Granite Killed a rear diff already!

[parcou]

So I took both front and rear diff's out, they both had 1 shim on the non gear side under the bearing so closest towards the crown gear. So this would be for a looser fit correct? Either way, not happy with the quality, you have to barely tighten the yolk almost leaving it loose for a smooth feeling, if you tighten them up where the case half's touch it is very notchy feeling and only in one spot in rotation, it's like something is out of round so to speak but can't see it. I have had only one run on this totally stock and on 2s no bashing, due to weather out here. Bearings are good and internals on the diff look good to with the planetary gears. I noticed on You Tube a lot of people shredding the diff gears on there Big Rocks also and getting the metal set posted above. I ordered the HR yolk and both metal diff and pinion, spendy but hope it resolves this issue. It's a great truck other wise I like it. I'm new to RC cars, been flying heli's for the past 8 years and needed a change, fitment with heli's is crucial specially in the drivetrain, so this is dissapointing, at least I cant crash it and cost me hundreds of dollars to repair and parts flying off in a 30 foot radius! Sorry Goofy, I'm not trying to Hijack your thread, you just had the perfect post, I was going to post the same topic and see you beat me to it.

Been there. With the plastic yoke, it is a balancing act. You do not want it loose, but you need to get it tight since the diff is under a lot of force and flex close in to play on the plastic yoke. Yes, there is a catchy spot so I get it as tight as I can where it is not so bad, but the yoke is not loose....then you add lube to the diff house it will help in that regard and be well. Many, including me have found great success with just the HR metal yoke alone with the other stock parts of the diff. For the metal yoke, you loctite the screws and tighten it down once you test and have the right shims in place for the gear mesh.

This is only for the rear since this is where the power module is located. No issues at all with all stock on the front.

 

[RCbuzz]

@Goofy ,
I never allow my BB's to get wet. Chromium BB's will rust. In minutes you can see them turn rusty brown. They are donefore at this point. Can't undo that.
With my FT for instance, before I drive it, I removed every BB and repacked them with 1/3 grease. (automotive Bearing grease)
Many new BB's were just Dry upon removing the seals. I think this is why many are having BB issues. Good to have spare sets of BB's on hand. Just part of the hobby to replace them here and there. Well before they contribute to more damage, i.e. stripped gears. Lube the Gears well also. Sometimes the factory doesn't install enough. Even the Diffs can be low on oil.

This, I never wash my cars and I don't run them in the rain.

After doing my first 100% rebuild on our first Granite I found seized bearings in the steering rack and replaced them out. The way that is designed its just going to happen on the bottom ones.

No locked up bearings in the drivetrain but did find several with unacceptable play (grab the center of the bearing and rock the outer ring). Replaced those, pulled the seals off several and added Superlube Synthetic Grease (great stuff btw).

Hub bearings I pulled the seals and let soak in WD40, it is all I had at the time and it actually did a decent job. Dried them out and repacked.

Since that rebuild that truck has been one of the most reliable 3S's we have.

I think Velo's comment on the metal yoke is the way to go. Seems like the plastic yoke just flexes too much under power. I want to see the plastic diff's succeed because 1. they are reasonable and 2. they want to $$ you on the cost of metal assemblies and parts. If you want a CNC Diff they are $75 each.

 

[Velodromed]

If you want a CNC Diff they are $75 each

Or you can build them for $40 in parts and using the stock diff internal gears.

 

[RCbuzz]

Perhaps the way to go if you are going to use a metal yoke but still...

 

[Goofy]

This, I never wash my cars and I don't run them in the rain.

After doing my first 100% rebuild on our first Granite I found seized bearings in the steering rack and replaced them out. The way that is designed its just going to happen on the bottom ones.

No locked up bearings in the drivetrain but did find several with unacceptable play (grab the center of the bearing and rock the outer ring). Replaced those, pulled the seals off several and added Superlube Synthetic Grease (great stuff btw).

Hub bearings I pulled the seals and let soak in WD40, it is all I had at the time and it actually did a decent job. Dried them out and repacked.

Since that rebuild that truck has been one of the most reliable 3S's we have.

I think Velo's comment on the metal yoke is the way to go. Seems like the plastic yoke just flexes too much under power. I want to see the plastic diff's succeed because 1. they are reasonable and 2. they want to $$ you on the cost of metal assemblies and parts. If you want a CNC Diff they are $75 each.

