Big Rock First time Diff maintenance. Couple of questions

[kantonburg]

So I removed the 4 screws on the bottom and pulled the front diff out.

I was real careful once I pulled the drive shafts off and getting the Yokes apart, but of course it flew apart all at once.

Is the first bearing on the input gear supposed to sit flush against the back of the input?

Reason I ask is when I took the yoke apart and re-seated the diff and input gear the face of the input sits on the side of the diff there is a TINY gap. I've read numerous times when tightening the yokes back together to make sure not to get it too tight because it will bind. I put them back together without screws and it still feels like the input is rubbing the diff part way around. It's nice and smooth then one section it's like it rubs a bit tighter. Not sure if this is normal or even matter once it's greased. I know nothing is perfect.

• Speaking of re-greasing (not refilling). Before do you re-grease do you just wipe off the old grease or do you use a de-greaser to clean the housing, diff, & input?

• When opening up the diff is it necessary to remove the bearing and shim?

• When you open up the diff to refill or change fluid and put it back together should you Locktite those screws since it metal to metal. I know it's typical, but wasn't sure being inside the yoke and greased up.

• I didn't have rubber gloves. I'm not going any further without them First world problems.

I did figure out that the yokes only go one way around the diff and input (each side goes on a particular side). Then saw the exploded view that showed the same way.

 

[Engineer]

I can't remember if it's tight against the bearing but just put some grease on the outside of the diff case and rotate it a few times. If there's still a thin layer of grease on the diff case then the input isn't grinding into it.

I believe the diff case is plastic so no Loctite needed.


If you can't tell, it's been awhile since I've serviced my 3S diffs...

 

[SrC]

Clean all with a degreaser before using fresh grease.
Yes, if there are any metal screws that screw into metal ONLY, use Blue Thread locker. No TL into plastic threads.
Seems the input gear and their BB's will seat better once the yokes and all are assembled. The 2 bearings seat into the yokes properly. They are indexed in there one way. Can't mess that up really. It is what it is. Plastic tolerances are what they are.
Make sure the bearings are in good working order. Don't overlook this while you have all apart and are in there.
Maybe a drop of oil on each BB, at minimum, if you don't disassemble the BB's completely and relube.

 

[kantonburg]

I can't remember if it's tight against the bearing but just put some grease on the outside of the diff case and rotate it a few times. If there's still a thin layer of grease on the diff case then the input isn't grinding into it.

I believe the diff case is plastic so no Loctite needed.


If you can't tell, it's been awhile since I've serviced my 3S diffs...

I assumed it was a metal housing. Maybe not.

Clean all with a degreaser before using fresh grease.
Yes, if there are any metal screws that screw into metal ONLY, use Blue Thread locker. No TL into plastic threads.
Seems the input gear and their BB's will seat better once the yokes and all are assembled. The 2 bearings seat into the yokes properly. They are indexed in there one way. Can't mess that up really. It is what it is. Plastic tolerances are what they are.
Make sure the bearings are in good working order. Don't overlook this while you have all apart and are in there.
Maybe a drop of oil on each BB, at minimum, if you don't disassemble the BB's completely and relube.

Is non-chlorinated brake cleaner ok? Or de-greaser only?

Is there a trick to getting the bearing off that diff? It spins nice and smooth, but I couldn't get it to move.

Thank you guys

 

[SrC]

The whole diff must be disassembled to remove the 2 BB's. Skip that. Just place a drop of oil on one side of each bearing after wiping them down if they spin nice, etc.
Don't get any solvent or degreaser onto the ball bearings at all! Just wipe clean. Then one drop of oil. Let penetrate. Reassemble all. Pay attention to the 2 input gear (pinion gear) BB's as well. A drop of oil each.

 

[kantonburg]

The whole diff must be disassembled to remove the 2 BB's. Skip that. Just place a drop of oil on one side of each bearing after wiping them down if they spin nice, etc.
Don't get any solvent or degreaser onto the ball bearings at all! Just wipe clean. Then one drop of oil. Let penetrate. Reassemble all. Pay attention to the 2 input gear (pinion gear) BB's as well. A drop of oil each.

