Notorious Issues with diffs possibly. Video in thread

Gecko1blx

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I have 100/500/30k F/C/R. You won't want 100k in the rear. When you're on the throttle you'll hardly be able to steer. 100k in the front allows you to turn very directly when off
Ok thanks. For general jumping and running on rough ground would you still recommend useing lighter oil in the rear diff? I'm only ask for fear of stripping the rear input gear because of lighter oil? Appreciate all the help.
 

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Ok thanks. For general jumping and running on rough ground would you still recommend useing lighter oil in the rear diff? I'm only ask for fear of stripping the rear input gear because of lighter oil? Appreciate all the help.
The input gear won't be affected by the rear diff oil. The centre diff oil will though, as thicker diff oil in the centre will distribute the power more towards the rear

As long as you're easy on the throttle and not landing on under power it should be fine regardless. You'll want make sure you get the best mesh possible by using 13x16 shims on the at the ring gear bearings too 👍
 

Gecko1blx

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The input gear won't be affected by the rear diff oil. The centre diff oil will though, as thicker diff oil in the centre will distribute the power more towards the rear

As long as you're easy on the throttle and not landing on under power it should be fine regardless. You'll want make sure you get the best mesh possible by using 13x16 shims on the at the ring gear bearings too 👍
So if I'm understanding correctly what you've said about useing 100/500/100 ( that's all I could get my hands on) is that with the heavier oil I will be actually creating more possible failure to that input gear because I'm actually giving it too much power? Versus letting the tires slip a little and giving power to the tires that need it? Hope that makes sense..lol thanks again
 

L3phturn

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So if I'm understanding correctly what you've said about useing 100/500/100 ( that's all I could get my hands on) is that with the heavier oil I will be actually creating more possible failure to that input gear because I'm actually giving it too much power? Versus letting the tires slip a little and giving power to the tires that need it? Hope that makes sense..lol thanks again

The main issue with 100k in the rear is that it will not want to turn under power. I don’t think it will make much difference to the input hear, the power applied there is coming from the center diff. It’s doing things like landing a jump on-throttle or on dull brake that will be a bigger issue. Most of the rear diff issues I have seen have more to do with the diff case cover flexing and allowing the diff to shift and strip the ring and pinion.
 

Gecko1blx

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The main issue with 100k in the rear is that it will not want to turn under power. I don’t think it will make much difference to the input hear, the power applied there is coming from the center diff. It’s doing things like landing a jump on-throttle or on dull brake that will be a bigger issue. Most of the rear diff issues I have seen have more to do with the diff case cover flexing and allowing the diff to shift and strip the ring and pinion.
That makes total sense. If the housing flexs then thsts when I'm stripping gears. So the obvious remedy for that is to upgrade the diff housing. Also sounds like I need to be more conscious of throttle input as well. Appreciate it.
 

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That makes total sense. If the housing flexs then thsts when I'm stripping gears. So the obvious remedy for that is to upgrade the diff housing. Also sounds like I need to be more conscious of throttle input as well. Appreciate it.

I heard very good advice from others on here - you don’t need the full aluminum housing, just the cover. I have ordered the Hot Racing diff housing covers. Much less expensive and I think will solve the problem.
 

Gecko1blx

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I heard very good advice from others on here - you don’t need the full aluminum housing, just the cover. I have ordered the Hot Racing diff housing covers. Much less expensive and I think will solve the problem.
Ok. So just the face of the diff house I need to replace not the whole housing. Wow, never realized that part was under so much stress.
 

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Ok. So just the face of the diff house I need to replace not the whole housing. Wow, never realized that part was under so much stress.

If you put bathe diff in and then try to hold it in by the bearings with your fingers and then roll the truck you will feel it move back against you. These powerful motors generate a lot of force through that ring and pinion, and some of it is directed out away from the pinion trying to push the ring (diff) away from it.
 

Gecko1blx

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If you put bathe diff in and then try to hold it in by the bearings with your fingers and then roll the truck you will feel it move back against you. These powerful motors generate a lot of force through that ring and pinion, and some of it is directed out away from the pinion trying to push the ring (diff)
I never realized the forces at play. Great explanation 👌 makes sense that "energy" needs to be transfered somewhere. These trucks are amazeing
If you put bathe diff in and then try to hold it in by the bearings with your fingers and then roll the truck you will feel it move back against you. These powerful motors generate a lot of force through that ring and pinion, and some of it is directed out away from the pinion trying to push the ring (diff) away from it.
If you put bathe diff in and then try to hold it in by the bearings with your fingers and then roll the truck you will feel it move back against you. These powerful motors generate a lot
 
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Iv had good luck with hr products in past. But i will not buy anuther hr motor pinion gear. Just stripped mine on second run. Yes the mesh was perfect and my motor had not moved. Must be soft metal and might be why i got it for $5 too. 👎
 

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Took it out for a proper run. Normal place was busy so an open field for speed runs was what I did. Ran almost a full battery pack before leaving. It’s running great again. What a difference the thicker diff oil made. Handles a lot differently. Thank you all again.

