Diff oil or grease?

[Ifti]

I've seem some users fill their diffs with synthetic grease rather then oil.
What are the benefits, or drawbacks to doing this??

 

[Billl DeLong]

generally, grease is just a bad idea all the way around, it won't provide much, if any resistance so the diffs will unload and "Cook" themselves causing premature wear. The car will perform extremely twitchy and be very difficult to drive, far better to tune with diff fluids:

 

[Ifti]

Thought I would post here rather then start another new thread - but when it comes to greasing the o-rings that go inside the differentials - is it best to use the black grease thats supplied with the kit for everything to do with the diffs?
I have some shock o-ring grease too, which I was going to use for greasing the o-rings in the diffs, but notice most use the supplied black grease with the diffs?......

 

[RaceBash]

It seems, to me, that anything but the thinnest of greases would just pack into the cavities away from the gears and then do nothing for damping.

 

[Billl DeLong]

Thought I would post here rather then start another new thread - but when it comes to greasing the o-rings that go inside the differentials - is it best to use the black grease thats supplied with the kit for everything to do with the diffs?
I have some shock o-ring grease too, which I was going to use for greasing the o-rings in the diffs, but notice most use the supplied black grease with the diffs?......

Any "waterproof" grease will do, generally the black grease that is provided in kits will do just fine, but I prefer to used tinted grease so I can make sure I have properly cleaned old grease in my rebuilds before applying fresh grease. I like to use Green Grease brand packed into a 10cc syringe:

 

[Ifti]

Great - thanks Bill!

 

[Nicochau]

Typically, you want a grease that seals the diff fluid. I use grease that goes in bikes fork shocks. Bike shops are a good place to look for those products.

 

[RustyUs]

I've seem some users fill their diffs with synthetic grease rather then oil.
What are the benefits, or drawbacks to doing this??

I'm guessing you viewed someone using grease in their gear diffs, and their diffs were probably not the sealed type. Having a gear diff that does not use o-rings and gaskets is the only reason to use grease IMO.

I have, and had, a few 1/10 scale RCs that came with sealed gear diffs, but manufacturer put grease in the sealed units for whatever reasons...shipping purposes, and low traction tracks back in the day would be my guess. After putting in some 5k diff fluid, even bashing on loose terrain, the "diffing out" was much less.

The ability to tune a gear diff to your liking; with fluid =

I'm sure most racing bred RC manufacturers do lots of testing into what works best in their RC platforms. I always start with kit default setups, and tweek from there.

 

[carolinagator]

Grease lets your diffs all turn free or "unload" easily. Grease lubricates better than silicone oil too so you get less wear.

 

[Billl DeLong]

Grease lets your diffs all turn free or "unload" easily. Grease lubricates better than silicone oil too so you get less wear.

This is kind of an ambiguous statement because there are many different brands of grease as well as silicone fluids and I'm not convinced that the best performing brand of grease will provide any less wear than the worst performance brand of silicone fluid. In contrast, I feel that grease unloads more and will spin up to were the center diff will be more likely to over heat and melt the plastic where if you were to use thicker silicone fluid then you would be less likely to over heat the diff which in turn would be less wear with silicone fluid

 

[carolinagator]

This is kind of an ambiguous statement because there are many different brands of grease as well as silicone fluids and I'm not convinced that the best performing brand of grease will provide any less wear than the worst performance brand of silicone fluid. In contrast, I feel that grease unloads more and will spin up to were the center diff will be more likely to over heat and melt the plastic where if you were to use thicker silicone fluid then you would be less likely to over heat the diff which in turn would be less wear with silicone fluid

Why do you think we put black grease on the diff outdrives? You don't want it to wear out.

Why do we put silicone grease on ball diffs? You don't want it to slip.

Years ago when I was running those old Ofna/Hong Nor buggies on dirt oval we were having problems with center diff spiders. After much research we found the silicone oil didn't provide sufficient lubrication, so we started mixing a little grease in it and it helped tremendously. Then the HoBao based Hyper7 came out and it's better diffs never failed.

As a rule of thumb the non silicone grease will provide better protection. There will always be the odd scenario that says otherwise though.

While I don't like to use grease cause of the nature of these cars are about handling and not longevity, I still use a lite dry graphite in my diffs to provide some extra film strength.

 

[Billl DeLong]

Just to clarify, for all TEKNO cars, you should apply grease on the rubber seals and grooved slots of the shafts of the out drives. In addition you should fill the diffs with silicone fluids ranging from 3K up to 1M.

Under no circumstance should anyone ever let their diffs go empty. I typically rebuild (re-grease the seals, fill fresh silicone fluids) of the diffs after every hour of run time.

note above on post #5 where I prefer Green Grease brand which is a synthetic grease which I believe does a better job than petroleum grease. Grease is what is used to hold the diff fluids for sealed diffs. If you pack a sealed diff with grease (without any silicone fluid) then you won't get proper load balance and will cause the center diff to "cook" and prematurely wear

It might be possible to pack the rear diff diff with grease only as a tuning option which might be similar to the feel of a 1K fluid filled diff, but I would never recommend this for the front or center diff, you definitely want those diffs filled with silicone fluid to get better wear life.