

https://www.arrmaforum.com/threads/how-to-shim-your-diff-with-pictures.7700/

This post answers most of your questions about the shimms.

Regarding to diff oil i would advise you to start with something around 50k/200k/30k and see if you like it. There is no best setup, it depends on how you want to drive your rc.
Heavier diff oil in the centre diff means more power to the rear wheels. So if you like wheelies go for 500k or more. If you want to keep it smooth go for 100k or less.
Same goes for the front and rear diffs. Heavier oil means less diff action. So if you like powerslide drifting, use heavier oils. If you like control and steering i.e. on a track, use lighter oils.
Also 6s (more power) needs some heavier oils than 4s.