I applaud your discipline, but driving in less than ideal conditions (rainy/dewy grass/snow/etc.) is half the fun (IMO). This obviously comes at a cost, and is something I'm willing to accept now that I have a better understanding on maintenance and the like .

How is the super lube when it comes to the high RPM of the bearings?

 

[BgSkyRC]

I appreciate you guys, great info all of you! I ordered the HR yolks and some shims so we'll see how it goes. I used to use TriFlow Superior Lubricant on my Heli's its great for metal parts and protects them from rusting, also the Triflow synthetic clear grease in the bearings, I still have some left, when I cleaned my Granite this last go, I put a very light coat on all the suspension pins and outer surfaces of the bearings, I noticed also the light rusting going on with them, but it all wiped off, I ran it through some snow. I should have the parts by this Saturday, I'll let you all know how it went.

 

[RCbuzz]

I applaud your discipline, but driving in less than ideal conditions (rainy/dewy grass/snow/etc.) is half the fun (IMO). This obviously comes at a cost, and is something I'm willing to accept now that I have a better understanding on maintenance and the like .

How is the super lube when it comes to the high RPM of the bearings?

I just can't stand seeing rust on my rigs and it seems even the electrics that are water resistant really are not. Not to mention the 3S diff housings don't keep water out either and steel bearings just die out so quick with water. I can understand the fun factor though .

Have not had any issues with super lube grease in any of the bearings I have serviced. It's not terribly thick and has good give (unlike red and tacky) if that makes any sense.

 

[SrC]

Preventive maintenance and inspection with any RTR brand when new out the box will provide a better intial experience, with less frustration.
The new Stocker BB's can be as good as replacement BB's if you just open them up ( popping just one rubber seal) and add 1/3 Automotive grease, then install the seal back. But always have a spare set of BB's. Just part of this hobby.

 

[SrC]

I just can't stand seeing rust on my rigs and it seems even the electrics that are water resistant really are not. Not to mention the 3S diff housings don't keep water out either and steel bearings just die out so quick with water. I can understand the fun factor though .

Have not had any issues with super lube grease in any of the bearings I have serviced. It's not terribly thick and has good give (unlike red and tacky) if that makes any sense.

+!
Superlube as a brand has been my favorite for RC use for 20+ years. Seems all my BB's and Main/input gears like them. We all have our favorites. What works for you.
SL Grease is thinner, but while also being tenacious enough. It's water proof and Synthetic, and can flow in Cold temps while handling High temps also. Thicker greases can bind up BB's. The trick is not to overfill them whatever you use. BB industry fills them aprox 1/3. Any more and the BB can bind up, then blows out the seals, the ball's cage lets go. This is how BB's explode.
With Motor BB's, I use Superlube Oil, or an even thinner Liberty Syn, oil. I use an RPM Large Bearing Blaster to clean out my used BB's once or twice before tossing, and replacing them. For many, BB's are just replaced. They are cheap enough. I get it.
Thicker greases are fine for the Main/input gears.

 

[RCbuzz]

+!
Superlube as a brand has been my favorite for RC use for 20+ years. Seems all my BB's and Main/input gears like them. We all have our favorites. What works for you.
SL Grease is thinner, but while also being tenacious enough. It's water proof and Synthetic, and can flow in Cold temps while handling High temps also. Thicker greases can bind up BB's. The trick is not to overfill them whatever you use. BB industry fills them aprox 1/3. Any more and the BB can bind up, then blows out the seals, the ball's cage lets go. This is how BB's explode.
With Motor BB's, I use Superlube Oil, or an even thinner Liberty Syn, oil. I use an RPM Large Bearing Blaster to clean out my used BB's once or twice before tossing, and replacing them. For many, BB's are just replaced. They are cheap enough. I get it.
Thicker greases are fine for the Main/input gears.

Well said! Only thing for me is I like to overfill them. (maybe 1/2+ full).

I actually like that some grease pushes through the seal. I think less contaminates get in them when that happens.

 

[SrC]

A great point. I will sometimes over pack certain BB's that tend to wear out fast. Like the Inner Hub BB's and small Outer Input gear BB's.
Just that before installing the seals, I will spin them up in my drill, expelling the extra grease that pushes out first, then install the seals back on. The seals will blow out if you don't do this.
If you were to use a R &T grease on the BB's, it is just too thick and pasty IMHO. Been there. Tried so many.
Mobil 1 Synthetic Red Grease is another Fav I have here. Very durable. Lucas Marine Grease is what I use on my slow Crawlers. Because I do run them in the water snow, blizzards, streams and mud. Just Never with my fast Basher BLX rigs.