Good deal thanks. I have a can of 3-in-1 love that stuff.

I want to check the fluids since I have the time and weather is crappy tomorrow. I know it'll need to be topped off.

 

[SrC]

If opening the diffs to check fluids and are low, You wont have 10K fluid to replace. Maybe you have some? IDK
Good to check no doubt. Your call. If the diffs feel smooth and don't leak they are fine as is

 

[Diggery]

I did the same thing last night!

Opened up the casing, removed the yoke but didn't split the diff itself. I have the same issue with a tight/rough spot during a rotation that I assumed was mesh between input and spur. They look perfect and no wear or damage. Truck is only 2 weeks old so it's not had loads of use yet.

Maybe I'll back off the yoke screws, but it only happens for a couple of spots during a rotation, the rest of the spin is silky!

 

[kantonburg]

If opening the diffs to check fluids and are low, You wont have 10K fluid to replace. Maybe you have some? IDK
Good to check no doubt. Your call. If the diffs feel smooth and don't leak they are fine as is

I do have 10K. I got some in case they were low.

I did the same thing last night!

Opened up the casing, removed the yoke but didn't split the diff itself. I have the same issue with a tight/rough spot during a rotation that I assumed was mesh between input and spur. They look perfect and no wear or damage. Truck is only 2 weeks old so it's not had loads of use yet.

Maybe I'll back off the yoke screws, but it only happens for a couple of spots during a rotation, the rest of the spin is silky!

That is what I had though with no screws. One spot. I'll definitely check and double check as I tighten the screws.

 

[kantonburg]

The front was a bit low. Where my fingers are it was leaning a awhile before I took the pic. There was none where the bearing is and opposite to where my fingers are.

The rear was even lower on diff fluid. The rear had more grease around the diff, input gear, and housing than the front did. Much more.

I filled them like @parcou did in this thread
I used 10k silicone diff fluid to fill.

Couple things I learned that might help someone else doing this for the first time. The front diff assembly comes out with 4 screws and the rear with 3 screws. No need to remove the wheelie bar. Although this is a mega. It works the same

Now getting the assembly back in I found it easier removing the tops screws to the shock tower and the screws to the top rod end at the wheel hub. Made it easier getting the drive shafts back in.

Hope this helps and thank you to all that helped me.

 

[SrC]

Good deal thanks. I have a can of 3-in-1 love that stuff.

I want to check the fluids since I have the time and weather is crappy tomorrow. I know it'll need to be topped off.

3 in 1 is ok'ish. It is a do it all oil. Not as durable for RC BB's IMHO. There are better oils for RC BB's. I guess what you have is fine. NP.
I have been using Super Lube oil for years. Comes in a 4oz bottle, Synthetic and works from freezing temps to boiling temps.
After trying many, including the overpriced RC boutique oils, this for me is the best out there. One bottle will last for many years.

 

[kantonburg]

3 in 1 is ok'ish. It is a do it all oil. Not as durable for RC BB's IMHO. There are better oils for RC BB's. I guess what you have is fine. NP.

What do you like to use? I have no qualms getting a better oil.

 

[SrC]

Re read above, I edited it with the oil I use. Some Home depots have it. But where I am I have to order from them. NP. Comes in a few days, then I go pick it up. I also use Super lube Grease also. Comes in a tub. Mobil 1 grease (red) is also good. IMO. I feel the Super lube oils are better around plastic.
I also have SuperLube silicone grease for the O- rings.( in shocks and diff o-rings) And Superlube Di-electric grease for the some of the electrics in some areas. I just make one order and stock upon on all. I use Super Lube products in general elsewhere on my Car and around the house and other projects.

BTW, make sure to only use proper silicone oil in the diffs. You may know this already. IDK. Stock is 10k. Can go thicker. 15k or so.
Follow @parcou .

 

[kantonburg]

Re read above, I edited it with the oil I use. Some Home depots have it. But where I am I have to order from them. NP. Comes in a few days, then I go pick it up. I also use Super lube Grease also. Comes in a tub. Mobil 1 grease (red) is also good. IMO. I feel the Super lube oils are better around plastic.
I also have SuperLube silicone grease for the O- rings.( in shocks and diff o-rings) And Superlube Di-electric grease for the some of the electrics in some areas. I just make one order and stock upon on all. I use Super Lube products in general elsewhere on my Car and around the house and other projects.