View attachment 118875

Where did you get the body?
 

dadlifex3

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Maybe I’m missing something or just not smart enough. Might be a little of both. Trying to shim this diff in the HR bulkhead. I’ve tried all sorts of combos with the side to side play. The pinion play. It spins freely until I put the cover on. Once I put the cover on the it grabs. Like catching and skipping. I’ve checked all the teeth and they look fine. It’s a newish diff. Any suggestions on what I could be doing wrong?

https://flic.kr/p/2ktJy5x
9D05792D-5F9F-4FDA-8343-0DE9372F2F0A.jpeg
I should add the diff worked perfectly in the factory bulkhead.
 

dadlifex3

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Ok, I have it so where the gears spin freely with no binding. There is no back and forth play with the input pinion. There is no side to side play with the diff. (.15 shim on the non gear side. .1 shim on gear side).

My question is about the play between the pinion and spur gear on the diff. How does this look? Maybe I should try and shim the pinion into the diff gear a little more?

https://flic.kr/p/2ktRmdW
 

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So if I'm understanding correctly what you've said about useing 100/500/100 ( that's all I could get my hands on) is that with the heavier oil I will be actually creating more possible failure to that input gear because I'm actually giving it too much power? Versus letting the tires slip a little and giving power to the tires that need it? Hope that makes sense..lol thanks again
100k is too heavy for the rear..... I like 60kFr-200-500k Center -30k rear. Too heavy in the rear will make the rig lose steering under throttle. IMHO.
Looks good from where I am sitting. You need a tick of play. I don't see from the video at least, any need to shim the input gear anymore. A tick of play is needed. As long as the ring gear is perfectly centric to the input gear. No gear binding at any point of the gears rotation. Just make sure the input cup is snug against the outer bearing with no slop, yet no binding to the bearings. These gear sets are not perfectly manufactured, so sometimes good enough has to do. Only your eyes and fingers can really know what good enough is at some point. Good luck. :cool:
 
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@SrC how a noto guna steer anyways under power. The front tires are in the air😂. I only had 500k and 10k i put 500 in center and mixed 10 and 500 together but thicker in front i would guess iv got 275 front 225 or 200 rear. 20 kgservo and turns fine on dirt,gravel. I don't run in grass too much traction. As long as the tires are on ground steers fine for me. All has to do with preference and conditions you drive in🤘.
 

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@SrC how a noto guna steer anyways under power. The front tires are in the air😂. I only had 500k and 10k i put 500 in center and mixed 10 and 500 together but thicker in front i would guess iv got 275 front 225 or 200 rear. 20 kgservo and turns fine on dirt,gravel. I don't run in grass too much traction. As long as the tires are on ground steers fine for me. All has to do with preference and conditions you drive in🤘.
I have to agree with @Yas.
Having both a Noto and Kraton, I find that I always want the rear at most to be 1/2 the weight of the front. Front/Rear Diff bias setup in this way gives you more traction steering wise. The SWB Noto has better turn in than the LWB Kraton FWIW. 500k Center is perfect IMHO, just that I settled with 60F/30R however. Yes we all drive differently.
I just feel 100k Fr and Rear is rather extreme and creates too much understeer on power.
I tend to fill my diffs completely. I bleed all the air out with a shock vacuum pump. If you underfill your diff with 100k for instance, it will feel closer to 60k or lower. Just my observations.
I can tell you that even with 60k/Fr. CST for me was very thick with little diff action in the front. That alone causes less turn in "Off" Thr. Using 60 in the Rear made both my rigs undriveable. I like big air also. But I don't always send it. I like some technical driving on the dirt.
I also feel that 100k at the Rear can really stress out the rear ring and input, gears. sun gear pins and outdrive cups.. 🤷‍♂️

Like you said though, we all drive different and expect different capabilities in regards. 👍

Although stock has matching weights at F and R, (10k) They are loose to begin with. Too much so. Like we all agree.
But at some point, the rear needs to have much looser diff action in the rear. If you notice, even with the EXB Kraton, Arrma opted to keep the rear 29mm diff "Open". The Fr. and Center are LSD's. Done to keep better diff Bias in the drivetrain. Better drivability.
 

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I am admitting defeat with this shimming issue. I got it working perfect with a factory bulkhead. After buying a hot racing bulkhead I cannot get this thing to shim correctly. I have literally tried 40 different ways of shimming. I am willing to bet I have damaged the crown here or the pinion gear just by trying different ways. I am done put a fork in me.
 

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I am admitting defeat with this shimming issue. I got it working perfect with a factory bulkhead. After buying a hot racing bulkhead I cannot get this thing to shim correctly. I have literally tried 40 different ways of shimming. I am willing to bet I have damaged the crown here or the pinion gear just by trying different ways. I am done put a fork in me.

I only ordered the HR diff case covers for my Noto. Cheaper that way and I suspect it will avoid issues like you are having. If I am wrong and I blow it all to hell I will replace all three with EXB diffs. ;)

My son's new Kraton EXB I run LSD in the rear with 5k fluid and minimal effect LSD plate stack. We've run a few packs through it but on ice and snow. Then again there is LOTS of diff action running on ice and snow, and the boy likes to spin donuts while doing 40k down the road with it. :D
 
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