 

[dure16]

A great point. I will sometimes over pack certain BB's that tend to wear out fast. Like the Inner Hub BB's and small Outer Input gear BB's.
Just that before installing the seals, I will spin them up in my drill, expelling the extra grease that pushes out first, then install the seals back on. The seals will blow out if you don't do this.
If you were to use a R &T grease on the BB's, it is just too thick and pasty IMHO. Been there. Tried so many.
Mobil 1 Synthetic Red Grease is another Fav I have here. Very durable. Lucas Marine Grease is what I use on my slow Crawlers. Because I do run them in the water snow, blizzards, streams and mud. Just Never with my fast Basher BLX rigs.

How do you attach the bearing to the drill?

 

[SrC]

I use a bit in the drill chuck of appropriate bearing size, loosely is fine and just spin it up, holding the BB with your finger, you should see the excess grease expel easily. Wipe off both sides of the races and install the Seals. And there is still plenty of grease remaining that will not push out the seals now.

FWIW, never spin up a BB fast in a drill that has been solvent cleaned and dry of any lube. This will ruin the whole BB in a heartbeat. In seconds. Been there. You can rotate them dry by hand to check them. That's all.
I also use a Heated Ultrasonic Cleaner bath to clean my well used BB's. Overkill for some guys . But I save money on BB's this way. Some come out like new again. Even a few rusted ones, came back to life using a Citrus degreaser bath solution. And a clean water cycle last. Wash then rinse cycle. 15 minute cycles. Compressed air dries them quick so they don't rust quickly. A Solvent spray ( Auto Brake cleaner) will also remove/displace any moisture before re-greasing them. Never use WD40.
Some BB's will clearly be junk. I weed out my used worn out ones this way.

 

[BgSkyRC]

What diff oil do you guys recommend? I am just starting out so racing around on fields and gravel dirt roads, small jumps nothing crazy for now. I looked in my owners manual and tried searching around here but can't find what the stock diff oil weight is. Thanks

 

[dure16]

What diff oil do you guys recommend? I am just starting out so racing around on fields and gravel dirt roads, small jumps nothing crazy for now. I looked in my owners manual and tried searching around here but can't find what the stock diff oil weight is. Thanks

I’m pretty sure stock is 10K. I’d probably just stick with that. Here’s some light reading on the topic:

https://www.teknorc.com/wp-content/uploads/2014/03/Differentials-and-Gearing1.pdf

 

[BgSkyRC]

I’m pretty sure stock is 10K. I’d probably just stick with that. Here’s some light reading on the topic:

https://www.teknorc.com/wp-content/uploads/2014/03/Differentials-and-Gearing1.pdf

Excellent! Thank you for the fast reply

 

[Velodromed]

What diff oil do you guys recommend? I am just starting out so racing around on fields and gravel dirt roads, small jumps nothing crazy for now. I looked in my owners manual and tried searching around here but can't find what the stock diff oil weight is. Thanks

I like around 15 rear and 25 front. Just ‘feels’ better with the front 8-10k heavier then the rear.

 

[BgSkyRC]

I like around 15 rear and 25 front. Just ‘feels’ better with the front 8-10k heavier then the rear.

Good to know, I have some 10k right now, but will definitely give that a try in the near future. I'd like to get a feel for it with the 10k in it, that way I can get a better understanding and feel for it when I change it later. I have only ran it one time, waiting for better weather. Thank you!

 

[Velodromed]

Good to know, I have some 10k right now, but will definitely give that a try in the near future. I'd like to get a feel for it with the 10k in it, that way I can get a better understanding and feel for it when I change it later. I have only ran it one time, waiting for better weather. Thank you!

I don’t do exact really. I don’t like to waste the stock oil, so I simply add higher cst oils to get an approximate. I just know that I like the front and the heavier than a rear as it helps control ‘diffing out’ during wheelies and while in the air. And I like the rear to be a bit heavier than stock because it seems to help apply traction more evenly at the rear during hard take offs.

 

[Goofy]

Only went with the input gear for now, will do more involved upgrade next breakage. I'm 99% sure this sounds right for a Granite, but would love a second set of ears to help ease my angst, lol.