BTW, make sure to only use proper silicone oil in the diffs. You may know this already. IDK. Stock is 10k. Can go thicker. 15k or so.
Follow @parcou .

Good deal. I'll check out super lube. Thanks
I had a tub of Red N Tacky so I used that around the diff, input, and yoke.
Speaking of the input gear. I see some posts calling it a sun gear. Where did the sun gear term come from?

I should have mentioned it in my reply above but I did fill with 10k silicone diff fluid.

edit: Is this the oil?

 

[SrC]

I have 3 in 1 also. But use it for other things around the house. It will work. But there is better if you choose.

Red and Tacky is used by many here also. Some have said its not that WP. But is fine I am sure. Anything is better than what Arrma used at the factory if they even use enough of it. Factory stuff smells like bacon fat, feels waxy like its a fat grease.

 

[kantonburg]

I have 3 in 1 also. But use it for other things around the house. It will work. But there is better if you choose.

Red and Tacky is used by many here also. Some have said its not that WP. But is fine I am sure. Anything is better than what Arrma used at the factory if they even use enough of it. Factory stuff smells like bacon fat, feels waxy like its a fat grease.

It's definitely waxy. Exactly like cold bacon grease. I didn't smell it though

"Some have said it's not that WP" What is WP?


Looks like Home Depot has free delivery too. I'm about 45 min - 1 hour each way to a Home Depot for me.

They have a bunch of different grades of the oil. I see one with PTFE which if I'm not mistaken doesn't attract dust.

 

[SrC]

WP with grease means that water wont break it down if wet. And stays put. Grease that turns milky in color when wet usually not the better grease. It thins out. Best WP grease doesn't mix with water. It sheds water for the most apart. Marine greases work that way, tends to be thicker also.
PTFE is Teflon. It's fine with BB's and most RC parts and plastics. More slippery. The PTFE is so very fine you cant see it. But it is a dry white substance in raw form, and no it wouldn't attract dust by itself. It is not a liquid.
Marketing over emphasizes teflon in their products. IMHO. Depends on a brand. Like it's some magic. It's not new technology. It works well depending how much is in the formula and the grade. Who really knows how much is in there.

 

[LudeNation]

This what I went with 30k from Losi. Going to use it on my Senton or would it better suited for a Granite?

 

[Kla912000]

So I removed the 4 screws on the bottom and pulled the front diff out.

I was real careful once I pulled the drive shafts off and getting the Yokes apart, but of course it flew apart all at once.

Is the first bearing on the input gear supposed to sit flush against the back of the input?

View attachment 129092

Reason I ask is when I took the yoke apart and re-seated the diff and input gear the face of the input sits on the side of the diff there is a TINY gap. I've read numerous times when tightening the yokes back together to make sure not to get it too tight because it will bind. I put them back together without screws and it still feels like the input is rubbing the diff part way around. It's nice and smooth then one section it's like it rubs a bit tighter. Not sure if this is normal or even matter once it's greased. I know nothing is perfect.

View attachment 129094

• Speaking of re-greasing (not refilling). Before do you re-grease do you just wipe off the old grease or do you use a de-greaser to clean the housing, diff, & input?

• When opening up the diff is it necessary to remove the bearing and shim?

• When you open up the diff to refill or change fluid and put it back together should you Locktite those screws since it metal to metal. I know it's typical, but wasn't sure being inside the yoke and greased up.

• I didn't have rubber gloves. I'm not going any further without them First world problems.

I did figure out that the yokes only go one way around the diff and input (each side goes on a particular side). Then saw the exploded view that showed the same way.

What do you need rubber gloves for? Afraid to get your hands dirty? Lol

 

[LudeNation]

What do you need rubber gloves for? Afraid to get your hands dirty? Lol

Actually if you don't use gloves over time the chemicals from what your using will get into your skin and could cause major problems later in life. Ask some older mechanics