Rebuilding my diffs?

[Mattyd926]

Ok so I knew prior to this sound that I needed to do the rear but now got this nasty clicking. I got all my rebuild stuff going to try the new Arrma diff carrier anyway my question is I have this grease my LHS sold me it’s fast eddies diff grease. It’s red and super super thick and tacky. They are telling me instead of diff oil just pack my diff and gearbox with this grease and I will never look back I’m told . I did a trial run and noticed more than anything when I get off the go pedal she slows down almost like a break kind of like it. What are y’all thoughts on this fast eddy grease vs fluids thanks

 

[SrC]

No matter what kind of grease you use, it generally equates to 1,000CST(1K) once the grease spreads out. It wont flow like an oil would. Not a good idea for any 1/8+ scale rig. I think 99% of us are using Silicone diff oil that is much much thicker Cst. Diff Oil is required in the 6S rigs diffs. That Red and Tacky Grease is only for diff input and ring gears. Not the satellite and sun gears within the diff. IMO. I don't know why any LHS would tell you that. But apparently yours did. FYI, am using 20K front, 250K center, 60K rear. That works for me. I am only using the new Arrma metal/alloy diff carrier at the center diff. You claim that the rig slows down faster with the grease installed???? None of the diffs are responsible for braking. I don't know what you are describing. Perhaps there's another issue altogether. A problem.

 

[crimsonfancy]

No matter what kind of grease you use, it generally equates to 1,000CST(1K) once the grease spreads out. It wont flow like an oil would. Not a good idea for any 1/8+ scale rig. I think 99% of us are using Silicone diff oil that is much much thicker Cst. Diff Oil is required in the 6S rigs diffs. That Red and Tacky Grease is only for diff input and ring gears. Not the satellite and sun gears within the diff. IMO. I don't know why any LHS would tell you that. But apparently yours did. FYI, am using 20K front, 250K center, 60K rear. That works for me. I am only using the new Arrma metal/alloy diff carrier at the center diff. You claim that the rig slows down faster with the grease installed???? None of the diffs are responsible for braking. I don't know what you are describing. Perhaps there's another issue altogether. A problem.

Diffs aren't hot enough to alter the viscosity of the "grease" in em and it slows it down imo. Plus, newly packed (if we're talking about inside of the actual differential) will still be fresh and not broken down yet over time. Even external grease will slow it down if it's cold out and diffs are cold early in the run time.
Diffs arent responsible for braking but thick stuff surrounding or especially inside of of the gear case that transfer to the wheels will certainly cause some slowing. Silicone will probably become less viscous quicker than standard farm or marine grease that is likely very similar to the stuff from Fast Eddy. See drop point.

 

[jondilly1974]

What rig are we taking about?

 

[SrC]

What rig are we taking about?

I believe this topic is regarding 6S diffs. @Mattyd926 has a Talion and OC, I assume 6S. Grease is not used on 6S. I am sure it has been done by other members here. I don't feel it is appropriate at all. I use grease in my 1/10 AE ProSC SE 4x4 2 diffs. But, they come that way and are optionally fillable with Gaskets and oil. Diff oils are best for sat. and sun gears. It is well known that grease only affords a 1K cst viscosity. It is not proper for most if not all 1/8 diffed rigs. Grease and silicone oils have different flow rates. If 1k cst is what you want in your 6S diffs, knock yourself out.

 

[jondilly1974]

I believe this topic is regarding 6S diffs

Ok he never mentioned a model. If it’s a Mega then grease is ok for those diffs. If it’s any of the BLX models then no.

 

[3d-rc.myshopify.com]

I did once upon a time work on this guys buggy. Same thing. He packed his diff with grease and it was like a break was applied when you let off. I decided to be a good sport and take a look at it for him. To my amazement he literally filled the from and rear bulk head with grease thinking that is how it was done. The was so much resistance it was like brakes were being applied. I'm sure you did it correctly but it reminded me of this situation.

 

[SrC]

I did once upon a time work on this guys buggy. Same thing. He packed his diff with grease and it was like a break was applied when you let off. I decided to be a good sport and take a look at it for him. To my amazement he literally filled the from and rear bulk head with grease thinking that is how it was done. The was so much resistance it was like brakes were being applied. I'm sure you did it correctly but it reminded me of this situation.

I build my diffs completely applying oil gradually as I install the sat and sun gears. I then vacuum out the air in a shock pump. Top off oil again completerly and I bolt on the ring gear while bleeding excess oil using the bleeder set screw on the diff cup when applicable. (There is none on the Arrma metal cup) The diff is not locked because silicone will flow at its designed Cst. Grease wont flow properly and merely locks up the diff. Then you are running lockers for all practical purposes and yes there will be drag while turning due to little if any diff action. It feels like you are driving a Crawler with drag brakes.
When using a grease in a diff that can call for it. You don't fill it. You merely coat the gears with it. And that always equates to 1K CST.
You don't fill or pack with grease. You only fill with Silicone Oil.
@Mattyd926 , how much grease did you actually go through???? It may have been cheaper to buy Silicone diff oil to begin with.

 

[Mattyd926]

Ok so def sounds like I f u. C t up new to rc maintenance and by golly I filled them both with grease diff and bulkhead. I will be replacing the rear all together now and will clean out the bulkhead. So 60 in the rear diff and what in the bulkhead?
Also I’m talking about my talion

 

[SrC]

My chosen diff weights work for me. Others here have good choices also. The factory filled weight are too thin. Hence the initial wear and tear on them. We all been through this. I like 60krear, 250k cntr. 20K frnt. Others will match front and rear. But the general consensus I feel is that the center has to be 250k and higher or even 500k to prevent diffing out under load which ruins your tires and drive train very fast. Remember thicker weight in the fr. vs the rear diff will make your rig push and understeer. These 6S rigs need all the steering you can get. IMO.
In the bulkhead for the ring gear , just smear some grease liberally onto the teeth. Thats all you need. You can also put a smear at the bottom of the bulkhead where it mates to the chassis to keep water and dirt out and act as a seal. Make sure you shim properly, for better durability.

I did once upon a time work on this guys buggy. Same thing. He packed his diff with grease and it was like a break was applied when you let off. I decided to be a good sport and take a look at it for him. To my amazement he literally filled the from and rear bulk head with grease thinking that is how it was done. The was so much resistance it was like brakes were being applied. I'm sure you did it correctly but it reminded me of this situation.

Sounds like a recipe for a fried ESC and motor with all that binding and resistance.