Center diff mount play front to back, shim how tight ?

[JMS RC]

Got a couple of different center diff mount setups in my Arrma's. Since I shimmed just about everything else, and read a bunch of good info on that right there. The play front to back in the center diff though is somewhat confusing, I understand that there has to be a little bit of play but how much ? On my outcast below i think the play is acceptable !? If I add a single 13x16x0.2mm shim in the front diff mount I have no play ! strange, by moving the spur gear front to back it feels a lot more than 0.2mm. How tight do you guys shim these ?

About the same in this setup, on this one i'm able to use a single shim and end up with the same play as the video above, the difference other than the different mounts are the bearings, video has aftermarket sealed bearings, this one uses stock.

 

[joostin420]

To make the center diff perfectly aligned with no play front to back - It took 4x Tekno bearing shims in the rear and 3x in the front of the hr center diff mount bearing cup holders. Built with fast eddy rubber sealed bearings and full hr center.

Tekno RC TKR1222 Diff Shims 13x16x.1 EB48 (10)

 

[bicketybam]

To make the center diff perfectly aligned with no play front to back - It took 4x Tekno bearing shims in the rear and 3x in the front of the hr center diff mount bearing cup holders. Built with fast eddy rubber sealed bearings and full hr center.

Tekno RC TKR1222 Diff Shims 13x16x.1 EB48 (10)

I have the same setup and I used 3 and 3. Nice and tight now

 

[JMS RC]

To make the center diff perfectly aligned with no play front to back - It took 4x Tekno bearing shims in the rear and 3x in the front of the hr center diff mount bearing cup holders. Built with fast eddy rubber sealed bearings and full hr center.

Tekno RC TKR1222 Diff Shims 13x16x.1 EB48 (10)

I have the same setup and I used 3 and 3. Nice and tight now

Thanks. So you guys shim it so there's no play at all !? I didn't wanna do that cause of the extra stress on the bearings as I think they expand somewhat when getting warmer ? I will order some .10mm shims as well and see how tight I can shim it.

 

[Paultro84]

I would also like to know if there should be no play at all. Obviously not having it tight tight but is having a little play a bad thing and why?

 

[bicketybam]

I would also like to know if there should be no play at all. Obviously not having it tight tight but is having a little play a bad thing and why?

I’ve been running mine on 6s for 4 weeks with a lot of play and nothing broke. So take that for what it is worth

 

[Paultro84]

Ya I bought my Outcast back in January and never paid any attention to the play in the center diff. I'll look in to it but I figure as long as the pinion and spur gear remain in contact, I'm not to worried about it. Haha

 

[2fast4u]

I would also like to know if there should be no play at all. Obviously not having it tight tight but is having a little play a bad thing and why?

IMO, A little play is better than tight (less friction, less heat, less wear) These bearings are surely not deep groove bearings so their primary design is for radial loads not axial (thrust) loads. Shimming them tight creates a thrust load. The only place I would shim for as little play as possible would be the front and rear diffs. Just to ensure maximum engagement of the teeth on the ring (crown) and pinion gears. And the sun and planetary gears internally. With no binding (notchyness) as a result.

 

[joostin420]

I feel that my setup is perfect and does not cause thrust - pressure on the bearings. I originally started off with 4x shims rear and 4x shims front and it was smooth prior to mounting the whole assembly to the chassis, but once installed it was tight. If I didnt remove 1x shim in the front there definately would be thrust - pressure on bearings.

I guess “tight” is not the right word for “perfect” alignment...