Granite New input gear, not mashing smoothly with diff - why?

[chilly81]

Superlube synthetic grease is very good and unlike lithium grease (including red and tacky, which is red lithium grease) it is safe on plastics. Use bare minimum though, just smear it onto the ring gear and you’re set.

That's interesting - I had always thought lithium was OK on plastic and it was petroleum that messed with it. Not may area of expertise though - could be wrong. I haven't noticed any degradation and I've been using it for quite a while. I was only referring to those hyped specialty greases that come in tiny tubes and cost a bunch. My gut feeling is they make no real difference vs plain grease in RC car applications.. but I haven't done any scientific testing to verify that. But if it's eating plastic that would be bad indeed!

Make sure the bearing on the diff yoke is pressed in all the way. The diff yokes are usually too tight when new, but do wear in.
I personally don't like that because the teeth end up being very pointy after and the worn out material is now mixed with your grease.

So what I do is remove the bearing and sand/file the back face of the yoke (where the bearing sits up against) down. Install the bearing and test again.
I just keep repeating that until it feels like it's spinning smoothly.

Now the case doesn't have to be left loose and you get a perfect mesh.

That's a good thought. I did think of those interactions you are addressing and made very sure everything was scraped out and super clean and seated fully (like 4 times!). But hadn't thought of sanding it out a bit.

 

[King blitz]

It's possible you may have been in the hobby to long! Obviously suffering from " diffatakeapartus disease"... no known cure currently.

Or he might have DIFFALITUS.

 

[xglide06]

Had the same issue on my big rock rear diff. Hot racing yoke solved it. It was still a little notchy but everything wore in and no problems since. Super smooth now

 

[PeighDay]

Had the same issue on my big rock rear diff. Hot racing yoke solved it. It was still a little notchy but everything wore in and no problems since. Super smooth now

+1 to the HR Diff yokes. Substantially easier to work with.

 

[chilly81]

I did take it out yesterday and it did seem to run fine. Until I broke another axle. Ironically, my typhon 3s stripped an input gear the same day. Maybe I'll try one of these upgrades when I fix that one.

 

[Velodromed]

I did take it out yesterday and it did seem to run fine. Until I broke another axle. Ironically, my typhon 3s stripped an input gear the same day. Maybe I'll try one of these upgrades when I fix that one.

Loosen your slipper a bit. On my 3s cars with stock drive trains I run it a bit loose because slipper pads are cheaper than axles and drive train parts. The can also be sanded a few times to remove the glaze.

 

[chilly81]

Loosen your slipper a bit. On my cars with stock drive trains I run it a bit loose because slipper pads are cheaper than axles and drive train parts. The can also be sanded a few times to remove the glaze.

Yeah I'm sure that will help but I feel I should be able to wheelie at will with a granite, and if I can't, my slipper is too loose. My typhon/bigrock maybe not as much. The granite popped a drive shaft (hing pin on stock one) on a straight rip with wheels even still on the ground going 25mph+ already... not a throttle-on landing or some weird high punch abuse (although I'm sure some of my past failures are due to that type of thing ). These 4S parts are so much more robust, I really want to try to get some in there. I'll probably get their input and diff too once I use up my remaining jenny's spares of 3s plastic ones.

 

[Velodromed]

Yeah I'm sure that will help but I feel I should be able to wheelie at will with a granite, and if I can't, my slipper is too loose. My typhon/bigrock maybe not as much. The granite popped a drive shaft (hing pin on stock one) on a straight rip with wheels even still on the ground going 25mph+ already... not a throttle-on landing or some weird high punch abuse (although I'm sure some of my past failures are due to that type of thing ). These 4S parts are so much more robust, I really want to try to get some in there. I'll probably get their input and diff too once I use up my remaining jenny's spares of 3s plastic ones.

I didn’t say loosen it all the way. I have no problem riding wheelies on my 3s cars with slightly loosened slippers. I also run higher viscosity oil in the differentials, which helps spread the load between the wheels. 20k rear and 30k front.

4s parts are great and can help bulletproof the drivetrain on a 3s car except for the driveshafts. Stock 3s drive shafts are always going to be a weak point. The 3S CVD’s are not much better and will break since the axle is made out of cheap sintered metal. They are also a little bit short, and are not so good with typhon/big rock arms.

To run 4S driveshafts you need to have v1 or v2, 4s arms and hubs. Below are my 4S builds. The yellow one is all v2 parts on a LWB chassis. The red one is a combination of 3S, V1 and V2 parts on a swb chassis. Both have v2 driveshafts.